HIGH-Tc UPDATE E-MAIL VERSION, VOL. 11, NO. 23, Dec. 1, 1997.

Published for the Division of Materials Sciences, Office of Basic Energy Sciences, USDOE, under Contract W-7405-eng-82 with the Ames Laboratory, Iowa State University. Funded by DMS/BES/USDOE, ARPA, ONR, NSF, and other agencies, organizations, and individuals.

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RBa2Cu3O7-d

Enhanced transition temperatures Tc and critical current densities Jc have been observed by M. Muralidhar and M. Murakami (SRL-ISTEC) in bulk (Nd,Sm,Eu)1-xGdxBa2Cu3Oy (0 <= x <= 0.25) [(Nd,Sm,Eu)-123] grown by the oxygen-controlled-melt-growth (OCMG) method. All samples with x > 0 exhibited a secondary peak in Jc vs. H, suggesting that field-induced pinning is active in this material. The maximum Jc value achieved at the secondary peak was 6 x 10^4 A/cm^2 in an applied field of 1.2 T (H||c) at 77 K for a sample with x = 0.25.

The mechanism of field-induced flux pinning in a Nd1+xBa2-xCu3O7-d single crystal, which exhibits a secondary peak in Jc vs. H, has been investigated by T. Mochida and M. Murakami (SRL-ISTEC). By measuring flux creep, the authors determined the apparent pinning energy U_0*. As a function of magnetic field H, U_0* showed maxima at fields that depended on the temperature, similar to the behavior of Jc vs. H.

A recent paper by M. Kato et al. (Tohoku) [Jpn. J. Appl. Phys. 36, L1291 (1997)] reports the preparation of high-Tc superconducting samples of YBa2Cu3O7-d with Tc ~ 90 K in a short time of 25 min. using a domestic microwave oven operated at 2.45 GHz and 200 W, without any post-heat treatment. A pellet of mixed powders of raw materials was surrounded by an uncompacted powder of the same materials and then was wrapped in glass wool to suppress rapid loss of heat from the pellet's surface. The sample was put in an alumina crucible with a volume of 30 cm^3, and an alumina cover was put on top. The authors found the optimum time of microwave heating to be 25 min. After 26 min. of irradiation, the pellet partially melted, and Y2BaCuO5 and BaCuO2 appeared. After 27 min. of irradiation, the pellet and powder melted completely, and the alumina crucible glowed orange and then cracked. (High-Tc Update takes no responsibility for damages by anyone foolish enough to try this experiment at home!)

The effect of oxygenation on the levitation force has been studied by D. Shi et al. (Cincinnati) for single-domain YBa2Cu3O7-d processed by the seeded melt-growth (SMG) method. The authors found that oxygenation annealing has a pronounced effect on the levitation force only in the initial period (~10 h) at 450^oC regardless of the sample volume. The experimental results show that the levitation force increases rapidly and begins to saturate after 10 h of oxygen anneal, indicating that top surfaces are mainly responsible for the levitation force. The data indicate that prolonged oxygen anneal will not significantly improve the levitation force in SMG YBa2Cu3O7-d.

Polarized neutron diffraction has been used by A. J. Markvardsen (Oxford) et al. to measure the magnetization density induced by an applied magnetic field in single-crystal PrBa2Cu3O6.24. The authors used a modified maximum-entropy method to invert the diffraction data. The resulting images give evidence for a number of features, including Pr on the Ba site and distortions of the Pr ion. A related paper by A. T. Boothroyd (Oxford) enumerates the possible magnetic structures that may be observed in RBa2Cu3O6+x compounds when a bilinear coupling exists between the R and Cu magnetic moments. The author also discusses the implications of this coupling for local relaxation probes at the R site.

The question of hole localization in Pr-doped RBa2Cu3O7-d systems [Gd1- xPrxBa2Cu3O7-d (x = 0.1 - 0.9) and R0.8Pr0.2Ba2Cu3O7-d (R = Yb, Er, Dy, Gd, and Nd)] has been studied experimentally by H.-C.I. Kao (Tamkang) et al. The authors suggest that hybridization between 4f states of the Pr ion and the conduction-band states in the CuO2 planes leads to hole localization, which is the mechanism for the suppression of superconductivity as the Pr concentration increases.

The trapping modes of Y2BaCuO5 (211) particles in melt-textured YBa2Cu3O7-d (123) have been studied by C.-J. Kim et al. (KAERI) as a function of the cooling rate, the volume fraction, and the size of the 211 particles.

Bi Cuprates

The zero-field current-voltage (I-V) characteristics of a thin Bi2Sr2CaCu2O8+d (Bi-2212) crystal have been measured by S. M. Ammirata (Ohio State) et al. and analyzed in two ways. The conventional approach yields ambiguous results, but a dynamical scaling analysis is successful, yielding a value of z ~~ 5.6 for the dynamical critical exponent.

The critical current of Bi-2223/Ag tapes with different secondary phase content has been measured in an applied magnetic field at 77 K by J. Horvat et al. (Wollongong). The phase content was altered by using different cooling rates after the final sintering or by using an additional sintering stage at a low temperature. The authors found that the strong-link component of the critical current could be enhanced by using processing that removed Bi-2201 at the interface of low-angle tilt boundaries.

In a related paper, B. Zeimetz et al. (Wollongong) report results using a two-step procedure in the final thermal cycle. The authors found that a sintering time of 50 h at 840^oC followed by a second step of 50 h at 820^oC yielded a critical current density almost double that using a one-step process (50 h at 840^oC). Comparative I_c(B) measurements and detailed microstructural analysis led the authors to conclude that the improvement is caused by the removal of Bi-2201 in the low-temperature step. The authors also find that their two-step process is essentially equivalent to a slow-cooling procedure used by other groups.

A preprint by M. Ishizuka (Sumitomo) et al. reports the properties of Bi-2223 tapes fabricated using sheath materials of Ag-Cu alloy doped with Ti, Zr, or Hf. The Cu composition in the sheath was varied from 0 to 10 at%. The ideal total sintering time was found to vary according to the Cu composition in the sheath. The best results for Jc were 4.1 x 10^4 A/cm^2 at 4.2 K and 14 T (parallel to the tape), and 2.2 x 10^4 A/cm^2 at 77 K and 0 T in a tape having a Ag - 10 at% Cu - 0.1 at% Hf sheath after sintering for a total of 200 h. The authors report that the total sintering time has a major influence on the microstructure and superconducting properties.

Hg Cuprates

The reactions occurring during the synthesis of (Hg,Bi)Ba2Ca2Cu3O8+d [(Hg,Bi)-1223, Tc = 130-134 K] have been studied by P.V.P.S.S. Sastry et al. (Florida State). The authors found that improved microstructural and magnetization properties resulted from the use of CaHgO2 as an external Hg source, which helps to control the Hg pressure during the synthesis of (Hg,Bi)-1223.

Strongly overdoped samples of HgBa2Ca2Cu3O8+d (Hg-1223) with Tc as low as 97 K have been prepared by M. Karppinen (Tokyo Tech and Helsinki University of Technology) et al. using highly oxidized BaCuO2+epsilon (epsilon ~~ 0.13) and BaO2 powders as starting materials for high- pressure synthesis at 5 GPa and 950^oC. Magnetization measurements showed that as the doped hole concentration increases and the anisotropy decreases, the H_[irr] vs. T/Tc characteristics improve.

Other Cuprates

As reported by H. Yamamoto et al. (NTT), a new superconducting cuprate has been synthesized in the Ba-Cu-O system by low-temperature thin-film growth with reactive coevaporation. The superconducting phase was obtained only after strong oxidation by ozone following film growth. Structural analysis suggests that the superconducting phase is represented by Ba2CuO3+d [02(n-1)n-Ba, n = 1] with K2NiF4-based structure. Resistivity measurements showed an onset Tc = 60-70 K and a zero-resistance Tc = 47 K, while magnetic measurements showed an onset Tc = 85-90 K.

Isothermal dc magnetization measurements with the magnetic field along the tetragonal c axis have been made by M. C. de Andrade et al. (UC-San Diego) on an overdoped Nd2-xCexCuO4-y single crystal (Tc ~~ 19 K) at temperatures down to a reduced temperature of T/Tc ~~ 0.02. The authors found a pronounced peak-effect anomaly in the irreversible part of the magnetization loop, and the magnetic field at which the peak occurs increased linearly with decreasing temperature down to T/Tc ~~ 0.05. The authors also report evidence for surface barriers.

A preprint by H. Shibata and T. Yamada (NTT) reports measurements of the far-infrared reflectivity along the c axis (E||c) in La2CuO4+d, La1.89Ca1.11Cu2O6+d (double pyramidal planes), and Nd2CuO4-xFx (T' phase) single crystals down to 9 cm^[-1]. All the insulating spectra in the normal state change to show a sharp plasma edge in the superconducting state. The authors discuss the obtained c-axis penetration depth lambda_c in terms of the Josephson-coupled-layer model.

Anomalies in the field-cooled and zero-field-cooled magnetizations of 110^oC annealed La2CuO4+d (0 < d < 0.12) are reported by P. H. Hor and S. T. Ting (TCSUH). The authors suggest that the anomalies are intrinsic, are electronic in origin, and are related to the existence of a critical hole concentration, P_c ~~ 0.06.

Vortices

A preprint by D. Bracanovic (Southampton) et al. reports a study of the transition from the vortex liquid to the vortex solid in clean, detwinned YBa2Cu3O7-d single crystals in fields up to 12 T using ac susceptibility and resistivity measurements. For mu_0H < 7 T, a sharp drop in the resistivity at a temperature T_m was found, indicative of a first-order transition, accompanied by an ac-field-independent abrupt onset of both chi' and chi" components. The ac susceptibility data suggest that just below T_m there is a transition region where the liquid and solid phases coexist. Above the multicritical field mu_0H_[mc] = 7 T, simultaneous broadening of both the rho(T) and the chi"(T) onset show that the first-order melting transition is suppressed.

Magnetization jumps at the first-order vortex transition have been studied by A. I. Rykov (SRL, ISTEC) in several YBa2Cu3O7-d single crystals subjected to different thermal treatments. The author found that the heights of the magnetization jumps depend on not only the sample preparation but also the measurement procedure. The dependence of the jump heights on the length of sample movement in a SQUID magnetometer was established. The author interprets the results in terms of the multipolar magnetic response from inhomogeneous magnetic states of the sample.

A preprint by J. Gilchrist (Grenoble) points out that various flux-flow problems in slabs and cylinders, and flux-creep problems in slabs, when simplified, reduce to the porous medium equation with possible sign changes. The equation's known self-similar solutions apply exactly or asymptotically if the boundary conditions are right. Flux creep in cylinders corresponds to a modified porous medium equation that has different explicit solutions and different focusing solutions.

Thin Films

The effects of thermal annealing on the microstructures at artificial grain boundaries of [100] tilted (2 x 18.4 degrees) SrTiO3 bicrystalline substrates have been studied by Q. D. Jiang et al. (TCSUH). The authors found that annealing at temperatures as low as 780^oC already can lead to the formation of a groove at the grain boundary on bicrystal substrate surfaces. This finding indicates that the thickness depression of YBa2Cu3O7-d films at bicrystal boundaries originates from the underlying grooved substrate. Defects characterized by round holes with diameters and depths ranging from several nanometers to a hundred nanometers also were observed.

A preprint by S.A.L. Foulds (Birmingham) et al. reports the use of electron-beam-induced voltage contrast (EBIV) [also called low- temperature scanning electron microscopy (LTSEM)] and modulated optical reflectivity (MOR) to study the electrical properties of superconducting microwave resonators. The YBCO resonators consisted of 200 micrometers wide central tracks of 8 mm length separated by 80 micrometers from a superconducting ground plane. Correlations found between the EBIV results close to the superconducting transition and the MOR results at room temperature indicate that MOR is a useful inspection tool for superconducting devices, especially since MOR is a contactless room- temperature technique. Additional details on the EBIV technique are contained in related preprints by M. Zamboni (SRL-ISTEC) et al. and S.A.L. Foulds and J. S. Abell (Birmingham).

As reported by M. Ban et al. (SRL-ISTEC), a SiO2 passivation film coated on YBa2Cu3O7-d microstrip line resonators has beneficial effects: The SiO2 passivation film does not degrade either Tc or the microwave characteristics, but it does protect the YBCO film from surface degradation and reaction with water.

Applications

The horizontal and vertical drift of the levitation gap in a rotating flywheel system making use of a high-temperature superconducting magnetic bearing has been studied experimentally by T. Hikihara (Kyoto) et al. The authors found significant changes occurring at the mechanical resonance revolution speeds of the flywheel.

Theory

A preprint by B. Barbiellini and P. M. Platzman (Bell Labs) discusses what could be learned about the momentum density of high-Tc cuprate superconductors from high-resolution Compton-profile and 2D-ACAR (two- dimensional angular correlation of annihilation radiation) positron- annihilation experiments. The authors suggest that these spectroscopies could resolve some important questions related to the role of electron- electron correlations and the nature of the Fermi surface.

According to a preprint by J. Ashkenazi (Miami), non-Fermi-liquid features of the high-Tc cuprates, and specifically the systematic behavior of the resistivity, Hall constant, and thermoelectric power, arise from an electronic structure based on large-U and small-U orbitals, and the resulting striped structure.

A theoretical analysis of the critical temperatures Tc(m,n) observed in superlattices of m YBa2Cu3O7-d and n PrBa2Cu3O7-d unit cells has been carried out by L. Jansen (ETH-Zurich) and R. Block (Amsterdam) in a microscopic approach based on indirect-exchange Cooper pairing between conduction electrons (quasiparticles) via oxygen anions. The results are in essential agreement with experiment for all values of m and n without any parameter adjustment. The authors also establish a theoretical correlation between Tc(m,n) and a normal-state property of the system, the Fermi wave vector k_F, as a function of m and n.

As shown by O. V. Danylenko (Moscow) et al., the effect of impurities with pronounced forward scattering upon the analytical properties of the quasiparticle Green's function differ significantly from those in the case of isotropic scattering. The authors show that if the superconducting pairing is due to forward electron-phonon scattering, the critical temperature Tc depends linearly on the electron-phonon coupling constant lambda and the isotope effect alpha is small. Isotropic impurity scattering is pair-weakening for s-wave and pair- breaking for d-wave superconductivity, while forward impurity scattering is pair-weakening in both channels.

The electromagnetic response of the CuO2 planes has been calculated by A. Bille and K. Scharnberg (Hamburg) within a strong-coupling theory using model tight-binding bands and momentum-dependent pairing interactions representing spin-fluctuation and phonon exchange. The superconducting state resulting from these interactions has d-wave symmetry. With phonon exchange included, the order parameter amplitude grows rapidly below Tc at elevated frequencies, which leads to improved agreement with the observed temperature dependence of the penetration depth.

The effect of spin fluctuations on the electron-phonon coupling constant lambda in high-temperature superconductors has been calculated by I. Grosu (Cluj). The author finds that spin fluctuations soften the phonon modes and produce an enhancement of lambda.

According to A. V. Balatsky (Los Alamos), patches of complex d_[xy] component are generated around magnetic impurities in the presence of coupling between the condensate's orbital moment and the impurity spin S_z in d_[x^2-y^2] superconductors. The author suggests that at low temperatures the d_[xy] patches undergo a phase transition into a phase- locked state via the Josephson effect. In this ordered phase, violation of time-reversal symmetry and parity occurs spontaneously, and an impurity magnetization and a d_[xy] component of the order parameter develop simultaneously.

A preprint by A. Gurevich (Wisconsin) and E. A. Pashitskii (Kiev) considers mechanisms that can account for the rapid decrease of the critical current density Jc(theta) with misorientation angle theta through grain boundaries in high-Tc superconductors. The authors find that the Jc(theta) dependence is determined primarily by the decrease of the current-carrying cross section by insulating dislocation cores and by progressive local suppression of the order parameter near the grain boundary. The model describes the observed quasi-exponential decrease of Jc(theta) with increasing theta.

Josephson Arrays

A square array of Josephson junctions with modulated strength in a magnetic field with half a flux quantum per plaquette (f = 1/2) has been studied by E. Granato (Sao Jose dos Campos) et al. using analytic arguments and dynamical simulations. The modulation is such that alternate columns of junctions are of different strength. Previous work has shown that with decreasing temperature, this system undergoes an XY transition followed by an Ising-like vortex-lattice-disordering transition at a lower temperature. In this paper, the authors investigate the consequences of the Ising transition, and they examine the role of edge effects on the resistive transition.

Dynamical simulations and scaling arguments have been used by E. Granato (Sao Jose dos Campos) and D. Dominguez (Bariloche) to study the current- voltage characteristics of a two-dimensional model of resistively shunted Josephson-junction arrays in the presence of percolative disorder at zero external field. The authors study the behavior as a function of temperature and p, the fraction of superconducting grains, both above and below the percolation threshold p_c.

Analytical and numerical studies of pinned superconducting states of open-ended Josephson-ladder arrays, neglecting inductances but taking edge effects into account, have been carried out by M. Barahona (MIT) et al. The authors determine a zero-temperature dynamic stability diagram as a function of the normalized current I and the frustration f. The diagram contains a depinned region at high current, a no-vortex region at low current and low f, and a narrow fully frustrated region near f = 1/2. In addition there are regions where two or more stable states (e.g., no-vortex and single-vortex configurations) coexist, depending upon the initial conditions.

As noted by M. Barahona (Stanford) and S. Watanabe (Copenhagen), when magnetic flux moves across layered or granular superconductor structures, the passage of vortices can take place along channels that develop finite voltage, while the rest of the material remains in the zero-voltage state. The authors present analytical studies of such behavior: They study row-switched states in underdamped two-dimensional Josephson arrays driven by a uniform dc current under external magnetic field. The authors also obtain the dc and ac spatial distributions of the junction phases and induced circulating currents.

Other Activities

The electrical resistivity and magnetic susceptibility of the spin- ladder cuprate Sr14-x AxCu24O41 (A = Ca, Y, La), consisting of two- dimensional Cu2O3 ladder planes and one-dimensional CuO2 chains, have been investigated by T. Adachi et al. (Tohoku). The authors present evidence indicating that holes in the ladder are paired and localized at low temperatures, where almost all Cu^[2+]^spins in the ladder form spin-singlet pairs.

A superconducting ceramic material in the system Ba-Nb-O-N with Tc = 22 K has been synthesized by G. K. Strukova et al. (Chernogolovka). The authors believe the superconductivity is associated with a perovskite- like cubic lattice of the general formula BaNbO3-xNy. The authors also report Tc as high as 23 K in oxygen-deficient Y0.2Ba0.8NbOx.

Contributed by John R. Clem

Contents: Preprints begin on page 5; Coming Events begin on page 11, Resources are on page 12, and FYI is on page 13. A picture of our Science Editor levitating is on page 13.

High-Tc Update is available without charge to interested persons. Recipients are expected to participate in this information exchange by sending us preprints, reprints, meeting news, research news, etc. Contributions to defray the cost of newsletter printing and mailing are welcome.

PREPRINTS To obtain a particular preprint, contact the first author at the address given at the end of the citation. Help us expand this list by sending us your complete preprint. Please specify where and when your paper was submitted. An * next to an entry indicates it is a correction or revision of a previous entry. PACS codes and/or key words are given at the end of the citation.

T. Adachi, K. Shiota, M. Kato, T. Noji, and Y. Koike, "Electrical and Magnetic Anomalies in the Spin-Ladder Cuprate Sr14-xAxCu24O41 (A=Ca, Y, La): Possibility of Hole Pairing in the Ladder." To be published in Solid State Commun. Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aramaki Aoba, Aoba-ku, Sendai 980-77, JAPAN.

I. N. Afanas'eva and G. M. Kuz'micheva, "The Crystal Structure of New Phases of (In,Cu)(Sr,Ho)2(Ho,Ce,Sr)1+kCu2O2k+6+d (k=0,1,2) Homologous Series." To be published in Zh. Neorgan. Khimii. Contact G. M. Kuzmicheva, Department of Solid State Physics and Chemistry, State Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 07 62; e-mail kuz7micheva@glasnet.ru or alekz@cs.msu.su. (In Russian.)

S. M. Ammirata, Mark Friesen, Stephen W. Pierson, LeRoy A. Gorham, Jeffrey C. Hunnicutt, M. L. Trawick, and C. D. Keener, "Dynamic Scaling at the Zero-Field 2D Superconducting Transition." Submitted to Phys. Rev. Lett. Department of Physics, Ohio State University, Columbus, OH 43210; Stephen W. Pierson's e-mail pierson@wpi.edu; Web site http://www.wpi.edu/~pierson/pubs.html; preprint also available at cond- mat@xxx.lanl.gov (#9711129).

J. Ashkenazi, "Stripes, Non-Fermi-Liquid Behavior, and Two-Component Transport in the High-Tc Cuprates." Submitted to J. Phys. Chem. Solids. Department of Physics, University of Miami, P.O. Box 248046, Coral Gables, FL 33124; e-mail ashkenazi@phyvax.ir.miami.edu; preprint also available at cond-mat@xxx.lanl.gov (#9710254).

A. V. Balatsky, "Magnetic Impurity Induced id_[xy] Component and Spontaneous Time Reversal and Parity Breaking in a d_[x^2-y^2]-Wave Superconductor." Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545; e-mail avb@groa.lanl.gov; preprint also available at cond-mat@xxx.lanl.gov (#9710323). 74.25Bt; 74.20.De; 74.62.Dh.

Masahito Ban, Katsumi Suzuki, and Youichi Enomoto, "SiO2 Passivation Film Effects on Microwave Characteristics of YBa2Cu3O7-x-Based Resonators." To be published in Physica C (in press). Kanto Technical Institute, Kawasaki Heavy Industries, Ltd., 118 Futatsuzuka, Noda, Chiba 278, JAPAN; telephone +81 471 24 0302; telefax +81 471 24 5917; e-mail ban_m@now.khi.co.jp. Key words: SiO2 passivation film, YBCO degradation, resonator, annealing, accelerated humidity testing, rf magnetron sputtering.

Mauricio Barahona, Steven H. Strogatz, and Terry P. Orlando, "Superconducting States and Depinning Transitions of Josephson Ladders." Ginzton Laboratory, Stanford University, Stanford, CA 94305; e-mail mauricio@loki.stanford.edu; preprint also available at cond- mat@xxx.lanl.gov (#9710224). 74.50.+r; 05.45.+b; 74.40.+k.

Mauricio Barahona and Shinya Watanabe, "Row-Switched States in Two- Dimensional Underdamped Josephson Junction Arrays." Ginzton Laboratory, Stanford University, Stanford, CA 94305; e-mail mauricio@loki.stanford.edu; preprint also available at cond- mat@xxx.lanl.gov (#9710204). 85.25.Cp; 46.10.+z; 05.70.Ln; 47.54.+r.

B. Barbiellini and P. M. Platzman, "Momentum Density of High Tc Copper Oxides." To be published in Mater. Sci. Forum. Department of Physics, University of California at Los Angeles, Los Angeles, CA 90024; e-mail bba@physics.ucla.edu; preprint also available at cond-mat@xxx.lanl.gov (#9710226). Key words: high-Tc superconductors, Compton profile, positron annihilation spectroscopy.

A. Bille and K. Scharnberg, "Anisotropic Strong Coupling Calculation of the Local Electromagnetic Response of High-Tc Superconductors." To be published in J. Phys. Chem. Solids. Fachbereich Physik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg, GERMANY; e-mail bille@physnet.uni-hamburg.de; preprint also available at cond- mat@xxx.lanl.gov (#9710319).

A. T. Boothroyd, "R-Cu Magnetic Coupling in RBa2Cu3O6+x, with Particular Reference to PrBa2Cu3O6+x." To be published in Physica B: Proc. of the Int. Conf. on Neutron Scattering (ICNS'97), Toronto, Canada, Aug. 17-21, 1997. Department of Physics, Clarendon Laboratory, Oxford University, Parks Road, Oxford OX1 3PU, UNITED KINGDOM; telephone +44 1865-272376 or -272200; telefax +44 1865-272400; e-mail a.boothroyd1@physics.ox.ac.uk. Key words: magnetic order, RBa2Cu3O6+x, non-collinear structures, relaxation phenomena.

D. Bracanovic, S. N. Gordeev, S. Pinfold, R. Langan, M. Oussena, P.A.J. de Groot, R. Gagnon, and L. Taillefer, "Comparative ac Susceptibility and Resistivity Studies of the Vortex Lattice Melting Transition in Detwinned YBa2Cu3O7-d Single Crystals." To be published in Physica C. Department of Physics, University of Southampton, Southampton SO17 1BJ, UNITED KINGDOM; S. N. Gordeev's telephone +44 1703 592058; telefax +44 1703 593910; e-mail sg@phys.soton.ac.uk. 74.25.Ha; 74.60.Ge; 74.72.Bk.

R. Cabre, Jna. Gavalda, R. Sole, X. Ruiz, J. Massons, M. Aguilo, and F. Diaz, "Single Domain Generation in YBCO Textured Samples." To be published in Physica C (in press). Contact F. Diaz, Laboratori de Fisica Aplicada i Cristallografia, Universitat Rovira i Virgili, Place Imperial Tarraco 1, E-43005 Tarragona, SPAIN; telephone +34 977 55 95 17; telefax +34 977 55 95 63; e-mail diaz@quimica.urv.es.

H. S. Chauhan, T. Mochida, M. Muralidhar, and M. Murakami, "Effect of Growth Temperature on Superconducting Properties of Nd-Ba-Cu-O." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998): Proc. of the 10th Int. Symp. on Supercond. (ISS'97), Gifu, Japan, Oct. 27-30, 1997. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), Morioka Laboratory, 3-35-2 Iioka-Shinden, Morioka, Iwate 020, JAPAN. Key words: Nd-Ba-Cu-O, solid solution, critical current, isothermal growth, pinning center.

X. H. Chen, T. F. Li, M. Yu, K. Q. Ruan, C. Y. Wang, and L. Z. Cao, "Resistivity and Thermoelectric Power of Bi2Sr2Ca1-xPrxCu2Oy System." To be published in Physica C (in press). Department of Physics, Structural Research Laboratory, University of Science and Technology of China, Heifei, Anhui 230026, PEOPLE'S REPUBLIC OF CHINA; telephone +86 551 3601064; telefax +86 551 3631760; e-mail chenxh@phys.ustc.edu.cn.

O. V. Danylenko, O. V. Dolgov, M. L. Kulic, and V. Oudovenko, "Normal and Superconducting State in the Presence of Forward Electron-Phonon and Impurity Scattering." Submitted to Phys. Rev. B. P.N. Lebedev Physical Institute, Leninsky Prospect 53, Moscow 117924, RUSSIA. 74.20.-z; 74.25.-q.

M. C. de Andrade, N. R. Dilley, F. Ruess, and M. B. Maple, "Competition Between Surface Barriers and Bulk Pinning in a Nd2-xCexCuO4-y Single Crystal Down to T/Tc =0.02." To be published in Phys. Rev. B. Department of Physics, Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA 92093-0319; telephone (619) 534-2493; telefax (619) 534-1241; e-mail mandrade@physics.ucsd.edu. 74.25.Dw; 74.60.Ec; 74.60.Ge; 74.72.-h.

S.A.L. Foulds and J. S. Abell, "Utilization of Beam-Blanking in Electron Beam-Induced Voltage Contrast Studies of High-Tc Superconducting Thin Films." Presented at EMAG'97, Cambridge, United Kingdom. Superconductivity Research Group, School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, UNITED KINGDOM; telephone +44 121 414 5170; telefax +44 121 414 5232; e-mail s.a.l.foulds@bham.ac.uk.

S.A.L. Foulds, D. P. Almond, P. Nokrach, F. Wellhoefer, P. Woodall, and J. S. Abell, "Electron-Beam Induced Voltage Contrast and Modulated Optical Reflectance Studies of YBCO Thin Film Resonators." Submitted to Supercond. Sci. & Technol. Superconductivity Research Group, School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, UNITED KINGDOM; telephone +44 121 414 5170; telefax +44 121 414 5232; e- mail s.a.l.foulds@bham.ac.uk.

K. Fujinami, T. Nakane, K. Peitola, R. Tellgren, M. Karppinen, and H. Yamauchi, "Hole Doping Mechanism and Structural Changes in Cu(Ba0.8Sr0.2)2(Yb1-xCax)Cu2O6+z." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998). Contact H. Yamauchi, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokoyama 226, JAPAN; telephone +81 45-924 5315; telefax +81 45-921 6953 or -924 5360; e-mail yamauchi@materia.titech.ac.jp. Key words: oxygen content, cation substitution, hole-doping mechanism, structural changes, bond-valence calculation.

John Gilchrist, "Flux Diffusion and the Porous Medium Equation." To be published in Physica C (in press). Centre de Recherches sur les Tres Basses Temperatures, Laboratoire Associe a l'Universite Joseph Fourier, CNRS, BP 166X, F-38042 Grenoble Cedex 9, FRANCE; telephone +33 4 7688 1000; telefax +33 4 7687 5060; e-mail gilchris@labs.polycnrs-gre.fr. Key words: flux creep, flux flow, ac susceptibility, magnetoresistance.

E. Granato, J. M. Kosterlitz, and M. V. Simkin, "Edge Effects in a Frustrated Josephson Junction Array with Modulated Couplings." To be published in Phys. Rev. B. Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12201 Sao Jose dos Campos, SP, BRAZIL; e-mail enzo@las.inpe.br; preprint also available at cond-mat@xxx.lanl.gov (#9710242). 74.50.+r; 74.60.Ge; 64.60.Cn.

Enzo Granato and Daniel Dominguez, "Current-Voltage Characteristics of Diluted Josephson-Junction Arrays: Scaling Behavior at Current and Percolation Threshold." To be published in Phys. Rev. B. Laboratorio Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, 12201 Sao Jose dos Campos, SP, BRAZIL; e-mail enzo@las.inpe.br; preprint also available at cond-mat@xxx.lanl.gov (#9709012). 74.40.+k; 74.50.+r; 64.60.Ht.

I. Grosu, "Spin Fluctuation Effect on Electron-Electron Coupling in High Temperature Superconductors." To be published in J. Supercond. Department of Physics, University of Cluj, 3400 Cluj, ROMANIA. Key words: spin fluctuations, high-temperature superconductivity, electron- electron coupling.

A. Gurevich and E. A. Pashitskii, "Current Transport Through Low-Angle Grain Boundaries in High-Temperature Superconductors." Applied Superconductivity Center, 917 Engineering Research Bldg., University of Wisconsin, 1500 Johnson Drive, Madison, WI 53706; telephone (608) 263- 2549; telefax (608) 263-1087. 74.20.De; 74.20.Hi; 74.60.-w.

Takashi Hikihara, Hitoshi Adachi, Shunsuke Ohashi, Yoshihisa Hirane, and Yoshisuke Ueda, "Levitation Drift of Flywheel and HTSC Bearing System Caused by Mechanical Resonance." To be published in Physica C (in press). School of Electrical Engineering, Kyoto University, Yoshida- honmachi, Sakyo-ku, Kyoto 606-01, JAPAN; telefax +81 75 751 1576; e-mail hikihar@sysnet.ee.kansai-u.ac.jp. Key words: HTSC bearing, flywheel, mechanical resonance, gyroscopic motion, drift. 74.90.+n; 62.40.+i.

P. H. Hor and S. T. Ting, "A Study of the Meissner and Shielding Effects in Annealed La2CuO4+d." Preprint #97:128; submitted to the Proc. of the 1997 Taiwan Int. Conf. on Supercond. & 5th Workshop on Low Temp. Physics, Taipei, Taiwan, Republic of China, Aug. 13-16, 1997. Texas Center for Superconductivity, University of Houston, Houston, TX 77204- 5932; telephone (713) 743-8200; telefax (713) 743-8201; e-mail preprints@www.tcs.uh.edu. 74.25.-q; 74.25.Ha; 74.60.Ge.

J. Horvat, Y. C. Guo, B. Zeimetz, H. K. Liu, and S. X. Dou, "Improvement of Grain Connectivity in Bi2223/Ag Tapes by Reducing Bi2201 Phase at Grain Boundaries." Submitted to Physica C. Centre for Superconducting and Electronic Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, AUSTRALIA; telephone +61 242 21 5730; telefax +61 242 21 5731; e-mail jhorvat@uow.edu.au. Key words: weak links, critical current, grain boundaries, grain connectivity, flux pinning.

Ling Hua, Jaimoo Yoo, Jaewoong Ko, Haidoo Kim, Hyungsik Chung, and Guiwen Qiao, "Microstructure and Phase Evolution of Ultrafine MgO Doped Bi-2223/Ag Tapes." To be published in Physica C (in press). Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, CHINA; telephone +86 24 3843531, ext. 55842; telefax +86 24 3891320; e-mail lhua@usa.net. Key words: Bi-2223/Ag tapes, critical current density, weak links, flux pinning.

Masayuki Ishizuka, Yoshiaki Tanaka, Takehiro Hashimoto, and Hiroshi Maeda, "Influences of Cu Composition and Sintering Condition in Bi-2223 Tapes Using Ag-Cu Alloy Sheath Doped with Ti, Zr or Hf." To be published in Physica C (in press). Research and Development Center, Sumitomo Heavy Industries, Ltd., 63-30 Yuhigaoka, Hiratsuka, Kanagawa 254, JAPAN. Key words: Bi-2223 tape, Ag-Cu alloy sheath, powder-in- tube technique, doping with Ti, Zr, or Hf.

L. Jansen and R. Block, "On Superconductivity in (YBa2Cu3O7- d)m/(PrBa2Cu3O7-d)n Superlattices: A Quantitative Analysis Based on Indirect-Exchange Pairing." Institut fuer Theoretische Physik, ETH- Hoenggerberg, CH-8093 Zurich, SWITZERLAND; telefax +41 1 633 1115; e- mail jansen@itp.phys.ethz.ch.

Q. D. Jiang, Z. J. Huang, A. Brazdeikis, M. L. Dezaneti, C. L. Chen, P. Jin, and C. W. Chu, "Non-Destructive Investigation of Microstructures and Defects at an Artificial Boundary of SrTiO3 Bicrystal Substrate." Preprint #97:130; submitted to Appl. Phys. Lett. Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5932; telephone (713) 743-8200; telefax (713) 743-8201. 61.16.Ch; 61.72.Mm; 68.35.-p; 68.35.Ct; 68.35.Bs.

Amish G. Joshi, D. G. Kuberkar, G. J. Baldha, and R. G. Kulkarni, "Effect of Mo and Mo-Ca Substitution on the Superconductivity of GdBa2Cu3O7-d." To be published in Physica C (in press). Contact R. G. Kulkarni, Department of Physics, Saurashtra University, Rajkot 360 005, INDIA; telephone +91 2817 8505; telefax +91 2817 7885.

E. Kandyel, T. Kamiyama, H. Asano, and M. Abou-Sekkina, "Synthesis, Structure, and Superconductivity of (Hg1-yTiy)Sr2(Ca1-xYx)Cu2Oz." To be published in Physica C (in press). Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305, JAPAN; telefax +81 298 557440; e-mail kandyel@mat.ims.tsukuba.ac.jp. Key words: superconductivity, Hg-based cuprate, Hg-1212, (Hg,Ti)Sr2(Ca,Y)Cu2Oz, crystal structure.

H.-C.I. Kao, F. C. Yu, and W. Guan, "Hole Localization in Pr-Doped RBa2Cu3O7-y Systems." To be published in Physica C. Department of Chemistry, Tamkang University, Tamsui 251, Taiwan REPUBLIC OF CHINA; telephone +886 2 625 1661; telefax +886 2 622 8458; e-mail kaohci@mail.tku.edu.tw; W. Guan's telephone +886 3 574 2542; telefax +886 3 572 3052. Key words: hole, Pr doped, RBa2Cu3O7-y.

M. Karppinen, H. Yamauchi, K. Fujinami, T. Ito, H. Suematsu, H. Sakata, and K. Matsuura, "Synthesis and Characterization of Strongly Over-Doped HgBa2Ca2Cu3O8+d Samples." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998). Contact H. Yamauchi, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokoyama 227, JAPAN; telephone +81 45-924 5315; telefax +81 45-921 6953 or -924 5360; e-mail yamauchi@materia.titech.ac.jp. Key words: Hg-1223 superconductor, high-pressure synthesis, excess oxygen, overdoping, Seebeck coefficient, irreversibility field.

Masatsune Kato, Kenji Sakakibara, and Yoji Koike, "Rapid Preparation of YBa2Cu3O7-x with Tc ~ 90 K Using a Domestic Microwave Oven." To be published in Jpn. J. Appl. Phys. Department of Applied Physics, Graduate School of Engineering, Tohoku University, Aramaki Aoba, Aoba- ku, Sendai 980-77, JAPAN. Key words: domestic microwave oven, YBa2Cu3O7-x, sample preparation, high-Tc superconductor, electrical resistivity, magnetic susceptibility.

Chan-Joong Kim, Young A. Jee, Il-Hyun Kuk, and Gye-Won Hong, "Crystal Growth and Y2BaCuO5 Segregation in Melt-Textured YBa2Cu3O7-y." Presented at the 10th Int. Symp. on Supercond. (ISS'97), Gifu, Japan, Oct. 27-30, 1997. Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr. Key words: melt-textured YBa2Cu3O7-y, Y2BaCuO5, segregation, pattern, interfacial energy.

I. Kirschner, R. Laiho, A. C. Bodi, and E. Laehderanta, "Temperature Pulse Induced Thermal Instability in Y1Ba2Cu3O7-d Superconductors." To be published in Physica C (in press). Department for Low Temperature Physics, Eoetvoes University, Puskin u. 5-7, H-1088 Budapest, HUNGARY; telephone +36 1 266 7929; telefax +36 1 266 0206. Key words: thermal and magnetic excitations, fluctuations, coherent domains, instability. 74.72.Bk; 75.40.-s.

T. Geetha Kumary, S. Kalavathi, M. C. Valsakumar, Y. Hariharan, and T. S. Radhakrishnan, "On Unusual Temperature Dependence of the Upper Critical Field in YNi2-xFexB2C." To be published in Physica C (in press). Contact M. C. Valsakumar, Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, INDIA, telephone +91 4114 40369; telefax +91 4114 40381; e-mail valsa@igcar.ernet.in. Key words: superconductivity, upper critical field, borocarbide, Landau levels, Fermi liquid, non-Fermi liquid. 74.60.-w; 74.72.Ny.

Sergey Lee, Maxim Kuznetsov, Nikolai Kiryakov, Denis Emelyanov, and Yuri Tretyakov, "Synthesis and Properties of Hg0.7Pb0.3(BaSr)2Ca2Cu3Oz Superconductors." To be published in Physica C (in press). Department of Chemistry, Moscow State University, B-234, 119899 Moscow, RUSSIA; telephone +7 095 9394729; telefax +7 095 9390998; e-mail sergey@tret.chem.msu.su. Key words: Hg-based superconductors, Hg-1223 phase, substitutions, ampoule synthesis, spray drying. 74.72.Jt.

A. A. Levin, Yu. F. Shepelev, Yu. I. Smolin, and A. A. Bush, "Structural Modulation and Hole Conductivity of the High-Tc Superconductor Bi4Sr4CaCu3O14+x." To be published in Physica C (in press). Institute of Silicate Chemistry, Russian Academy of Sciences, 199155 Saint Petersburg, RUSSIA; telefax +7 812 2185401. Key words: Bi4Sr4CaCu3O14+x, modulated structure, x-ray data.

V. V. Luparev and G. M. Kuz'micheva, "The Cation Distribution and Structure Peculiarities of a Perovskite-Like (Hg,Ce,Cu)(Sr,Pr)2(Pr,Sr)Cu2O6+d and (Hg,[])(Sr,Pr)2(Pr,Sr)2Cu3O8+d Phases" ([]=vacancy). To be published in Zh. Neorgan. Khimii. Contact G. M. Kuz'micheva, Department of Solid State Physics and Chemistry, State Lomonosov Academy of Fine Chemical Technology, 86 pr. Vernadsky, Moscow 117571, RUSSIA; telephone +7 095 248 07 62; e-mail kuz7micheva@glasnet.ru or alekz@cs.msu.su. (In Russian.)

L. P. Ma, H. C. Li, R. L. Wang, and L. Li, "A New Method to Study the Mixed State of High-Tc Superconductors by Using the Relaxation of Resistivity." To be published in Physica C (in press). Beijing Laboratory of Vacuum Physics, Center for Condensed Matter Physics, Chinese Academy of Sciences, P.O. Box 2724, Beijing 100080, PEOPLE'S REPUBLIC OF CHINA. Key words: effective pinning energy, relaxation, resistivity, flux creep, high-Tc superconductor.

A. Markvardsen, J.-E. Jorgensen, A. Wannberg, and R. G. Delaplane, "Synthesis and Neutron Powder Diffraction Study of Nd2-xBa2+xCu2Ti2O11 for x=0.0 and 0.3." To be published in Physica C. Contact J.-E. Jorgensen, Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, DENMARK; telephone +45 8942 3333; telefax +45 8619 6199.

A. J. Markvardsen, A. T. Boothroyd, B. Buck, G. J. McIntyre, and Th. Wolf, "Magnetization Density in Single-Crystal PrBa2Cu3O6.24." To be published in J. Magn. & Magn. Mater. Contact A. T. Boothroyd, Department of Physics, Clarendon Laboratory, Oxford University, Parks Road, Oxford OX1 3PU, UNITED KINGDOM; telephone +44 1865-272376 or -272200; telefax +44 1865-272400; e-mail a.boothroyd1@physics.ox.ac.uk. Key words: magnetization, density, neutron scattering, polarized, superconductors, high Tc, rare-earth transition-metal compounds.

T. Mochida and M. Murakami, "Field Induced Flux Pinning in the Nd1+xBa2- xCu3O7-d Single Crystal." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 1-16-25 Shibaura, Minato-ku, Tokyo 105, JAPAN; telephone +81 3 3454 9284; telefax +81 3 3454 9287; e-mail mochida@istec.or.jp. Key words: flux pinning, fishtail effect, flux creep.

M. Muralidhar and M. Murakami, "Effect of Gd Addition on the Superconducting Properties of the (Nd-Sm-Eu)123 System." Submitted to the Proc. of the 4th Int. Union of Mater. Res. Soc. Int. Conf. in Asia (IUMRS-ICA), Chiba, Japan, Sept. 16-18, 1997. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 3-35-2 Iioka-Shinden, Morioka, Iwate 020, JAPAN; telephone +81 19 635-9015 or -9016; telefax +81 19 635-9017; e-mail miryala@istec.or.jp.

Akihiko Nishida, Chihiro Taka, and Kazumi Horai, "ESR Observations in Mn-Doped YBa2Cu3O7-d Superconductors." Presented at the 10th Int. Symp. on Supercond. (ISS'97), Gifu, Japan, Oct. 27-30, 1997; submitted to Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998). Faculty of Science, Department of Applied Physics, Fukuoka University, Fukuoka 814-0180, JAPAN. Key words: Mn substitution, ESR, Korringa relaxation, bottleneck, spin dynamics.

I. M. Obaidat, H. P. Goeckner, and J. S. Kouvel, "Vortex Pinning in a Rotated YBa2Cu3O7-d Crystal." To be published in Physica C (in press). Department of Physics, University of Illinois, Room 2236, 845 W. Taylor Street, Chicago, IL 60607-7059; telephone (312) 996-3400; telefax (312) 996-9016.

D. Prabhakaran and C. Subramanian, "Metal-Insulator Transition in the Pr Substituted Bi-2212 Bulk Textured Crystals." To be published in Physica C (in press). Crystal Growth Centre, Anna University, Madras 600 025, INDIA; telefax +91 44 235 2774; e-mail crystal@sirnetm.ernet.in.

I. Puica, V. Popescu, P. Mazzetti, A. Stepanescu, and Gh. Ciobanu, "Current-Influenced Voltage Noise in Bulk Polycrystalline High-Tc Superconductors." To be published in Physica C (in press). Department of Physics, "Politehnica" University Bucharest, Spl. Independentei 313, 77206 Bucharest, ROMANIA; telefax +40 1 6367704; e-mail pop@physics2.physics.pub.ro. Key words: polycrystalline HTSC, fluctuation effects, Josephson junctions. 74.40.+k; 74.50.+r.

A. I. Rykov, "Magnetization Jumps in Large Crystals of YBa2Cu3O7-d with Inhomogeneous Vortex States." To be published in Physica C. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536 0618; telefax +81 3 3536 5714. Key words: YBa2Cu3O7, single crystal, mixed state, magnetization jumps, first order transition.

Alexandre I. Rykov and Setsuko Tajima, "On the Origin of Peak Effect in High-Tc Superconductors." To be published in Proc. of the 10th Int. Symp. on Supercond. (ISS'97), Gifu, Japan, Oct. 27-30, 1997. Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536 0618; telefax +81 3 3536 5714. Key words: peak effect, first-order vortex transition, magnetization jumps, melting line.

P.V.P.S.S. Sastry, K. M. Amm, D. C. Knoll, S. C. Peterson, and J. Schwartz, "Synthesis and Processing of Bi-Doped Hg1Ba2Ca2Cu3Oy Superconductors." Submitted to Physica C. National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr., Tallahassee, FL 32310; telephone (850) 644-1447; telefax (850) 644-0867; e-mail pamidi@magnet.fsu.edu. Key words: Hg1Ba2Ca2Cu3Oy superconductor, Bi-doping, quenching studies, CaHgO2 source, magnetization.

Donglu Shi, D. Qu, and B. A. Tent, "Effect of Oxygenation on Levitation Force in Seeded Melt Grown Single-Domain YBa2Cu3Ox." To be published in Physica C (in press). Department of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45211; telephone (513) 556- 3096; telefax (513) 556-2569.

H. Shibata and T. Yamada, "Far-Infrared Reflectivity Along the c-Axis in La2CuO4+d, La1.89Ca1.11Cu2O6+d, and Nd2CuO4-xFx Single Crystals." To be published in Phys. Rev. B. NTT Basic Research Laboratories, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-01, JAPAN; telephone +81 462 40 3356; telefax +81 462 40 4675; e-mail shibata@will.ntt.jp. 74.25.Gz; 74.72.Dn; 74.72.Jt.

Jacek Sosnowski, "Selected Topics of the Transport Current Flow Through the Oxide Superconducting Ceramics." Presented at the VII Nat. Symp. on Supercond., Miedzyzdroje, Poland, Sept. 1-3, 1997; to be published in Molecular Phys. Reports. Electrotechnical Institute, Pozaryskiego 28, 04-703 Warsaw, POLAND; telephone +48 22 123478; telefax +48 22 127535; e-mail sosnow@iel.waw.pl.

G. K. Strukova, V. V. Kedrov, V. N. Zverev, S. S. Khasanov, I. M. Ovchinnikov, I. E. Batov, and V. A. Gasparov, "On the Synthesis and the Electric and Magnetic Properties of Superconducting Barium-Niobium-Oxide Compounds." To be published in Physica C (in press). Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow 142432, RUSSIA; e-mail strukova@issp.ac.ru. 61.10.-i; 74.25.Ha; 74.62.-c; 74.70.-b; 74.80.Bj.

H. Suematsu, H. Okamura, S. Nagaya, and H. Yamauchi, "'Large-Area TEM' Observation of the Distribution of Y-211 Particles in YBCO Superconductors Melt-Grown Under Varying Oxygen Pressure." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998). Contact H. Yamauchi, Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokoyama 227, JAPAN; telephone +81 45-924 5315; telefax +81 45-921 6953 or -924 5360; e-mail yamauchi@materia.titech.ac.jp. Key words: large-area TEM observation, YBCO, varying oxygen partial pressure method, flux pinning, Y-211, twin boundary.

A. Tokiwa-Yamamoto, S. Adachi, M. Kikuchi, A. Fukuoka, K. Tanabe, and Y. Syono, "Shock-Loading Effects on Superconductivity of HgBa2CuOy." To be published in Physica C (in press). Superconductivity Research Laboratory, International Superconductivity Technology Center (ISTEC), 10-13 Shinonome 1-chome, Koto-ku, Tokyo 135, JAPAN; telephone +81 3 3536 0618; telefax +81 3 3536-5714; e-mail yamamoto@istec.or.jp.

E. E. Tornau, S. Lapinskas, and A. Rosengren, "Order-Disorder Phase Transition in Bismuth-Based High-Temperature Superconductors." To be published in Physica C (in press). Semiconductor Physics Institute, Gostauto 11, 2600 Vilnius, LITHUANIA; telephone +370 2 617902; telefax +370 2 627123; e-mail et@et.pfi.lt. Key words: order-disorder phase transition, ice rule, bismuth superconductors. 74.72.Bk; 74.62.Dh; 64.60.Cn.

N. V. Vo, J. E. Ostenson, J. O. Willis, D. E. Peterson, J. L. Smith, H. K. Liu, and S. X. Dou, "Magnetization Studies and Irreversibility Behavior of High-Tc Superconducting Bi(Pb)-2223 Multifilamentary Ag- Sheathed PIT Tapes Prepared from Differently Synthesized Precursor Powders." Preprint #LA-UR-97-4206; to be published in Phys. Rev. B. Superconductivity Technology Center, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, NM 87545; telephone (505) 665-6859; telefax (505) 665-3164; e-mail nvv@lanl.gov.

Hideki Yamamoto, Michio Naito, and Hisashi Sato, "A New Superconducting Cuprate Prepared by Low-Temperature Thin-Film Synthesis." To be published in Advances in Superconductivity X (Springer-Verlag, Tokyo, 1998): Proc. of the 10th Int. Symp. on Supercond. (ISS'97), Gifu, Japan, Oct. 27-30, 1997. MATSUDA Research Group, Materials Research Laboratories, NTT Basic Research Laboratories, 3-1 Wakamiya, Morinosato, Atsugi-shi, Kanagawa 243-01, JAPAN; telephone +81 462 40 3523; telefax +81 462 70 2364; e-mail hideki@will.brl.ntt.co.jp. Key words: new high-Tc cuprate, Ba-Cu-O, reactive co-evaporation, low-temperature synthesis, strong oxidation.

Suk-Woo Yang, Hyung-Shik Shin, Il-Hyun Kuk, Gye-Won Hong, and Chan-Joong Kim, "Plastic Extrusion of YBa2Cu3O7-y-Ag Composite Superconducting Wires Using Pyrophoric Synthetic Powder." Presented at the 10th Int. Symp. on Supercond. (ISS'97), Gifu, Japan, Oct. 27-30, 1997. Contact Chan-Joong Kim, Superconductivity Research Laboratory, Korea Atomic Energy Research Institute, P.O. Box 105, Yusung, Taejon 305-600, SOUTH KOREA; telephone +82 42 868 8908; telefax +82 42 862 5496; e-mail cjkim2@nanum.kaeri.re.kr.

M. Zamboni, S.A.L. Foulds, S. Koishikawa, K. Matsumoto, M. Murakami, and J. S. Abell, "Magneto-Optic and Electron Beam-Induced Voltage Contrast Studies of YBCO Thin Films." Presented at the 3rd European Conf. on Appl. Supercond. (EUCAS'97), Veldhoven, The Netherlands, June 30-July 3, 1997. Contact S.A.L. Foulds, Superconductivity Research Group, School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, UNITED KINGDOM; telephone +44 121 414 5170; telefax +44 121 414 5232; e-mail s.a.l.foulds@bham.ac.uk.

B. Zeimetz, H. K. Liu, and S. X. Dou, "Microstructural Study of Bi2223/Ag Tapes Made Using a Two-Stage Sintering Procedure." Submitted to Supercond. Sci. & Technol. Centre for Superconducting and Electronic Materials, University of Wollongong, Wollongong NSW 2522, AUSTRALIA; telephone +61 242 215766; telefax +61 242 215731; e-mail bpz01@uow.edu.au.

D. N. Zheng, S. Ali, H. A. Hamid, C. Eastell, M. Goringe, and D. P. Hampshire, "The Critical Current of the Chevrel Phase Superconductor: Lead-Molybdenum-Sulphur with Gadolinium." To be published in Physica C (in press). Department of Physics, University of Durham, South Road, Durham DH1 3LE, UNITED KINGDOM; telephone +44 191 374 2123; telefax +44 191 374 3749; e-mail d.n.zheng@durham.ac.uk.

COMING EVENTS (An * indicates a previously listed event.)

Jan. 15 - 16, 1998: Military and Commercial Applications for Low Cost Cryocoolers (MCALC II) -- An Industry Assessment Workshop, Humphrey's Half Moon Inn, Shelter Island, Calif. Sponsored by the Electronic Industries Association (EIA) in cooperation with DARPA, NRL, and CNVEO. Special Wireless Base Station Conclave on Jan. 16 (afternoon) will include participants from Lucent, Ericson, Nokia, Nortel, and from the superconductivity community Conductus, STI, and SCT. Purpose of the workshop is to promote an ongoing dialog among suppliers and users of cryocoolers. Technical presentations, market information, and supplier booths. Representatives from the supplier community will give a brief description of their corporation's product capabilities. One of the tangible results of the program will be an industry-wide directory of current products and services. User presentations from IR markets, medical markets, wireless industries, commercial and surveillance industries, cool computing market, and the large-volume military market. For further information, contact Eric Samuelson, EIA ALCEM, 2500 Wilson Boulevard, Arlington, VA 22201; telephone (703) 907-7546; telefax (703) 907-7549; e-mail cryo@eia.com; Web site http://www.eia.org/ieg/cryo.

*Feb. 19 - 24, 1998: First International Conference on New Theories, Discoveries, and Applications of Superconductors and Related Materials (New3SC-1), Baton Rouge, La. Call for papers. Purpose of conference is to attempt to determine if "a radical change is needed in the fundamental approach to superconductivity, or if the conventional approaches are likely to bear fruit soon." Conference will focus on new ideas and measurements, concepts, and models of the mechanism and origin of high-temperature superconductivity. Discussion time will be provided throughout the conference. Subjects include superconductors, giant magnetoresistance, and ferroelectric materials. Abstract deadline, December 15, 1997. For further information, contact J. D. Fan, Chairman New3SC, P.O. Box 9767, Baton Rouge, LA 70813-9767; telephone (504) 771- 3926; telefax (504) 771-3926; e-mail new3sc@grant.phys.subr.edu; Web site http://www.phys.subr.edu/conference/new3sc.htm.

*April 19 - 24, 1998: The Seventh Conference on Frontiers of Electron Microscopy in Materials Science, Kloster Irsee, Irsee, Germany. Purpose of this meeting is to establish the current state of the art of quantification of all relevant techniques used in electron microscopy including XEDS, EELS, Z-contrast, HREM, conventional TEM, CBED, and in- situ. Topical area: quantitative methods in electron microscopy. Number of participants limited to 100 (30 invited speakers, 20 invited session chairs, and 50 participants). Abstract deadline, January 15, 1998; registration deadline, February 16, 1998. The organizers of FEMMS98 also announce the availability of up to five graduate student awards to participate in FEMMS98. The applicant must have good standing in a recognized academic graduate degree program and must participate in FEMMS98 as the author or co-author of a paper. For information, contact Kloster Irsee, Schwaebisches Tagungs- und Bildungszentrum, Klosterring 4, 87660 Irsee, Germany; telephone +49 8341 906-00; telefax +49 8341 742-78; Web site http://femms98.llnl.gov.

May 4 - 8, 1998: Workshop on Complex Systems, International Centre of Condensed Matter Physics, Universidade de Brasilia, Brazil. Sponsored by CAPES, CNPq, FAP-DF, FINEP, ICTP (Trieste, Italy) and IUPAP. Plenary talks include the following topics: self-organized criticality and punctuated equilibria; the science and the surprise of artificial worlds and the science of surprise in nature and in life; spin glasses, glasses, and granular materials; statistical mechanics of globular and lamellar polyelectrolytes (effective interactions, structure, and phase transitions); theory of wetting, line and boundary tensions, and fluctuations in the structure of interfaces; and complex systems and simple statistical laws. Limited funds available to cover living and travel expenses. Application deadline for financial support, December 15, 1997; abstract deadline, February 20, 1998. For information, contact Workshop on Complex Systems, Centro International de Fisica da Materia Condensada, Universidade de Brasilia, Caixa Postal 04513, 70919- 970 Brasilia-DF, Brazil; telephone +55 61 348 2572; telefax +55 61 273 3884; e-mail info@iccmp.br.

*May 26 - 28, 1998: 10th International Cryocooler Conference, Monterey Conference Center, Monterey, Calif. Technical program will consist of oral and poster sessions. Invited technical topics include Stirling and pulse-tube cryocoolers, J-T and sorption cryocoolers, G-M and TEC cryocoolers, new concepts, component developments, modeling and test techniques, performance and life test data, applications and integration issues, and low-cost coolers. Oral and poster sessions. Abstract deadline, December 12, 1997. For information, contact Peter Kittel, ICC10, MS-244-10, NASA/Ames Research Center, Moffett Field, CA 94035- 1000; telephone (650) 604-4297; telefax (650) 604-1094; e-mail pkittel@mail.arc.nasa.gov.

*July 19 - 24, 1998: Superconducting Superlattices II -- Native and Artificial: Symposium SD81 of the SPIE's Annual Meeting on Optical Science, Engineering, and Instrumentation, San Diego Convention Center and the Marriott Hotel & Marina, San Diego, Calif. Conference will include papers devoted to structural, electronic, transport, and other phenomena in such heterostructures and intercalates. Experimental and theoretical papers which are related to superconducting superlattices are solicited in the following areas: (1) epitaxial and morphological properties, interface smoothness and disorder, layer thickness fluctuations, interdiffusion, and strain, structure of defects; (2) critical temperature, critical currents, and critical magnetic fields; (3) nature of c-axis transport in cuprates and artificial superlattices; (4) electronic structure, charge redistribution, localization, single- particle and collective excitations; (5) Josephson phenomena in natural and artificial superlattices and Josephson plasma oscillations; (6) structure of flux lines, thermal and field-induced flux motion, intrinsic flux pinning; (7) effective dimensionality and dimensional crossovers, superconductivity in ultrathin layers, Kosterlitz-Thouless transition; and (8) proximity effects: superconductors in contact with insulators, semiconductors, normal metals, ferro- and antiferromagnets, piezoelectrics, etc. Abstract deadline, December 22, 1997. Abstracts may be submitted by Web page, e-mail, regular mail, or fax. Proceedings to be published. For information, contact SPIE, P.O. Box 10, Bellingham, WA 98225; telephone (360) 676-3290; telefax (360) 647-1445; e-mail SD98@spie.org; Web site http://www.spie.org.

*July 19 - 24, 1998: Superconducting and Related Oxides: Physics and Nanoengineering III, Symposium SD82, is third in the series of SPIE conferences focused on basic issues in physics and materials science of high-temperature superconductors and related compounds that may be relevant for their applications in electronics, optics, and optoelectronics. Venue is the same as in the previous listing. Scientists and engineers engaged in research on superconducting materials and related compounds, as well as their novel applications, are invited to participate. Original papers are solicited on, but not limited to, the following topics: (1) structural, transport, magnetic, and thermal properties of thin films of cuprates and related compounds; (2) homoepitaxy and new substrate materials; (3) search for novel high- temperature superconducting phases by atomic engineering; (4) composition and structure of defects; (5) anion and cation substitutions, metal-insulator transition, and localization; (6) proximity effects; surface and interface effects; superconductors in contact with insulators, semiconductors, normal metals, ferro- and antiferromagnets, piezoelectrics, etc.; (7) novel device concepts, electric field effect in heterostructures, hybrid optoelectronic devices, and cryo-electronics. A round-table discussion is planned in which representatives of prominent groups in industry, academia, and national laboratories will be invited to expound on their respective progress and strategies in combining basic physics and materials research and developing specific applications, and discuss the future of superconducting electronics. Abstract deadline, December 22, 1997. Abstracts may be submitted by Web page, e-mail, regular mail, or fax. Proceedings to be published. For information, contact SPIE, P.O. Box 10, Bellingham, WA 98225; telephone (360) 676-3290; telefax (360) 647- 1445; e-mail SD98@spie.org; Web site http://www.spie.org.

RESOURCES

Information

New Book: Mossbauer Spectroscopy of Sophisticated Oxides, edited by A. Vertes and Z. Homonnay. Papers collected in this volume involve application of Mossbauer spectroscopy to the investigation of oxides having complex, intricate, and versatile features. Chapters include: physical basis of Mossbauer spectroscopy; Mossbauer effect in inorganic glasses; Mossbauer effect in magnetic oxides; Mossbauer spectroscopy of high-Tc superconductors; and Mossbauer effect studies of alkali metal ferrates (IV), (V), and (VI). Publ. 1997; 340 pp.; price $75; ISBN 963 05 6953 1. For information, contact Akademiai Kiado Rt., P.O. Box 245, H-1519 Hungary; telephone +36 1 204-3973; telefax +36 1 204-3973.

Books: Quantum Statistical Theory of Superconductivity, by Shigeji Fujita and Salvador Godoy. Designed primarily as a guide for graduate students to the essential aspects of superconductivity. Five preparatory chapters review a number of advanced physical concepts such as free-electron model of metals, theory of lattice vibrations, and Bloch electrons. The remaining chapters deal with the theory of superconductivity describing the basic properties of type I, type-II compound, and high-Tc superconductors, and treats quasiparticles using Heisenberg's equation of motion. The book includes step-by-step derivations of mathematical formulas, sample problems, and illustrations. Publ. 1996; 358 pp.; price $59.50 (U.S. and Canada), $71.40 (elsewhere); ISBN 0-306-45363-0.

The New Superconductors, by Frank J. Owens and Charles P. Poole, Jr., offers a descriptive, non-mathematical presentation of the latest superconductors and their properties for the non-specialist. Highlights include chapters on superfluidity, the copper-oxide superconductors, fullerenes, and prospects for future research. Book also features many examples of commercial applications, an extensive glossary that defines superconductivity terms, and a supplementary list of readings for the interested lay reader. Publ. 1996; 215 pp.; price $39.50 (U.S. and Canada), $47.40 (elsewhere); ISBN 0-306-45453-X.

For information or orders contact Plenum Publishing Corporation, Dept. TNC, 233 Spring Street, New York, NY 10013-1578; telephone (212) 620- 8047 or (800) 221-9369; telefax (212) 647-1898; Web site http://www.plenum.com/.

FYI (High-Tc Update takes no responsibility for want ads listed in this section.)

Position available: Postdoctoral position available at Central Research Institute of Electric Power Industry (CRIEPI) in Tokyo, Japan, for an individual with strong background in materials research or crystal growth of high-Tc cuprates. Appointment will be for up to two years. Salary: 376,000 Japanese Yen per month or higher. Position to be funded by a Japanese governmental organization. Ph.D. in physics, materials science, or chemistry is required. Application deadline, December 25, 1997. Applicants should send CV to Yoichi Ando, CRIEPI, 2- 11-1 Iwato-kita, Komae, Tokyo 201, Japan; telefax +81 3 3480-3401; e- mail ando@criepi.denken.or.jp.

[I will try to make the picture available on the Web soon!]

FIG. 1. Science Editor, John R. Clem, happily levitating at the 10th International Symposium on Superconductivity (ISS'97), October 27-30, 1997, Gifu, Japan, organized by the Superconductivity Research Laboratory (SRL), International Superconductivity Technology Center (ISTEC). The aluminum disk supporting him is held up by several rings of Nd-Fe-B magnets levitating over 200 melt-textured YBCO disks at 77 K.

High-Tc Update is the high-Tc superconductivity information exchange newsletter. Please send 1) preprints, reprints, and other research reports; 2) descriptions of on-going work; 3) meeting announcements and summaries.

The information contained herein is intended for limited distribution. Readers are expected to respect the rights of the authors.

Please address all contributions and inquiries to: Dr. Sreeparna Mitra, A219 Physics, Ames Laboratory/Iowa State University, Ames, Iowa 50011-3020. Telephone: (515) 294-3877 Telefax: (515) 294-1134. E-mail: MITRA@AMESLAB.GOV or MITRA@IASTATE.EDU

Project Director/Editor: Sreeparna Mitra
Science Editor: John R. Clem
High-Tc Update, Vol. 11, #23, December 1, 1997.