Oxygen Disorder Effects in High-Tc Superconductors

ISBN-13: 9781461278672 / Angielski / Miękka / 2011 / 231 str.

Ivan K. Schuller; J. L. Moran-Lopez

Opis

The papers in this book represent the proceedings for the International Conference on Oxygen Disorder Effects in High Tc Superconductors, held April 18-21, 1989 at the International Centre for Theoretical Physics, Trieste, Italy. It was recognized very early in the field of ceramic superconductors that oxygen plays a crucial role as far as the physical properties of these ma terials are concerned. The preparation requires special heating and cooling cycles which allow proper uptake of oxygen, relationships were found between the oxygen concentration and the superconducting transition temperature in many of the compounds and quite recently it was recognized that many (if not all) of the compounds present oxygen ordering in the intercalating planes. Moreover, it seems that the presence of superconductivity is strongly correlated with the presence of orthorhombic phases although several groups have also claimed the presence of superconductivity in tetragonal phases. Whether oxygen ordering plays or not a crucial role for the superconductivity remains to be seen. However it is clear that the ordering of oxygens and their thermodynamic properties is an interesting subject on its own right. All these reasons led us to organize a Conference on Oxygen Disorder Effects in High-Tc Superconductors in attempt to identify unsolved problems and to have an open discussion of the presently known facts."

Spis treści

Phase Diagrams: Experimental and Theoretical Studies.- Powder Neutron Diffraction Study of the Structural Phase Diagram of the Ba1?x KxBiO3 System.- Electron Microscopic Studies of Oxygen Ordering Phenomena in YBa2 Cu3 O7??.- Local Atomic Displacements in High Tc Oxydes Studied by Pulsed Neutron Scattering.- Oxygen Stoichiometry and Superconductivity in Ceramics.- Oxygen Ordering in YBA2Cu3O6+?: A Phase Diagram Calculation.- States of Oxygen Ordering in YBa2Cu3Oz.- Electronic Structure.- Effects of Correlation and Disorder on the Electronic Properties of RBa2 Cu3 O6+x.- Tight-binding Investigation of the Electronic Properties of Ordered and Disordered Defects in the YBaCuO system.- Electronic Structure of the Cuprate and Bismuthate Superconductors.- Magnetic Properties.- Flux Pinning and Thermally Activated Flux Flow Behavior in Single Crystalline YBa2Cu3O7 and Bi2Sr2CaCu2O8.- Superconducting Phase Diagram of. High Tc Ceramic.- Magnetic Ordering of Rare Earth (R) Ions in RBa2Cu3O7?? Compounds (R=Nd, Sm, Dy, Er; 0? ? ?1).- Spin and Hole Dynamics in Doped Anisotropic Heisenberg Antiferromagnets.- Spin-hole Model with Magnetic Vortex-antivortex Pairing Mechanism for Doped La2 CuO4.- Chemical Substitutions.- Study of Superconducting ANsD Parent Phases by Chemical Modifications.- Experimental Study of High Temperature Superconductors through Substitutions.- Theoretical Study of Oxygen Disorder Effects in YBa2 (Cu1?x Mx)3 O7?y (M=A1, Co, Fe, Ga).- Phonons.- Characterization of Twins and Twin Domains of YBaCuO Single Crystals by Micro-Raman Scattering.- Summary.- Oxygen Disorder Effects in High Tc Superconductors, 1989.