Large single crystal Bi-2212 along the c-axis prepared by floating zone method

The cation solubility limits of the n= 2 and n= 3 superconducting phases in the Bi2(SrxCa1 −x)n+1CunOy system were established along tie lines with compatible phases via electron probe microanalysis on bi- (or poly-) phasic samples prepared at 860°C. Pb additions (15 mol% of the Bi content) were used to facilitate formation of the n= 3 phase. In each case football-shaped volumes in composition space were established as the solubility limits which bordered on the nominal compositions 2212 or 2223 (Bi:Sr:Ca:Cu) with the long axis parallel to the Sr-Ca side of the quaternary (i.e., Sr-to-Ca intersolubility) but also extending toward Bi and Cu. This means that, for the most part, the superconducting phases are alkaline-earth deficient relative to the ideal 2212 and 2223 compositions. The Pb content in the 2223 phase is typically 10% of the Bi content. Tc variations could be correlated with variations in Sr or (Sr + Bi) content and the length of the c-axis parameter.

Solid‐Solution Ranges of the n= 2 and n= 3 Superconducting Phases in Bi2(SrxCa1 −x)n+1CunOy and the Effect on Tc

Crystal growth and annealing experiments of the high Tc superconductor Bi2Sr2CaCu2O8 + δ

Growth mechanism of Bi2Sr2CaCu2Ox superconducting whiskers

This paper deals with the growth of single crystals of HTSC materials. We describe the main techniques and innovations of the last few years. The materials reviewed here are from the Y-Ba-Cu-O system, the Bi-Sr-Ca-Cu-O system and the Tl-Ba-Ca-Cu-O system.

http://iopscience.iop.org/article/10.1088/0953-2048/6/8/001/pdf

Crystal growth of HTSC materials

Single crystal growth of the superconductor Bi2.0(Bi0.2Sr1.8Ca1.0)Cu2.0O8

The compound Ba2YCu3O7-y(7-y<6.7) was prepared using a successive heat treatment of a sample by (1) quenching from high temperature, (2) sealing in a gold capsule, (3) heating and cooling in a furnace and (4) annealing at 420°C followed by (5) final quenching. Linear depression of the superconducting transition temperature occurred with increasing c dimensions of the final products. The orthorhombic phase with 7-y<6.5 could not be prepared, and the tetragonal phase with the c cell dimension of 11.743-11.757 A was also unstable below 570°C, and unknown green phases were produced instead of Ba2YCu3O7-y.

Preparation of Ba 2 YCu 3 O 7− y with T c below 65 K

Stability of aluminium orthophosphate in the system NH3AIPO4−P2O5−H2O

Ba2YCu3O7-y(7-y\fallingdotseq6.48) was prepared by quenching a specimen from 735–738°C in air, and subsequently annealing at 420°C in a sealed gold capsule. The material may have been a superconductor for about 3 min after the opening of the gold capsule, but it changed to a nonsuperconducting material with high electrical resistivity by the reaction with moisture in air. The lattice constants of the material are abnormal, and a superstructure was observed for 30–40% of the particles by electron microscopy.

Michiko Kobayashi

Papers

Single crystal growth of the superconductor Bi2.0(Bi0.2Sr1.8Ca1.0)Cu2.0O8

Preparation of Ba 2 YCu 3 O 7− y with T c below 65 K

Stability of aluminium orthophosphate in the system NH3AIPO4−P2O5−H2O

Structural and Electrical Anomalies of Ba2YCu3O7-y at the Oxygen Stoichiometry of 6.48