Kenichi Hoshino

Superconductivity in YBa2Cu3-yNiyO7-δ

Superconductivity in alloyed compounds YBa2Cu3-yNiyO7-δ has been studied in order to gain direct insights on the roles different Cu sites play in electrical conduction. Electron probe microanalysis as well as X-ray powder diffraction analysis shows that Ni is actually substituted for Cu in the oxygen-deficient perovskite compound for y at least as much as 0.27. Electrical resistivity measurements revealed that the substituted Ni does not substantially destroy the superconductivity.

Analysis of Crystal Structure of an Y-Ba-Cu Oxide

Results of the analyses on crystal structure and chemical composition of dark-green crystals mainly found in an Y-Ba-Cu oxide specimen which shows high-Tc superconductivity are reported. Crystal structure is investigated by the electron diffraction method and is determined to be orthorhombic with lattice parameters a=1.22 nm, b=0.561 nm and c=0.714nm, and with a space group Pnma (No. 62) or Pna21 (No. 33). Expected d-values are presented and are successfully compared with the X-ray powder diffraction spectrum obtained from this oxide. Chemical composition is analyzed by the EPMA method and is determined to be Y2BaCuO5-y for the oxide.

The Machangqing copper-molybdenum deposits, Yunnan, China- an example of Himalayan porphyry-hosted Cu-Mo mineralization

SummaryThe Machangqing copper-molybdenum deposits occur in the Shanjian fold belt, Yunnan Province, China. Two types of ores are distinguished: (1) Cu-Mo quartz veinlets in magnetite-series granite porphyry; and (2) Cu-Mo skarns occurring at the contact between the Ordovician sedimentary sequence and the granite porphyry. With decreasing temperature and

Substitution for copper in a high-Tc superconductor YBa2Cu3O7–δ

a_{K^ + } /a_{H^ + }

Metallogenic epochs in the Inner Zone of southwest Japan

of hydrothermal fluids initially in equilibrium with K-feldspar, the following alteration patterns developed within the porphyry, from the center outwards: silicification, K-silicate, phyllic and argillic alteration. The paragenetic sequence of alteration minerals observed in the Cu-Mo skarns resulted from decreasing temperature and/or increasing

Hydrothermal alteration in an exhumed crustal fault zone: Testing geochemical mobility in the Caleta Coloso Fault, Atacama Fault System, Northern Chile

a_{Ca^{2 + } } /a_{H^ + }^2