High-pressure synthesis of 0212-, 1201- and 1212-type copper oxides

High-pressure synthesis technique was applied for 0212-, 1201- and 1212-typ e copper oxides, to find several new phases. the (Nd, Ce)(2+x)CaCu2Oy phase has a shear structure derived from the 0212 structure. It has an orthorhom bic phases. The (Nd,Ce)2_C Y I = 19.3 A which are related to the tetragonal lattice as as = /2a, bs = 5,/2b, superlattice of a(s) = 5.4, b(s) = 27.4 a nd c(s) = 19.3 Angstrom which are related to the tetragonal lattice as a(s) = root 2a, b(s) = 5 root 2b, c(s) = c. Two step weak ferromagnetic transit ions were observed at 150 and 40 K in this Ce-doped phase. The 1201 phase o f CCa2CuO5+delta was prepared for the first time. Superconductivity appeare d below approximate to 11 K in the samples with high excess oxygen contents . The 1212 phases of RuSr(2)LnCu(2)O(8) were isolated for smaller rare eart h elements of Ln = Dy, Y, Ho, Er. The Y-analogue undergoes ferromagnetic tr ansition near 150 K followed by superconducting transition at 39 K. (C) 200 1 Elsevier Science B.V. All rights reserved.