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The Phase Change Due to Oxygen Content in the LnBa 2 Cu 3 O y Compound Systems (Ln=Tm, Gd, Sm)

1989; Institute of Physics; Volume: 28; Issue: 4A Linguagem: Inglês

10.1143/jjap.28.l609

1347-4065

Mineo Kogachi, Shigemitsu Nakanishi, Kiyotaka Nakahigashi, Hiroyuki Sasakura, Shinnosuke Minamigawa, Nobuo Fukuoka, Akira Yanase,

Advanced Condensed Matter Physics

The phase change due to oxygen content y (7> y >6) was investigated for TmBa 2 Cu 3 O y (TBC), GdBa 2 Cu 3 O y (GBC) and SmBa 2 Cu 3 O y (SBC) by means of X-ray diffraction and electrical resistivity. The phase boundary between orthorhombic and tetragonal phases moved toward the oxygen-rich side when the system changed as TBC→YBa 2 Cu 3 O y (YBC)→GBC→SBC. The plateau in the critical temperature T c was observed in the intermediate region of 6.7> y >6.4 for each system, supporting the existence of an orthorhombic-II phase. It seemed to exhibit a system dependence, i.e., a decrease in T c in the order of TBC, YBC, GBC and SBC.