Phase stability in the LaBaCuO system at 980°C and 200 bar oxygen pressure

✍ Scribed by M.R. Chandrachood; K.K. Singh; D.E. Morris; A.P.B. Sinha

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 248 KB
• Volume: 241
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)02317-4

✦ Synopsis

The LaOLs-BaO-CuO pseudo-ternary phase diagram at 200 bar oxygen pressure was explored by a solid-state reaction at 980"C of numerous compositions. The phases which formed have been identified by X-ray diffraction. Significant differences from phases formed in air are noticed. BaCuO2 and Ba2CuO3 arc absent, Ba2Cu3Os+~ is stabilized. La2CuO4 remains stable, in addition LaCuOa is formed in high pressure. Both La2CuO4 and LaCuO3 show an extended solubility with Ba 2+ replacing La 3+. The following phases do not form in a high P(O2): LaBa2Cu3OT, LaBa2Cu4Os, La4BaCusO~3, LaaBaaCu6Oio, La2BaCu206 and La2BaCuOs. This is possibly because LaCuO3 is a highly oxidized phase (FCV~ 3.0), which is therefore strongly favored at elevated P(O2) of 200 bar. Tie-lines have been worked out and a tentative phase diagram is presented.