Phase diagrams and ionic defects in the 2212 and 2201 phases of the bismuth system

✍ Scribed by Yasushi Idemoto; Shinichi Kobayashi; Kazuo Fueki

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 689 KB
• Volume: 229
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90811-7

✦ Synopsis

The compositional diagrams representing the stability regions of the 2212 and 2201 phases of the bismuth system were constructed for several temperatures above 820°C. The actual densities of both phases were determined by pycnometry and compared with the theoretical densities. It was found that the maximum ion deficiency is about 2% for the 2212 phase and nearly zero for the 2201 phase. The valences of Bi and Cu were determined by chemical analysis and the excess oxygen was calculated. The maximum excess oxygen was found to be 2.5% and 3% for the 2212 and 2201 phases, respectively. From the ion deficiency and the excess oxygen, it was concluded that the excess oxygen occupies not the vacancy but the interstitial site.