Cerium distribution coefficient and its dependence on oxygen partial pressure in Nd2−xCexCuO4 single crystal growth

✍ Scribed by K. Gamayunov; I. Tanaka; H. Kojima

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 418 KB
• Volume: 218
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90047-t

✦ Synopsis

A strong dependence of the cerium distribution coefficient (Kc~) on oxygen partial pressure P[O2] has been shown in direct .lalm 0.2 arm TSFZ experiments by changing the oxygen pressure during Nd2_xCe~CuO4 single crystal growth. The ratio of K°~ /Kc~ has been found to be equal to ~ 0.62. Absolute values of Kc~ measured from zone compositions have been found to be about 2.42, 3.37 and 9.06 at P[O2 ] = 0.1, 0.2 and 2.0 atm, respectively. Our experiment shows good agreement between measured and calculated Kc~ values. We have shown that the quite large difference in Kc~ obtained in a number of investigations is explained by a strong dependence of Kc~ on P[O2]. We have also shown that a reason for this dependence is the variable valence of Ce. Cerium effectively incorporates in a Nd2_,CexCuO4 single crystal in the form of Ce +4 ion.