Oxygen nonstoichiometry and defect equilibrium in La2 ? xSrxNiO4 + δ |
| |
| Authors: | Takashi Nakamura Keiji Yashiro Kazuhisa Sato Junichiro Mizusaki |
| |
| Institution: | Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-Ku, Sendai, 980-8577, Japan |
| |
| Abstract: | Nonstoichiometric variation of oxygen content in La2 ? xSrxNiO4 + δ (x = 0, 0.1, 0.2, 0.3, 0.4) and decomposition P(O2) were determined by means of high temperature gravimetry and coulometric titration. The measurements were carried out in the temperature range between 873 and 1173 K and the P(O2) range between 10? 20 and 1 bar. La2 ? xSrxNiO4 + δ showed the oxygen excess and the oxygen deficient compositions depending on P(O2), temperature, and the Sr content. The value of partial molar enthalpy of oxygen approaches zero as δ increases in the oxygen excess region, which indicate that the interstitial oxygen formation reaction is suppressed as δ increase. The relationship between δ and logP(O2) were analyzed by two types of defect equilibrium models. One is a localized electron model, and the other is a delocalized electron model. Both models can well explain the oxygen nonstoichiometry of La2 ? xSrxNiO4 + δ with a regular solution approximation. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
