N 30 Naumovich, E. N. Defect formation in LaGa(Mg,Ni)O3-delta: A statistical thermodynamic analysis validated by mixed conductivity and magnetic susceptibility measurements [Текст] / E. N. Naumovich, V. V. Kharton, A. A. Yaremchenko, M. V. Patrakeev, D. G. Kellerman, D. I. Logvinovich, V. L. Kozhevnikov // Physical Review B: Condensed Matter and Materials Physics. - 2006. - Vol. 74, № 6. - С. 064105/1-064105/12. - Библиогр. : с. 064105/11 (55 назв.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): МАГНИТНАЯ ВОСПРИИМЧИВОСТЬ -- ПРОВОДИМОСТЬ -- ГАЛЛАТ ЛАНТАНА -- ПЕРОВСКИТЫ Аннотация: A statistical thermodynamic approach to analyze defect thermodynamics in strongly nonideal solid solutions was proposed and validated by a case study focused on the oxygen intercalation processes in mixed-conducting LaGa0.65Mg0.15Ni0.20O3−delta perovskite. The oxygen nonstoichiometry of Ni-doped lanthanum gallate, measured by coulometric titration and thermogravimetric analysis at 923–1223 K in the oxygen partial pressure range 5 10−5 to 0.9 atm, indicates the coexistence of Ni2+, Ni3+, and Ni4+ oxidation states. The formation of tetravalent nickel was also confirmed by the magnetic susceptibility data at 77–600 K, and by the analysis of p-type electronic conductivity and Seebeck coefficient as function of the oxygen pressure at 1023–1223 K. The oxygen thermodynamics and the partial ionic and hole conductivities are strongly affected by the pointdefect interactions, primarily the Coulombic repulsion between oxygen vacancies and/or electron holes and the vacancy association with Mg2+ cations. These factors can be analyzed by introducing the defect interaction energy in the concentration-dependent part of defect chemical potentials expressed by the discrete Fermi-Dirac distribution, and taking into account the probabilities of local configurations calculated via binomial distributions Полный текст |