T 44 The Structure, Nonstoichiometry, and Thermodynamic Characteristics of Oxygen in Strontium Ferrite Doped with Niobium, SrFe1-xNbxO3-δ / P. V. Anikina, A. A. Markov, M. V. Patrakeev, I. A. Leonidov, V. L. Kozhevnikov // Russian Journal of Physical Chemistry A. - 2009. - Vol. 83, № 5. - P699-704 : il. - Bibliogr. : p. 704 (14 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): НЕСТЕХИОМЕТРИЯ -- КИСЛОРОД -- ФЕРРИТ СТРОНЦИЯ -- ДОПИРОВАНИЕ -- НИОБИЙ Аннотация: The influence of doping with niobium on the structure and oxygen nonstoichiometry of strontium ferrite SrFe1 –xNbxO3 –δ(x= 0.05, 0.1, 0.2, 0.3, and 0.4) was studied. The content of oxygen in the doped derivatives was determined by coulometric titration as a function of temperature (650–950°C) and oxygen partialpressure in the gas phase (10–4–1 atm). The partial molar enthalpies ΔΉo(x,δ) and entropies ΔSo(x,δ) of oxygen in SrFr1−xNbxO3 –δ were calculated. An analysis of ΔSo(x,δ) dependences showed that the model of a random distribution of ions and vacancies over accessible sites in the oxygen sublattice allowed the experimental data to be described satisfactorily. An increase in the partial enthalpy ΔHo(x,δ) as nonstoichiometry δ decreased was indicative of weak repulsive interactions between oxygen ions in the structure of SrFe1 –xNbxO3 –δ Полный текст |