Open AccessThermally stimulated oxygen desorption in Sr2FeMoO6-δ
Author(s) -
Н. А. Каланда
Publication year - 2019
Publication title -
izvestiâ vysših učebnyh zavedenij. materialy èlektronnoj tehniki
Language(s) - English
Resource type - Journals
eISSN - 2413-6387
pISSN - 1609-3577
DOI - 10.17073/1609-3577-2018-1-48-53
Subject(s) - activation energy , oxygen , desorption , chemistry , diffusion , analytical chemistry (journal) , crystallite , limiting oxygen concentration , crystallography , thermodynamics , chromatography , organic chemistry , adsorption , physics
Polycrystalline Sr 2 FeMoO 6-δ specimens have been obtained by solid state synthesis from partially reduced SrFeO 2.52 and SrMoO 4 precursors. It has been shown that during oxygen desorption from the Sr 2 FeMoO 6-δ compound in polythermal mode in a 5%H 2 /Ar gas flow at different heating rates, the oxygen index 6–δ depends on the heating rate and does not achieve saturation at T = 1420 K. Oxygen diffusion activation energy calculation using the Merzhanov method has shown that at an early stage of oxygen desorption from the Sr 2 FeMoO 6-δ compound the oxygen diffusion activation energy is the lowest Е а = 76.7 kJ/mole at δ = 0.005. With an increase in the concentration of oxygen vacancies, the oxygen diffusion activation energy grows to Е а = 156.3 kJ/mole at δ = 0.06. It has been found that the dδ/d t = f ( Т ) AND dδ/d t = f (δ) functions have a typical break which allows one to divide oxygen desorption in two process stages. It is hypothesized that an increase in the concentration of oxygen vacancies V ·· leads to their mutual interaction followed by ordering in the Fe/Mo–O1 crystallographic planes with the formation of various types of associations.