High-Temperature X-Ray Diffraction Investigation of the Decomposition Process in Manganese-Gallium Spinel Mn1.5Ga1.5O4

• Published in: Journal of structural chemistry Vol. 59; no. 2; pp. 370 - 376
• Main Authors: Venediktova, O. S., Bulavchenko, O. A., Tsyrulnikov, P. G., Afonasenko, T. N., Vinokurov, Z. S., Tsybulya, S. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.03.2018; Springer Nature B.V
• Subjects: Atomic; Atomic/Molecular Structure and Spectra; Cations; Chemistry; Chemistry and Materials Science; Crystallization; Decomposition; Gallium; Inorganic Chemistry; Manganese; Molecular; Optical and Plasma Physics; Oxygen atoms; Physical Chemistry; Solid State Physics; Spinel; Stoichiometry; Thermogravimetry; Vacancies; X-ray diffraction; high-temperature X-ray diffraction; phase transformations; manganese-gallium spinel; aluminum-manganese spinel; manganese-containing double oxides
• ISSN: 0022-4766; 1573-8779
• DOI: 10.1134/S0022476618020166

The stability of spinel-type mixed Mn 1.5 Ga 1.5 O 4 oxide prepared in an inert medium (1000 °C, Ar) is studied by thermogravimetry and high-temperature X-ray diffraction in air in a wide temperature range 30–1000 °C. On heating, reversible decomposition processes of initial spinel are observed. From 30 °C to 600 °C oxygen atoms attach to the surface layer of initial Mn 1.5 Ga 1.5 O 4 spinel to form a new phase distinct from parent oxide by the oxygen stoichiometry (cation vacancies are formed). The product of decomposition is two oxides: Mn 1.5 Ga 1.5 O 4 and Mn 1.5– x Ga 1.5– x [·] x O 4 . On the contrary, above 600 °C a loss of oxygen occurs, the concentration of cation vacancies decreases in Mn 1.5– x Ga 1.5– x [·] x O 4 , and the reverse process of single phase oxide crystallization takes place. At 1000 °C the spinel phase forms again whose composition is similar to that of the initial parent phase Mn 1.5 Ga 1.5 O 4 . On cooling the decomposition of this phase is again observed due to oxygen attachment.