Phase Transformations in the Mn–Ga–O System Depending on the Preparation Conditions

• Published in: Journal of structural chemistry Vol. 59; no. 7; pp. 1631 - 1638
• Main Authors: Venediktova, O. S., Bulavchenko, O. A., Afonasenko, T. N., Tsysul’nikov, P. G., Gerasimov, E. Yu, Tsybulya, S. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2018; Springer Nature B.V
• Subjects: Annealing; Atomic; Atomic/Molecular Structure and Spectra; Cations; Chemistry; Chemistry and Materials Science; Gallium oxides; Inorganic Chemistry; Manganese oxides; Molecular; Optical and Plasma Physics; Phase transitions; Physical Chemistry; Solid State Physics; Spinel; Superstructures; phase transformations; manganese-gallium spinel; manganese-containing double oxides; powder X-ray diffraction
• ISSN: 0022-4766; 1573-8779
• DOI: 10.1134/S0022476618070156

Manganese-gallium samples with cation ratios Mn:Ga = 1:2, 1.5:1.5, and 2:1 are synthesized by coprecipitation with subsequent annealing in air in a temperature range 600–1200 °C. Powder XRD, TEM, and BET methods are used to study the physicochemical characteristics of the samples. It is found that in the air at the annealing temperature of 600 °C finely dispersed low-temperature Mn 3– x Ga x O 4 spinels primarily form in all series, but in the whole temperature range (600–1200 °C) the system is multiphase. Annealing at 800–1200 °C leads to an increase in the concentration of simple oxides (β-Mn 3 O 4 and β-Ga 2 O 3 ). Only simple α-Mn 2 O 3 and β-Ga 2 O 3 oxides exist in a Mn:Ga = 2:1 series at 800 °C. In the sample with a cation ratio Mn:Ga = 1.5:1.5 annealed in air at 1000 °C, the formation of a superstructure based on the spinel structure is found.