Li4GeO4-Li2CaGeО4 phase equilibria and Li2+xCa1-xGeO4 solid solutions

V Nikolov; R Nikolova; N Petrova; P Tzvetkov; I Koseva

doi:10.1016/j.heliyon.2024.e28815

Li₄GeO₄-Li₂CaGeО₄ phase equilibria and Li_2+xCa_1-xGeO₄ solid solutions

Heliyon. 2024 Mar 29;10(7):e28815. doi: 10.1016/j.heliyon.2024.e28815. eCollection 2024 Apr 15.

Authors

V Nikolov¹, R Nikolova¹, N Petrova¹, P Tzvetkov², I Koseva²

Affiliations

¹ Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria.
² Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria.

Abstract

Detailed studies of the Li₄GeО₄-Li₂CaGeО₄ system by solid-phase syntheses of various compositions from pure Li₄GeО₄ to pure Li₂CaGeО₄ in the temperature range from 25 to 1125 °C is investigated for a first time. Solid state synthesis powders are characterized by X-ray and DSC/TG methods. Concentration and temperature two-phase regions of Li₄GeО₄ and Li₂CaGeО₄ as well as two-phase regions of Li₂CaGeО₄ and Li_2+2xCa_1-xGeO₄ are established. Region of pure Li_2+2xCa_1-xGeO₄ solid solution are detected too and it structure is investigated. Being structural analog to Li_2+2xZn_1-xGeO₄ and Li_2+2xMg_1-xGeO_4, Li_2+2xCa_1-xGeO₄ has own specific local environment of the metal ions. The obtained results are compared with those for Li₄GeО₄-Li₂ZnGeО₄ system and for Li_2+2xZn_1-xGeO₄ solid solution. The differences of the phase diagrams and structural features of the solid solutions are discussed.

Keywords: A. inorganic materials; A. oxide materials; B. solid state reactions; C. crystal structure; C. phase diagrams; D. X-ray diffraction.