High Temperature Stability in the Cs2O–SrO–Al2O3–SiO2 System

Samples in two ternary Cs2O–Al2O –SiO2 and SrO–Al2O3–SiO2 systems and in the quaternary Cs2O–SrO–Al2O3–SiO2 system were prepared using a solid-phase synthesis method from precursors obtained under hydrothermal conditions. Quantitative elemental analysis was performed by X-ray fluorescence spectroscopy, the phase content was determined by X-ray powder diffraction. A comparative stability analysis was carried out using thermogravimetry up to 1500°С. The melting temperature was determined by visual polythermal analysis using a high-temperature microscope. Significant difference in thermal stability of the samples depending on the Cs2O content has been observed. Regardless of the ratio of Al2O3 : SiO2, the samples with a Cs2O content up to 10 mol % have the highest thermal stability, with their mass losses being less than 3%. Higher Cs2O concentration increases the melting point: the samples with the least thermal stability due to the cesium vaporization show the highest liquidus temperature up to 1910°C.