Phase formation in Al2O3‒BaO system at heating in air atmosphere

The phase formation in the Al2O3‒BaO system, predominantly containing α-Al2O3, during heating in an air atmosphere was investigated. The phase composition was analyzed using X-ray diffraction, while morphology and particle size were examined through scanning electron microscopy. The specific surface area of the synthesized powders was determined using the BET method. It was found that the BaAl2O4 phase forms within the temperature range of 1000‒1100 °C. Further temperature increases up to 1300 °C did not result in changes to the phase composition. The particle size of alumina and barium-containing additives increased from 210 nm to 355 nm with rising temperature. The specific surface area decreased from 7.57 m²/g at 1000 °C to 6.41 m²/g at 1300 °C. The coherent scattering area of α-Al2O3 decreased by approximately 46 % as the temperature increased from 1000 °C to 1300 °C, while that of the BaAl2O4 compound increased by about 55 %. Ill. 5. Ref. 8. Tab. 2.