On the Existence of Ternary Compounds in the CaO-BaO-Al<sub>2</sub>O<sub>3</sub> System

In this article in order to verify the probability of the formation of the compound CaBaAl 4 O 8 , a thermodynamic analysis of the following possible solid-phase reactions of its formation was carried out: formation of CaBaAl 4 O 8 from the initial components - calcium carbon dioxide, barium carbon dioxide and aluminum oxide; the probability of formation of dual compounds CaAl 2 O 4 and BaAl 2 O 4 from the same raw materials (since the compound CaBaAl 4 O 8 is located on the BaAl 2 O 4 -CaAl 2 O 4 conjugate) and the possibility of formation of the compound CaBaAl 4 O 8 from binary compounds CaAl 2 O 4 and BaAl 2 O 4 . As a result of our experimental studies, the existence of ternary compounds Вa 3 CaAl 2 O 7 and ВaCa 2 Al 8 O 15 was confirmed, and it was found that the Вa 3 CaAl 2 O 7 compound exists in the system at least up to a temperature of 1400 °C. Thus, our studies have determined an increase in the temperature limits of its existence, in contrast to the data of previous researchers, who indicated 1250 °C as the upper temperature of existence of Вa 3 CaAl 2 O 7 .