Subsolidus Phase Equilibria of the CaO‐B ₂ O ₃ ‐BaO System

Abstract

The “subsolidus” phase relations at room temperature in the system CaO‐B 2 O 3 ‐BaO are investigated. Specimens of various compositions were prepared from appropriate ratios of CaCO 3 , B 2 O 3 , and BaCO 3 , and fired from 780° to 1040°C according to their melting points. There are three ternary compounds in this system. The crystal structures of these compounds were determined by X‐ray diffraction (XRD). CaBa 2 (BO 3 ) 2 and Ca 5 Ba 2 B 10 O 22 are monoclinic structures. The lattice constants a = 14.221 Å, b = 4.569 Å, c = 11.926 A, β= 99.947°, and V = 763.4 å 3 for CaBa 2 (BO 3 ) 2 and a = 15.714 å, b = 6.184 å, c = 10.204 å, β= 93.954°, and V = 989.29 å 3 for Ca 5 Ba 2 B 10 O 22 are obtained. The third compound, CaBa 2 (B 3 O 6 ) 2 , is isostructural with the high form of BaB 2 O 4 with lattice constants a = 7.167 å and c = 35.298 å. Powder second harmonic generation efficiencies of these ternary compounds were measured using a homemade apparatus.