SUBSOLIDUS PHASE-EQUILIBRIA OF THE CAO-B2O3BAO SYSTEM

The ''subsolidus'' phase relations at room temperature in the system CaO-B2O3-BaO are investigated. Specimens of various compositions were prepared from appropriate ratios of CaCO3, B2O3, and BaCO3, and fired from 780 degrees to 1040 degrees 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). CaBa2(BO3)(2) and Ca5Ba2B10O22 are monoclinic structures. The lattice constants a = 14.221 Angstrom, b = 4.569 Angstrom, c = 11.926 Angstrom, beta = 99.947 degrees, and V = 763.4 Angstrom 3 for CaBa2(BO3)(2) and a = 15.714 Angstrom, b = 6.184 Angstrom, c = 10.204 Angstrom beta = 93.954 degrees, and V = 989.29 Angstrom 3 for Ca5Ba2B10O22 are obtained. The third compound, CaBa2(B3O?)(2), is isostructural with the high form of BaB2O4 with lattice constants 7.167 Angstrom and c = 35.298 Angstrom. Powder second harmonic generation efficiencies of these ternary compounds were measured using a homemade apparatus.