Investigation of the physico-chemical properties of calcium borophosphate glasses. Effect of the substitution of sodium for calcium

Abstract Calcium borophosphate glasses have been prepared by quenching melted mixtures of Ca(PO 3 ) 2 and B 2 O 3 . Their physical and chemical properties, such as glass transition and crystallization temperatures, density, microhardness, solubility in water and UV edge absorption, are studied as a function of the molar fraction B/B+P. The interpretation of the results are based on the presence of BO 4 units and B–O–P bridges in phosphate-rich glasses. The substitution of sodium for calcium, for a constant B/B+P ratio ( x =0.2), induces mainly the decrease of the intensity of the crystallization peak, which tends to vanish. This unexpected behaviour results, most probably, from an increasing disorder in the structure.