Properties of glasses from fluoride to phosphate composition

A set of glasses with compositions Pb0.3Ga0.2In0.15Zn0.15Ca0.2F2.35(1−x)(PO3)2.35x (x: 0, 0.1, 0.25, 0.5, 0.75, 0.9 and 1) was prepared to study the change of the physical and structural properties of glasses ranging from fluoride to a metaphosphate glass. The fluoride-based and the phosphate-based glasses were prepared by using fluoride compounds and oxides, carbonates, and NH4H2PO4 as the phosphates components. The fluorophosphate glasses were obtained by melting a proportionate mixture of the two basic compositions. Density, d, refractive index, nd, optical transparency window, characteristic temperatures such as glass transition (Tg) and onset of crystallisation (Tx), were measured as a function of composition. The Pb0.3Ga0.2In0.15Zn0.15Ca0.2F2.35 glass had a glass transition temperature of 265°C, nd=1.564, d=5.64 g cm−3 whereas the Pb0.3Ga0.2In0.15Zn0.15Ca0.2(PO3)2.35 glass had Tg=500° C, nd=1.594, d=3.44 g cm−3. Structural changes of the glasses as a function of PO3/F ratio, was determined from the infrared and Raman spectra of the samples.