Optical and thermal properties of binary calcium phosphate and barium phosphate glasses

Binary calcium phosphate and barium phosphate glasses corresponding to xCaO–(100 − x)P2O5 and xBaO–(100 − x)P2O5, respectively, have been prepared in the range of 20 ⩽ x ⩽ 50. Assessment of the optical and thermal properties reveal that refractive index (n) and glass transition temperature (Tg) show a minima while thermal expansion coefficient (α) and thermo-optic coefficient (dn/dT) change monotonically as the amount of modifying oxides, CaO and BaO, increase. α > 9 × 10−6/°C is required for the calcium phosphate and barium phosphate glasses to exhibit negative dn/dT.