Physical, mechanical and structural properties of BaO–CaF2–P2O5 glasses

• (50 − X)BaO–XCaF2–50P2O5 glasses were prepared by melt quenching technique.
• Mechanical properties were studied using Vickers indentation technique.
• Short range structure was investigated using Raman and infrared spectroscopy.
• Physical and mechanical properties of glasses were correlated with their structure.

Mechanical properties and structure of melt-quenched ternary barium phosphate glasses belonging to the composition (50 − X)BaO–XCaF2–50P2O5 (X = 0 to 10 mol%) were studied using Vickers indentation and vibrational spectroscopy. Elastic moduli of prepared samples were calculated using the Makishima and Mackenzie (M–M) model. Density of glasses was measured using the Archimedes method, while molar volume and atomic packing density were calculated from measured density to study structural changes in the glass matrix. Vickers hardness and brittleness increased and fracture toughness decreased with increase in CaF2 content. This can be attributed to increase in the compactness of phosphate bonds and reduction in the molar volume of glasses with partial substitution of Ba2 + with Ca2 +. Infrared and Raman spectroscopies revealed that the glass network mainly consisted of metaphosphate units arranged in chain and ring structures together with small amounts of ultraphosphate and pyrophosphate units.