Effect of external stresses on calcium phosphate glass investigated by IR spectroscopy

The effect of external stress on calcium phosphate glasses was investigated because they experience high stress in practical uses such as mastication. In order to understand the structural change of calcium phosphate glasses caused by an applied stress, the IR reflection peak shift of the phosphate structural band of the calcium phosphate glass fiber due to a bending stress was measured. The peak shift represents the change of the P-O-P bond angle. The IR reflection peak of the phosphate structural bands near approximately 1300 and approximately 910 cm(-1) shifted to a higher wavenumber under tensile stress and to a lower wavenumber under compressive stress when calcium phosphate fiber with a uniform structure was employed. This indicates that the P-O-P bond angle increases under tensile stress and decreases under compressive stress. The extents of both peak shifts were larger with a lower [corrected] Ca/P ratio than with a higher [corrected] Ca/P ratio. Therefore, phosphate glass with a higher Ca/P ratio is expected to withstand loads under external stress.