Structure and elastic properties of low-temperature sealing phosphate glasses

The structure of 56P2O5–10B2O3–4Al2O3–15Li2O–15Na2O glasses doped with alkaline earth oxides is investigated by infrared reflectivity measurements and polarized Raman scattering. Vibrational modes are assigned to different types of atomic motion in the glass network. These glasses exhibit a distribution of chains of PO4 tetrahedra which are held together by bonding between the non-bridging oxygens of the tetrahedra and the metal cations. Room temperature ultrasonic velocities (both longitudinal and transverse) in these glasses are determined by the pulse-echo technique. The experimental results are used to obtain elastic constants. The measured values of Youngʹs, shear and bulk moduli for our glasses show a good agreement with the theoretically calculated results based on the Makishima and Mackenzie model. A correlation between glass structure and elastic property is discussed in terms of a chain entanglement mechanism of PO2 groups.