Pressure-induced structural changes in titanophosphate glasses studied by neutron and X-ray total scattering analyses

In this paper, the densification mechanism of two titanophosphate glasses (binary 73TiO2-27P2O5 and ternary 68TiO2-5Al2O3-27P2O5) is investigated. The glasses are densified by isostatic N2-mediated pressure treatment at elevated temperature and the pressure-induced structural changes are studied by neutron and X-ray total scattering analyses. The medium range structure change is revealed from the change in the first sharp diffraction peak (FSDP), where the density increase by pressurization is correlated with the decreased medium range repeating spacing calculated from the position of FSDP. The hot compression treatment also increases the medium range order, as shown by the increased correlation length calculated from the width of FSDP. The short range structure changes are examined by separating PO and TiO pair distribution functions (PDF) using differential neutron and X-ray PDFs. Pressurization is also found to increase the coordination number of Ti, as previously observed for other network formers in densified glasses.