Transverse phonons and intermediate-range order in Sr-Mg fluorophosphate glasses

Vibrational and ultrasonic spectroscopies have been employed to study the composition and polarization dependence of the vibrational and elastic properties of the pseudo-binary mixed fluoride-phosphate glass-forming system xSr(PO3)(2)-(1-x)(0.62MgF(2)-0.38AlF(3)) with x: 0, 0.04, 0.06, 0.1, 0.15, 02, 0.3, 0.4, 0.8, 0.9 and 1. Compositioninduced alterations in the short-range order have been quantitatively followed by means of Raman and IR specroscopies. The analysis has shown that the incorporation of the phosphate groups in the fluoride network results in a less interconnected network with suppressed rigidity. The specific amorphous materials have been used as a model system in terms of wide glass-forming ability to elucidate the effect of variation in connectivity between the fluoride and phosphate sub-networks on the Boson peak nature. Emphasis has been given in the lowfrequency Raman phenomenology, which in conjunction with the elastic properties allowed us to establish a possible link between the Boson peak and the transverse phonons in these glasses. (C) 2019 Elsevier B.V. All rights reserved.