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Alkali phosphate, phosphate-silicate, and phosphate-germanate glasses were studied by means of high-temperature acoustics and Rayleigh-Mandelstam-Brillouin (RMBS) and Raman scattering (RS) spectroscopies. Temperaturetemporal dependences of the ultrasound velocity in the glass melts were measured at temperatures up to 1550 °C. From the RMBS spectra the Landau-Placzek ratio and frequency shifts were found. A theory of the fluctuations freezing at the cooling of the glass melt was applied to separate the contributions of the frozen-in density and concentration fluctuations to the Rayleigh scattering losses. A comparison was drawn with the losses in silica glass. The RS spectra allowed the identification of the constant-stoichiometry groups. The feasibility of the system xNa2O-(40 -x)K20-3OAl2O3-30P205 for the fabrication of low-scattering glasses was ascertained.

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