The Raman spectra of single-crystal YVO₄, GdVO₄, and ZrSiO₄ with a zircon structure, as well as CaWO₄ and BaWO₄ with a scheelite structure, are studied in detail over a wide temperature range 14–800 K. An inhomogeneous splitting of the A _1g (ν₂) vibrational lines in the Raman spectra of YVO₄ and GdVO₄ and the A _g (ν₁) vibrational lines in the spectrum of CaWO₄ is detected. It is shown that the profiles of these lines can be decomposed into two components, whose integrated intensities are redistributed with temperature and also depend on the matrix kind in which they are detected. The phenomenon observed is associated with the thermally activated processes of disorientation of the tetrahedral anions in the zircon and scheelite structures.

Zirconium dioxide ZrO₂ and hafnium dioxide HfO₂ are investigated using high-temperature Raman spectroscopy in the temperature range 300–2080 K, including the regions of the monoclinic-tetragonal phase transitions revealed in these materials. An analysis is made of the specific features observed in the evolution of the high-temperature Raman spectra of both the monoclinic (m) and tetragonal (t) modifications of ZrO₂ and HfO₂ with variations in the temperature. The polarized Raman spectra of the metastable tetragonal phases in solid solutions based on zirconia and hafnia are used to identify the symmetry of vibrations in the spectra of the tetragonal modifications of pure zirconium and hafnium dioxides, which exist at high temperatures.

Raman scattering spectroscopy has been used to study the melting behavior and structure of Mo-O complexes alkali-metal molybdates rich in MoO₃: Li₄Mo₅O₁₇, K₂Mo₃O₁₀, and M₂Mo₄O₁₃ (M = Li, Na, K). The complex structure of the anion motif in these molybdates, made up of edge-sharing [MoO₆] octahedra, transforms on melting into short chains of [MoO₄] tetrahedra. We discuss the general trends in the variation of the chain structure of the anion motif in melts across the series of alkali-metal molybdates as the MoO₃ concentration increases from mono- to tetramolybdate compositions.

The vibrational spectra of single crystals of the LiGd₉(SiO₄)₆O₂ and Ca₂Gd₈(SiO₄)₆O₂ oxyapatites have been studied using Raman spectroscopy at room and high temperatures. The spectra of internal and external vibrations in these structures have been resolved. The structural transformation of the LiGd₉(SiO₄)₆O₂ and Ca₂Gd₈(SiO₄)₆O₂ oxyapatites in the processes of melting and crystallization, as well as during rapid quenching of the melt, has been investigated. It has been found that the melting of the LiGd₉(SiO₄)₆O₂ compound has an incongruent character and that new metastable disordered phases are formed during rapid quenching of the Ca₂Gd₈(SiO₄)₆O₂ melt.