Temperature-dependent Raman spectroscopic study of ferroelastic K2Sr(MoO4)☆☆Project supported by the Natural Science Foundation of Anhui Province, China (Grant Nos. KJ2018A0588 and KJ2017A625).

Abstract

Raman scattering measurements of K2Sr(MoO4)2 were performed in the temperature range of 25–750 °C. The Raman spectrum of the low-temperature phase α-K2Sr(MoO4)2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm−1 are related to Mo–O bending vibrations in MoO4 tetrahedra, while the Raman bands in the wavenumber region of 650–950 cm−1 are attributed to stretching vibrations of Mo–O bonds. The temperature-dependent Raman spectra reveal that K2Sr(MoO4)2 exhibits two sets of modifications in the Raman spectra at ∼150 °C and ∼475 °C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150 °C to 475 °C suggests structural instability of the medium-temperature phase β-K2Sr(MoO4)2.