Effect of hydrostatic pressure on the vibrational properties and the structure of SrWO4 and PbMoO4

Raman spectra of SrW04 are measured up to 35 kbar at 300 K. At (21 ± 2) kbar the doubly‐degenerate Eg modes are observed to split which indicates a structural transformation to a lower symmetry. The high pressure Raman spectra are similar to spectra of the structure of ZnW04. Raman spectra of PbMoO4 are also measured up to 35 kbar at both 300 and 80 K, but no evidence of a structural change is observed. The pressure dependence of the phonon spectra suggests the presence of harmonic phonon‐phonon interaction in this system. The possible origins of the different high pressure form of the scheelites are discussed on the basis of lattice phonon‐phonon interaction.