Abstract
We report experimental and calculated Raman scattering investigations of KNb 1-x Ta x O 3 (x = 0.4, 0.5, 0.6) solid solutions as a function of hydrostatic pressure. The observed phase transitions sequence in the range from room pressure to 12 GPa is similar to the temperature-induced structural phase transformations: orthorhombic (ferroelectric) to tetragonal (ferroelectric) to cubic (paraelectric). Furthermore, it was observed that the domain of stability of ferroelectricity at high pressures increases with Nb-content. For the first time, some DFT calculations of theoretical Raman spectra are reported in order to support the experimental observations of pressure-induced phase transitions.