Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

The pressure-driven tetragonal-to-monoclinic phase transition in CaWO4 and related scheelite-structured orthotungstates is analysed in terms of spontaneous strains. Based upon our previous high-pressure X-ray diffraction results and the Landau theory, it is suggested that the scheelite-to-fergusonite transition is of second order in nature. Copyright (c) EPLA, 2007.