X-ray studies of phase transitions of (Ca,Sr)-åkermanite solid solutions

Abstract

Abstract The phase transitions of the solid solutions (Ca1- x Sr x )2MgSi2O7 (0 ≤ x ≤ 0.32) of modulated melilites are studied by X-ray diffraction. The variation of the intensity and the FWHM of satellite reflections reveal different transition temperatures. Two ranges of different ordering are found in the range of incommensurate modulation. The mechanism of the phase transition into the incommensurately modulated structure is discussed by including the diffuse scattering above the transition.