LOW-TEMPERATURE STUDIES ON THE TWO-DIMENSIONAL MODULATIONS IN AKERMANITE-TYPE CRYSTALS: CA2MGSI2O7 AND CA2ZNSI2O7

Abstract

Two-dimensional modulation in synthetic akermanite (Ca2MgSi2O7) and hardystonite (Ca2ZnSi2O7) has been studied by the single-crystal X-ray diffraction methods in the temperature range between 18 and 297 K. It is found that change of the modulation wavelength Ca2MgSi2O7 is slight, but that in Ca2ZnSi2O7 it is noticeable and indicates a plateau-like temperature dependence. The plateau-like region may be regarded as an independent phase with a specific q [~0.2924(3)].