Low-temperature studies on the two-dimensional modulations in åkermanite-type crystals: Ca2MgSi2O7 and Ca2ZnSi2O7.

Two-dimensional modulation in synthetic åkermanite (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)]. [ABSTRACT FROM AUTHOR]