γ-ray-diffraction study of an incommensurate phase: Application to quartz

We report the first application of {γ}-ray diffractometry to the study of an incommensurate phase. We review the peculiar characteristics of this technique, which allows high-precision measurements of the temperature variation of the modulation vector, even within the narrow range of existence of the incommensurate phase of quartz (1.3 K around 846 K). The high resolution of {γ}-ray diffractometry allows us to observe a global hysteresis in the temperature variation of the modulation wave vector and to follow the broadening of the Bragg peak during the first-order transition between the incommensurate and the {α} phases.