Refined Observations of Satellite Reflections in the Intermediate Phase of Quartz

Abstract

An incommensulate phase (IP) between α and β phases of quartz was studied by X-ray diffraction methods under well-controlled temperature conditions. In particular, the topographs owing to satellite reflections (SR) were used. The modulation vectors q_i make an angle φ with the bisector of the two-fold axes of α-quartz. In the range between T_C+0.1 and +1.8 K (T_C: The transition temperature from IP to α) the T-dependence of |q| and φ were precisely measured. IP has a domain structure along the c-axis, each domain being characterized by the sign of φ. The second harmonics of q could also be observed faintly in the vicinity of T_C.