The Intermediate Phase of Quartz. II Behaviour near the First-Order Transition Temperature

The behaviour of the transition of quartz in a range of 0.1 K immediately above the transition temperature (T c ) was studied mainly in the cooling run from the intermediate phase (IP) to the α phase. Rod-like entitles parallel to the c -axis are formed, the thickness being an order of 30–100 µm. They cause an inhomogeneous strain in the crystal. This texture (super-modulated structure) is intrinsic since it exists more clearly when the α phase does not coexist in the specimen. It is transformed into the α phase at T c . It is suggested that the entity is a commensurate phase. In the final chapter, the structure of IP over the whole temperature range and the natures of transition from the β to the α phase through IP are discussed based on our observations including those of Part I (J. Phys. Soc. Jpn. 54 (1985)1868).