Observations of the α-β phase transition in quartz: a review of imaging and diffraction studies and some new results

Although the α-β quartz transition traditionally has been treated as a simple, second-order phase transition, a wealth of studies performed over the past two decades has documented the complex nature of this transformation. It now appears that α quartz undergoes a first-order transition to an incommensurately modulated phase that is stable over a 1.3°C interval. This intermediate phase consists of an ordered mosaic of Dauphine microtwins that occur as triangular prisms elongate along c, and these prisms grow finer with increasing temperature. The discovery of this incommensurate phase was achieved through a series of diffraction and imaging experiments using a variety of methods, and this paper reviews the process by which the existence of the intermediate phase of quartz was established. In addition, results from the authors' transmission electron microscopy experiments on the α-β transition are presented. -from Authors