The hydrothermal growth of alpha-quartz and the nature of the physico-chemical defects detected in the resulting crystal

The development of cr-quartz for high frequencies devices leads to a strong reduction of the thickness of the piezoelectric sheet. Such a thickness is comparable to the size of the defects. Consequently, the main objective for the improvement of the performances of alpha -quartz used as a piezoelectric material is to reduce the density of physico-chemical defects. Our work has been focussed in two directions: (i) the identification of different physico-chemical defects using the overlap of different techniques (X-ray topography, IR spectroscopy, Cathodoluminescence, Thermo-luminescence, EPR,...), (ii) attempts at improving the correlations between the different parameters governing the hydrothermal crystal growth of alpha -quartz and the nature or the density of defects.