Le quartz α : un ancien matériau à la base d’applications du futur

The A-quartz : an ancient material for the applications of the future

Interface Hautes Pressions (I.C.M.C.B.-E.N.S.C.P.B.) Ecole Nationale Supérieure de Chimie et de Physique de Bordeaux, Talence

Abstract

The a-quartz is the low temperature form of quartz. Its physico-chemical, optical and piezoelectrical properties have led such a material to be used in different industrial applications and consequently have improved the development of its crystal growth. The low value of the α → β transition (573°C) has imposed the hydrothermal process. This process implies the formation, into the a SiO₂ lattice, of chemical and physical defects, their density being closely related to the different parameters governing the crystal growth: ΔT, T, P, the nature of the nutrient, the seeds and the solvent.

The future applications are mainly focussed on the telecommunications due to the high frequency stability of a quartz. The multiplication of the channels leads to the use of high frequencies and imposes severe geometrical requirements for the piezoelectric material, in particular the thickness, its value becoming of the same order of the size of the defects. Consequently, the hydrothermal process for the crystal growth of a quartz must be optimized or in the near future renewed.