The anelasticity of natural and synthetic quartz at low temperatures—abstract∗

Abstract

Certain imperfections in alpha quartz are found to introduce anelastic absorption at low temperatures in crystal resonators. For a shear wave of 5 mc, absorption peaks are observed at approximately 20 and 50 deg K in unirradiated samples. X irradiation effects a lowering of the amplitude of the 50 deg K absorption, while a new absorption is introduced at 100 deg K. The results of acoustic absorption measurements on a number of selected samples of synthetic quartz resonators suggest that, whereas the 50 deg K absorption is attributable to excess oxygen, the 100 deg K defect involves aluminum which is present substitutionally in the crystal structure. X-irradiation-induced lowering of the resonant frequency of crystal resonators is clearly the re sult of a lowering of the elastic modulus associated with the 100 deg K anelastic absorption. (auth)