Effect of Alkali Ions on Electrical Conductivity and Dielectric Loss of Quartz Crystals,

Because of the importance of alkali ions in relation to frequency stability of quartz resonators, we have investigated the electrical properties of various Li-swept and Na-swept quartz crystals both natural and synthetic. These properties are of two types dielectric loss measurements, particularly at cryogenic temperatures and electrical conductivity measured between 100 deg. and 400 deg. C. In the case of the dielectric measurements, we studied the two well known loss peaks due to A1-Na pairs and established a calibration for the lower temperature peak tan delta max of 1.5 x 10 to the minus 5th power corresponding to 1 ppm of A1-Na pairs. High quality synthetic crystals and a natural crystal were found to have primarily Li as compensation for A1 in the as-grown condition. The absence of an analogous A1-Li peak leads to the conclusion tha Li resides on the 2-fold symmetry axis of the A104 tetrahedron to which it is bound.