Abstract
Precise values of the dielectric constant of gadolinium gallium garnet (GGG) single crystals are reported. The dielectric constant has been measured using a substitution method at 1 kHz and room temperature. The effect of impurities, lattice imperfections and lack of stoichiometry on the dielectric constant has been studied. The value of the dielectric constant of a pure GGG crystal along (111) is 12.11+or-0.02. For a GGG crystal containing 1% excess of Gd2O3, the dielectric constant is 12.24+or-0.01. Wafers of alpha -Al2O3 cut from pure and Cr-doped CVD-grown single crystals and from Czochralski-grown single crystals were also investigated, to investigate the effects of purity and perfection on the dielectric constant.