Low-Frequency Dielectric Constants of the Alkaline Earth Fluorides by the Method of Substitution

The 1000-Hz 300°K dielectric constants of the alkaline earth fluorides were measured to an accuracy of 0.01% by the method of substitution. Reproducibly different values for various crystals of the same type were obtained which varied beyond the experimental error. The ranges of results for various crystals of each type measured along with further separation by manufacturer are: CaF2, Harshaw, 6.7984–6.7988, Optovac, 6.8074–6.8432; SrF2, Harshaw, 6.4647–6.4664, Optovac, 6.4700–6.4703; and BaF2, Harshaw, 7.3590–7.3595, Optovac, 7.3606–7.3630. The spread for each type of crystal is thought to be attributable to random trace impurities.