Dielectric Properties of Hydrogen Halides. I. Hydrogen Bromide

Static dielectric constants of solid hydrogen bromide have been measured from 186 to 70°K, and dispersion and loss below 89°K in the frequency range 15 cy to 5 Mc. Special cell designs minimized formation of cracks and voids in the polycrystalline sample, as such flaws were shown by several lines of evidence to cause serious errors. Static dielectric constants above 117°K are in quite good agreement with Onsager's equation. In phase II, stable below 113°K, the dielectric constant rises to a peak of 200 at 89°K, then falls to a value of 32 at 70°K in phase III. The principal dispersion below 89°K follows a circular arc locus with α=0.3, and a rate expression with activation energy 2.7 kcal/mole. A second dispersion is observed at much higher frequencies with energy 1.59 kcal/mole, and it is suggested that the two dispersions are a consequence of crystal anisotropy.