Dielectric Characteristics of Bismuth Oxide Solid Solutions with a Fluorite-Like Crystal Structure

A series of Bi2O3-rich solid solutions with a fluorite-like crystal structure have been synthesized and analyzed with respect to their dielectric properties as functions of temperature and frequency. The existence of several common dielectric characteristics indicates a strong influence of the fluorite prototype cell on the frequency and temperature dependence of the dielectric properties. These characteristics, common to Bi2O3 solid solutions with the face-centered cubic δ structure, the tetragonal β structure, and the rhombohedral anti-α-AgI crystal structure, are (i) a frequency-dispersive increase in permittivity and dielectric losses because of a space-charge polarization, (ii) a frequency-independent permittivity and a linear temperature dependence of permittivity with a positive trend in the low-temperature range where the space-charge polarization is insignificant, and (iii) two frequency-dispersive relaxations above room temperature.