Crossover from an ordinary ferroelectric to a relaxor in Sr2 + xBi4–xTi5–xNbxO18

Abstract

Sr_{2 + x}Bi_4–xTi_5–xNb_xO₁₈ materials with x = 0.2, 0.4, 0.6, 0.8, and 1 are synthesized. Investigations of the dielectric constant of the samples reveal an increase in the blurring of the phase transition as the share of titanium ions substituted for niobium ions grows. The Burns temperature and the temperature corresponding to the dielectric permittivity maximum are determined for all of the above compositions. Crossover from a normal ferroelectric to a relaxor ferroelectric in Sr_{2 + x}Bi_4–xTi_5–xNb_xO₁₈ samples is observed.