Effects of rare-earth dopants on the ferroelectric and pyroelectric properties of strontium Barium Niobate ceramics

Effects of various rare-earth (RE) dopants (Y³⁺, La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tm³⁺, Dy³⁺, Er³⁺, and Yb³⁺) on the dielectric, ferroelectric, and pyroelectric properties of Sr_0.5Ba_0.5Nb₂O₆ (SBN50) ceramics were investigated. In the present studies, the doping concentrations of all the RE dopants were fixed at 1mol%. Their potential usefulness in pyroelectric applications was discussed based on their measured pyroelectric detectivity figure of merit (FOM). On the basis of our studies, for RE dopants with atomic numbers smaller than Nd, their dielectric constants were greatly increased, while for RE dopants with atomic numbers larger than Sm, their dielectric constants as well as dielectric losses became smaller. Among various dopants, Eu-doped SBN showed the most improved ferroelectric properties. Its remnant polarization (P_r ) was increased to 4.86 μC/cm² as compared with 3.23 μC/cm² obtained in undoped SBN50. On the other hand, Gd-doped SBN exhibited the largest pyroelectric coefficient of 168 μC/m² K, which was over three times of that of the undoped sample (49 μC/m² K). The work shows that Gd-doped SBN exhibits the greatest potential for pyro-applications because it bears the largest FOM of 0.45 × 10^-5Pa ^-0.5 [Correction: After online publication on 11/05/2008, an error was found in this article. The original value, 1.35 × 10^-5Pa^-0.5, was incorrect. The data has been replaced with the correct value.]. © 2008 American Ceramic Society.