Effect of substitution of Nd3+ for Bi3+ on the dielectric properties and structures of Sr Bi2-χ Ndχ Nb2 O9 bismuth layer-structured ceramics

Single phases of Sr Bi2-χ Ndχ Nb2 O9 (χ=0, 0.1, 0.2, and 0.4) ceramics were prepared by the solid-state reaction method and studied by dielectric and Raman spectroscopy. The substitution of Nd3+ for Bi3+ induced a dielectric relaxation behavior for Sr Bi2-χ Ndχ Nb2 O9 (χ=0.1, 0.2, and 0.4). When χ=0.4, the dielectric response of Sr Bi1.6 Nd0.4 Nb2 O9 is characteristic of typical relaxor ferroelectrics, which could be attributed to the disorder induced by the Nd3+ substituting for Bi3+ in Bi2 O2 layers. The dielectric relaxation of Sr Bi1.6 Nd0.4 Nb2 O9 was fitted using the Vögel-Fulcher relationship, which indicates that Sr Bi1.6 Nd0.4 Nb2 O9 is analogous to a spin glass with thermally activated polarization fluctuations above a static freezing temperature. Raman spectra of Sr Bi2-χ Ndχ Nb2 O9 ceramics could indicate that the structural distortion of Nb O6 octahedron decreases with the increase in Nd content, which results in the decrease in Tm for Sr Bi2-χ Ndχ Nb2 O9 ceramics.