Ceramics-Silikáty 57, (4) 290 - 296 (2013)

Sr_0.5Ba_0.5Nb₂O₆ (SBN50) ceramic doped with different concentration of Lanthanum, La according to stoichiometric formulation of Sr_0.5-3y/2La_yBa_0.5Nb₂O₆ (LSBN) with y = 0.01, 0.03, 0.05 and 0.07 prepared using traditional ceramic method at the calcination temperature of 1200^oC and sintered at 1300^oC at varied sintering time. The effects of the sintering time and La³⁺ substitution on the morphological, compositional, structural and electrical properties of the LSBN is presented using scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and dielectric analysis. The XRD spectra confirm the presence of TTB structure in the ceramics. The Curie temperature (T_c) of the ceramic identified from the dielectric studies performed in the temperature range of 28^oC to 300^oC. The temperature dependent dielectric exhibits broad peaks indicating a diffuse phase transition and relaxor behavior of the ceramic. The measured density of the samples is proportional to the sintering time and inversely proportional to the amount of the La³⁺ substitution. The solubility limit of La³⁺ ions in the SBN solid solution is at y ~ 0.05. This observation is also supported by the dielectric results where the dielectric properties of the ceramic deteriorate for y > 0.05 La substitution.