Exploration mixture of salts in synthesis SrBi2Nb2O9 aurivillius phase doped with Ba2+ and La3+ using molten salts method

The double-layer Aurivillius phase Sr0.8Ba0.2Bi2Nb2O9 (SBBN) and Sr0.8Ba0.2Bi1.875La0.125Nb2O9 (SBBLN) have been synthesized by the molten salts method using both Na2SO4/K2SO4 and NaCl/KCl as fluxes. The effect of La3+ doped on structure, morphology, and dielectric properties was investigated. X-ray diffraction pattern shows that single-phase Aurivillius compounds were obtained for NaCl/KCl fluxes, whereas using a Na2SO4/K2SO4 flux confirmed the formation of Aurivillius compounds that are mixed with other phases. The SBBLN cell volume is smaller compared to SBBN, with the substitution of smaller La3+ (1.16Å) than Bi3+(1.17Å). With La3+ doped, the ferroelectric transition temperature (TC) significantly decreased as the degree of distortion of the bismuth layers decreased, since the effect of 6s2 lone pair electron Bi3+ was reduced. SEM images showed anisotropic plate-like grains. FTIR analysis showed the presence of Nb-O vibrations that do not shift with the substitution of La3+, since they do not substitute into Nb-site on perovskite layers.