Reverse micellar synthesis, structural characterization and dielectric properties of Sr-doped BaZrO3 nanoparticles

Sr-doped BaZrO3 nanoparticles with strontium content varying from 5 to 20 mol % were successfully synthesized by reverse micellar method at 900 °C for the first time. Systematic studies have been carried out to establish the structural and electrical properties of the as prepared nanoparticles. These nanoparticles were characterized using powder X-ray diffraction, transmission electron microscopy, BET surface area and dielectric measurements. X-ray diffraction analysis showed the formation of monophasic and highly crystalline nanoparticles which could be indexed in cubic BaZrO3 with contraction of lattice on strontium substitution. A monotonic shift of diffraction pattern towards higher angel confirms the formation of solid solutions of Ba1−xSrxZrO3 (0.05 ≤ x ≤ 0.20) which was corroborating well with lattice parameter studies. Transmission electron microscopic studies showed the formation of cubic, spherical and hexagonal nanoparticles with an average grain size of 40-65 nm. Energy dispersive X-ray spectroscopic studies confirmed the presence of dopant (Sr2+) in the BaZrO3 matrix and estimated chemical species corroborate well with the loaded composition. Specific surface area of the solid solution comes out to be in the range of 104-244 m2 g-1. Smallest particle of size 40 nm shows highest surface area 244 m2 g-1 for 20 mol% Sr-doped BaZrO3. Dielectric and impedance studies were also carried out as a function of frequency and temperature to explore the electrical properties of Sr-doped BaZrO3. The dielectric constant of Ba1−xSrxZrO3 (0.05 ≤ x ≤ 0.20) was found to be in the range of 13-25 for x = 0.05 to x = 0.20 with nearly similar dielectric loss of the order of 0.02. The conductance increases linearly with increase in frequency at room temperature, however the impedance has an inverse effect.