Structural and Dielectric Characterization of Nanocrystalline (Ba, Pb)ZrO₃ Developed by Reverse Micellar Synthesis

Nanocrystalline zirconates of barium and lead have been synthesized using a modified reverse micellar route (avoiding alkoxides). The entire solid solution of Ba_1−xPb_xZrO₃ (0≤x≤1) has been synthesized for the first time. Powder X-ray diffraction studies show the monophasic nature of the powders after heating at 800°C except minor impurities of ZrO₂ (2%–3%) at a higher lead content (x=0.50 and 0.75). The oxides crystallize in the cubic structure till x=0.25; for higher values, they crystallize in the orthorhombic structure. The particle size obtained from X-ray line-broadening studies and transmission electron microscopic studies is found to be in the range of 20–60 nm for all the oxides obtained after heating at 800^oC. The grain size of the solid solution of Ba_1−xPb_xZrO₃ (0≤x≤1) was found to increase with the lead content. The dielectric constant of the solids corresponding to Ba_1−xPb_xZrO₃ (0≤x≤1) was found to be a maximum at x=0.50. Note that the cubic to orthorhombic transition is also observed between x=0.25 and 0.5. Dielectric properties with respect to variation in frequency and temperature are reported for these nanocrystalline oxides for the first time.