Structural, dielectric and optical properties of sol-gel synthesized 0.55Ba(Zr0.2Ti0.8)O3-0.45(Ba0.7Ca0.3)TiO3 ceramic

Lead-free polycrystalline ceramic 0.55Ba(Zr0.2Ti0.8)O-3-0.45(Ba0.7Ca0.3)TiO3 (0.55BZT-0.45BCT) was synthesized by sol-gel method and the dielectric, impedance and optical properties of this ceramic were studied. X-ray diffraction analysis revealed the formation of pure perovskite phase with the coexistence of tetragonal and rhombohedral structures. The high value of dielectric constant (similar to 6,985) with low dielectric loss (similar to 0.013) was obtained at room temperature. Bulk and grain boundary resistances were measured by impedance analysis, which revealed negative temperature coefficient of resistance behaviour in this ceramic. The estimated value of optical band gap was found to be similar to 3.16 eV, which is related to the presence of intermediate energy levels. Two emission bands one at similar to 365 nm (UV region) and another at similar to 465 nm (blue region) were observed in photoluminescence spectrum at room temperature.