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Abstract: Barium titanate–nickel composites (BaTiO3–Ni) were synthesized at a low temperature using a sol–gel method and sintered in a reducing atmosphere. XRD, FE-SEM, Raman spectroscopy and TGA were performed to confirm the phases of BaTiO3 and Ni, the morphology and tetragonal crystal structure of BaTiO3 and the weight loss. The results indicate that by controlling the experimental conditions (temperature and atmosphere) during the sintering process, the grain size of the BaTiO3–Ni composite can be controlled. The average grain size of the dense BaTiO3–Ni composite was in the range of 0.6–1.5µm. In addition, the dielectric constant increased from ~2000 for monolithic BaTiO3 to ~11,000 by increasing the Ni content. The enhanced dielectric properties of the BaTiO3–Ni composite are due to the well-dispersed nickel particles in the BaTiO3 matrix. [Copyright &y& Elsevier]

Abstract: We have fabricated lead-free Bi0.5(Na0.75K0.25)0.5TiO3 (BNKT) ceramics by a conventional process (CP) and reactive templated grain growth (RTGG) methods. The effect of grain orientation on structure, dielectric, complex impedance and electrical properties was investigated. The phase formation and grain morphology of BNKT ceramics were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. High dielectric constant and low dielectric loss was observed for grain oriented (textured) BNKT ceramics. Complex impedance, temperature dependent ac and dc conductivity were performed to explore the conduction behavior of the prepared BNKT ceramics. [Copyright &y& Elsevier]

The effects of CuO, ZnO, and Li2O (0.2wt.%) additions on the piezoelectric and ferroelectric properties of 0.2Pb(Mg1/3Nb2/3)O3–0.8Pb(Zr0.475Ti0.525)O3 (designated as PMNZT) ceramics were investigated. The density of sintered sample was strongly affected by small amounts of CuO, ZnO, and Li2O addition. From the X-ray diffraction analysis, single phase of polycrystalline Perovskite was confirmed. The dielectric and piezoelectric constants of PMNZT ceramics doped with CuO, ZnO, and Li2O were higher than that of pure ones. The improvement of piezoelectric properties was maximized at various 0.2 wt.% doped PMNZT samples. The maximum dielectric constant (#x03B5;r=1423) and minimum dielectric loss (tan δ=0.0019) at room temperature were obtained with Li2O addition. The electromechanical coupling factor, k33 of 0.2 wt.% of CuO, ZnO, and Li2O doped and pure PMNPZT ceramics were found to be 0.72, 0.68, 0.75, and 0.20, respectively. And the piezoelectric constant, d33 of CuO, ZnO, and Li2O doped and pure ceramics were found to be 330, 332, 418, and 95 pC/N, respectively. These values are comparable to that of pure ones and we will discuss which impurity would be the best dopant to improve the piezoelectric and dielectric constants of pure sample. [Copyright &y& Elsevier]