Dielectric and Conductivity Study of SrBi2Ta2O9 Ceramic by Microwave Sintering Technique

Bismuth layered structure SrBi2Ta2O9ceramic is prepared by the microwave sintering technique via solid state route at 1100°C. X-ray diffraction analysis is used to analyze the phase purity and identifies the orthorhombic phase with A21am space group. The fracture surface morphology of the sintered pellet is visualized by scanning electron microscopy. Diffusive phase transition behavior is existed in the temperature dependence dielectric study at Tc= 305°C. The electrical ac and dc conductivity study shows the negative temperature coefficient of resistance behavior. Activation energy from the Arrhenius plot is studied to discuss the fatigue property.

Extrinsic Scaling Effects on the Dielectric Response of Grained BaTiO3 Films

A set of gradient stresses is used in Landau thermodynamic theory to explain the dielectric diffusion of BaTiO3 films grown on thick copper foils. Every grain in the films is treated as a single domain core that is surrounded by boundaries with low dielectric constant. The dielectric diffusion is mainly induced by the diffusive phase transition caused by the gradient stresses. The low dielectric constant boundaries suppress the peak value of the dielectric constant. The results agree with the experiments.

The Crystalline, Dielectric and Pyroelectric Properties of (1-x)Pb(Sc0.5Ta0.5)O3-xPb(Zr0.52Ti0.48)O3 Relaxor Ferroelectric Ceramics

The (1-x)PST-xPZT(PSTZT) complex perovskite relaxor ferroelectric ceramics were prepared by wolframite precursor process(named two-step-sintering method, TSSM) and conventional oxides mixing method (named one-step-sintering method, OSSM), respectively. The experimental results demonstrated that pure perovskite PSTZT ceramics could be acquired by OSSM or TSSM. The temperature dependence of permittivity and dielectric loss of PSTZT ceramics indicated that PSTZT ceramics are relaxor ferroelectric ceramics with a complete diffusive phase transition. The pyroelectric properties of PSTZT ceramics prepared by OSSM and TSSM were also investigated via quiet-state method. It was found that the larger the x value of (1-x)PST-xPZT is, the lower the pyroelectric coefficient of PSTZT ceramics is. The pyroelectric coefficient of 0.9PST-0.1PZT ceramics is about (8~25) × 10-8C/cm2·K at room temperature. The pyroelectric figure of merit of PSTZT ceramics was also discussed.

The Dielectric, Piezoelectric and Pyroelectric Properties of (1-x)PST-xPZT Relaxor Ferroelectric Ceramics

ABSTRACTPb(Sc1/2Ta1/2)O3 (PST) relaxor ferroelectric ceramics were investigated widely in the past decades for their excellent pyroelectric, ferroelectric and dielectric properties and comprehensive applications in uncooled focal plane arrays infrared detectors and other electronic devices. However, some other ferroelectrics could be added into the PST ceramics to form the complex perovskite ferroelectrics with better electric properties. In this paper, (1-x)PST-xPZT(PSTZT) relaxor ferroelectric ceramics were prepared by wolframite precursor process (named two-step -sintering method, TSSM). The experiment results showed that the PSTZT ceramics with pure perovskite structure could be prepared by using TSSM. The temperature dependence of permittivity and dielectric loss of PSTZT ceramics were investigated in detail, which indicated that PSTZT ceramics showed partly diffusive phase transition with little frequency dispersion. The dielectric and pyroelectric properties of PSTZT ceramics were also investigated and discussed.