Papers by Keyword: Bismuth Layered Structure

Abstract: The bismuth layered structure materials (BLSFs) with general formula of the (Bi₂O₂)₂+(A_m-1B_mO_3m+1)²-, have attracted considerable attention for high-temperature piezoelectric applications. Hot pressing is a useful densifying and texture technique for enhancing the piezoelectric properties. In this present study, four different types (m=1, 2, 3, 4) of ceramics with Aurivillius structure were prepared and the influential factors of textured degree was investigated systematically by hot pressing method. The result indicates that the value of m is larger, the BLSFs ceramics is easier to get high degree of texture and high piezoelectric properties in the parallel of the hot pressing direction.

Abstract: Bismuth layered structure SrBi₂Ta₂O₉ ceramic 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 T_c = 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.

Abstract: Calcium bismuth niobate (CaBi₂Nb₂O₉, CBN) is a high Curie temperature (Tc) piezoelectric material, however, their piezoelectric properties are very poor. In order to improve the piezoelectric performance of CBN, the Eu modification and texture method (templated grain growth, TGG) were applied in this material system. The piezoelectric properties of CBN ceramics were significantly enhanced by Eu modification. The 5mol% Eu dopants in CBN ceramics have a higher piezoelectric constant and higher Tc (d₃₃=12.8pC/N, Tc=945°C) than that of undoped CBN ceramics (d₃₃=6.2pC/N, Tc=930°C). Highly textured 5mol% Eu doped CBN ceramics with 92% Lotgering factor were obtained by the TGG technique. The piezoelectric properties of textured and modified CBN ceramics are anisotropic on different directions of perpendicular (d₃₃=0.1pC/N) and parallel (d₃₃=20.5pC/N) to tape stacking direction. Furthermore, they had excellent thermostable piezoelectric properties from room temperature to near Curie temperature. The textured Eu modified CBN ceramics with high Tc and high piezoelectric properties might be a promising candidate for high-temperature piezoelectric applications.

Abstract: Sr(Bi1-xSmx)8Ti7O27 ceramics were prepared by Sm2O3-substitution for Bi2O3 through solid-state reaction route. The dielectric properties of the sintered bodies such as er, Q and tf were investigated. The ceramics were characterized by SEM, XRD, DTA and TG, which behaved high dielectric constant of 128 ~154 at the frequency of 10 GHz.