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Among Aurivillius-phase ferroelectric ceramics, CaBi2Nb2O9 is considered as the best candidate with potential applications in ultrahigh-temperature piezoelectric devices due to the highest Tc (∼940 °C). This paper reports that BiMn co-substitution at A and B sites gives rise to dramatic enchantments in ferroelectricity, piezoelectricity, and electrical resistivity of CaBi2Nb2O9 ceramics. The optimum composition (Ca0.97Bi2.03Nb1.99Mn0.01O9) with a Tc of 953 ± 3°C shows a high ferroelectric remnant polarization (Pr), field-induced strain (S33), piezoelectric activity d33 and d 33 ∗ with values of ∼11.1 µC/cm2, 4.9 × 10−4, 20.8 and 26.1 pC/N, respectively, which are about two to three times those of CaBi2Nb2O9. Significant ferroelectric remnant polarization (Pr = 11.1 µC/cm2), field-induced strain (S33 = 4.9 × 10−4), and piezoelectric activity (d33 = 20.8 pC/N, d 33 ∗ = 26.1 pC/N) are simultaneously induced in ultrahigh Tc CaBi2Nb2O9 piezoceramics by BiMn substitution. [ABSTRACT FROM AUTHOR]

Piezoelectric thermal stability is often a critical issue for many piezoelectric materials in practical applications. Lead-free piezoelectric ceramics, (1−x)K0.5Na0.5NbO3– xAgNbO3 (KNN-AN, with x = 0–0.35) have been synthesized by a conventional solid state sintering method. The temperature dependence of the dielectric, ferroelectric and piezoelectric properties of lead-free piezoelectric ceramics was investigated. The piezoelectric properties exhibit a very good thermal stability up to high temperature, which is a significant improvement from other KNN-based piezoceramics. [ABSTRACT FROM PUBLISHER]

The relaxation behaviors of barium titanate ceramics were investigated in the temperature range of 200–450°C. The diffuse dielectric anomalies were described by the universal dielectric relaxation law (UDR) and polaron theory. It is indicated the dielectric relaxation of barium titanate at high temperatures is associated with the hopping localized oxygen vacancies. [ABSTRACT FROM PUBLISHER]

The geometry, dipole moments and electron properties (Mulliken charges and density of states) of substituted β PVDF-based polymers (PVDF, PVDCN, PADFB and PVDC) were studied by density functional theory. The results show that the optimised geometries of chains are bent and distorted. Dipole moments reduce with increasing chain lengths, especially in PVDCN and PVDC. PADFB presents the largest dipole moment (5.97 Debye), which can attribute to its narrow energy gap (0.12 Ha) and large Mulliken charges. It is concluded that substitution with similar radii atoms would maintain the dipole moments of the long chain, and the dipole moments would increase when the substitution reduces the energy gap in some degree. [ABSTRACT FROM AUTHOR]

SnO2/ZnO nanocomposite was synthesized from mixed ethanol and water systems and the ethanol-sensing properties of sensors based on SnO2/ZnO were investigated. The structure and morphology of the products was characterized by x-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The results showed that the diameter of the liked pine needle SnO2 was about 40 nm with a length about 300 nm, which are uniformly dispersed on the surface of the ZnO nanosheets. The growth process of the SnO2/ZnO nanocomposite was discussed. The results of gas sensing properties of SnO2/ZnO nanocomposite sensor showed high and quick response to ethanol vapor at 5.0 v. This sensor showed the advantages of high selectivity, strong stability, and prompt response/recovery characteristics in detecting ethanol vapor at 5.0 v. [ABSTRACT FROM AUTHOR]

Monodisperse (Ba0.6Sr0.4)TiO3 nanoparticles have been successfully synthesized by a liquid-solid-solution method at low temperature of 160°C. The purity dependence on the concentration of mineralizer has been investigated. Subsequently, the (Ba0.6Sr0.4)TiO3 thick film has been deposited on Pt/Ti/SiO2/Si substrates by an electrophoretic deposition method and capacitance verse voltage (C-V) as well as leakage current density versus electrical field (J-E) characteristics has been studied. The dielectric tunability of 82.6% can be obtained and the dominant leakage mechanism is Schottky emission for positive biases as the Pt bottom electrode negatively biased. [ABSTRACT FROM AUTHOR]

Uniformity nanosheets of CuO were prepared by a mild hydrothermal synthesis method. Phase analysis was carried out using x-ray diffraction (XRD) and the result confirmed the CuO nanosheets as a single phase. The field-emission scanning electron microscopy (FE-SEM) was used to observe the morphology of CuO nanosheets while the gas sensing properties of these unique CuO nanosheets were tested at a static state system. The results show that the CuO has uniformity nanosheets, and the gas sensing property show that the CuO nanosheets gas sensor has a stable gas response and the same gas sensitivity trend to tested gases. This method may be suitable for larger-scale production of these CuO nanosheets for practical applications. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric ceramics, (Na0.5Bi0.5) 0.92Ba0.08TiO3 (BNT-BT) have been synthesized by a conventional solid state sintering method. The dependence of temperature on dielectric and ferroelectric properties of lead-free piezoelectric ceramics were investigated. The ceramics exhibit a giant strain with the increase of temperature. The piezoelectric coefficient (d33) is about 149pC/N at RT. The electromechanical properties were explained based on a field induced antiferroelectric-ferroelectric phase transition. [ABSTRACT FROM AUTHOR]