Transport and Dielectric Properties of Mechanosynthesized La2/3Cu3Ti4O12 Ceramics

La2/3Cu3Ti4O12 (LCTO) powder has been synthesized by the mechanochemical milling technique. The pelletized powder was conventionally sintered for 10 h at a temperature range of 975–1025 °C, which is a lower temperature process compared to the standard solid-state reaction. X-ray diffraction analysis revealed a cubic phase for the current LCTO ceramics. The grain size of the sintered ceramics was found to increase from 1.5 ± 0.5 to 2.3 ± 0.5 μm with an increase in sintering temperature from 975 to 1025 °C. The impedance results show that the grain conductivity is more than three orders of magnitude larger than the grain boundary conductivity for LCTO ceramics. All the samples showed a giant dielectric constant (1.7 × 103–3.4 × 103) and dielectric loss (0.09–0.17) at 300 K and 10 kHz. The giant dielectric constant of the current samples was attributed to the effect of internal barrier layer capacitances due to their electrically inhomogeneous structure.

Copper Doped α-MnO2 Nano-sphere: A Metamaterial for Enhanced Supercapacitor and Microwave Shielding Applications

α-MnO2 nanoparticles with increasing copper doping concentration have been synthesized through a modified hydrothermal technique. Doping-induced microstructural defects inside the host material lead to a giant dielectric constant 1.6 ×...

Giant dielectric constant and high-temperature dielectric relaxation properties in La-doped SrTiO3 ceramics

[Formula: see text] (SLTO) ceramics ([Formula: see text] = 0.05, 0.10, 0.15) were prepared with giant dielectric constant by the traditional solid-state method at 1350[Formula: see text]C. The temperature dependence of the dielectric constant was obtained at the temperature ranging from 29[Formula: see text]C to 500[Formula: see text]C and the frequency ranging from 2 kHz to 2 MHz. Two sets of relaxation peaks appear in the low temperature (region I) and the high temperature (region II), respectively. For region I, we conclude that the relaxation behavior is related to the oxygen vacancy migration. For region II, the two relaxation processes are caused by grain boundary for high frequency and Sr or Ti defects at grain interior for low frequency. With the doping amount reaching 0.15, the relaxation peaks disappear and become a common phase transition because of the aggravation of lattice distortion. These possible physical mechanisms of two sets of relaxation peaks are briefly discussed.

Colossal Permittivity and Multiple Effects in (Zn + Ta) co-doped TiO2 Ceramics

The search for giant dielectric constant materials is imperative because of their potential for important applications for the areas of device miniaturization and energy storage. In this work, we report a (Zn + Ta) co-doped TiO2 (ZTTO) ceramics that manifests high dielectric permittivity (>104) and low dielectric loss. This dielectric property shows a high stability in wide temperature range (25-200℃) and frequency range(20-106Hz). The crystalline structure, microstructure and dielectric properties of ZTTO ceramics were systematically investigated. XPS, Impedance spectroscopy and frequency dependent dielectric constant under DC bias results reveal that the colossal dielectric properties of (Zn2+1/3Ta5+2/3)xTi1-xO2 ceramics were mainly caused by electron-pinned defect-dipoles (EPDD) model, internal barrier layer capacitance (IBLC) effect and electrode effect. This work would provide a guidance to further researching the colossal permittivity CP materials.

Temperature evolution of (quinuclidinium)[FeCl4]: a plastic/polar magnetic hybrid compound with a giant dielectric constant

The temperature evolution of (quinuclidinium)[FeCl4] shows the occurrence of an intricate series of phase transitions, involving notable modifications on the physical properties.