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Dielectric loss
About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.
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TL;DR: In this paper, it was shown that a conventional surface barrier layer capacitor (SBLC) effect, while it contributes significantly to the observed colossal permittivity, is not the dominant effect, rather, there exists a subtle chemical compositional gradient inward from the pellet surface, involving the concentration of Ti3+ cations gradually increasing from zero at the surface without the introduction of any charge compensating oxygen vacancies.
Abstract: (Nb+Al) codoped rutile TiO2 ceramics with nominal composition Ti4+0.995Nb5+0.005yAl3+0.005zO2, z = (4–5y)/3 and y = 0.4, 0.5, 0.6, 0.7, and Ti4+0.90Nb5+0.05Al3+0.05O2 have been synthesized. The resultant samples in ceramic pellet form exhibit a colossal dielectric permittivity (>∼104) with an acceptably low dielectric loss (∼10–1) after optimization of the processing conditions. It is found that a conventional surface barrier layer capacitor (SBLC) effect, while it contributes significantly to the observed colossal permittivity, is not the dominant effect. Rather, there exists a subtle chemical compositional gradient inward from the pellet surface, involving the concentration of Ti3+ cations gradually increasing from zero at the surface without the introduction of any charge compensating oxygen vacancies. Instead, well-defined Gr ± 1/3[011]* satellite reflections with the modulation wave-vector q = 1/3[011]r* and sharp diffuse streaking running along the Gr ± e[011]* direction from electron diffraction su...
168 citations
TL;DR: Dielectric spectroscopy covering more than 18 decades of frequency has been performed on propylene carbonate in its liquid and supercooled-liquid state and finds evidence for additional processes in the crossover regime.
Abstract: Dielectric spectroscopy covering more than 18 decades of frequency has been performed on propylene carbonate in its liquid and supercooled-liquid state. Using quasioptic submillimeter and far-infrared spectroscopy, the dielectric response was investigated up to frequencies well into the microscopic regime. We discuss the alpha process whose characteristic time scale is observed over 14 decades of frequency and the excess wing showing up at frequencies some three decades above the peak frequency. Special attention is given to the high-frequency response of the dielectric loss in the crossover regime between alpha peak and boson peak. Similar to our previous results in other glass-forming materials, we find evidence for additional processes in the crossover regime. However, significant differences concerning the spectral form at high frequencies are found. We compare our results to the susceptibilities obtained from light scattering and to the predictions of various models of the glass transition.
168 citations
TL;DR: In this article, the synthesis of Co doped ZnO nanoparticles by combustion method using citric acid as a fuel for 0, 1, 3, 5% and 10% of Co doping was reported.
Abstract: We report the synthesis of Co doped ZnO nanoparticles by combustion method using citric acid as a fuel for 0%, 1%, 3%, 5% and 10% of Co doping. The structural, optical and dielectric properties of the samples were studied. Crystallite sizes were obtained from the X-ray diffraction (XRD) patterns whose values are decreasing with increase in Co content up to 5%. The XRD analysis also ensures that ZnO has a hexagonal (wurtzite) crystal structure and Co2+ ions were successfully incorporated into the lattice positions of Zn2+ ions. The TEM image shows the average particle size in the range of 10–20 nm for 3% Co doped ZnO nanoparticles. The energy band gap as obtained from the UV–visible spectrophotometer was found gradually increasing up to 5% of Co doping. The dielectric constants (ɛ′, ɛ″), dielectric loss (tan δ) and ac conductivity (σac) were studied as the function of frequency and composition, which have been explained by ‘Maxwell Wagner Model’.
168 citations
TL;DR: In this article, the authors investigated the dielectric properties of BaTiO 3 /epoxy composites with different types of treated ceramic powders and measured the properties of these composites as functions of temperature and frequency.
Abstract: Multi-doped BaTiO 3 /epoxy composites with the different types of treated ceramic powders are under investigation. The ceramic/epoxy composite with the 900°C treated ceramic powder has the highest dielectric constant, while lower values for those with powders treated at higher temperatures. Longer grinding of 20 h can have different heat-treated composites with similar dielectric constants. Dielectric properties of these composites were measured as functions of temperature and frequency. The increase of dielectric loss at frequencies above 1 MHz is due to the mechanism of domain-wall motion. The composite with semi-conducting fillers can have a limited increase in dielectric constant, but a large increase in dielectric loss. To have the best dielectric properties of the multi-doped BaTiO 3 /epoxy composite thick films for the printed wiring boards, the ceramic ratio need to be maximized without losing the board flexibility. A proper powder treatment is required to maximize the powder loading and performance.
166 citations
TL;DR: In this article, an equivalent circuit model was set up to evaluate the influence of dispersion and spatial distribution of multiwalled carbon nanotubes on the dielectric properties.
166 citations