Topic
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 article, the correlation between the chemical composition, microstructure, and microwave properties of composites based on lightly Tb/Tm-doped Sr-hexaferrites (SrTb0.01Tm0.98O19) and spinel ferrites (AFe2O4, A = Co, Ni, Zn, Cu, or Mn), which were fabricated by a one-pot citrate sol-gel method, was investigated.
Abstract: Herein, we investigated the correlation between the chemical composition, microstructure, and microwave properties of composites based on lightly Tb/Tm-doped Sr-hexaferrites (SrTb0.01Tm0.01Fe11.98O19) and spinel ferrites (AFe2O4, A = Co, Ni, Zn, Cu, or Mn), which were fabricated by a one-pot citrate sol–gel method. Powder XRD patterns of products confirmed the presence of pure hexaferrite and spinel phases. Microstructural analysis was performed based on SEM images. The average grain size for each phase in the prepared composites was calculated. Comprehensive investigations of dielectric properties (real (e′) and imaginary parts (e′′) of permittivity, dielectric loss tangent (tan(δ)), and AC conductivity) were performed in the 1–3 × 106 Hz frequency range at 20–120 °C. Frequency dependency of microwave properties were investigated using the coaxial method in frequency range of 2–18 GHz. The non-linear behavior of the main microwave properties with a change in composition may be due to the influence of the soft magnetic phase. It was found that Mn- and Ni-spinel ferrites achieved the strongest electromagnetic absorption. This may be due to differences in the structures of the electron shell and the radii of the A-site ions in the spinel phase. It was discovered that the ionic polarization transformed into the dipole polarization.
91 citations
TL;DR: In this paper, the dielectric properties of six subtropical and tropical fruits along with four associated insect pests were measured between 1 and 1800 MHz using an open-ended coaxial-line probe technique and at temperatures between 20°C and 60°C.
Abstract: Knowledge of the dielectric properties of commodities and insect pests is important in developing thermal
treatments for postharvest insect control based on radio frequency (RF) and microwave energy. The dielectric properties of
six subtropical and tropical fruits along with four associated insect pests were measured between 1 and 1800 MHz using an
open-ended coaxial-line probe technique and at temperatures between 20°C and 60°C. The dielectric loss factor of the fruits
and the insects decreased with increasing frequency at constant temperatures. Especially over 10 to 300 MHz, the log of the
dielectric loss factor decreased linearly with the log of increasing frequency. The loss factor of the fruits and the insects
increased almost linearly with increasing temperature at 27.12 MHz radio frequency, but remained in a small range at
915 MHz microwave frequency. Both the dielectric constant and the loss factor were the highest in avocado fruit. The
dielectric loss factors of insects were generally larger than that of the host fruit at all tested frequencies. But those values
were within the same order of magnitude, suggesting that differential heating of insects in fresh fruits was unlikely to occur
in RF and microwave systems. Direct measurement of electrical conductivity of fruit pulps can also provide a good estimation
of the dielectric loss factor at 27.12 MHz. Matching the electrical conductivity of saline solution can be an effective and simple
means to improve heating uniformity of the fruit when subjected to RF systems.
91 citations
TL;DR: In this paper, nitrogen-doped carbon nanotube (N-CNT)/polymer nanocomposites exhibiting relatively high and frequency independent real permittivity ( e′ ) together with low dielectric loss (tan δ ) were synthesized by chemical vapor deposition, and their nanocom composites were prepared by melt-mixing with polyvinylidene fluoride (PVDF).
91 citations
TL;DR: In this article, a (1−x)(Bi,La)(Fe0.95Ga0.05)O3-xPbTiO3 (BLGF-PT) with La concentrations of 0, 10, and 20 at.
Abstract: Crystalline solutions of (1−x)(Bi,La)(Fe0.95Ga0.05)O3–xPbTiO3 (BLGF–PT) have been fabricated with La concentrations of 0, 10, and 20 at. %. The BLGF–PT system has been found to have excellent insulation resistivity ⩽1013 Ω cm. In addition, La substituent was found to decrease the coercive field, resulting in much improved dielectric and piezoelectric properties. A shift in the morphotropic phase boundary of BLGF–PT with increasing La content was identified for x=0.3, 0.4, and 0.43. We have achieved optimized dielectric constant, loss factor, Curie temperature, remnant polarization, and piezoelectric d33 properties of 881, 0.037, 386 °C, 30 μC/cm2 and 163 pC/N, respectively, for 0.6BLGF–0.4PT with 10 at. % La. These results clearly demonstrate that BLGF–PT is a competitive alternative piezoelectric material to Pb(Zr,Ti)O3 with reduced lead content.
91 citations
TL;DR: The dielectric properties of layer perovskites in the Dion−Jacobson (KCa2Nb3O10, HCa2 Nb4O13, KLa 2NbTi2O10) and Ruddlesden−Poppper (K2La2Ti3O 10) series were investigated in this article.
Abstract: The dielectric properties of layer perovskites in the Dion−Jacobson (KCa2Nb3O10, HCa2Nb3O10, CsPb2Nb3O10, HPb2Nb3O10, KCa2NaNb4O13, KLa2NbTi2O10) and Ruddlesden−Poppper (K2La2Ti3O10) series, and of...
91 citations