Dielectric loss

About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.

Microwave properties of zinc, barium and lead borosilicate glasses

Abstract: The trend to fabricate mulitlayer structures of microwave dielectric ceramics cofired with low melting conductors results in the demand of additives for low temperature sintering. Low-melting glasses are good candidates for low temperature sintering aids. When the concentration of the added low-melting glasses reaches a high content of about 10–20 mol%, their microwave properties will certainly affect the performance of the final multilayer devices. It is the object of this study to investigate the microwave properties of low-melting ZnO–B 2 O 3 –SiO 2 , BaO–B 2 O 3 –SiO 2 , and PbO–B 2 O 3 –SiO 2 glasses. The parallel plate dielectric resonator rod method was employed for measurements of relative dielectric constants, quality factors, and temperature coefficients of frequency in the microwave frequency range. A thermo-mechanical analyzer was used to determine deformation temperatures of glasses. Properties of these three glass systems are chiefly determined by the amount of structural modifier oxides (ZnO, BaO, and PbO) and the ionic size of the modifying cations (Zn 2+ , Ba 2+ , Pb 2+ ). In contrast, the effect of the ratio of B 2 O 3 to SiO 2 is relatively small. The frequency constants of these three glass systems range from 500 to 3400, which are equivalent to tan δ of 0.02–0.003 at 10 GHz. The temperature coefficients of frequency range from −3 to −155 ppm/°C.

Dielectric Properties of Rare Earth Substituted Cu-Zn Ferrites

Abstract: Samples with the chemical formula Cu0.5Zn0.5Fe2−xRxO4 (R = La, Nd, Sm and Gd; x = 0 and 0.1) were prepared by the standard ceramic method. The real part of the dielectric constant e′ and the ac electrical conductivity σac are measured and the dielectric loss tangent tan δ is calculated in the frequency range 50–105 Hz and from room temperature up to ≅800 K. e′ and tan δ are found to decrease with increasing the frequency while σac is generally increased. On the contrary e′, σac and tan δ are increased with temperature. No relaxation was detected in tan δ(f) in the investigated frequency range while tan δ(T) showed two maxima. The composition dependence of the dielectric parameters is discussed and the results are explained using Koops's model. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Comparing calorimetric and dielectric polarization modes in viscous 2-ethyl-1-hexanol.

Abstract: Dielectric relaxation and dynamic heat capacity measurements are compared for 2-ethyl-1-hexanol near its glass transition temperature Tg in order to further clarify the origin of the prominent Debye-type loss peak observed in many monohydroxy alcohols and other hydrogen-bonding liquids. While the dielectric spectrum e″ displays two distinct polarization processes that are separated by a factor of 2000 in terms of the peak frequency, the heat capacity cp″ shows only a single peak. The dielectric process with lower amplitude and higher peak frequency coincides with the calorimetric signal, whereas the large dielectric Debye signal is not associated with calorimetric modes. The authors conclude that the Debye process corresponds to a transition among states which differ in energy only in the case of an external electric field.