Dielectric loss

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

Temperature coefficients of capacitance of solids

Abstract: An earlier treatment of temperature coefficient of capacitance, γ c [1] has been extended to include most solids. Materials are divided into those with given ranges of permittivity, e, and temperature coefficient of polarisability. It appears that, for low dielectric loss, high permittivity glasses, like simple ionic compounds, always have a positive γ c, whereas paraelectrics and polymers have negative γ c. Ferroelectrics can have any value of γ c. Limitations in γ c and e for given classes of solid are discussed.

Temperature stable Li2Ti0.75(Mg1/3Nb2/3)0.25O3-based microwave dielectric ceramics with low sintering temperature and ultra-low dielectric loss for dielectric resonator antenna applications

Abstract: Microwave dielectric ceramics are considered to be one of the key materials of dielectric resonators/filters and have wide application prospects in fifth generation (5G) mobile communication systems. Here we prepared two kinds of low-sintering temperature and high-performance microwave dielectric ceramics with monoclinic rock salt structure by adding a small amount of V2O5 and 0.6CuO–0.4B2O3 sintering aids to Li2Ti0.75(Mg1/3Nb2/3)0.25O3 (LTMN0.25). The sintering temperature of LTMN0.25 ceramics with 2 wt% V2O5 and 1 wt% 0.6CuO–0.4B2O3 additions could be effectively reduced from 1170 °C to below 910 °C due to the liquid phase effects resulting from the additives. Typically, high performance microwave dielectric properties can be obtained in the LTMN0.25 + 2 wt% V2O5 ceramic sintered at 910 °C for 2 h, with a er ∼ 20.7, a Q × f ∼ 60 460 GHz and a TCF ∼ +4.3 ppm °C−1. The best dielectric properties of er ∼ 19.9, a Q × f ∼ 60 950 GHz and a TCF ∼ −6.1 ppm °C−1 were obtained for the samples with 1 wt% 0.6CuO–0.4B2O3 sintered at 870 °C for 2 h. A prototype dielectric resonator antenna (DRA) was fabricated by LTMN0.25 + 1 wt% 0.6CuO–0.4B2O3 ceramic. The antenna resonated at 10.02 GHz with a bandwidth ∼175 MHz at −10 dB transmission loss (S11). Moreover, the chemical compatibility with Ag powder suggests that the LTMN0.25 + 2 wt% V2O5 and LTMN0.25 + 1 wt% 0.6CuO–0.4B2O3 ceramics may be suitable candidates for low temperature co-fired ceramic technology applications.

Synthesis and properties of multiferroic La-modified BiFeO3 ceramics

Abstract: Multiferroic Bi(1−x)LaxFeO3 was synthesized by a modified Pechini approach. Optimal conditions for the synthesis of single-phase Bi(1−x)LaxFeO3 powder were reported. A conventional sintering process was used to fabricate Bi(1−x)LaxFeO3 ceramics. Ferroelectric and magnetic loops measured at room temperature indicate the coexistence of ferroelectricity and magnetism. The La modification of BiFeO3 has a beneficial effect on the ferroelectric and magnetic properties. The ceramic samples show a stable dielectric constant and quite low dielectric loss between 100 Hz and 10 MHz. The piezoelectric constants of Bi(1−x)LaxFeO3 ceramics were first reported.