Percolative ceramic composites with giant dielectric constants and low dielectric losses

3D Finite Element Method simulations were employed in order to describe tunability properties in anisotropic porous paraelectric structures. The simulations predicted that properties of a ceramic can be tailored by using various levels of porosity. Porous Ba0.6Sr0.4TiO3 (BST) ceramics have been studied in order to investigate the influence of porosity on their functional properties. The BST ceramics with various porosity levels have been obtained by solid-state reaction. Lamellar graphite in different concentration of 10, 20 and 35 vol.%was added as sacrificial pore forming agent. The structural, microstructural, dielectric and tunability properties were investigated. By comparison with dense BST ceramic, porous samples present a fracture mode transformation from intragranular to an intergranular fracture and a decrease of grain size. Lower dielectric constants, low dielectric losses, but higher values of tunability than in the dense material were obtained in the porous BST structures as a result of local field inhomogeneity generated by the presence of air pores-ceramic interfaces.

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Dielectric Behavior and Phonon Damping in Low-Dielectric Constant Perovskite Materials

MRS Proceedings ◽

10.1557/proc-511-165 ◽

1998 ◽

Vol 511 ◽

Author(s):

Ram S. Katiyar ◽

Igor Siny ◽

R. Guo ◽

A. S. Bhalla

Keyword(s):

Raman Spectra ◽

Charge Compensation ◽

Relaxor Ferroelectrics ◽

Dielectric Behavior ◽

Dielectric Constants ◽

Dielectric Losses ◽

Low Dielectric ◽

Close Packed Structure ◽

Crystal Fibers ◽

Laser Heated

ABSTRACTWe have carried out a comparative study of the dielectric losses in some complex perovskites with both 1:1 and 1:2 compositions of the B ions, namely, SrAl1/2Nb1/2O3 (SAN), SrAl1/2Ta1/2O3 (SAT) and BaMg1/3Ta2/3O3 (BMT). The samples were prepared in two forms, viz. ceramics and single-crystal fibers, the latter were grown by laser heated pedestal growth technique (LHPG). All of these materials possess low dielectric constants, low losses and high Q values. In contrast to relaxor ferroelectrics, that as a rule exhibit broad features in their Raman spectra, SAN, SAT and especially BMT have very narrow phonon lines in the Raman spectra. A linear correlation is found between the microwave dielectric losses and the width of first order phonon lines in a sequence of BMT → SAT → SAN ceramics with increasing phonon damping. Moreover, the phonon damping decreases in materials with non-close-packed structure where there is enough space for undisturbed phonon vibrations. The problem of charge compensation in compounds with the Bsite disorder is also discussed.

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Design and Preparation of Benzoxazine Resin with High-Frequency Low Dielectric Constants and Ultralow Dielectric Losses

ACS Applied Polymer Materials ◽

10.1021/acsapm.8b00083 ◽

2019 ◽

Vol 1 (4) ◽

pp. 625-630 ◽

Cited By ~ 10

Author(s):

Jiangbing Chen ◽

Ming Zeng ◽

Zijian Feng ◽

Tao Pang ◽

Yiwan Huang ◽

...

Keyword(s):

High Frequency ◽

Dielectric Constants ◽

Dielectric Losses ◽

Low Dielectric

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Microstructure, Crystalline Phase, and Dielectric Property Analyses of TiO2 Composition with ZrO2 Addition

Materials Science Forum ◽

10.4028/www.scientific.net/msf.660-661.641 ◽

2010 ◽

Vol 660-661 ◽

pp. 641-645

Author(s):

José Vitor C. Souza ◽

Pedro José Castro ◽

Maria do Carmo de Andrade Nono ◽

Sergio Luiz Mineiro

Keyword(s):

High Dielectric Constant ◽

Raw Materials ◽

Weight Ratio ◽

Satellite Communications ◽

Dielectric Constants ◽

Sintering Behavior ◽

Dielectric Losses ◽

Low Dielectric ◽

A Value ◽

High Dielectric

For microwave applications, including mobile and satellite communications, ceramic resonators should have a high dielectric constant, low dielectric losses, and high frequency stability. In this sense, TiO2-ZrO2 ceramics have been investigated as a function of sintering behavior, phase composition, and microstructure. The ceramics were densified reaching a value of about 86% of theoretical density at 1400°C sintering temperature. The ceramics are prepared by mixing raw materials with the following TiO2-ZrO2 weight % ratio: 100 to 0, 90 to 10, and 80 to 20, respectively. The measured dielectric constants are between 79 and 88 values, while the quality factor due to dielectric losses are between 2820 and 5170. These results point out the influence of Ti/Zr ratio on controlling the dielectric properties.

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