Structure and Microwave Dielectric Properties of Ca₅A₄TiO₁₇ (A = Nb, Ta) Ceramics

Authors

Tony Joseph, National Institute for Interdisciplinary Science and Technology (CSIR)
P. S. Anjana, National Institute for Interdisciplinary Science and Technology (CSIR)
Steven Letourneau, Boise State UniversityFollow
Rick Ubic, Boise State UniversityFollow
Sander Smaalen, University of Bayreuth
M. T. Sebastian, National Institute for Interdisciplinary Science and Technology (CSIR)

Document Type

Article

Publication Date

5-15-2010

Abstract

Ca₅A₄TiO₁₇ (A = Nb, Ta) dielectric ceramics were prepared by the conventional solid-state ceramic route. The structure and microstructure of the ceramics were investigated by X-ray diffraction, transmission electron microscopy and scanning electron microscopic techniques. The electron diffraction patterns of Ca₅A₄TiO₁₇ were indexed according to the model in P2₁/c. The microwave dielectric properties of the sintered ceramics were measured in the frequency range of 3–6 GHz. Ca₅Nb₄TiO₁₇ ceramics had a relative permittivity, ^ε_r = 44.9 (porosity corrected value 49.4), quality factor, Q_u × f = 17,600 GHz (at 4.13 GHz) and temperature coefficient of resonant frequency, τ_f = −112.9 ppm °C⁻¹, whereas for Ca₅Ta₄TiO₁₇, the obtained values were 40.1 (porosity corrected value 44.1), 16,450 GHz (at 4.22 GHz) and −53.6 ppm °C⁻¹, respectively. The density of Ca₅A₄TiO₁₇ ceramics was increased by adding small amounts of zinc borosilicate (60ZnO–30B₂O₃–10SiO₂) glass. The effect of glass addition on the microwave dielectric properties of Ca₅A₄TiO₁₇ ceramics was also investigated.

Publication Information

Joseph, Tony; Anjana, P. S.; Letourneau, Steven; Ubic, Rick; Smaalen, Sander; and Sebastian, M. T.. (2010). "Structure and Microwave Dielectric Properties of Ca₅A₄TiO₁₇ (A = Nb, Ta) Ceramics". Materials Chemistry and Physics, 121(1-2), 77-82. https://doi.org/10.1016/j.matchemphys.2009.12.046