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We prepared (1−x)CaTiO3xLaAlO3 (0 ≤ x ≤ 1) microwave dielectric ceramics using a conventional two-step solid-state reaction method, and investigated microwave dielectric properties of the ceramics in terms of A/B-site ionic-parameters. Ionic-parameters such as ionic polarizability, A-site bond valence, and ionic rattling were linked to the microwave dielectric properties. As the LaAlO3 content x in the (1−x)CaTiO3xLaAlO3 ceramics increased from 0.3 to 0.7, the dielectric constant gradually decreased, which was attributed to the decrease of polarizability deviation and suppression of the cation rattling. The temperature coefficient of the resonant frequency decreased as the content of LaAlO3 increased because of the increase of A-site cation bond valence. The quality factor value (Q × f) increased as LaAlO3 content increased because of the enhancement of the order degree of B-site cation. A significant deterioration of the temperature coefficient of the resonant frequency and Q × f value was observed at the composition x = 0.5. These decreases were attributed to a phase transition from orthorhombic crystal (for x ≤ 0.5) to rhombohedral crystal (for x > 0.5).


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Understanding microwave dielectric properties of (1−x)CaTiO3xLaAlO3 ceramics in terms of A/B-site ionic-parameters

Show Author's information Zhanming DOUGan WANGJuan JIANG( )Fan ZHANGTianjin ZHANG( )
Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials and School of Material Science and Engineering, Hubei University, Wuhan 430062, China

† These authors contributed equally to this work.

Abstract

We prepared (1−x)CaTiO3xLaAlO3 (0 ≤ x ≤ 1) microwave dielectric ceramics using a conventional two-step solid-state reaction method, and investigated microwave dielectric properties of the ceramics in terms of A/B-site ionic-parameters. Ionic-parameters such as ionic polarizability, A-site bond valence, and ionic rattling were linked to the microwave dielectric properties. As the LaAlO3 content x in the (1−x)CaTiO3xLaAlO3 ceramics increased from 0.3 to 0.7, the dielectric constant gradually decreased, which was attributed to the decrease of polarizability deviation and suppression of the cation rattling. The temperature coefficient of the resonant frequency decreased as the content of LaAlO3 increased because of the increase of A-site cation bond valence. The quality factor value (Q × f) increased as LaAlO3 content increased because of the enhancement of the order degree of B-site cation. A significant deterioration of the temperature coefficient of the resonant frequency and Q × f value was observed at the composition x = 0.5. These decreases were attributed to a phase transition from orthorhombic crystal (for x ≤ 0.5) to rhombohedral crystal (for x > 0.5).

Keywords:

(1−x)CaTiO3xLaAlO3 (CTLA) microwave dielectric ceramics, ionic polarizability, bond valence, cation rattling effect
Received: 04 September 2016 Revised: 10 September 2017 Accepted: 10 November 2017 Published: 02 March 2017 Issue date: March 2017
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Publication history

Received: 04 September 2016
Revised: 10 September 2017
Accepted: 10 November 2017
Published: 02 March 2017
Issue date: March 2017

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© The author(s) 2016

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