Title: Structural characteristics and microwave dielectric properties of Mg₂Ti_1-x(Mg_1/3B_2/3)_xO₄ (B = Nb⁵⁺, Ta⁵⁺) ceramics

Authors: Sung Ho Kim; Eung Soo Kim

Addresses: Department of Materials Engineering, Kyonggi University, Suwon 16227, South Korea ' Department of Materials Engineering, Kyonggi University, Suwon 16227, South Korea

Abstract: The effects of structural characteristics on the dielectric properties of Mg₂Ti_1-x(Mg_1/3B_2/3)_xO₄ (B = Nb⁵⁺, Ta⁵⁺, 0.025 ≤ x ≤ 0.1) ceramics were investigated at various microwave frequencies. For the entire range of the compositions sintered at 1450°C for 4 h, a single phase of inverse spinel structure with cubic symmetry was confirmed with a relative density higher than 96% of the theoretical value. Owing to the dependence of the quality factor (Qf) on the bond valence between the cation and the oxygen ion, the specimens at x = 0.05 showed the highest Qf value. Although the dielectric polarisability was increased with (Mg_1/3B_2/3)⁴⁺ content, the theoretical dielectric constant (K_M) and the experimentally measured one (K_mea.) decreased due to the larger ionic radius of (Mg_1/3B_2/3)⁴⁺ (B = 0.667 Å) when compared to Ti⁴⁺ (0.605 Å). Since the temperature coefficient of resonant frequency (TCF) was affected by the K value, TCF of the specimens decreased with decreasing the K value.

Keywords: magnesium titanate; inverse spinel structure; bond valence; microwave dielectric properties.

DOI: 10.1504/IJNT.2018.096348

International Journal of Nanotechnology, 2018 Vol.15 No.6/7, pp.578 - 586

Published online: 26 Nov 2018 *

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