Title: Structural characteristics and microwave dielectric properties of Mg2Ti1-x(Mg1/3B2/3)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 Mg2Ti1-x(Mg1/3B2/3)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 (Mg1/3B2/3)4+ content, the theoretical dielectric constant (KM) and the experimentally measured one (Kmea.) decreased due to the larger ionic radius of (Mg1/3B2/3)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.
International Journal of Nanotechnology, 2018 Vol.15 No.6/7, pp.578 - 586
Received: 08 May 2021
Accepted: 12 May 2021
Published online: 21 Nov 2018 *