Spinel-type solid solution ceramic MgAl2O4-Mg2TiO4 with excellent microwave dielectric properties

• Published in: Journal of alloys and compounds Vol. 898; p. 162905
• Main Authors: Yang, Xizhi, Lai, Yuanming, Zeng, Yiming, Yang, Fan, Huang, Fangyi, Li, Baoyang, Wang, Fanshuo, Wu, Chongsheng, Su, Hua
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.03.2022; Elsevier BV
• Subjects: Bonding strength; Ceramics; Dielectric properties; Grain size; Mg2TiO4 ceramic; MgAl2O4 ceramic; Microwave dielectric property; Solid solutions; Spinel-type solid solution; MgAl2O4 ceramic; Microwave dielectric property; Spinel-type solid solution; Mg2TiO4 ceramic
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.162905

In this work, a series of (1-x)MgAl2O4-xMg2TiO4 (expressed as (1-x)MA- xMT) (0.0 ≤ x ≤ 0.9) ceramics were successfully prepared via a solid-state reaction, and the effect of Mg2TiO4 content on the phase compositions, microstructures and microwave dielectric properties of MgAl2O4 ceramics have been investigated. The MgAl2O4 could form a solid solution with Mg2TiO4, and the grain size of the (1-x)MA-xMT ceramics gradually increased with the increase of sintering temperature. The dielectric constants (εr) of (1-x)MA-xMT ceramics steadily increased with the increase of Mg2TiO4 content. The εr values were mainly affected by secondary phase and dielectric polarizability. The quality factor (Qf) of (1-x)MA-xMT ceramics was closely related to the relative density, secondary phase, cation vacancies and Ti valence; whereas the temperature coefficient of resonance frequency (τf) highly depended on the Al-site bond strength. For the sample at x = 0.9, the 0.1MA-0.9MT ceramics sintered at 1350 °C for 4 h exhibited the optimized microwave dielectric properties: εr = 12.36, Qf = 236,600 GHz and τf = −61 ppm/°C. •Mg2TiO4 enters into the lattice of MgAl2O4 and forms a solid solution.•MgAl2O4 can improve the sintering ability of Mg2TiO4 ceramics.•Mg2TiO4 can improve the microwave dielectric properties of MgAl2O4 ceramics.•High Qf value (236600 GHz) was obtained in 0.1MA-0.9MT ceramic sintered at 1350.