Compositional modulation in ZnGa2O4 via Zn2+/Ge4+ co-doping to simultaneously lower sintering temperature and improve microwave dielectric properties

• Published in: Journal of advanced ceramics Vol. 10; no. 6; pp. 1360 - 1370
• Main Authors: Xiong, Ying, Xie, Hongyuan, Rao, Zhenggang, Liu, Laijun, Wang, Zhengfeng, Li, Chunchun
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.12.2021; Springer Nature B.V; College of Information Science and Engineering,Guilin University of Technology,Guilin 541004,China; Guangxi Key Laboratory of Optical and Electronic Materials and Devices,College of Material Science and Engineering,Guilin University of Technology,Guilin 541004,China%School of Materials Science and Engineering,Nanchang University,Nanchang 330031,China%Guangxi Key Laboratory of Optical and Electronic Materials and Devices,College of Material Science and Engineering,Guilin University of Technology,Guilin 541004,China%College of Information Science and Engineering,Guilin University of Technology,Guilin 541004,China%College of Information Science and Engineering,Guilin University of Technology,Guilin 541004,China; Guangxi Key Laboratory of Optical and Electronic Materials and Devices,College of Material Science and Engineering,Guilin University of Technology,Guilin 541004,China; School of Materials Science and Engineering,Nanchang University,Nanchang 330031,China
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Composition; Crystallization; Dielectric properties; Doping; Frequency stability; Glass; Materials Science; Microstructure; Nanotechnology; Natural Materials; Permittivity; Q factors; Research Article; Sintering; Spinel; Structural Materials; Thermal stability; Titanium dioxide; ceramics; spinel; composition modulation; dielectric properties
• ISSN: 2226-4108; 2227-8508
• DOI: 10.1007/s40145-021-0511-0

AB 2 O 4 -type spinels with low relative permittivity ( ε r ) and high quality factor ( Q × f ) are crucial to high-speed signal propagation systems. In this work, Zn 2+ /Ge 4+ co-doping to substitute Ga 3+ in ZnGa 2 O 4 was designed to lower the sintering temperature and adjust the thermal stability of resonance frequency simultaneously. Zn 1+ x Ga 2−2 x Ge x O 4 (0.1 ⩽ x ⩽ 0.5) ceramics were synthesised by the conventional solid-state method. Zn 2+ /Ge 4+ co-substitution induced minimal variation in the macroscopical spinel structure, which effectively lowered the sintering temperature from 1385 to 1250 °C. All compositions crystallized in a normal spinel structure and exhibited dense microstructures and excellent microwave dielectric properties. The compositional dependent quality factor was related to the microstructural variation, being confirmed by Raman features. A composition with x = 0.3 shows the best dielectric properties with ε r ≈ 10.09, Q × f ≈ 112,700 THz, and τ f ≈ −75.6 ppm/°C. The negative τ f value was further adjusted to be near-zero through the formation of composite ceramics with TiO 2 .