Grain size engineered 0.95MgTiO3–0.05CaTiO3 ceramics with excellent microwave dielectric properties and prominent mechanical performance

• Published in: Journal of the American Ceramic Society 2022-01, Vol.105 (1), p.299-307
• Main Authors: Yu, Yan, Wang, Yingjin, Guo, Weijia, Zhu, Chaoqiong, Ji, An, Wu, Hao, Liang, Shujian, Xiong, Shan, Wang, Xiaohui
• Format: Article
• Language: English
• Subjects: Bend strength; Ceramics; Communications systems; Diamond pyramid hardness; Dielectric properties; Grain size; grain size engineering; high reliability; Mechanical properties; Microwave communications; microwave dielectric properties; Miniaturization; Modulus of elasticity; Permittivity; Reliability; Resonant frequencies; Sintering; Ultrafines
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.18045

Microwave communication systems are being developed with the goal to achieve miniaturization and high reliability. There are urgent requirements for microwave dielectric materials to exhibit low sintering temperatures, excellent microwave dielectric properties, and prominent mechanical performance. However, simultaneously achieving these requirements is a significant challenge. These concerns have been addressed in the uniform ultrafine‐grained 0.95MgTiO3–0.05CaTiO3 ceramics with an average grain size of ~0.6 µm via a grain size engineering strategy. Interestingly, the sintering temperature in the unique two‐step sintering method of 1250℃/1 min and 1130℃/10 h is much lower (200–300℃) than that obtained in the conventional sintering method reported previously (1400–1450℃). Excellent dielectric properties are achieved, with relative permittivity εr = 20.11, quality factor Q × f = 68 613 GHz, and temperature coefficient of resonant frequency τf = 1.81 ppm/℃. The bending strength σf, Vickers hardness Hv, and elastic modulus E reach up to 212.4 MPa, 10.1 GPa, and 200.7 GPa, respectively. These values are significantly enhanced over those of samples obtained via the conventional sintering method with an average grain size of ~2.5 µm. For the first time, uniform ultrafine‐grained microwave dielectric materials with excellent microwave dielectric properties and prominent mechanical performance were synthesized. This work provides a guideline for developing other high‐performance microwave dielectric materials and makes a significant contribution to the miniaturization and high reliability of microwave dielectric devices.