ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 55, (1) 14 - 19 (2011)


LOW-TEMPERATURE SINTERED (ZnMg)₂SiO₄ MICROWAVE CERAMICS WITH TiO₂ ADDITION AND CALCIUM BOROSILICATE GLASS
 
Li Bo, Tang Bin, Zhang Shuren, Jiang Hongmei
 
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, P. R China

Keywords: Willemite (Zn₂SiO₄), Microwave ceramics, Dielectric property, Microstructure, Millimeter-wave frequency, Low temperature co-sintered ceramics (LTCC)
 

The low-temperature sintered (ZnMg)₂SiO₄-TiO₂ microwave ceramic using CaO-B₂O₃-SiO₂ (CBS) as a sintering aid has been developed. Microwave properties of (Zn₁₋ₓMgₓ)₂SiO₄ base materials via sol-gel method were highly dependent on the Mg-substituted content. Further, effects of CBS and TiO₂ additives on the crystal phases, microstructures and microwave characteristics of (ZnMg)₂SiO₄ (ZMS) ceramics were investigated. The results indicated that CBS glass could lower the firing temperature of ZMS dielectrics effectively from 1170 to 950°C due to the liquid-phase effect, and significantly improve the sintering behavior and microwave properties of ZMS ceramics. Moreover, ZMS-TiO₂ ceramics showed the biphasic structure and the abnormal grain growth was suppressed by the pinning effect of second phase TiO₂. Proper amount of TiO₂ could tune the large negative temperature coefficient of resonant frequency (τf) of ZMS system to a near zero value. (Zn0.8Mg0.2)₂SiO₄ codoped with 10 wt.% TiO₂ and 3 wt.% CBS sintered at 950°C exhibits the dense microstructure and excellent microwave properties: εᵣ = 9.5, Q.f = 16 600 GHz and τf = −9.6 ppm/°C.


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