New microwave dielectric system of Li4x Mg3(1−x)Al6(1−x)Ti5x O12 with adjustable thermal stability and high quality factor
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Li4x Mg3(1−x)Al6(1−x)Ti5x O12 (x = 0.2, 0.4, 0.6, 0.8) ceramics were prepared by a solid state reaction method. The phase evolution, microstructure and composition of ceramics were investigated using X-ray powder diffractometer, scanning electron microscope, energy dispersive spectrometer. The microwave dielectric properties of ceramics were studied by a network analyzer. Both MgAl2O4 and Li4Ti5O12 have a cubic spinel structure, whereas no uniform solid solution was formed in Li4x Mg3(1−x)Al6(1−x)Ti5x O12 ceramics. There were Al-rich compounds and Ti-rich compounds in the mixed phases. With increasing x form 0.2 to 0.8, Al-rich compounds decreased and Ti-rich compounds increased. A complex phase evolution was appeared in the process, such as Mg2TiO4, Li2MgTi3O8 and Li4Ti5O12 compounds. With increasing x values, the sintering temperature was reduced from 1280 to 925 °C. Li4x Mg3(1−x)Al6(1−x)Ti5x O12 ceramics presented an excellent comprehensive performance with ε r of 11.5–26.5, Q × f values of 7102–30,191 GHz and τ f values of −55.4 ~ +5.7 ppm/ °C.
KeywordsSinter Temperature Apparent Density MgAl2O4 Microwave Dielectric Property High Quality Factor
This work was supported by Natural Science Foundation of China (Nos. 11464009 and 11364012), Natural Science Foundation of Guangxi (Nos. 2015GXNSFDA139033, 2014GXNSFAA118312, 2014GXNSFAA118326 and 2013GXNSFAA019291), Research Start-up Funds Doctor of Guilin University of Technology (Nos. 002401003281 and 002401003282) and Project of Outstanding Young Teachers’ Training in Higher Education Institutions of Guangxi.
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