| Summary: | 碩士 === 崑山科技大學 === 電子工程研究所 === 101 === YNbO4 microwave dielectric ceramics prepared by a reaction-sintering process were investigated. The mixture of raw materials was sintered directly and no calcination stage was involved. Single phase YNbO4 ceramics with monoclinic structure were obtained. Sintering temperature was lowered with the addition of CuO and some Cu-rich phases formed at the grain boundaries. Maximum density 5.14 g/cm3 and shrinkage 15.02% were found in 1250oC/6h sintering YNbO4 with 0.3wt.％ CuO addition（YNC3）. Maximum density 5.09 g/cm3 and shrinkage 16.9% were found in 1100oC/6h sintering YNbO4 with 0.3wt.％ CuO addition（YNC5）. Microwave dielectric properties: εr＝15.53, Qxf＝14,174 GHz (10.33GHz) and τf＝－39.73 ppm/oC were obtained for 1300oC/6h sintering YNC3 ceramics. εr＝15.69, Qxf＝18,420 GHz (10.17GHz) and τf＝－35.76 ppm/oC were obtained for 1250oC/6h sintering YNC5 ceramics.
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