MICROWAVE DIELECTRIC PROPERTIES OF Re4 (La4Pr2) (SiO4)6-x (PO4)xO2 APATITE

• Main Authors: Bo-Hao Tong, 童柏豪
• Other Authors: Yung-Jen Lin
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/xc3u6n

碩士 === 大同大學 === 材料工程學系(所) === 102 === This study was based on solid-state synthesized, apatite-structured microwave dielectric ceramic materials. Experiments were divided into four parts. In the first part, We changed alkaline earth metal in Re4(La4Pr2)(SiO4)4(PO4)2O2, and Re= Mg, Ca, Sr, Ba, to observe the effects of different ions of alkaline earth metal and different sintering temperature on microwave properties. Experiments showed the best composition was Ca4(La4Pr2)(SiO4)4(PO4)2O2 sintered at 1475 oC. Its Qxf = 29776 GHz, εr =13.8, and τf = -1.7 ppm/oC. Second part was to remove phosphate (PO4) from compositions in the first part to study the microwave dielectric properties of “pure” silicate materials. This part showed best composition Ba4(La4Pr2)(SiO4)6O2 with optimum sintering temperature of 1350 oC, Qxf = 19138 GHz, εr =14.9, τf = 3.7 ppm/oC. The third part was to use GeO2 to substitute SiO4 or PO4 in the compositions of Ca4(La4Pr2)(SiO4)4(PO4)2O2 and Ba4(La4Pr2)(SiO4)6O2. The results showed that Ca4(La4Pr2)(GeO4)4(PO4)2O2 was the best composition. It’s sintering temperature was 1600 oC, Qxf = 24427 GHz, εr =15.0, τf =12.6 ppm/oC. From the experimental results, the replacement of GeO4 would increase the dielectric constant. The sintering temperature would also increase. The fourth part was based on the best specimen, Ca4(La4Pr2)(SiO4)4(PO4)2O2, in the first part. Boron oxide (B2O3) was used as sintering aids. The results showed that optimal addition was 1wt%. Its sintering temperature was lowered to 1375 oC. Its Qxf = 6846 GHz, εr =13.6, τf = -8.0 ppm/oC. Adding boron oxide (B2O3) could reduce sintering temperature by 100 oC, but it also reduced the quality factor.