Effect of TiO2 Doping of MgAl2O4 Ceramics on Sintering and Dielectric Properties

• Main Authors: JIAN,QIAO-YOU, 簡巧佑
• Other Authors: LIN, HUEY-JIUAN
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/4c64p6

碩士 === 國立聯合大學 === 材料科學工程學系碩士班 === 106 === In this research, TiO2 doped MgAl2O4 ceramics were synthesized by the conventional solid-state reaction route. High purity oxide powders of Al2O3 and MgO were used as the starting materials for the synthesis of MgAl2O4 spinels. The influence of TiO2 doping amount (0、3、5、7、10 mol%) and sintering temperature (1200 oC , 1250 oC , 1300 oC , 1400 oC , 1500 oC ) on the sintered structure and dielectric properties were discussed. Experimental results showed that the addition of TiO2 can enhance the sinterability of powders synthesized and lower the nucleation temperature of MgAl2O4. However, the second phase also increases as the TiO2 content and sintering temperature increase. A complete MgAl2O4 phase can be formed at 1250 oC without residual MgO and Al2O3. The densified MgAl2O4 ceramic body were sintered at 1500 oC with different holding time (2 hr, 5 hr, 8 hr), in order to find better sintering conditions. The results showed that with the increase of holding time, density of ceramics with 3 mol% or 5 mol% TiO2 doping increased significantly, but 7 mol% and 10 mol% TiO2 doping showed no change. Since the doping of TiO2 could greatly promote the formation of MgAl2O4 phase and the density of MgAl2O4 ceramic body, the dielectric loss of MgAl2O4 would be greatly reduced. Conversely, due to the formation of the second phase with more doping of TiO2, the dielectric loss would be increased. In this study, the optimized conditions for MgAl2O4 ceramics were with 3 mol% TiO2 doping and sintered at 1500oC with 8 hr. The dielectric properties were εr=8.24, tanδ=1.75×〖10〗^(-4), τƒ=-41.4 ppm/ oC .