Preparation and Characterization ofLanthanum-Indium(Gallium)-ZirconiumOxides by Chemical Coprecipitation

• Main Authors: Chieng-Teh Wu, 吳俊德
• Other Authors: Chen-Feng Kao
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/75632737716500939344

碩士 === 國立成功大學 === 化學工程學系碩博士班 === 91 === Chemical coprecipitation has high homogeneity, high reactivity, high quality and exact stochiometry. The goal of this study is that the lanthanum-indium /gallium/- zirconium oxide powders were prepared by coprecipitation method. The synthesis, characterization and electrical properties of the above compounds were investigated. The precursors of lanthanum-indium-zirconium and lanthanum —gallium- zirconium oxide with OH- ligands were prepared by coprecipitation. After freeze drying, the precursors were calcined at 1100 ℃ for 2 h and were calcined at 900 ℃ for 4 h to obtain the corresponding compounds without zirconium respectively. It indicated from XRD patterns that the major compounds were LaInO3 and LaGaO3, respectively. Calcined powders were pressed into disks and then were sintered for 8h at various temperatures. From XRD patterns, it revealed that they formed solid solution systems of LaInO3-La2Zr2O7 and LaGaO3 -La2Zr2O7,respectively. LCR meter was used to measure the electrical capacity of the samples. Dielectric constants were calculated from the electrical capacity via the formula. It was found that both of the two systems have low dielectric constants. The dielectric constants of LaInO3-La2Zr2O7 system were all below 40 and those of LaGaO3-La2Zr2O7 system were all below 60. The dielectric constant decreases with increasing sintering temperature and frequency, measured by the LCR. The hardness of sintered bodies increases with increasing the sintering temperature. The mechanical properties of LaInO3 and LaGaO3 were truly improved by adding zirconium. The optimal additions of zirconium are 1mole% for both of the above systems. From the variations of susceptibility with temperature analyzed by SQUID, we found that products exhibit diamagnetisim.