Preparation and characterization of Lanthaum Zinc Zirconium by coprecipitation

• Main Authors: Chi-Hsiang Lee, 李啟祥
• Other Authors: Chen-Feng Kao
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/15182254544160282048

碩士 === 國立成功大學 === 化學工程研究所 === 83 === The precursors with OH- ligands were prepared from La( NO3)3.6H2O, Zn(NO3)2.6H2O, and ZrOCl2.8H2O by coprecipitation method. After TGA/DTA measurements, the powder was heated for 4 hours to obtain corresponding compound. The structures were confirmed by X-ray diffraction pattern. In the study, we investigated not only the properties of the ternary system but also the sintered bodies at different conditions. The sintered bodies in this experiment is in three conditions. (a)Sintered bodies were heated in air and deminished at the temperature gradient of 20K/min. (b) Sintered bodies were heated in air and quenched. (c)Sintered bodies were heated in N2 and deminished at the temperature gradient of 20K/min. It indicated from this experiment that: (1)When the compound of La:Zn=2:1 was heated at 1473K,the structure is La2ZnOx and it is unstable. (2)When the compound of Zn:Zr=1:1 was heated at 1673K , the structure is the mixture of ZnO,and ZrO2. (3)The structure is a mixture of ZnO, ZrO2, and La2O3 when the compound of La:Zn:Zr=0.1:0.9:1 was calcined at 1173K.The major structure is perovskite-orthorhombic when the compound of La:Zn: Zr=0.5:0.5:1 was calcined at 1173K. When the compound of La: Zn:Zr=0.9:0.1:1 was calcined at 1173K， the major structure is pyrochlore. (4)The structure of sintered bodies are unstable for heated in nitrogen atmosphere. (5)The susceptibility of the sample La:Zn:Zr=0.5:0.5:1 is much lower at 1373K,1473K,1573 K,and 1673K.