硼热还原法制备LaB_6粉末

FABRICATION PROCESS OF LaB_6 POWDER BY BOROTHERMIC REDUCTION METHOD

研究了采用硼热还原法制备LaB6 粉末的反应合成工艺 .La2 O3-B系反应热力学分析表明 ,气体分压对LaB6 的形成有重要影响 ,减小气体分压可以明显降低LaB6 的合成温度 ;结合DTA测定结果 ,确定了制备LaB6 粉末的合成温度 .同时 ,对不同温度和保温时间条件下所生成的LaB6 粉末的相组成、颗粒尺寸与形貌以及纯度进行了测试分析 ,实验结果表明 ,La2 O3-B系制备LaB6 粉末的优化工艺是真空度133Pa ,192 3K保温 6h ,所合成的LaB6 粉末平均粒径为 6 μm ,纯度达 99.2 % ,颗粒形态比较规整 ,多数呈近似团块状 .

The synthesis of LaB6 powder by borothermic reduction method from the la2O3-B system was investigated systematically. Thermodynamic analysis showed that the partial pressure of resultant gases played an important role during the formation of LaB6 powder, and that the synthetic temperature decreased notably by reducing the partial pressure. The synthetic conditions were determined combining the resulting of DTA analysis. The phase compositions of the products at different temperatures for different holding times were analyzed by X-ray diffraction, and the powder morphology and purity were examined by scanning electronic microscope and chemistry analysis separately. It is pointed out that the optimal conditions to fabricate LaB6 powder from the La2O3-B system are a holding time of 6 h at 1923 K under 1 Torr pressure, and that LaB6 powders are obtained with purity of 99.2% and regular shape in average diameter of 6 μm.