聚丙烯酰胺凝胶法制备纳米BeO粉体前驱体的热分解过程及结晶机理

采用聚丙烯酰胺凝胶法制备纳米BeO粉体,通过TG-DSC、XRD和SEM等测试手段研究凝胶前驱体的热分解过程和所得粉体的性能,并借助负离子配位多面体生长基元理论分析热分解过程中纳米BeO的结晶机理。结果表明:随着温度的升高,凝胶前驱体内的有机凝胶逐渐分解,同时凝胶前驱体内的硫酸铍盐脱除结晶水;当温度达到600℃左右时,有机凝胶完全分解,得到纳米级的无水硫酸铍;继续升高温度,纳米级的无水硫酸铍分解得到纳米BeO;热分解过程中,纳米硫酸铍通过生长基元Be(SO4)6断键形成纳米BeO,成核过程为受迫状态下的非均匀成核。

Thermal decomposition of precursor gel and crystalline mechanism of BeO nanopowders synthesized by polyacrylamide gel method

The BeO nanopowders were synthesized by the polyacrylamide gel method.The thermal decomposition process of precious gel and the properties of the obtained powder were investigated by TG-DSC,XRD and SEM,and the crystalline mechanism of nano-BeO in the thermal decomposition process was indicated by growth units model theory of anion coordination polyhedron.The results show that the organic gel in the precious gel is disintegrated gradually,and meanwhile the crystal water of the beryllium sulfate salt in precious gel is removed with the increase of temperature;when the temperature is about 600 ℃,the organic gel is disintegrated completely and nano-BeSO4 is obtained;BeO nanopowders are achieved under higher temperature.During the thermal decomposition of BeSO4 processes,the chemical bonds of its growth units Be(SO4)6-break down and nano-BeO forms,and the process of crystal nucleus formation is heterogeneous nucleation under the forced condition.