【摘要】 本文在纯水溶剂和乙醇/水混合溶剂中沉淀制备亚微米和纳米CaF2粉体,对沉淀产物的粒径控制进行了研究。用TEM和XRD对CaF2沉淀的粒径和形貌进行表征。在纯水溶剂中,通过改变反应物浓度和反应物混合速度以控制形核和晶粒长大比例,成功制备了粒径分别为242nm,79nm和51nm的CaF2粉体。在混合溶剂中,通过改变水/乙醇的体积比改变混合溶剂的介电常数从而改变CaF2的溶解度的方法,在1∶1,1∶4和纯乙醇中分别获得粒径为31nm,23nm和12nm的CaF2粉体,沉淀粒径的倒数和混合溶剂介电常数的倒数间呈线性关系。结果表明,在水溶液中通过控制形核和晶粒长大比例适宜制备粒径较大的沉淀粉末,混合溶剂中改变CaF2的溶解度适合制备纳米级沉淀粉体,两种手段综合运用,可以在大范围内调节沉淀粉末粒径。更多还原

【Abstract】 Synthesis and size control of the CaF₂ powders in the sub-micron and nano-meter ranges were investigated by precipitation method in the pure water solvent and ethanol/water mixed solvents.The particle size and morphology of CaF₂ powders were characterized by transmission electron microscopy（TEM） and X-ray diffractometry（XRD）.The results indicate that in the aqueous solvent,CaF₂ powders with the average particle sizes of 242nm,79nm and 51nm were obtained through controlling the ratio of nucleation to grain growth by means of changing the adding speed and the concentration of the reactants.In the mixed solvents with the volume ratios of water to ethanol 1∶1,1∶4 and pure ethanol solvent,CaF₂ powders with the average size of 34nm,20nm and 12nm were prepared successfully,and the linear relationship between the reciprocal of CaF₂ particle size and the reciprocal of dielectric constant of mixed solvents is demonstrated.In conclusion,combining the means of controlling the ratio of nucleation to grain growth in the aqueous solvent,which is suitable for synthesizing larger precipitate powders,with the way changing the volume ratio of water to ethanol in the mixed solvents,which is effective to control the size of the nano-meter precipitates,can be utilized to control the particle size in the large range from submicron to nanometer.更多还原