纳米粉ZnO的制备及低温热容研究

Preparation and Low Temperature Heat Capacity of the ZnO Nano-Powders

采用液相沉淀新方法制备了ＺｎＯ纳米晶超微粉末，ＸＲＤ和ＴＥＭ分析结果表明，平均粒径为１８ｎｍ，纤锌矿晶相结构，粒径分布范围较窄．化学分析和ＩＣＰ联合测定，其纯度＞９９．９％．在７８～３７０Ｋ温区，用高精密全自动量热仪测定了热容，拟合出热容随温度变化的多项式方程： Ｃｐ＝ ４０．０４２＋ ２４．５５４Ｘ＋ ０．９３０３３Ｘ２＋ ２．１６４９Ｘ３一 １．８３８９Ｘ４；并与粗晶 ＺｎＯ热容文献值进行比较，从能量的角度分析了各热容曲线不同的原因．

The 18nm ZnO ultrafine powders with the wurtzite phase were prepared by using a new method of liquidoid precipitation, and characterized by XRD, TEM. The heat capacities of the powder in 78 similar to 370K were also measured with a high precision automatic adiabatic calorimeter and compared with that of the coarse crystal powders cited from literature. The relation between heat capacities and grain sizes of the nano ZnO powders was demonstrated in the view of energetics. The results obtained show that the distribution of the nano ZnO powders is narrow, and their purity is more then 99.9%. The polynomal equation fitted expressing the change of heat capacities with temperatures is C-p = 40.042 + 24.554X + 0.93033X(2) + 2.1649X(3) - 1.8389X(4).