纳米氧化锌的低温热容和热力学性质

Low-temperature Heat Capacity and Thermodynamic Functions of Nano ZnO

用扫描电子显微镜(SEM)测定了纳米氧化锌试样的粒径,SEM结果表明ZnO试样平均粒径为30nm.在83～350K温区,用精密低温绝热量热计测定了ZnO的等压摩尔热容,拟合出其等压摩尔热容与热力学温度的函数关系式:Cp=-3.249+0.2400T-3.413×10-4T2+4.485×10-7T 3.根据热容与热力学函数关系,计算了以298.15K为基准的纳米ZnO的热力学函数,并与粗晶ZnO和18nmZnO热容文献报导值进行了比较,从能量角度分析了不同粒径ZnO热容曲线差别产生的原因.

The size of nano ZnO powders was determined to be 30 nm in diameter by SEM. The isobaric molar heat capacity C-P of the nano ZnO was measured with high precision adiabatic low-temperature calorimeter in temperature range from 83 K to 350 K. The relationship of C-p with temperature T was established as: C-P = -3.249 + 0.2400T - 3.413x10(-4)T(2) + 4.485x10(-7)T(3). The thermodynamic functions of the nano ZnO, relative to the standard temperature of 298.15 K, were derived based on the heat capacity data through thermodynamic relationship. The measured C-p values were compared with those of coarse crystal and 18 nm ZnO powders cited from literature and the difference between the C-p curves was analyzed.