摘要
采用水热法合成Mn_(1.8)Co_(0.1)Mg_(0.1)P_2O_7·2H_2O,证实其热脱水产物为Mn_(1.8)Co_(0.1)Mg_(0.1)P_2O_7。利用热重/微分热重/差热分析、傅里叶变换红外光谱、原子吸收分光光度、X射线衍射和扫描电镜等技术对样品进行表征。研究4种加热速率下空气气氛中(热脱水过程)的非等温动力学,发现其为单一的热脱水过程。用Kissinger-Akahira-Sunose方程迭代法计算出表观活化能E_a值,证实脱水过程是一个具有唯一动力学三因子的单步骤动力学过程。用Málek方程确定了热脱水过程的动力学模型f_((a))和指前因子A,提出以?esták-Berggren模型作为脱水过程的机理函数。最佳拟合得出热脱水过程的的动力学三因子为E_a=79.97±6.51 kJ/mol,ln A=16.83,f_((a))=a^(0.520)(1-a)^(1.255)。利用活化络合物理论并结合A值,计算活化过程的热力学函数。
Mn1.8Co0.1Mg0.1P2O7·2H2O was synthesized via hydrothermal method and the thermal dehydration product was confirmed to be Mn1.8Co0.1Mg0.1P2O7.The thermogravimetry/differential thermogravimetry/differential thermal analysis,Fourier transform infrared,atomic absorption spectrophotometry,X-ray diffraction and scanning electron microscopy techniques were employed for sample characterization.Non-isothermal kinetics was studied under air atmosphere at four heating rates and the single thermal dehydration process was observed.Iterative Kissinger-Akahira-Sunose equation was used to calculate the apparent activation energy Eαvalues.Dehydration process was confirmed to be a single-step kinetic process with the unique kinetic triplets.Málek’s equations were used to determine the kinetic model f（α）and pre-exponential factor A.？esták-Berggren model was suggested to be the mechanism function for the dehydration process.The best fit led to the kinetic triplets of Eα=（79.97±6.51）k J/mol,ln A=16.83 and f（α）=α^0.520（1-α）^1.255（αis the extent of conversion）.The thermodynamic functions of activation were calculated using activated complex theory together with A value.
