基于微量热技术研究钼酸钙纳米饼原位生长的热动力学及机理

Abstract

近年来，对纳米材料的生长过程研究取得了重大的进步，同时也发展了多种方法研究其生长机理。但鲜有方法能够原位的获取纳米材料生长过程的瞬时变化热动力学信息。本文利用高精度、高灵敏度的RD496-III型微量热计获得了CaMoO4纳米饼的生长过程的原位特征热谱信息，结合热动力学方程获取了CaMoO4纳米饼生长的热动力学特征生长参数阐述了其原位生长机理；CaMoO4纳米饼的生长过程经历了反应成核与晶体生长两个阶段，在298.15 K时其反应成核速率和晶体生长速率分别为1.57 × 10−3s−1、3.50 × 10−3s−1，以及深刻的诠释了原位生长过程产生的热变速率与溶液中离子浓度、晶体的成长、溶解、聚集、扩散之间的关系。本文旨在为研究纳米材料原位生长机理提供新的技术方法，进一步为纳米材料非平衡生长过程的热动力学信息的物理化学发展奠定了基础。 In recent years, great progress has been made to investigate the growth process of nanomaterials, and its growth mechanism has also been expanded by various methods. However, there are few methods to acquire the instantaneous thermodynamics information via in situ. In this paper, we use a RD 496-III microcalorimeter with high precision and high sensitivity to obtain the in situ heat flow curves in the growth process of CaMoO4 nanocake. The growth parameters of CaMoO4 nanocake were acquired by thermodynamics equation to investigate the energy and morphology evolution of the CaMoO4 growth mechanism. Results showed that the growth process of CaMoO4 nanocake had gone through two stages, including the phase nucleation and the crystal growth, whose nucleation rate and crystal growth rate were 1.57 × 10−3s−1 and 3.50 × 10−3s−1 respectively at 298.15 K. Moreover, the relationships between the rate of heat change in situ growth process and the ion concentration, crystal growth, dissolution, gathered, and diffusion have been analyzed in-depth. This paper is aimed to provide an effective method to study the in situ crystal growth, and further to build the foundation for thermal dynamic information of non-equilibrium growth process of nanomaterials in physical chemistry development.