Effect of Temperature Treatment on Electrical Property, Crystal Structures and Lattice Strains of Precipitated CaCO3 Nanoparticles

In this study, the effect of temperature treatment during the preparation process of calcium carbonate (CaCO3) nanoparticles was systematically examined for a drug delivery carrier. The CaCO3 powder was prepared by the precipitation method at different annealing temperatures. The morphologies, elemental compositions and crystal structures of the synthesized CaCO3 powder were analyzed by Scanning Electron Microscope/Energy-Dispersive Spectroscopy and X-ray Diffractometry (XRD), respectively. The result shows that the particle size increased with an increase in annealing temperature. Based on the crystal structure analyzed from XRD, the sample was perfectly matched with the calcite/vaterite polymorphs phases. The crystallite size and lattice strains of the CaCO3 powder were calculated from the full width at half maximum parameter. The results show that the increase in annealing temperature leads to an increase in crystallite size and a decrease in lattice strain. The CaCO3 powder has a dielectric constant of 6.0-6.8 that reduced with the increase in applied frequency. The crystal structure, crystallite size, lattice strain, and dielectric properties of CaCO3 powder are dependent of the annealing temperature. Such properties confirm that CaCO3 powder is suitable for drug delivery carrier application.

本研究针对药物递送载体应用，系统考察了碳酸钙（CaCO3）纳米颗粒制备过程中温度处理的影响。研究采用沉淀法，在不同退火温度下制备了碳酸钙粉体。分别采用扫描电子显微镜/能量色散光谱仪（Scanning Electron Microscope/Energy-Dispersive Spectroscopy）与X射线衍射仪（X-ray Diffractometry，XRD）分析了合成碳酸钙粉体的形貌、元素组成与晶体结构。结果表明，粉体粒径随退火温度升高而增大。基于X射线衍射的晶体结构分析结果，所制备样品与方解石/球霰石晶型相完全匹配。通过半高宽参数计算了碳酸钙粉体的晶粒尺寸与晶格应变。结果显示，退火温度升高会使晶粒尺寸增大，同时晶格应变降低。该碳酸钙粉体的介电常数为6.0~6.8，且随外加频率升高而降低。碳酸钙粉体的晶体结构、晶粒尺寸、晶格应变及介电性能均与退火温度相关。上述性能证实，该碳酸钙粉体适用于药物递送载体应用场景。