X-ray diffraction is a method to study the phase and crystal structure of a substance by using the diffraction phenomenon of X-rays in a crystal. X-ray diffractometer is a kind of instrument to realize X-ray diffraction technology, mainly composed of X-ray source, sample and sample position orientation adjustment mechanism system, X-ray detector and diffraction pattern processing and analysis system.

In scientific research, X-ray diffraction can not only characterize the structure and phase of materials. In fact, the XRD pattern also includes crystallographic information such as the space group, bond length, grain size, and lattice stress of the synthetic material. 

XRD refinement can verify the correctness of structural analysis. When an element in the crystal material is replaced or partially replaced, we can also use the isomorphic structure to carry out refinement and obtain the crystal structure of the replacement material. 

XRD structure refinement analysis is to replace the single hkl scattering amount with the total scattering amount, and use the mathematical model to fit the experimental data, separate the scattering amount of each phase, and realize quantitative phase analysis. The fitting process is to continuously adjust the parameter values in the model, and finally achieve the best agreement between the experimental data and the calculated values of the model.