When analyzing the crystal structure through diffraction experiments, the thermal diffuse scattering intensity is often deducted as the background. However, when studying the thermal properties of materials, this part of strength can not be ignored. It contains important information of atomic thermal vibration and lattice dynamics. Chromium nitride (CrN) material, a material possessing distinctive physicochemical properties, has garnered considerable attention in recent years, accompanied by a continuous stream of theoretical and experimental investigations. X-ray diffraction (XRD) experiments were performed on CrN powders at 25℃ and 600℃, and the TDS intensity was found to display remarkable oscillatory features. Through fitting theoretical predictions to experimental data, it is revealed that the TDS intensity of CrN is predominantly contributed by the independent thermal vibrations of Cr atoms. The significant contribution to its wave shape is that thermal vibration correlation effect for the 5th nearest-neighbor atomic.
At 25℃, the interatomic thermal vibration correlation coefficients μ for the 1st to 5th nearest-neighbor atomic pairs are determined to be 0.71, 0.56, 0.49, 0.41 and 0.32, respectively. The interatomic force constants α are calculated to be 0.745, 0.788, 0.292, 0.430 and 0.143 eV/Ų, which show an overall decreasing trend with increasing interatomic distance r and are also dependent on the atomic species. In addition, the TDS intensity of CrN increases significantly at 600℃, because the increased temperature leads to enhanced atomic thermal vibration. It is worth noting that the correlation coefficient μ of thermal vibration between atoms remains almost unchanged relative to their values at 25℃.These findings provide necessary quantitative parameters for studying the thermodynamic properties of materials, and lay a solid foundation for the subsequent calculation of the relationship between specific heat capacity and phonon dispersion.