Crystal Structure Analysis And Thermal Diffuse Scattering Intensity Analysis Of Powder Crystal Sc₂O₃

The values of correlation effectsμis an important basis for studying the thermal properties of materials,but it cannot be directly measured under the present conditions.In order to obtain the values of correlation effectsμ,the crystal structure and thermal diffuse scattering intensity of crystals are studied in this paper.The powder crystal Sc₂O₃was tested at 26,300 and 600℃by X-ray diffraction method.Three Sc₂O₃powder crystals with different temperatures were analyzed by using the program of Rietveld fine calculation software,and the crystal structure parameters（lattice constant,atomic coordination number Z,atomic distance r,etc.）were obtained.The isotropic temperature factors B of Sc₂O₃at 26,300 and 600℃are 0.332935,1.1085 and 0.965726（?）²,respectively.0.822,2.761,1.796（?）²;1.08985,2.93655,2.09003（?）².Maximum entropy analysis technique is used to visualize the electron density distribution of Sc₂O₃crystals.The fully diffracted back-base intensity equation of Sc₂O₃is expanded from the theoretical formula of the thermal diffuse scattering intensity.Then,the refined crystal structure parameters are used to simulate the thermal diffuse scattering intensity of Sc₂O₃,and the fully diffracted back-base intensity map containing the nearest neighbor atom to the 14th neighbor atom（r is3.8164（?））is obtained.By comparing the experimental results with the theoretical calculation results,we get the magnitude of the interatomic thermal vibration correlation effect valueμcorresponding to each atomic distance r.The results show that the thermal diffuse scattering strength of Sc₂O₃crystals is closely related to the thermal vibration of atoms.The largest contribution to the vibration shape of the thermal diffuse scattering strength is the thermal vibration correlation effect between the 7th nearest atom Sc₁-Sc₂.