Theoretical Study On Dislocations In The Rare Gas Solid

Rare-gas crystal is a kind of crystal materials with the most simple interatomic interaction, and is a kind of basic crystals researched most extensively both theoretically and experimentally. Since the middle of last century, physicists have all along conducted studies on the rare gas crystals. The interaction between atoms in it are very simple contrasted with the other crystals, due to the full shell structure of the electron maintained by the atoms in rare gas crystal. However, with the continuous development of science, high accuracy requirements of interatomic interaction and data in experiment of the rare gas solid are expected. Defect research mainly focuses on the rare gas film materials, and the dislocation in crystal have not discussed enough, which we found after the investigation on the current research of the rare-gas solid. The classical dislocation model(Peierls-Nabaro, called the P-N model) is able to give the dislocation core width and the corresponding Peierls stress quantificationally, but this model is established on foundation of the elastic theory, and cannot reflect the influence of the lattice discrete effect to dislocation nature. At present, discrete dislocation lattice theory has been established basically based on the crystal lattice dynamics, which has made up for the original P-N model. The main research assignment of this article was applying the modified discrete dislocation lattice theory to the rare-gas crystals, further comprehending the physical meaning of the related parameters in the dislocation equation during the discussion.This paper uses Lennard-Jones pair interaction potential to describe the interatomic interaction based on which the elastic constants of the body and isolated single closed-packed plane of four rare gas crystals(neon, argon, krypton, xenon)are calculated, the coefficient of the second-order derivative which describes the discrete effect and the anisotropic energy factors are both obtained. In addition, the expression of the generalized stacking-fault energy on the closed-packed plane of the rare-gas solid and the analytical Fourier function expression are both derivated, the factor in the modified force law are given by fitting to the numerical data. Finally, we get the half-width and the corresponding Peierls stress. The results show that Peierls stress under the discrete effect modified decreases to 10-7, and dislocation width grows larger correspondingly.There are five parts of this article, the first part contains two sections(1,2), 1st mainly introduces the rare-gas crystal research background briefly, 2nd has carried on the introduction of the rare-gas crystal's dislocation and the dislocated equation. The second part mainly has carried on the computation of the body elastic constants and the isolated single closed-packed plane of the rare-gas crystal. The third part mainly calculates the generalized stacking-fault energy surface of the closed-packed plane, as well as obtains the corresponding parameters in the dislocation equation solution by fitting the modified generalized stacking-fault energy function to the numerical solution. The fourth part mainly calculates the second order derivative coefficient that describing the discrete effect and the anisotropic energy factors, and has obtained the dislocation core structure and the Peierls stress in the rare-gas crystal using the existing method of solving dislocation equations. The fifth part gives the summary of the work and makes some briefings to the later research work.