Cutoff of long-wave phonons in a nanocrystal due to a nonuniform strain field

2019-10-14 22:12:37

boundary strain field phonon phonons

责任者: Meshcheryakov, V.V. 单位: Inst. of Steel & Alloys, Moscow, Russia 来源出处: Journal of Experimental and Theoretical Physics(J. Exp. Theor. Phys. (USA)),1997/05/,(5):1010-15 摘要: This paper considers the effect of extended monopole and dipole strain fields on the low-frequency boundary of the phonon spectrum in a crystal of finite dimensions. The boundary shift depends on the dynamical volume of the nonuniform strain region, which is determined by the parameters of the crystal and the sources of stress. An increase in the volume of the deformed region leads to a decrease in the undistorted part of the crystal, where a phonon with the largest wavelength be produced. A monopole strain field is more efficient in cutting off long-wave phonons than a dipole strain field, and can “soften” the phonon spectrum. If a source generates stresses of the order of those on an interatomic scale, these effects can be the strongest and must diverse in crystals or phase precipitates with dimensions of less than 106 cm 关键词: internal stresses;nanostructured materials;phonons;precipitation;soft modes;long-wave phonons cutoff;nanocrystal;nonuniform strain field;dipole strain fields;monopole strain fields;low-frequency boundary;phonon spectrum;boundary shift;deformed region;phase precipitates;soft modes