Channels of Relaxation of Elastic Stresses in Pentagonal Nanoparticles

Abstract

On the basis of continuous elastic models relaxation channels of elastic stresses inside the pentagonal needle-like nanoparticles (PNNPs) are considered. Six models are analyzed: 1. creation of a dislocation inside the PNNP; 2. opening of a gap in the PNNP; 3. creation of a disclination bound with the PNNP surface; 4. splitting of the pentagonal axis; 5. growth of monocrystalline region around the PNNP axis; 6. displacement of the pentagonal axis towards the periphery of the PNNP. An energetic balance and the possibility of realization for each of these channels are discussed.Auf der Grundlage elastischer Kontinuumsmodelle werden Relaxationskanale der elastischen Spannungen ini Inneren von pentagonalen nadelformigen Nanopartikeln (PNNP) untersucht. Sechs Modelle werden analysiert: I. Bildung einer Versetzung im PNNP, 2. Offnung einer Liicke im PNNP, 3. Bildung einer an der PNNP-Oberflache gebundenen Disklination, 4. Aufspaltung der pentagonalen Achse, 5. Wachstum eines einkristallinen Bereiches um die PNNP-Achse, 6. Verschiebung der pentagonalen Achse zur Peripherie der PNNP. Ein Energieausgleich und die Moglichkeit fur die Realisierung jedes dieser Kanale werden diskutiert.') SU-142092 Troitsk, Moscow region, USSR. ' ) SU-194021 Leningrad, USSR.

Dislocations and Disclinations in Gradient Elasticity

“…where the various symbols have been defined earlier in (10). By introducing (19) to (21) and (24) into the general expression (11) for the strain energy, we find the elastic energy per unit dislocation length as…”

Importance of Disclinations in Severe Plastically Deformed Materials

“…It was proposed, [36] that the principal relaxation channels in pentagonal particles are the creation of additional lattice dislocations, displacement of the pentagonal axis (which is equivalent to the motion of the disclination towards the surface of the nanoparticle, splitting of the pentagonal axis (i.e., formation of new partial disclinations) and the emergence of pores in the disclination core. These findings are in good agreement with the available experimental results.…”

Misfit Disclinations and Dislocation Walls in a Two-Phase Cylindrical Composite

“…Insertion of (3), (6), (23) and (24) into the criterion DW N < 0 for the generation of a disclination array yields q < q cN ðaÞ, where q is given by (8) and…”

“…Disclination mechanisms of residual or misfit stress relaxation have also been discussed in literature with application to pentagonal nanoparticles [23][24][25][26] and thin-film structures [27][28][29][30][31][32][33][34]. The use of disclination terms in this context may be supported by the geometrically-based concept of interface disclinations [35][36][37].…”