Crystal Dislocations: Their Impact on Physical Properties of Crystals

Abstract

It is rare to find technical applications involving a material of any crystal structure that is not impacted by dislocations—which affect the material’s mechanical properties, interfaces, martensitic phase transformations, crystal growth, and electronic properties, to name a few. [...]

Atomistic simulation of α‐Al2O3 nanoparticle plastic anisotropy under compression

“…In the bulk, the plastic deformation of sapphire is characterized by several slip systems including $$\frac{1}{3}\langle 1\bar{2}10\rangle (0001)$$ basal slip ( c ), prismatic $$\frac{1}{3}\langle 1\bar{2}10\rangle \lbrace 10\bar{1}0\rbrace$$ ( m ) and $$\frac{1}{3}\langle 10\bar{1}0\rangle \lbrace 1\bar{2}10\rbrace $$ ( a ) slip, rhombohedral slip $$\frac{1}{3}\langle 0\bar{1}11\rangle \lbrace 01\bar{1}2\rbrace$$ ( R ), and various pyramidal and twinning slip systems. Several studies have focused on the deformation of bulk α‐alumina, especially in an intermediate‐to‐high‐temperature regime where it shows high‐strength and ductility 14–25 . Castaing and collaborators have investigated the mechanical properties of sapphire single crystals under compression for temperatures ranging from 25 to 1800°C 15 .…”

“…Several studies have focused on the deformation of bulk 𝛼-alumina, especially in an intermediate-to-high-temperature regime where it shows high-strength and ductility. [14][15][16][17][18][19][20][21][22][23][24][25] Castaing and collaborators have investigated the mechanical properties of sapphire single crystals under compression for temperatures ranging from 25 to 1800 • C. 15 Compression axis (CA) along the 𝑐 axis or tilted 45 • out lead to prismatic 𝑎 (for 𝑇 > 200 • C) and basal 𝑐 (for 𝑇 > 600 • C) slips, respectively. Also, Lagerlof et al have characterized dislocation slip and twinning in sapphire using transmission electron microscopy (TEM).…”

An object‐oriented geometric engine design for discontinuities in unfitted/immersed/enriched finite element methods

“… Dislocations These are linear defects that generally occur in crystalline materials, for example, metals, diamonds, rocks, or ceramics 81 . Dislocations could result in phase transformations and grain growth, and even change material properties 82 . The geometrical configuration of a dislocation is represented by a glide plane with unit normal vector (see Figure 1E), where either side of the glide surface shears with respect to another.…”

“…81 Dislocations could result in phase transformations and grain growth, and even change material properties. 82 The geometrical configuration of a dislocation is represented by a glide plane with unit normal vector n (see Figure 1E), where either side of the glide surface shears with respect to another. Unlike cracks, the bare presence of dislocations can result in stresses in the material, even without applying external tractions.…”

Independent Channel Method for Nanoribbons with Dislocation and Fano Defects

“…[3] One of the typical structural defects is the planar dislocation, which in nanoribbons is commonly present along its reduced cross section producing small changes in the energy and huge alterations in its mechanical and transport properties. [4] In contrast, 2D materials have an extensive surface area favoring catalysis [5] and sensing applications. [6] At the same time, this surface area makes them susceptible to the adsorption of molecules or Fano defects, [7][8][9] which may greatly affect the transport properties because the reflected wave from a Fano defect may interfere and destroy the travelling one in the main system.…”