Eshelby untwisting

Abstract

The concept of Eshelby untwisting, the effect of an axial screw dislocation driving an intrinsically twisted nanocrystal towards a straighter configuration more consistent with long-range translational symmetry, is introduced here....

Mechanical properties and peculiarities of molecular crystals

“…145 Simulations of screw dislocations under the constraints of a force field are illustrative of the mechanical relaxation. [146][147][148] Alternatively, a helix of a given sense can be viewed as a helix of the opposite sense from an orthogonal direction. Many dislocations orthogonal to the growth direction could lead to an overall twist in the direction perpendicular to the cores.…”

Crystal Structure and Twisted Aggregates of Oxcarbazepine Form III

“…One of the possible explanations for a twisted fiber is Eshelby twisting. , According to Eshelby’s theory, an axial screw dislocation in a nanocrystal creates an elastic stress field that can be partially relaxed through continuous twisting of the crystal. The Eshelby and other twisting and untwisting mechanisms have been discussed and modeled in molecular crystals such as benzil. , While Eshelby twisting could be one of the possible mechanisms of twisting in OXCBZ form III, it is highly unlikely that the twist in a large number of crystals of OXCBZ III would be synchronized since dislocation formation is generally stochastic. The other most common cause of twisting has been identified as the presence of compositional and structural inhomogeneities in a crystal, producing a lattice mismatch that generates a twist moment at the growth front.…”

Leveling up Organic Semiconductors with Crystal Twisting

“…P scales with h according to a power law, P = const· h n , where n ranges from 1.8 to 5.4 for small-molecule banded spherulites . The exponent reflects a balance of twisting and untwisting as well as elastic and plastic deformations. , A cross-sectional SEM of a triisopropylsilylethynyl anthradithiophene (TIPS ADT) banded spherulite collected along the growth direction displays distinct regions of face-on and edge-on crystal orientations in bundles of helicoidal fibrils that twist cooperatively (Figure ). All ⟨ hkl ⟩-dependent material properties are patterned into banded spherulite films with frequencies determined by P .…”

“…25 The exponent reflects a balance of twisting and untwisting as well as elastic and plastic deformations. 32,96 A cross-sectional SEM of a triisopropylsilylethynyl anthradithiophene (TIPS ADT) banded spherulite collected along the growth direction displays distinct regions of face-on and edge-on crystal orientations in bundles of helicoidal fibrils that twist cooperatively (Figure 3). All ⟨hkl⟩-dependent material properties are patterned into banded spherulite films with frequencies determined by P. This section provides an overview of properties that follow this pattern, namely linear dichroism, linear birefringence, fluorescence, charge mobility, solubility, and reactivity.…”