Charged Dislocations and the Strength of Ionic Crystals

Grain boundary structure and solute segregation in titanium-doped sapphire bicrystals

“…As discussed previously, variations in vacancy formation energies are predicted to occur with changes in grain boundary structure [21][22][23]. In this study, the ratio of donor/acceptor species at a grain boundary can be used as a rough measure of grain boundary charge 15 Kikuchi electron diffraction data confirms that this twist boundary has the same misorientation angle (i.e.…”

“…The ability of grain boundary dislocations to accommodate excess solute has been demonstrated by recent Monte Carlo studies of solute segregation in cubic alloys [20][21][22][23]. Calculations on pure twist boundaries show that grain boundary solute concentrations increase linearly with twist angle up to about ≈ 35°, at which point saturation occurs.…”

“…Kitayama [6] has shown that relative surface energies in sapphire exhibit greater anisotropy as temperature decreases from 1800°C to 1600°C 21 . If the trend towards greater anisotropy in surface energy continues with further cooling, large differences in surface energies should promote faceting onto low-energy planes.…”

Effect of plastic deformation on the transport phenomena in Pb0.95Sn0.05Se single crystals

“…In this case the point-defect formation can proceed also by the motion of the split edge dislocations having 'sitting' jogs (Hirth and Lothe 1968). From the existing models describing the dislocation generation processes on the yielding plateau (when deformation proceeds by lateral widening of the slip strips (Papazian and Vardanian 1997)) and for the fast deformation hardening stage the most likely model for the NaC1-type lattice materials is the model of dislocation generation by a double lateral slip of the screw dislocations (Johnston and Gilman 1960, Forie and Murphy 1962, Gilman 1962, Wiedersich 1962, Vladimirov et al 1969. According to this model a screw dislocation section of length I during its move in the main slip plane under strains applied executes a lateral slip on a distance h* in a plane laying at angle a to the primary slip plane.…”

О Движении И Размножении Дислокаций В Эпитаксиальных Феррошпинелях

“…Линейную плотность заряда на дислокации можно оценить также исходя из теории Эшелби [15]. Согласно Эшелби, критическое сдвиговое напряжение Y, электростатическое по происхо-ждению, которое необходимо преодолеть для отрыва заряженной дислокации от окружающего ее облака положительных ионных вакансий, имеет вид…”