Dislocations in LaBr[sub]3[/sub] crystals

X. W. Zhou; F. P. Doty; Pin Yang

doi:10.1117/12.831055

11 September 2009 Dislocations in LaBr₃ crystals

X. W. Zhou, F. P. Doty, Pin Yang

Proceedings Volume 7450, Penetrating Radiation Systems and Applications X; 745005 (2009) https://doi.org/10.1117/12.831055
Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States

Abstract

Using a many-body embedded ion method potential for La-Br system, molecular dynamics simulations have been performed to study dislocations in the UCl₃ type of LaBr₃ crystal including identification of dislocation line energy, core structure, migration mechanism, and mobility. We found that dislocations with the < 0001 > Burgers vector can move under shear stresses, but they retain perfect dislocations during the motion rather than dissociated partials as commonly seen in metal systems. Unlike the < 0001 > edge dislocations whose mobility increases with temperature, the < 0001 > screw dislocations may become sessile at high temperatures due to thermally activated dissociation of the core. Dislocations with the <1120 > Burgers vector were found to be sessile due to non-planar dissociation at the core. Because the < 0001> dislocations can only slip on the {1 1 00 } prism plane and often only the edge dislocations are operative, the stresses created during any thermal mechanical processes cannot be effectively relieved by the plastic deformation mechanism. Considering that LaBr₃ tend to cleave along the {1 1 00 } prism plane, the simulations shed some lights on why this material is so brittle and how large LaBr₃ crystals tend to fracture during growth.

Citation Download Citation

X. W. Zhou, F. P. Doty, and Pin Yang "Dislocations in LaBr₃ crystals", Proc. SPIE 7450, Penetrating Radiation Systems and Applications X, 745005 (11 September 2009); https://doi.org/10.1117/12.831055

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