Micropillar compression of LiF  single crystals: Effect of size, ion irradiation and misorientation
Soler, R.; Molina-Aldareguia, J. M.; Segurado, J.; Llorca, J.; Merino Rubio, Rosa Isabel; Orera Clemente, Víctor Manuel
Int. J. Plasticity., 2012, vol. 36, p. 50-63
Micropillar compression tests have become a popular research topic in recent years to study the effect of specimen size (in the range of micron and sub-micron pillar diameter) on the mechanical properties of single-crystals. The flow stress was generally found to scale with an inverse power of specimen diameter. The precise mechanisms responsible for this behavior are still a matter of debate. Usually the pillars are prepared by FIB milling, creating defects that can affect to their mechanical properties. In the paper by J. Soler et al, directional solidification of LiF-NaCl and LiF-KCl eutectics and subsequent controlled etching or the matrix (chloride) has been used to prepare forest of LiF micropillars (diameter of 1 to 5 microns). Their deformation upon uniaxial compression was studied. The flow stress increases by 30% in Ar+-irradiated micropillars. No size-effect was observed when compression was done along the  crystallographic direction, where there is strong resistance to dislocation motion.