Directional dependence of c-plane slip in single crystals of mercuric iodide

Abstract

An experimental study of plastic deformation in thin single crystals of mercuric iodide (Hgl2) subjected to (0 0 1) [1 0 0] and (0 0 1) [1 1 0] shear loadings has established a directional dependence to the phenomenon of (0 0 1) orc-plane slip in Hgl2. The average stressess c for the “onset of yielding” were 12.6 psi (86.9 kPa) for (0 0 1) [1 0 0] shear and 16.5 psi (113.8 kPa) for (0 0 1) [1 1 0] shear; the average values of the deformation parameters 0, interpreted as a “bulk yield stress”, were 24.7 psi (170.3 kPa) for (0 0 1) [1 0 0] shear and 37.7 psi (259.9 kPa) for (0 0 1) [1 1 0] shear. These values are in agreement with the theoretical relationss c(θ)=s c(0)/cosθ ands 0(θ)=s 0(0)/cosθ, whereθ is the smallest angle between 〈1 0 0〉 crystallographic axis and the direction of shear stress applied in the (0 0 1) plane.