Plastic Deformation by Twinning in CsHSO₄ Single Crystal

Abstract

Plastic deformation by mechanical twinning with (001) twin plane has been observed in the b-plate of CsHSO₄ single crystals at room temperature. A parallelogram-shaped hysteresis loop is found between the external shear stress and the deformation angle of the crystal plate. The maximum deformation angle is found to be 24° which is very close to 2(β−90°), where β=101.51° is the monoclinic angle of the crystal lattice. A microscopic model based on the crystal structure for the twin structure is proposed.