Unusual features of (120) and (12¯2) deformation twins in monazite (monoclinic LaPO4) were described. These were kinks and other irregularities in (120) twins, and V-shaped indentations on (120) and (12¯2) twin planes. A twinning shear analysis suggested that the kinks were a type-II deformation twin mode with a shear direction of [2¯10]. Shear strain compatibility required extensive plastic deformation in the kink. The V-shaped indentations were suggested be analogous to similar structures in body-centered cubic metal deformation twins.

(120) and (12¯2) Monazite Deformation Twins. R.S.Hay: Acta Materialia, 2003, 51[18], 5255-62