Stacking disordering in hexagonal BN induced by shearing under ball milling

Significant stacking-disordering within basal planes, such as heavy stacking faults, basal plane twinning or even entirely disordered stackings and shearing of lattice planes, delamination and kink bands were frequently found in most hexagonal BN (h-BN) grains after milling. It is evident that most of these high-energy defect structures are created by simultaneous shearing rather than by dissociation of a perfect dislocation. As a result of frequent shearing, the unit-cell shape of the [11 (2) over bar 0] lattice image changes from a rectangle to a rhombi. Nonbasal plane defects such as half Frank loops, and interstitial and vacancy loops with high-energy stacking configurations were also frequently found. These deformation structures stem inherently from the structural characteristic of h-BN and are significantly different from those observed in fee metals such as copper.