Relations between ferroelectric polarization and mechanical twinning in stoichiometric lithium niobate single crystal

The relationships between ferroelectric polarization and mechanical twinning in stoichiometric LiNbO3 were investigated. It had found that three sets of the mechanical twins crossed one another. Here, the boundary shape and the polarization of intersected twins were observed. Mechanical twins of LiNbO3 revealed a head-to-tail arrangement of ferroelectric polarization. A complicated polarization was observed at the crossed points and the spatial relations of the polarizations at those crossed points could be interpreted. The origin of the preferred cracking was related to the stress concentration and dislocation pile-up at the crossed point of the intersected twin lamellae.