In situ TEM observation of domain switch in LaNbO4 added to NiO–Y2O3 stabilized ZrO2 ceramic composite

The morphology of domain structure in LaNbO 4 added to YSZ–NiO composite was examined using a focused ion beam prepared specimen in a transmission electron microscope with a straining stage. It is confirmed for the first time that the morphology is changed under load through domain boundary movement. The driving force for this domain switch is the difference in Gibbs free energy between domains with different crystallographic orientations. This domain switch improves toughness by dissipating stress build-up at the crack tips.