COMPRESSIVE BEHAVIOR AND DOMAIN-RELATED SHAPE-MEMORY EFFECT IN LANBO4CERAMICS

The yielding phenomenon of polycrystalline LaNbO4 at room temperature under compression and the shape memory effect have been investigated, using an Instron 8530 material testing machine and a Nikon QM micro-ha rdness tester. The yielding phenomenon has been found, and explained i n terms of the orientation state of grains with respect to the directi on of the applied stresses. The shape memory effect behavior has been discovered instead of the rubber-like behavior in the monoclinic LaNbO 4, which is related to the domain boundary motion and new domain forma tion in response to the applied stress. Based on the observation of do main formation in the vicinity of the indentation, the mechanism for t he shape memory effect has been suggested.