Time-of-Flight Pulsed Neutron Diffraction Study on Uniaxial Stress-Induced Domain Switching in LaNbO4

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Abstract
The domain orientation switching phenomena in the ferroelastlc material LaNbO4 were observed by means of a time-of-flight neutron diffraction technique using a position-sensitive area detector. When stress is applied to the direction nearly perpendicular to (100) of one of the domains in the specimen, the a- and c-axes are easily transformed into the c- and a-axes of another domain, respectively. The domains with [001] nearly parallel to the stress direction do not switch orientation. Thus, the domain which occupied 34% of the specimen at the initial stage expanded up to 92% of the total volume by switching from other orientated domains. The estimated stress was 600 gW/mm2 at the final stage. The mechanism of switching orientation can structurally be interpreted by a small rotation and a small displacement of NbO4 tetrahedra at the domain boundary which is a transient zone with a prototype structure.