Domain structure, phase transformation, mechanical behavior and shape memory effect in a rare-earth orthoniobate lanthanum niobate

"Rare-earth orthoniobates, such as LaNbO$\sb4$, undergo a tetragonal-to-monoclinic phase transformation. Both high- and low-temperature phases possess the scheelite structure, and the low temperature monoclinic phase is heavily domained. The transformation mechanism is unknown. The domain structure in the monoclinic phase was reported as ""type III"" twins with highly mobile boundaries, exhibiting a rubber-like behavior in monoclinic LaNbO$\sb4$ single crystals. This behavior implies a new dimension for ductile ceramics and smart materials and clearly indicates the necessity for a thorough and systematic investigation of rare-earth orthoniobates. In the present study, using LaNbO$\sb4$ as an archetypal system, the scope of the investigation has involved several central features: (1) determining the structure of the domains in the monoclinic phase; (2) establishing the transformation mechanism; (3) verifying the rubberlike behavior and (4) exploring the shape memory effect in polycrystal ceramic LaNbO$\sb4$."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Li, Jian

Contributors dc:contributor

• Wayman, C. Marvin

• Engineering, Materials Science

Statement dc:rights

• Copyright 1995 Li, Jian

Language dc:language

eng

Identifier

AAI9624416
(UMI)AAI9624416

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21662