Structural microstructural and magnetic investigations on textured epitaxial NiMnGa thin films on Sapphire (11-20) and MgO (100) substrates

International Conference on Smart Materials & Structures

June 15 -17, 2015 Las Vegas, USA

Amit Sharma

Posters-Accepted Abstracts: J Material Sci Eng

Abstract :

Ferromagnetic Shape Memory Alloys are promising candidates for sensor and actuator application because of their high recoverable strain and faster response. In the present work the structure, micro-structure and texture of oriented NiMnGa thin films deposited on Al2O3 (11-20) and MgO (100) substrates at elevated temperatures by magnetron sputtering are investigated. X-raydiffraction along with pole figure measurement reveals the presence of orthorhombic phase with strong (202) orientation in the film deposited on sapphire (11-20) substrate and (400) orientation on MgO (100) substrates. Nanotwins with 7 modulated twin boundary has been observed in the martensitic plates in transmission electron microscopy investigations. High temperature X-ray diffraction and magnetic measurements were used to investigate the in-situ phase transformations in the film. Both the films have phase transformation temperatures (Martensite-Austenite) near to room temperature which makes them extremely useful for actuator based devices. Field emission scanning electron microscopy (FE-SEM) and rocking curve measurement with high resolution x-ray diffraction reveals uniform microstructure and excellent crystalline quality (low mosaicity) in the films.