Probing structure and microstructure of epitaxial Ni–Mn–Ga films by reciprocal space mapping and pole figure measurements

0353131 - FZÚ 2011 RIV GB eng J - Journal Article
Ge, Y. - Heczko, Oleg - Hannula, S.-P. - Fähler, S.
Probing structure and microstructure of epitaxial Ni–Mn–Ga films by reciprocal space mapping and pole figure measurements.
Acta Materialia. Roč. 58, č. 20 (2010), 6665-6671. ISSN 1359-6454. E-ISSN 1873-2453
Grant - others:AVČR(CZ) M100100913
Institutional research plan: CEZ:AV0Z10100520
Keywords : reciprocal space mapping * thin film * Ni–Mn–Ga * martensite * magnetic shape memory
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.781, year: 2010

The crystal structure and complex twinning microstructure of epitaxial Ni–Mn–Ga films on (1 0 0) MgO substrates was studied by X-ray diffraction using 2θ scans, pole figure measurements and reciprocal space mapping (RSM). Above the martensitic transformation temperature the film consists of single austenite phase with lattice constant a = 5.81A at 419 K. At room temperature some epitaxially grown residual austenite with a = 5.79A remains at the interface with the substrate, followed by an intermediate layer exhibiting orthorhombic distortion, atrans = 6.05A, btrans = 5.87A, ctrans = 5.73A and a major fraction of 14M (7M) martensite, a = 6.16A, b = 5.79A, c = 5.48A. The seven-layered modulation of this metastable martensite structure is directly observed by RSM. The intermediate phase observed close to interface indicates the existence of an instable, pre-adaptive martensite phase with a short stacking period.
Permanent Link: http://hdl.handle.net/11104/0192458