Probing the Martensitic Microstructure of Magnetocaloric Heusler Films by Synchrotron Diffraction

Schwabe S, Schleicher B, Niemann R, Huehne R, Walter P, Nielsch K, Waske A, Faehler S (2018)

Publication Type: Journal article

Publication year: 2018

Journal

Energy Technology Wiley-Blackwell

Book Volume: 6

Pages Range: 1453-1462

Journal Issue: 8

DOI: 10.1002/ente.201800175

Abstract

First-order, magnetocaloric materials are promising for energy efficient solid-state cooling because of their high entropy changes, but they have the drawback of a hysteresis due to the nucleation and growth of the involved phases. Here, synchrotron based X-ray diffraction is used to investigate epitaxial Ni−Mn−Ga−Co thin films grown on Pb(Mg1/3Nb2/3)0.72Ti0.28O3 (PMN-PT). This integral method is used to test several hypotheses regarding structure and orientation of the martensite, whose nucleation was proposed to be the decisive contribution to hysteresis in Heusler materials. The measurements are compared to a recently proposed model of the martensitic nuclei, combining the phenomenological martensite theory with the adaptive concept. This investigation demonstrates that the diffraction patterns are consistent with a martensitic nucleus built from 8 variants forming a-b laminates. Additionally, it is shown that in accordance with the surface morphology of these films only a subset of nuclei occur, namely those needed to form type X martensite.

Involved external institutions

Deutsches Elektronen-Synchrotron DESY DE Germany (DE) Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e.V. (IFW) / Leibniz Institute for Solid State and Materials Research Dresden DE Germany (DE)

How to cite

APA:

Schwabe, S., Schleicher, B., Niemann, R., Huehne, R., Walter, P., Nielsch, K.,... Faehler, S. (2018). Probing the Martensitic Microstructure of Magnetocaloric Heusler Films by Synchrotron Diffraction. Energy Technology, 6(8), 1453-1462. https://doi.org/10.1002/ente.201800175

MLA:

Schwabe, Stefan, et al. "Probing the Martensitic Microstructure of Magnetocaloric Heusler Films by Synchrotron Diffraction." Energy Technology 6.8 (2018): 1453-1462.

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