Electronic excitation induced modifications of nanostructured Ni-Ti shape memory alloy thin films

V. Kumar1, R. Singhal1*, R. Vishnoi2, M. Gupta3, P. Sharma1, M. K. Banerjee4, K. Asokan5,  H. Sharma1, A. Gupta6, D. Kanjilal5

1Department of Physics, Malaviya National Institute of Technology Jaipur, JLN Marg, Malviya Nagar, Jaipur 302017, India

2Department of Physics, Vardhman College, Bijnor, U.P. 246701, India

3UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001, India

4Department of Mettalurgical and Materials Engineering, Malaviya National Institute of Technology Jaipur, JLN Marg, Malviya Nagar, Jaipur 302017, India

5Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India

6Amity Center for Spintronic Materials, Amity University, Sector 125, Noida 201303, India

Adv. Mater. Lett., 2017, 8 (4), pp 486-492

DOI: 10.5185/amlett.2017.6211

Publication Date (Web): Mar 15, 2017

E-mail: rsinghal.phy@mnit.ac.in

Abstract


In the present work, the effects of 120 MeV Au ion irradiation at different fluences ranging from 1×1012 to 3×1013 ions/cm2 on structural and electrical properties of thin films of Nickel-titanium (Ni-Ti) shape memory alloys (SMAs) grown on Si substrate using DC magnetron co-sputtering is studied. The surface morphology, crystallization and phase transformation behaviour of these films were investigated using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Four-terminal resistivity measurement method. XRD pattern reveals that both the phases-martensite as well as austenite exist in the pristine film. Resistivity measurements revealed a two way transformation from cubic to rhombohedral and from rhombohedral to monoclinic phase in pristine film and decrease in its transformation temperature with increased fluence. At higher fluences 5×1012 and 1×1013 ions/cm2, films showed non-metallic behaviour which could be due to the disorder occurring in these films due to ion impact and precipitate formation. The elemental composition of pristine film is determined by Rutherford backscattering spectroscopy. 

Keywords

SMA, NiTi, SHI irradiation.

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