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

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

V. Kumar¹, R. Singhal^1*, 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

Full Article

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 1×10¹³ions/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.