1 23 Indian Journal of Physics ISSN 0973-1458 Volume 88 Number 7 Indian J Phys (2014) 88:691-694 DOI 10.1007/s12648-014-0474-x Surface evolution of NiO thin film under 800 keV Ar 8+ ion irradiation P. Mallick, D. K. Mishra, P. Kumar & D. Kanjilal