Study of structural short order and surface changes of SiO2 compounds A. Oufakir, L. Khouchaf, M. Elaatmani, A. Zegzouti, G. Louarn and A. Ben Fraj MATEC Web Conf., 149 (2018) 01041 Published online: 14 February 2018 DOI: 10.1051/matecconf/201814901041