Sol-gel transition in silica alkaline solutions. A NMR study H Zanni, P Nieto, L Fernandez, R Couty, P Barret, A Nonat and D Bertrandie J. Chim. Phys., 91 (1994) 901-908 Published online: 29 May 2017 DOI: 10.1051/jcp/1994910901