Evidence of the evolution from solid solution to surface segregation in Ni-doped SnO2 nanoparticles using Raman spectroscopy - Herrera Aragón, Fermin Fidel; Coaquira, José Antonio Huamaní; Hidalgo, Pilar; Silva, S. W. da; Brito, S. L. M.; Gouvêa, Douglas; Morais, P. C. (Journal of Raman Spectroscopy, 2011)