Spectroscopic studies and down conversion luminescence in OH- -free Pr3+-Yb3+ co-doped low-silica calcium aluminosilicate glasses - González, L. J. Borrero; Nunes, Luiz Antônio de Oliveira; Carmo, J. L.; Astrath, F. B. G.; Baesso, M. L. (Journal of Luminescence, 2014)