Broadband NIR emission and NIR-to-visible upconversion in micro and nanostructured sol-gel rare earth-doped materials for photonic applications - Aquino, F. T.; Pereira, R. R.; Muscelli, W. C.; Ferrari, J. L.; Ribeiro, S. J. L.; Gonçalves, Rogéria Rocha (Encontro Nacional sobre Terras Raras, 2014)