Yb3+-Er3+-Tm3+ co-doped nano-glass-ceramics tuneable up-conversion phosphor J. Méndez-Ramos, V. D. Rodriguez, V. K. Tikhomirov, J. del-Castillo and A. C. Yanes Eur. Phys. J. Appl. Phys., 43 2 (2008) 149-153 Published online: 19 July 2008 DOI: 10.1051/epjap:2008101