Blue up-conversion emission in Tm3+/Yb3+ co-doped Pb2P2O7-Nb2O5- XF2 (X = Mg, Ca, Sr, Ba) glass and glass-ceramics - Manzani, Danilo; Ribeiro, S. J. L (International Conference on Optical, Optoelectronic and Photonic Materials and Applications - ICOOPMA, 2018)