Spectral and time-resolved analysis of rare earth-doped SnO2 emission

In this work, the existence of different crystal field sites for the rare-earth-doped tin dioxide nanopowder and RE-doped SiO2-SnO2 glass-ceramics is investigated. The slightly different crystal field symmetries have been resolved by using site-selective fluorescence line-narrowing spectroscopy. The obtained results show that a variety of optically non equivalent sites exist for the europium ion in the tin dioxide oxide structure associated to different allowed positions of the oxygen vacancies, whereas additional spectral disorder is found in the case of the glass-ceramic matrix. Ultrafast spectroscopy performed on Eu3+-doped tin dioxide nanocrystals shows that host-rare earth energy transfer occurs at a transfer rate of about 1.5×106 s-1. Similar experiments carried out for the Er3+-doped glass-ceramic system also validate the hypothesis that both host and matrix-excited RE emissions are decoupled due to the different origins of the involved physical mechanisms.