@article{ravaro_morais_scalvi_li_2007,  title={Visible emission from Er-doped SnO2 thin films deposited by sol-gel},  volume={53},  ISSN={0366-6913},  url={https://doi.org/10.1590/S0366-69132007000200013},  DOI={10.1590/S0366-69132007000200013},  number={326},  journal={Cerâmica},  publisher={Associação Brasileira de Cerâmica},  author={Ravaro, L. P. and Morais, E. A. and Scalvi, L. V. A. and Li, M. Siu},  year={2007},  month={Apr},  pages={187–191} }