${\mathrm{SnO}}_2$ nanoparticles having an average particle size of 5 nm were precipitated in transparent glasses by irradiation with an 800-nm femtosecond laser pulse. Glasses, prepared to codope ${\mathrm{Sn}}^{4+}$ and ${\mathrm{Eu}}^{3+}$ ions by a sol-gel method, were heated in a ${\mathrm{H}}_2$ gas atmosphere, in which the Sn ions are coordinated by two oxygen ions with point defect of a molecularlike electronic structure. Upon laser pulse irradiation, the twofold-coordinated Sn atoms are activated to react with oxygen, resulting in the formation of ${\mathrm{SnO}}_2$ nanocrystals. The precipitated ${\mathrm{SnO}}_2$ crystals grew up to circa 5-nm size by the Joule-heating effect of the laser. The fluorescence intensities of the codoped ${\mathrm{Eu}}^{3+}$ ions were enhanced higher than 100 times that of the glass without nanocrystals by exciting with an energy corresponding to the absorption edge of the ${\mathrm{SnO}}_2$ nanocrystals, the energy of which is effectively transferred to the ${\mathrm{Eu}}^{3+}$ ions. It was found that the ${\mathrm{Eu}}^{3+}$ ions are located in the glass structure from the fluorescence line narrowing spectroscopy.

• Received 1 May 2003

DOI:https://doi.org/10.1103/PhysRevB.68.104204