Enhancing the sensitization of Ce3+ on Sm3+ by tri-doping Gd3+ in hexagonal NaYF4

Sm 3+ is one of the most fascinating activators because of its dominate emissions in visible region with abundant potential applications. However, its absorbing cross section and ability to be sensitized are ineffective and unpractical due to the low quenching concentration. In this work, a series of β-NaYF 4 : Ce 3+ /Gd 3+ /Sm 3+ were synthesized. Pure hexagonal phase of all samples was guaranteed by powder XRD patterns and SEM images, despite the morphology was influenced by rare earth components. The luminescence properties of β-NaYF 4 : Ce 3+ /Gd 3+ /Sm 3+ were systemically investigated by the photoluminescence excitation spectra, emission spectra and life time decay curves. Tri-doping Gd 3+ into β-NaYF 4 was found to be very helpful to enhance the sensitization of Ce 3+ on Sm 3+ . Furthermore, the rate equation of sensitizers was induced to analyze details of competition between ET Ce → Gd and Ce → Sm. Rate equation analysis also indicated that the enhancing effect of Gd 3+ on sensitization is mainly due to the greatly improved energy utilization efficiency.