Low temperature and decay lifetime photoluminescence of Eu and Tb nanoparticles embedded into SiO2

In the present work, we have studied the photoluminescence (PL) and decay lifetime of Tb and Eu nanoparticles (NPs) at low temperatures. The NPs were obtained by ion implantation into a SiO2 matrix. Concerning the PL yield of Tb, it has a maximum at 12 K and decreases with increasing temperatures reaching a minimum at 300 K. On the other hand, the PL lifetime of the PL band centered at 542 nm remains almost constant at a value of 1.6 ms. Concerning Eu, two bands are observed, one narrow centered around 618 nm and the other in the blue-green region (from 400 up to 550 nm). Both PL bands show a minimum yield at 12 K, and then they start to increase with increasing temperatures, reaching their maximum at around 100 K. Then, they start to decrease their yield reaching a minimum at 300 K, being this yield similar to the one obtained at 12 K. For the Eu PL lifetime, two different results were obtained. The narrow PL band centered at 618 nm shows a lifetime of the order of 1.6 ms independent of the temperature. Conversely, the blue-green PL band is strongly temperature dependent, being of the order of several ms for temperatures lower than 100 K down to 500 µs at 300 K.