Photon conversion in Tb,Yb:CaxSr1-xAl2O4 nanocrystals

In this work the fabrication and the photoluminescence properties of CaxSr1-xAl2O4 nanocrystals doped with Ca, Tb and Yb are investigated. The photoluminescence quantum yield measured at 980 nm of the Yb doped CaxSr1-xAl2O4 nanocrystals is found to be 8% for an excitation in the ultraviolet range. However the quantum efficiency decreases with the insertion of Tb. Photoluminescence excitation experiments and time-resolved photoluminescence both conclusively demonstrate that no energy transfer between Tb and Yb occurs in this host matrix.