Evidence of non-radiative energy transfer from the host to the active ions in monoclinic ZrO2:Sm3+

Abstract
We present the photoluminescence characterization of pure and 0.2 mol% samarium-doped zirconium oxide, prepared by the sol-gel process and annealed at 1000 °C to stabilize the monoclinic phase. Under excitation at 320 nm the Sm3+-doped monoclinic zirconium oxide shows strong emission at the green (569 nm) and red (607, 613 and 618 nm) bands, corresponding to the 4G7/26H9/2 and 4F3/26H9/2 samarium transitions, respectively; whereas the undoped sample only shows a broadband emission centred at 495 nm. The main mechanism that allows the samarium emission under UV excitation appears to be non-radiative energy transfer from the ZrO2 host to the Sm3+ ions.