Luminescence properties of Sm3+-doped polycrystalline ZrO2

We obtained samarium-doped zirconia using two different routes. In one, atomic layer deposited thin crystalline films were doped by using ion implantation; this sample was mainly monoclinic. The other method, the skull-melting technique, yielded polycrystalline bulk zirconia containing both monoclinic and tetragonal phases of ZrO2. Thorough photoluminescence (PL) measurements of Sm emission in these materials were performed using pulsed laser excitation at 405, 320 and 230 nm, respectively corresponding to direct, defect-related and host-sensitized excitation. Both samples exhibited well-resolved emission series of Sm3+. In general, the recorded spectra may be considered as superpositions of two different sets of lines attributable to Sm3+ centers in different crystalline phases of ZrO2. These results have been confirmed by time-resolved measurements, which also suggest that all emission lines originate from a common initial state (4G5/2) with a lifetime of about 1 ms. As expected, the host-mediated excitation leads to a prolonged decay profile attributed to the retarded energy transfer from host to guest.