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 (⁴G_5/2) 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.