Superlattice-stabilized structure and charge transfer assisted photoluminescence enhancement in a samarium-doped high entropy perovskite oxide

Abstract

To find suitable matrix materials for rare earth (Ln³⁺) ions has always been key to developing Ln³⁺-doped phosphor materials. High-entropy oxides (HEOs), benefiting from the multiple ionic occupations and lattice distortions with lowered local symmetry, might be rather promising to generate photoluminescence (PL) emissions, which however unfortunately are not yet explored. Here, we report a Sm³⁺-doped Ca(Zr_0.2Ti_0.2Sn_0.2Hf_0.2Nb_0.2)O₃ (Ca(M₅)O₃) orange-red-emitting phosphor. The structure, photoluminescence (PL) properties, chromatic properties and temperature-dependent PL are systematically studied. The high entropy structure brings about superlattice satellites with the reflection vector . The doping of Sm³⁺ ions is helpful in grain growth of the HEO ceramics. The charge transfer state (CTS) presenting the energy transfer from the matrix to dopants (O²⁻-Sm³⁺) in excitation spectra was observed with the center at around 290 nm. The temperature-dependent PL study reveals excellent thermal stability. In addition, the relation between the high entropy structure and PL enhancement is comprehensively studied. These findings can provide some new ideas for the development of Ln³⁺-doped phosphors and the application of high entropy oxide materials.