An efficient synthetic strategy for uniform perovskite core-shell nanocubes NaMgF₃:Mn2⁺, Yb³⁺@NaMgF₃:Yb³⁺ with enhanced near infrared upconversion luminescence

Uniform perovskite core-shell nanocubes NaMn_1-xMg_xF₃@NaMgF₃ and NaMn1_-xMg_xF₃:Yb³⁺@NaMgF₃:Yb³⁺ have been successfully synthesized via a facile one-pot co-precipitation method at room temperature. The core-shell structures were carefully characterized by powder X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy and energy-dispersive X-ray elemental mapping. It was found that the formation mechanisms of the novel core-shell structures consisting of aggregation of precursor molecules/ions, multiple nucleation, surface re-crystallization and further phase transformation. In addition, the DFT calculations further showed that Mn²⁺ ions tend to aggregate in NaMgF₃:Mn²⁺, and which may be one of important intrinsic factors for formation the unique NaMn_1-xMgxF₃@NaMgF₃ structure in this case. Besides, the unique core-shell structures NaMn_1-xMgxF₃:Yb³⁺@NaMgF3:Yb³⁺ can obviously enhance near-infrared upconversion luminescence of Mn²⁺, that may find high potential in multiple high-resolution imaging applications.