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 NaMn1−xMgxF3@NaMgF3 and NaMn1−xMgxF3: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 consist 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+, which may be one of the important intrinsic factors for the formation of the unique NaMn1−xMgxF3@NaMgF3 structure in this case. Besides, the unique core–shell structures NaMn1−xMgxF3:Yb3+@NaMgF3:Yb3+ can obviously enhance the near-infrared upconversion luminescence of Mn2+, which may find high potential in multiple high-resolution imaging applications.