Fig. 4: Crystal structure and chemical composition of MgO/MgF2:Cr3+ heterostructures.
From: Self-powered near-infrared mechanoluminescence through MgO/MgF2 piezo-photonic heterojunctions
a Schematic illustration of the MgO/MgF2 interface and local coordination environment of [MgO6], [CrF4O2], and [MgF6] units. b Rietveld refinement of XRD pattern for MgO/MgF2:0.005Cr3+, confirming the coexistence of MgO and MgF2 phases with good crystallinity of Rwp = 11.01% and χ2 = 1.50. c SEM image and corresponding EDS elemental mapping for Mg, O, and F, showing the spatial distribution and phase separation within a representative heterostructure particle. d HRTEM image revealing the well-defined interface between MgO (D = 2.973 Å, (111)) and MgF2 (D = 2.592 Å, (101)) domains. e FFT diffraction pattern from the HRTEM image, with characteristic spots assigned to MgO (110) and MgF2 (101) planes. f SAED pattern of the heterostructure, confirming the coexistence of polycrystalline MgO and MgF2 phases with indexed diffraction rings corresponding to both components. Source data are provided as a Source Data file.
