Investigations Of The Dopant Of Mg²⁺ And Gd³⁺ On Enhancing The Luminescence Properties For The Long Persistent Phosphor Of Perovskite SrZrO₃:Sm³⁺

Inorganic materials based on the perovskite structure have a stable composition and flexible structure,which can provide a good local coordination environment for the luminescent centre and can be used as an ideal alternative luminescent host material.SrZrO₃with an ABO₃perovskite structure was chosen as the host for the long persistent luminescent material,with the rare earth ion Sm³⁺as the luminescent centre.SrZrO₃:Sm³⁺,SrZrO₃:Sm³⁺,Mg²⁺and SrZrO₃:Sm³⁺,Gd³⁺orange-red long persistent phosphors were synthesized by high-temperature solid-phase method under air atmosphere.The structures and properties of the SrZrO₃-based long persistent phosphors were determined by X-ray diffraction,scanning electron microscopy,X-ray photoelectron spectroscopies,fluorescence spectra,persistent decay curves and thermoluminescence spectra.Combining the characterisation results and theoretical analysis,the luminescence mechanism of the synthesised materials are inferred and constructed,and the prospects for their research and development are given.（1）SrZrO₃:Sm³⁺orange-red long persistent phosphors were synthesised by inequivalent substitution of Sr²⁺with Sm³⁺,corresponding to the standard card PDF#75-0467,with cell prism length a=b=c=4.089?and cubic perovskite structure.The fluorescence spectra show that the the quenching concentration of Sm³⁺is 1.2%which quenching mechanism is the electric dipole-electric dipole interaction between Sm³⁺;the orange-red luminescence of materials are due to the ⁴G_5/2→⁶H_5/2,⁴G_5/2→⁶H_7/2and ⁴G_5/2→⁶H_9/2transitions of Sm³⁺.The thermoluminescence spectra show that the trap energy level of the SrZrO₃:Sm³⁺materials is0.714 e V,which is a suitable trap energy level for long persistent luminescence.The luminescence mechanism of the material is constructed based on crystal defect theory and energy band theory.（2）The co-doping of alkaline earth metal ions with Mg²⁺can improve the crystallinity of SrZrO₃:Sm³⁺materials,increase the stability of internal defects and effectively improve the luminescence of SrZrO₃:Sm³⁺materials.The fluorescence spectra show that the co-doping of Mg²⁺enhances the fluorescence intensity of SrZrO₃:Sm³⁺materials without changing the shape and position of spectral peaks.The decay curves show that the introduction of Mg²⁺significantly enhances the persistent performance of SrZrO₃:Sm³⁺materials.The thermoluminescence spectra show that the co-doping of Mg²⁺is able to greatly increase the concentration of oxygen vacancies defects within the material at a suitable trap depth.The electron-hole pair luminescence mechanism of the material is constructed by energy band theory and crystal defect theory.（3）SrZrO₃:Sm³⁺,Gd³⁺materials were prepared and their structures and luminescence properties were investigated.The fluorescence spectra showed that the excitation spectra of Sm³⁺and the emission spectra of Gd³⁺overlapped in energy level and there was an energy transfer process from Gd³⁺to Sm³⁺.The afterglow decay curves indicate that the introduction of Gd³⁺as a sensitizing ion can significantly improve the long afterglow luminescence of SrZrO₃:Sm³⁺materials.The thermoluminescence spectra show that the introduction of Gd³⁺can significantly increase the concentration of effective traps inside the material.Based on the above analysis,the luminescence mechanism of the material is established by combining energy band theory and crystal defect theory.