The Influence Factors Of The 3d Transition Metal Ions (Mn²⁺,F³⁺,Ni²⁺) Luminescence In Inorganic Compounds

In recent years,3d transition metal ions are gradually replacing traditional rare earth ions as the activator of a new generation of luminescent materials by virtue of their low price and rich spectral properties.Before the synthesis of such luminescent materials,if the luminescent properties of the doped 3d transition metal ions can be predicted,the blindness of the experimental synthesis can be reduced so as to greatly improve the development of the new material research efficiency,but so far the direct correlation between the luminescent properties of such materials and local coordination structure of 3d ions is not clear in the literature.Therefore,the study of the factors influencing the luminescence of 3d transition metal ions and the prediction of luminescence properties of 3d transition metal ions are the key topic that needs to be addressed in the field of luminescent materials.In this thesis,our research focuses on Mn²⁺,Ni²⁺and Fe³⁺.On the one hand,we collect the luminescence spectra of luminescent materials activated by Mn²⁺,Ni²⁺and Fe³⁺reported in the literature over the past 60 years.On the other hand,we use the First-principles calculation to relax the local coordination structures of transition metal ions in these luminescent materials.Through comprehensive analysis,we find that the main factors affecting the emission wavelength of Mn²⁺are the average bond length between Mn²⁺and its ligand ions and the ligand orbital energy.With the increase of the crystal field distortion,the emission wavelength of Mn²⁺will be redshifted,but the amplitude of the shift is small.Fe³⁺has the same 3d electron configuration as the Mn²⁺,and so the relationship between the luminescence wavelength and the local coordination structure is similar to that of Mn²⁺,except that the defect levels contributed by Fe³⁺are generally lower than those of Mn²⁺.So these levels are easy to be affected by the ligand orbital energy.For Ni²⁺,we have mainly studied the ¹E_g,³T_1g and ³T_2g energy levels,which are close to the ground state.The³T_1g and ³T_2g energy levels are mainly influenced by the average bond length between the Ni²⁺and ligand ions and crystal field splitting energy,while the ¹E_g energy level is mainly influenced by the average bond length between the Ni²⁺and ligand ions and Racah parameter B.With the increase of the crystal field distortion,all three energy levels of Ni²⁺will be blue shifted.Our results are not only helpful to the understanding of the luminescence properties of 3d ions,but also can predict the luminescence properties of 3d ions according to the local coordination structure,thus providing a solid theoretical support for the experimental development of new transition-metal activated phosphors.