Study On The Luminescence Properties Of Mn And Cr-doped Rare Earth ScTaO₄

In this thesis,the preparation of ScTaO₄fluorescent materials doped with transition metal ions Mn⁴⁺and Cr³⁺and their deep red and near-infrared luminescence properties were investigated.The Mn⁴⁺-activated ScTaO₄series of deep red oxide phosphors,ScTaO₄series of deep red oxide phosphors co-doped with different cations and Mn⁴⁺,and Cr³⁺-activated ScTaO₄series of near-infrared oxide phosphors were prepared,respectively.In order to systematically characterize and test the crystal structure,surface morphology,fluorescence properties,and thermal burst properties of the prepared phosphors,powder X-ray diffraction（XRD）,fluorescence spectroscopy（PL）assay,UV reflectance spectroscopy-visible diffuse reflectance spectroscopy（UV-vis DR）,and scanning electron microscopy（SEM）were used,and their potential applications in LED and other fields were discussed.potential applications in LEDs and other fields.The details of the study are as follows:（1）The Mn⁴⁺-activated deep red emitting phosphor was obtained by doping Mn⁴⁺in ScTaO₄using a high-temperature solid-phase method.The valence states of doped Mn ions were studied in detail by XPS technique and EPR technique.And the concentration quenching and temperature quenching mechanisms of the luminescence of Mn ions were analyzed by studying their fluorescence excitation spectra,emission spectra and UV-Vis diffuse reflectance spectra.It is found that Mn-doped ScTaO₄phosphor has a strong dark red luminescence at 655 nm,and the emission comes from ²E_g→⁴A_2gof Mn⁴⁺.The intensity of the luminescence is greatest when the Mn⁴⁺ion doping concentration x in Sc_1-xTa O₄:x Mn⁴⁺is 0.005.（2）We explored the methods to enhance the luminescence intensity of ScTaO₄:Mn⁴⁺phosphor,and the effects of different cation doping on the luminescence performance of the samples were investigated.Finally,it was found that compared with other cations,the appropriate amount of Zr⁴⁺doping was able to increase the luminescence intensity of the phosphor on the basis of the original best effect.The doping of Zr⁴⁺did not cause a change in peak shape or peak position,and the co-doping of Mn⁴⁺and Zr⁴⁺can not only effectively improve the luminescence intensity of Mn⁴⁺but also slow down its temperature quenching effect,and the change of luminescence characteristics caused by the co-doping of Zr⁴⁺provides a valuable reference for the design of new Mn⁴⁺-doped phosphors and the regulation of luminescence performance.（3）A kind of near-infrared luminescent material with longer wavelength and wider half-peak width was prepared by high-temperature solid-state method:monoclinic Sc_1-xTa O₄:x Cr³⁺.The crystal structure and luminescent properties of the samples have been investigated.Based on this material,we have also made a near-infrared light-emitting diode device,which shows good infrared light-emitting properties.This provides fundamental research data for the design of Cr³⁺-doped infrared light-emitting materials,which can provide useful guidance for the design and synthesis of new NIR light-emitting materials.