Study On Luminescence Properties Of Mn⁴⁺ Doped Perovskite Structure Tungstate

Metal ion-doped photoluminescent materials play an important role in industrial production and daily life.Among them,Mn⁴⁺activated phosphors have broad application prospects in agriculture,sensing,lighting and display.In order to design high-efficiency Mn⁴⁺activated phosphors meeting the needs of various fields,tungstate oxide with perovskite structure was chosen as the host material to investigate the luminescence properties of Mn⁴⁺in this paper.The main work is as follow:(1)A series of Mn⁴⁺doped K_1-xLa_1+x/3Mg WO₆and K_1-xLi_xLa Mg WO₆phosphors were synthesized by high-temperature solid-phase reaction method.The K⁺of A site in KLa Mg WO₆host was replaced by La³⁺/Li⁺,which greatly increased the emission intensity of Mn⁴⁺peaking at 697 nm.The optimal samples was K_0.3La_1.233Mg WO₆:0.006Mn⁴⁺.Compared with the KLa Mg WO₆:0.006Mn⁴⁺,the PL intensity for K_0.3La_1.233Mg WO₆:0.006Mn⁴⁺under 467 nm blue light excitation is enhanced by 9.7times.The internal quantum efficiency of K_0.3La_1.233Mg WO₆:0.006Mn⁴⁺sample reaches 87%under 467 nm excitation.Further,Eu³⁺was introduced into the K_0.3La_1.233Mg WO₆:0.006Mn⁴⁺sample.A series of K_0.3La_1.233Mg WO₆:0.006Mn⁴⁺,y Eu³⁺samples were synthesized.In the Mn⁴⁺and Eu³⁺co-doped K_0.3La_1.233Mg WO₆samples.strong emission of Mn⁴⁺and Eu³⁺can be obtained at the same time,the emission peaks are at 697 nm and 613 nm,respectively.And the total PL intensity is increased by 40%compared with the Mn⁴⁺single-doped one.More importantly,the luminescence intensity ratio(I_Mn/I_Eu)of Mn⁴⁺and Eu³⁺varies monotonously with the increase of excitation wavelength and temperature in a certain excitation wavelength/temperature range.This unique characteristic makes the phosphor promising to be used in the field of optical temperature sensing and wavelength detection(2)A novel deep red phosphor K_0.5La_0.5Sr Mg WO₆:Mn⁴⁺with high quantum efficiency was designed and synthesized by A-site multi-cation substitution.Under the excitation of near ultraviolet or blue light,it can emit deep red light with peak at 695nm.The PL spectrum of the sample overlaps with the absorption spectrum of the phytochrome P_FR.Compared with other Mn⁴⁺activated oxide phosphors,the doping concentration of Mn⁴⁺in K_0.5La_0.5Sr Mg WO₆is obviously higher.Its optimal doping concentration reaches to 1.5%mol.The internal quantum efficiency of K_0.5La_0.5Sr Mg WO₆:1.5%Mn⁴⁺is as high as 92.4%,and the external quantum efficiency is 72.5%,which is close to the commercial red phosphor K₂Si F₆:Mn⁴⁺.Under the excitation of 365 nm near ultraviolet light,the integrated intensity of K_0.5La_0.5Sr Mg WO₆:0.015Mn⁴⁺phosphor is 2.1 times that of commercial red phosphor K₂Si F₆:Mn⁴⁺.In addition,the thermal stability of the sample was also discussed.