Study On The Performance Of SrGd₂Al₂O₇ Phosphor Doped With Mn⁴⁺ For Plant Lighting And Temperature Sensing

Phosphors converted light-emitting diodes（pc-LED）have many potential applications in lighting,medicine,scientific research and other fields,among which phosphors are the most important.In recent years,a variety of phosphors have been widely reported.The transitional Mn⁴⁺ion has a unique 3d³ electronic structure,and its excellent luminous properties have aroused people’s research interest.However,its current performance is not enough to meet people’s needs.In this paper,Sr Gd₂Al₂O₇（SGAO）is used as the matrix to prepare a series of new Mn⁴⁺ions doped phosphors,and its optical properties are studied as follows:A series of far-red SGAO:Mn⁴⁺/Ca²⁺phosphors were prepared by high temperature solid phase method,and their luminescence properties and application prospects in plant lighting were investigated.SGAO:Mn⁴⁺phosphor has a wide absorption band in the range of 260-550 nm,which is very suitable for LED pumping.The optimal doping concentration is 0.1mol%,the concentration quenching mechanism is dipole-fourth order interaction,the optimal excitation wavelength is 340nm,and the emission spectrum is far-red wavelength with 709 nm as the central wavelength.The internal quantum efficiency（IQE）is 34.93%,and the thermal stability is 29.3%at 150℃.Codoped Ca²⁺ions were used for charge compensation to obtain stronger far-red emission,it does not change the shape or position of the launch peak and the IQE of SGAO:0.1%Mn⁴⁺,11%Ca²⁺phosphor reached 60.56%,1.73 times of the former,and the thermal stability reached 33.3%at 150℃,which is also slightly improved.Moreover,the emission spectrum of the phosphor is well matched with the absorption spectrum of the photosensitive pigment PFR,and at the same time it is outside the absorption spectrum of the photosensitive pigment PR,so it is especially suitable for regulating plant growth in the field of plant lighting.A series of SGAO:Bi³⁺/Mn⁴⁺phosphors were prepared by high temperature solid phase method,and their luminescence properties and application prospect in temperature sensing field were investigated.SGAO:Bi³⁺phosphor has strong absorption in the ultraviolet region,and the optimal excitation wavelength is 300 nm,which meets the conditions of pumping with LED.The optimal doping concentration of Bi³⁺ion was determined to be 4mol%,the concentration quenching mechanism is analyzed as dipole-dipole interaction,and the energy transfer between Bi³⁺and Mn⁴⁺ions is explored.The energy level transition diagram of ET process between Bi³⁺and Mn⁴⁺ions is given,and the mechanism of thermal quenching of Bi³⁺ion is explained.The performance and application of SGAO:Bi³⁺/Mn⁴⁺phosphor in temperature sensing were studied.It was found that the maximum S_a was 8.573%K^-1 and the maximum S_r was 1.927%K^-1 at 473 K,which provides an alternative scheme for optical temperature sensing materials.