Synthesis And Performance Control Of Tantalate-based Red-near Infrared Luminescent Material

Tantalate phosphors are widely used in indoor lighting and plant lighting due to their excellent physical and chemical properties.In this paper,Ba₂LaTaO₆ doped with rare earth Eu³⁺ions and Mn⁴⁺transition metal ions as red phosphors have been studied,mainly focusing on the optimal doping concentration of phosphors and the performance of phosphors.Finally,white LED and red LED for plant lighting have been packaged to estimate applications of phosphors.It also provides a new way to control the properties of tantalate red phosphor.The main studies include:1.In order to study the application of tantalate phosphors in the field of white light emitting diodes,a series of Ba₂LaTaO₆:Eu³⁺phosphors were prepared by high-temperature solid-state method.It is found that the phosphor emits orange red light at593 nm under excitation at 393 nm,with an optimal doping concentration of 0.35 mol.The temperature dependent photoluminescence spectra of phosphors exhibit an abnormal thermal quenching phenomenon,which first increases and then decreases with the increase of temperature.The luminous intensity of the phosphor is 80.62%of that at room temperature at a temperature of T=473 K.A W-LED device based on Ba₂LaTaO₆:0.35Eu³⁺orange red phosphor is packaged.The chromaticity coordinates of the W-LED are（0.3097,0.3131）,close to the chromaticity coordinates of standard white light（0.3333,0.3333）.The results show that the phosphor can be well applied to trichromatic W-LED.2.In order to study the application of tantalate phosphors in the field of plant lighting,a series of Ba2LaTaO6:Mn⁴⁺phosphors were prepared using a high-temperature solid-state method.The phosphors emit deep red light at 678 nm after excited by ultraviolet light at 358 nm,and the optimal doping concentration is 0.003mol.Mn⁴⁺is mainly affected by strong crystal fields.In addition,the luminescent intensity of the phosphor at T=398 K is 47.5%of that at room temperature.And the quantum yield reaches 30.6%.Finally,a red LED based on Ba₂LaTaO₆:0.003Mn⁴⁺phosphor was packaged to evaluate whether the phosphor can be used in the field of plant lighting.3.In order to improve the luminescent intensity,thermal stability,and quantum yield of Ba₂LaTaO₆:0.003Mn⁴⁺phosphors,a series of Ba₂LaTaO₆:0.003Mn⁴⁺,M⁺（Li,Na,K）phosphors were prepared using a high-temperature solid-state method.K⁺ions greatly improved the luminescent intensity of the phosphor.The luminescent intensity of the phosphor is increased to 176%after doping K⁺ions.And the luminescent intensity of the phosphor at T=398 K is 74.7%of that at room temperature.The quantum yield increased to 68.6%.Finally,red LEDs based on Ba₂LaTaO₆:0.003Mn⁴⁺,0.009K⁺and Ba₂LaTaO₆:0.003Mn⁴⁺phosphors were packaged,representively.The light emitted by red LEDs can be absorbed by plant chlorophyll a and Phytochrome P_R.The results show that phosphor can be used in the field of plant lighting.