Preparation And Properties Of Phosphor For Fruit And Vegetable Preservation Lighting LED

As a new type of light source with advantages of energy saving and environmental protection,LED is not only widely used in daily lighting,but also has superior photoelectric performance in Light-controlled preservation technology.According to the principle of crop photosynthesis,there are currently three LED lighting technology schemes applied to plants to supplement light or keep fresh fruits and vegetables:a)blue LED chip+red LED chip;B)blue LED chip+red phosphor;C)near-ultraviolet LED chip+blue phosphor+red phosphor.Therefore,the blue and red phosphors play a very important role in the technology of fruit and vegetable preservation lighting.The purpose of this paper is to develop new blue and red phosphors with near-ultraviolet excitation,which have potential application value in preparing artificial light source in the field of preservation illumination of fruits and vegetables.(1)BaMgSi₄O₁₀:0.04Eu²⁺,x Sr²⁺and blue phosphor BaMgSi₄O₁₀:Eu²⁺were prepared by high temperature solid phase method,with a wide excitation band of 250 nm to 400 nm.It also has wide emission band,with full widths at half-maximum(FWHMs)of about 65 nm centered at 464 nm.When the doping concentration of Eu²⁺is 0.04,the luminescence intensity is the strongest,and then the luminescence intensity is reduced due to concentration quenching.According to the XRD pattern,the XRD peak of the samples shifted to the right as the doping concentration of Sr²⁺increased,but no impurity peak was found.Through the analysis of excitation and emission spectra of different doping concentrations,it is found that the doping concentration of Sr²⁺increases,and the excitation and emission spectra of the samples are red-shifted.According to the thermal stability test of the samples,the emission peak of the samples appears blue shift to some extent with the increase of temperature,while the thermal stability of the sample decreases due to the incorporation of Sr²⁺.When the temperature rises from room temperature to 150?,the luminescence intensity of the sample with Sr²⁺doping concentration of 46%decreases by 8%compared with that of the sample without Sr²⁺doping.In this research,the influence of temperature on the luminescence of samples is explained by using the configuration coordinates.The results show that the blue phosphor BaMgSi₄O₁₀:Eu²⁺,x Sr²⁺are expected to be used in LED lighting for Light-controlled preservation technology.(2)BaMgSi₄O₁₀:Eu³⁺,BaMgSi₄O₁₀:Tb³⁺and BaMgSi₄O₁₀:Eu³⁺,Tb³⁺phosphors were synthesized by the traditional solid phase reaction method.The crystal structure,luminescence,concentration quenching and Tb³⁺?Eu³⁺energy transfer effect were studied.The results showed that the samples BaMgSi₄O₁₀:Eu³⁺phosphors showed red color under the excitation of365nm wavelength,and the peak luminescence was 613nm.The samples BaMgSi₄O₁₀:Tb³⁺phosphors emitted green light with a peak value of 541nm under excitation at near-ultraviolet wavelength of 377nm.With the increase of Tb³⁺concentration,the luminescence intensity of the samples increased first and then decreased,resulting in concentration quenching.The optimal doping concentration was 25%.When Eu³⁺was mixed with BaMgSi₄O₁₀:0.25Tb³⁺,the energy transfer phenomenon between Tb³⁺and Eu³⁺was observed,which was caused by the electric dipole-electric dipole interaction.(3)Using a 365 nm near-ultraviolet(UV)LED chip combining with the as-perpared blue phosphor BaMgSi₄O₁₀:0.04Eu²⁺and red phosphor BaMgSi₄O₁₀:0.25Tb³⁺,0.08Eu³⁺,a high quality phosphor-activated blue-LED and red-LED device was fabricated.The test results show that the performance of the device is relatively good.