Luminescent Properties For Rare Earth Ions Doped Titanate Phosphors

As a new type of solid-state lighting source,White LED has many advantages such as small size,long service life,energy conservation,environmental protection,and so on.Combination of three-color LED chip and violet-blue LED chip with phosphor are the common ways to achieve white light emission.Phosphor is an important part of white LED,so the optimization of the luminescent properties of the phosphors plays an important role in the development and application of white LED.In this paper,different methods were used to prepare titanate phosphors excited by near-ultraviolet light,and also the luminescent properties and temperature sensing properties were systematically studied.The main contents and results are as follows:?1?NaLa_1-xEuxTi₂O₆ red phosphors were synthesized by high-temperature solid-state reaction method.The samples could be excited by near-ultraviolet light,and red emission was obtained.It was confirmed that the exchange interaction between Eu³⁺ions was the main reason for concentration saturation according to Van's model.With the increase of Eu³⁺ concentration,the light-emitting color of the samples could be turned from white to red.Based on Arrhenius's model,it was validated that the crossover process was responsible for the temperature quenching behavior.At last,the Judd-Ofelt parameters of Eu³⁺ in NaLaTi₂O₆ phosphors were calculated according to the Judd-Ofelt theory and emission spectra.?2?Na₂(La_1-xEux)₂Ti₃O₁₀ red phosphors were prepared by high-temperature solid-state reaction method.Na₂(La_1-xEux)₂Ti₃O₁₀ red phosphors could be excited by near-ultraviolet light.According to Van's model,exchange interaction between Eu³⁺ions was attributed to the concentration quenching behavior of Eu³⁺.The self-quenching behavior of the fluorescence of Eu³⁺ was studied by Auzel's model.In addition,the temperature quenching behavior was observed,and the Arrhenius's model was used to confirm that crossover process was the main mechanism.?3?K₂(La_1-xEr_x)₂Ti₃O₁₀ green phosphors were prepared by sol-gel-combustion method.K₂(La_1-xEr_x)₂Ti₃O₁₀ phosphors could be excited by near-ultraviolet light and emit green light.Van's model was used to investigate the concentration quenching behavior of the samples,and the electric dipole-dipole interaction was confirmed to be the main mechanism.In addition,the temperature sensing properties of K₂(La_1-xEr_x)₂Ti₃O₁₀ samples were investigated.And the results showed that Er³⁺ concentration had significant influences on its temperature sensing properties.With the increase of Er³⁺concentration,the temperature sensitivity decreased gradually.