Design And Properties Of Bi³⁺ Doped Galliate Persistent Luminescence Materials

Persistent luminescence（Pers L）is a special optical phenomenon in which a material can absorb and store the energy of external light irradiation such as ultraviolet（UV）or visible light,and after the stoppage of the irradiation,the stored energy is slowly released in the form of luminescence under certain conditions,time ranges from a few minutes to several hours.As a special energy storage luminescence material,it has been widely used in architectural decoration,information display,security indication,and now gradually extended to the application fields of information anti-counterfeiting,biological detection,and optical imaging.So far,most of the Pers L material substrates with good performance are concentrated in aluminate system and silicate system,but the disadvantages of easy decomposition of aluminate in water and high calcination temperature of silicate limit their applications.Therefore,it is important to develop a Pers L material with simple synthesis conditions and stable physicochemical properties for research and application.In this paper,Sr Ba Zn₂Ga₂O₇:Bi³⁺,an orange Pers L material,and Ca YGa O₄:Bi³⁺,a blue Pers L material,synthesized by conventional high temperature solid phase reaction method,and the crystal structure,PL and Pers L properties of the samples were investigated by XRD,PL and Pers L spectra.The details of the study are as follows:（1）The orange Pers L material Sr Ba Zn₂Ga₂O₇:Bi³⁺was prepared by high-temperature solid-phase method.After excitation at 329 nm light source for 3 min,Sr Ba Zn₂Ga₂O₇:Bi³⁺can emit bright orange Pers L with a broadband at 400 nm-800 nm and the peak is located near 585nm,and the Pers L performance of the sample is enhanced and then weakened with the increase of the concentration of doped ion Bi³⁺.The best concentration is 0.2%Bi³⁺,and the Pers L time can reach 16 min.（2）The blue Pers L material Ca YGa O₄:Bi³⁺was prepared by high-temperature solid-phase method.The optimal doping concentration of Bi³⁺is 0.3%,and the sample can emit bright blue Pers L after 1 min of excitation at 317 nm light source,with an asymmetric broadband at 340nm→650 nm and the peak at 430 nm,which can be attributed to ³P₁→¹S₀ of Bi³⁺.With the increase of doping ion Bi³⁺concentration,the Pers L of the sample is enhanced and then weakened,and the optimal Pers L time can reach 40 min.（3）On the basis of（2）,the Pers L performance of the sample is improved by partial substitution of Ca by Sr.The influence of substitution of different Sr concentrations on the Pers L performance of Ca YGa O₄:Bi³⁺is studied.When the substitution concentration of Sr is0.2%,the Pers L performance of the sample reaches the best,and the longest Pers L time can reach 135 min.The results show that by partially substituting Ca for Sr,more defects are created in the crystal,and more electrons are captured by these traps,thus improving the Pers L properties of the sample.