Li^+,Zn^(2+),Mg^(2+)掺杂Lu_2O_3∶Er^(3+)荧光粉的制备及发光特性

用微波高温固相法合成了Er^(3+)单掺Lu_2O_3,Li^+与Er^(3+)共掺Lu_2O_3及Li^+,Zn^(2+),Mg^(2+)掺杂Lu_2O_3∶Er^(3+)的荧光粉。实验表明金属离子Li^+、Zn^(2+)、Mg^(2+)、Er^(3+)掺杂Lu_2O_3,不影响Lu_2O_3的立方晶相。扫描电子显微镜测量表明,Li^+掺杂可以有效改善粉体的分散性和形貌,Li^+,Zn^(2+),Mg^(2+)共掺杂获得的粉体颗粒分布更加均匀,粒径范围为80～100 nm。379 nm激发下,Li^+与Er^(3+)共掺样品发光较单掺Er^(3+)样品在565 nm处的发光增强了4.5倍,而Li^+、Zn^(2+)、Mg^(2+)与Er^(3+)共掺样品较其发光增强5.3倍。980 nm激发下,Li^+与Er^(3+)共掺样品,Li^+、Zn^(2+)、Mg^(2+)与Er^(3+)共掺样品的发光分别比单掺Er^(3+)样品在565 nm处发光增强23倍与39倍,在662 nm处发光强度分别增强20倍与43倍。379 nm激发下,较单掺Er^(3+)的样品,掺杂Li^+的样品和Li^+,Zn^(2+),Mg^(2+)和Er^(3+)共掺的样品荧光寿命均有所增加,而Zn^(2+)、Er^(3+)共掺及Mg^(2+)、Er^(3+)共掺样品的荧光寿命则有所缩短。

Mg^(2+)掺杂对上转换发光材料Na_(2)Zn_(3)Si_(2)O_(8):Er^(3+)发光性能的影响

采用高温固相法成功合成了新型Mg^(2+)掺杂Na_(2)Zn_(3)Si_(2)O_(8):Er^(3+)荧光粉,研究了其物相结构、上转换发光特性以及热稳定性和单色性。研究结果表明,Mg^(2+)离子的掺杂对Na_(2)Zn_(3)Si_(2)O_(8):Er^(3+)晶体结构没有影响,并且在980 nm激发下出现了Er^(3+)离子的绿色和红色特征发射带,Mg^(2+)离子的掺入使Er^(3+)离子在661 nm处的红色发射强度提高了16倍,这归因于随着掺杂Mg^(2+)离子CO32-基团和OH-基团数量的逐渐减少,无辐射跃迁几率减少,最终导致发光强度的增强。通过热稳定性研究发现,Na_(2)Zn_(3)Si_(2)O_(8):3%Er^(3+)、1%Mg^(2+)在25℃~250℃温度范围内表现出较好的热稳定性,并随着温度的升高样品呈橙红色发光。优化后的样品在固态照明领域有潜在应用价值。

Upconversion luminescence and temperature sensing performance of Er^(3+) ions doped self-activated KYb(MoO_(4))_(2) phosphors

In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.

Concentration effect and temperature quenching of upconversion luminescence in Ba Gd_2ZnO_5:Er^(3+)/Yb^(3+) phosphor

Er^3＋/yb^3＋ codoped zincate BaGd2ZnO5 phosphors were synthesized via a traditional solid state reaction. The crystal structure and phase purity were checked by means of X-ray dfluence of Eiffraction （XRD）, and the results showed that pure phase BaGd2ZnO5 phosphors with various Er^3＋/yb^3＋ concentrations were obtained. The Er^3＋ and Yb^3＋ doping concentrations on the green and red upconversion emissions was studied. It was found that both green and red upconversion emissions under 980 nm excitation were two-photon processes independent from the rare earth doping concentrations. However, the upconversion luminescence intensities greatly depended on the rare earth doping concentration. Furthermore, the population processes of upconversion luminescence and the quenching mechanisms were analyzed. The temperature-dependent green upconvcrsion luminescence was studied, and the temperature quenching process of two green upconversion emissions was modeled. The thermal quenching processes of the green upconversion emissions could be well explained by the model we proposed.