溶胶-凝胶法制备Eu^(3+)-Ce^(3+)共掺杂TiO_2及光催化性能

采用溶胶-凝胶法制备了Eu^(3+)-Ce^(3+)共掺杂TiO_2纳米粉体,以亚甲基蓝溶液为目标降解物、用正交试验方法考察了内部因素和外部因素对掺杂样品的光吸收和光催化性能的影响,同时采用XRD、FE-SEM、UV-Vis吸收谱等表征了样品结构与性能。结果表明,最佳的实验方案是热处理温度为550℃、Ce^(3+)的掺杂量为0.02mol%、Eu^(3+)的掺杂量为0.2mol%,最佳的外部环境是共掺杂TiO_2纳米粉体光催化剂加入量为0.15 g/50 mL、亚甲基蓝溶液的初始pH值及浓度分别为6.5和10 mg/L。样品的晶粒尺寸在20 nm左右,共掺样品的光催化率明显比单掺和未掺样品的高,且吸收边向可见光红移了53nm左右。共掺样品对亚甲基蓝降解反应符合一级动力学模式。共掺样品光催化率的提高归因于Eu^(3+)和Ce^(3+)的协同作用,一方面增加有效的空穴电子数;另一方面可使样品吸收更低能量的波长而被激发。

Quenching Photoluminescence of Eu(III) by Cu(II) in ZnO:Eu3++Cu2+ Compounds by Solution Combustion Method

In this study Cu2++Eu3+ co-doped ZnO(ZnO/Cu2++Eu3+) solid solution powders were synthesized by solution combustion method using as oxidant agent zinc nitrate hexahydrate and as fuel urea;the Cu2+ concentrations were 0, 1, 2, 3, 10, and 20 %Wt;the Eu3+ ion concentration was fixed in 3%Wt. The samples after were annealed at 900°C by 20 h in air. The structural results showed the largely presence of a wurtzite solid solution of Cu2++Eu3+doped ZnO, at high Cu2+ doping CuO and Eu2CuO4 phases are also present. Morphological properties were analyzed using scanning electron microscopy (SEM) technique. However it is important to remark that the Cu2+ ions suppress the Eu3+ ion photoluminescence (PL) by means of an overlap mechanism between Cu2+ absorption band and Eu3+emission band (e.g. 5D0→7F2) of the Eu3+ emission spectra.

Effects of two strategies on afterglow behavior of Lu_(2)O_(3):Eu single crystal scintillator:Co-doping with Pr^(3+)and solid solution with Sc_(2)O_(3)

In this paper,effect of two strategies on afterglow behavior of Lu_(2)O_(3):Eu single crystal scintillato r,Pr^(3+)codoping and solid solution with Sc_(2)O_(3),were studied systematically.Two groups of Lu_(2)O_(3):5 at%Eu,x at%Pr(x=0,0.2,0.5,1,2 and 5)and(Lu1-yScy)_(2)O_(3):5 at%Eu(y=0,20 at%,50 at%and 70 at%)single crystals were grown by floating zone(FZ)method in air atmosphere.The structures of as-grown crystals were determined by X-ray diffraction(XRD).The scintillation,photoluminescence properties and carrier trap states were investigated through afterglow,X-ray excitation luminescence(XEL),transmittance,photoluminescence excitation(PLE)and photoluminescence(PL),PL decay and thermal stimulated luminescence(TSL)curves.It is found that with the increase of Pr^(3+)concentration,the afterglow level of the system decreases at the expense of scintillation luminescence efficiency.Meanwhile,although Sc_(2)O_(3):Eu presents much lower afterglow intensity than Lu_(2)O_(3):Eu,the addition of Sc_(2)O_(3)will just increase the afterglow level of the(Lu1-yScy)_(2)O_(3):5 at%Eu single crystal system.Possible mechanisms for above phenomena are discussed based on experimental results.

Preparation and characterization of Er^(3+)-Yb^(3+)-Ce^(3+) co-doped transparent glass ceramic containing nano Ca_5(PO4)_3F crystals

A transparent glass ceramic tri-doped with Ce3＋/Er3＋/yb3＋ was fabricated by the high-temperature melting technique and following heat-treatment. X-ray diffraction and transmission electron microscope results demonstrated that Cas（PO4）3F（FAP） nanocrystals, possessed with preferable emission performances for the 1.54 μm transition for doping Er3＋, were homogeneously pre- cipitated among the glass matrix with a mean size of 30 rim. Addition of Ce3＋ greatly enhanced 1.54 ~tm fluorescence of Er3＋ by the cross relaxation energy transfer between Er3＋ and Ce3＋. Meanwhile, incorporation of Ce3＋ dramatically decreased the visible upcon- version emission intensity of glass ceramic than that of glass, suggesting that Ce3＋ might incorporate into the FAP nanocrystals. The properties of this transparent glass ceramic showed the potential application as an efficient 980 nm pumped infrared laser medium.

Effect of Sr^2+ and Dy^3+ co-doping on coloration and temperature stabilization of a γ-Ce2S3 red pigment

In this paper,a Sr^2+and Dy^3+co-doped γ-Ce2S3 red pigment was synthesized via a combination of coprecipitation and sulfurization processes.Mixed oxide was prepared by presintering the coprecipitates,(Ce,Sr,Dy)CO3,followed by high-temperature sulfurization under a CS2 atmosphere.The effects of the sulfurization temperature,time,and doped proportion on the phase composition,color performance and temperature stability of γ-Ce2S3 were systematically studied.The results show that a stable γ-Ce2S3 red pigment can be obtained through Sr^2+and Dy^3+co-doping at 730℃ for 200 min.The diffraction peaks of all the samples shift to higher 2θ values with increasing doping proportion,indicating that part of the Dy^3+species enter the lattice and form a solid solution.The band gap of the samples remains practically constant at 2.01-2.04 eV,which causes their red color.The best red-color quality(L*=37.13,a*=34.77,b*=29.44) is achieved when the pigment has a Dy^3+/Ce^3+molar ratio of 0.15,and the material maintains its excellent red color(L*=31.49 a*=30.94 b*=25.33) after being heated at 410℃ for 30 min.