Preparation of CaS∶Eu^(2+), Sm^(3+) by Solid Reaction Method and Its Photostimulated Luminescence

The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that crystal structure of CaS has formed at 700 ℃. Spectrum analysis results show that the samples which were stimulated by 980 nm laser after excited by ultraviolet lamp emit red luminescence peaking at 649 nm.

Separation of Neighboring REElementsfrom Sm_2O_3Eu_2O_3Gd_2O_3 System by a Stepwise ChlorinationChemical Vapor Transport Reaction

The mutual separation characteristics were investigated for the neighboring Sm, Eu and Gd from their ternary oxide mixture Sm 2O 3 Eu 2O 3 Gd 2O 3 by a stepwise chlorination chemical vapor transport reaction within 6 h using AlCl 3 as complex former. The rare earth chlorides were more readily transported and concentrated in the middle temperature range of 980～1100 K and the transport efficiency was in the order of Sm≈Gd>Eu. The separation factor, expressed as molar ratio for the resulting chlorides, was 1 70 for Eu∶Sm, 1 88 for Eu∶Gd, 1 24 for Sm∶Gd in the higher temperature region, and 2 76 for Sm∶Eu, 2 83 for Gd∶Eu and 1 12 for Gd∶Sm in the lower temperature region, respectively. All results are much higher than those of the conventional wet process.

Synthesis and Characterization of IR Up-Conversion Material SrS∶Eu, Sm

Europium and samarium co-doped strontium sulfide (SrS∶Eu, Sm) infrared up-conversion phosphor was synthesized through calcining the precursor, which prepared by wet-method with strontium carbonate (SrCO_3), sulphur (S), europium oxide (Eu_2O_3) and samarium oxide (Sm_2O_3) as the starting materials, lithium fluoride (LiF) as the fluxing agent, at 750～1200 ℃ in carbon-reducing atmosphere. XRD analysis shows that SrS crystal structure is formed at 750 ℃, most completely at 1100 ℃. The IR up-conversion luminescence properties were characterized by excitation, emission, up-conversion excitation, up-conversion emission and thermoluminescence spectra. The spectral analysis associated with the physical model of up-conversion luminescence shows that the IR up-conversion luminescence is resulted from electron trapping process of Sm 3+ energy level. The thermoluminescence peak does not appear below 500 ℃ indicating the trapping energy level is appropriately deep, 800～1400 nm near infrared light can be the release light to realize up-conversion luminescence.

Microstructure and mechanical properties of AZ91 magnesium alloy with minor additions of Sm, Si and Ca elements

The effects of Sm, Si and Ca on the microstructure and mechanical property of AZ91 magnesium alloy were investigated by means of optical microscopy (OM), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and tensile testing. The results indicated that the addition of 1.5 wt.% Sm with or without 0.8 Si/Ca led to a decrease in the volume fraction of the β-Mg17Al12 phase and the formation of the intermetallic compounds of Al-Sm, Mg2Si, MgAlCa and Al2Ca. The microstructure of AZ91 alloy was significantly refined and distribution became discrete with additions of Sm and Ca;the average grain size of the α-Mg matrix was reduced from 239.7 ± 16.9 μm to 66.34 ± 5.10 μm. The AZ91-Sm-Ca alloy exhibited a good combination of yield strength at 135 MPa, ultimate tensile strength at 199 MPa and elongation at 4.32%, which was ascribed to grain refinement strengthening. Furthermore, the T6 treated AZ91-Sm-Ca alloy possessed yield strength of 154 MPa and elongation of 7.1%, which was due to grain refinement strengthening and reduction in discontinuous precipitates.

Solvent extraction kinetics of Sm(Ⅲ),Eu(Ⅲ) and Gd(Ⅲ) with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester

Solvent extraction kinetics of Sm（Ⅲ）, Eu（Ⅲ） and Gd（Ⅲ） from hydrochloric acid have been focused on using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester （P507） with Anordning for Kontinuerlig Undersokning av Fordelningsfaktore rid Vatske Extraction （AKUFVE）. Compared with the conventional set-up, some advantages emerge obviously, for example, fast phase separation, easy operation and convenience of kinetic data acquisition. First of all, the extraction mechanism was discussed based on the dimeric model of P507. Secondly, the effects of stirring speed were investigated and 420 r-min-1 was determined of the following experiments. The effects of pH, concentration of rare earth elements （REEs） and P507 on the extraction rate were analyzed. The results indicated that the extraction mechanism changed with the increasing concentration of P507. Then, the experiments with different temperature were carried out. It turned out that the values of apparent activation energy （Ea） for Sm（Ⅲ）, Eu（Ⅲ） and Gd（Ⅲ） extracted by P507 were 26.80 kJ-mol-1, 13.40 kJ.mol-1 and 1.10 kJ- mol- 1 respectively, the resistance of the entire process was limited by diffusion or both of diffusion and reaction. Finally, the correlation equations were obtained, and the theoretical results fit with the experimental data well, most relative error was within ± 30%.

新型红色荧光粉Sr_(3)CaNb_(2)O_(9):Sm^(3+),Eu^(3+)的发光特性和能量传递分析

利用高温固相反应法制备一系列单基质荧光粉Sr_(3)CaNb_(2)O_(9):xSm^(3+),yEu^(3+)(x=0.04~0.09,y=0.03~0.15),并对样品的物相形貌、发光性能、能量传递机制和CIE色坐标进行分析。研究表明,Sr_(3)CaNb_(2)O_(9):xSm^(3+)荧光粉在激发波长为407 nm时的浓度淬灭点为x=0.07。在Sr_(3)CaNb_(2)O_(9):0.07Sm^(3+),yEu^(3+)荧光粉中,随着Eu^(3+)掺杂浓度的增加,Sm^(3+)的发光强度降低而Eu^(3+)发光强度却先增加后降低,Eu^(3+)的浓度淬灭点为y=0.09。Sm^(3+)→Eu^(3+)的能量传递以电偶极-电偶极相互作用为主,能量传递效率达到76.6%。色坐标图表明Eu^(3+)离子的加入可使色坐标从橙红色区域向纯红色区域移动。此外,样品还具有较高的色纯度和较低的色温。结果表明,Sr_(3)CaNb_(2)O_(9)∶Sm^(3+),Eu^(3+)荧光粉有望成为白光LED发出红光物质的候选材料。

Improving luminescent property of SrIn_2 O_4 :Eu^(3+) by co-doped A^+ (A = Li, Na, K) or Sm^(3+)

A series of SrIn2 O4 ：Eu^3＋ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission （619 nm）; however, they have a low absorption of near-ultraviolet light with the wavelength of 400nm–405 nm. When co-doped with A^＋ （A=Li, Na, K）, the emission intensity of SrIn2O4 ：Eu^3＋ is significantly enhanced, but its emission and excitation spectral profile is unchanged. With co-doping Sm^3＋ , not only is the emission intensity of SrIn2 O4 ：Eu^3＋ enhanced, but also the absorption is broadened and strengthened in the range of 400 nm–405nm. The effect of Sm^3＋ -doped content on the emission intensity of SrIn2O4 ：Eu^3＋ , Sm^3＋ is investigated, and the optimal Sm^3＋ content is 0.02 mol.

Effects of Doping Trace Sm^(3+) and Gd^(3+) on Luminescent Character of Y_2O_2S∶Eu^(3+)

After trace Sm^3＋ ions and Gd^3＋ ions doping, the emission intensity of red phosphors Y2O2S： Eu^3 ＋ was enhanced and the voltage character （relation between emission intensity and excitation voltage） was improved while the other properties of physics and chemistry were not changed. The origins of enhancement and improvement are discussed. Probably the distortion and the defect of crystals are decreased by the substitution of Gd^3＋ for Y^3＋ instead of Eu^3＋ for Y^3＋ , and thus the Eu^3＋ crystal field is improved, and radiationless process and energy loss resulted from crystal defect are weakened, which leads to increased luminescence intensity and voltage character improvement. The overlapping fluorescent spectra of Y2O2S： Sm^3＋ emission and Y2O2S：Eu^3＋ excitation as well as Eu^3 ＋ excitation spectra transitions spectra lead to energy transfer from Sm^3 ＋ sensitization of Sm^3＋ ions fectively. containing Sm^3＋ excitation the possibility of resonance ions to Eu^3＋ ions, and the to Eu^3＋ ions is achieved effectively.

CaS:Eu,Sm的微波合成与发光性能研究

采用微波合成法快速合成了红外光激励发光材料CaS：Eu，Sm。研究了输出功率对样品发光性能的影响，Eu，Sm双掺杂离子的不同掺杂浓度对发光性能的影响（确定了最佳掺杂浓度），不同助熔剂对发光性能的影响。XRD测试结果表明，CaS：Eu，Sm样品为面心立方结构；SEM照片显示样品粒径在400～500nm范围内；光谱分析表明，样品的红外光激励发光响应范围位于800-1600nm，上转换发光峰值位于655nm，对应于Eu^2＋离子4f^65d→4f^7（^8S7/2）跃迁。

红外上转换材料CaS:Eu,Sm的制备

采用碳还原法,制备了电子俘获型红外上转换材料(CaS:Eu,Sm).研究了反应机理、还原原理、红外上转换机理以及灼烧温度对 CaS晶格形成和发光性能的影响.样品的XRD测试结果表明, CaS:Eu,Sm为面心立方结构,样品的激发谱位于200～600nm,样品的荧光发射光谱是峰值分别位于567nm,606nm和630nm的宽带谱,上转换发光峰值位于625nm,上转换发光的光谱响应范围位于800～1600nm.

电子俘获材料CaS:Eu,Sm红外上转换光衰减特性的研究

根据电子俘获机制 ,提出了CaS :Eu ,Sm红外上转换发光的衰减模型 ,建立了速率方程并进行了初步的求解 ,其解具有三级指数衰减的形式 .从实验上测定了Cas :Eu ,Sm在不同温度下的红外上转换光衰减特性 ,对实验结果进行了非线性拟合 。

低温燃烧合成红外响应材料CaS:Eu,Sm及性能表征

以金属硝酸盐-尿素作为原料体系,引入了升华硫粉,通过低温燃烧法一步合成了硫化物体系红外响应材料。对硝酸盐-尿素体系的低温燃烧过程进行了分析,根据氧化-还原反应的化合价理论计算了尿素燃料的理论用量。燃烧点火温度为600℃,反应时间为2min～3min,产物为红色云层状疏松多孔的纳米粉末,粒径为36nm左右。对样品进行XRD物相分析证明产物为CaS晶相,面心立方结构。光谱分析表明:自然光可以有效激发样品使之储能;样品在800nm～1600nm之间具有宽光谱红外响应效应;红外转换发光峰值波长位于655nm,对应于Eu2+离子的4f65d→4f7(8S7/2)跃迁。

存储型上转换发光材料CaS:Eu,Sm的发光机理研究

采用低温燃烧合成（LCS）法制备了存储型上转换发光材料CaS：Eu，Sm，并对其上转换发光机理进行了研究。研究表明：样品的激发光谱位于200-600nm之间，紫外或可见光均可有效地激发该材料来完成充能过程，且可见光激发占优势；样品的红外响应光谱范围为800～1600nm，由辅助激活离子Sm所形成的劈裂的深陷阱能级是该材料具有宽频谱红外转换特性的根本原因；样品的热释光谱高温峰值位于351．02℃，计算得到的陷阱能级深度为0．82eV，深度适中，利于激发能的储存和上转换发光的产生。

CaS:Eu,Sm荧光粉表面二氧化硅包覆对其光激励发光特性的影响(英文)

改进了CaS∶Eu,Sm荧光粉在实时剂量计系统中的稳定性和实用性。以不同体积的正硅酸乙酯作为前驱体,采用溶胶凝胶法对CaS∶Eu,Sm荧光粉进行表面包覆。分别使用荧光分光光度计和酸度计对荧光粉的发光特性和防水特性进行表征。实验结果显示当质量分数为5%时,包覆层能明显提高荧光粉的稳定性且不影响荧光粉的发光强度。从材料的光激励发光和剂量响应测试实验中可以得出材料的退火特性以及相应的辐射剂量值。以CaS∶Eu,Sm荧光粉为基础的辐射剂量测试系统显示在0.1～300 Gy范围内具有良好的线性关系。结果显示表面包覆层明显抑制光激励发光特性,而且随着辐射剂量的增加,这种影响愈来愈显著。最后,我们提出了以光激励发光技术为基础的辐射剂量在线测试改进系统。

CaS∶Eu,Sm光存储材料的光谱特性

CaS∶Eu,Sm是一种典型的电子俘获型光存储材料,文章采用湿法在还原气氛中制备了CaS∶Eu,Sm粉末样品。测量了这种光存储材料的XRD、激发光谱、发射光谱、光激励发光光谱、热释光谱以及光激励发光衰减曲线。XRD结果表明样品在1 050℃晶格已经形成。光谱测试结果说明紫外光可激发该材料,作为信息写入光源。样品被紫外光源饱和激发后,用980 nm红外激光激励,发射出峰值位于635 nm的红光。光激励发光起初衰减较快,随后有一个较长的平缓期。且样品具有合适深度的陷阱能级,能够稳定存储信息。对CaS∶Eu,Sm的光存储机理进行了探讨。

CaS∶Eu,Sm及其在农用转光膜上的应用原理

利用稀土直接掺杂工艺合成了一种“常光充能”型电子陷获材料 Ca S∶Eu,Sm,它不仅具有 Ca S∶ Eu无机发光材料的荧光光谱特性 ,而且具有红外升频转换特性 ,可将 0 .8～1 .6μm的红外光直接转换为～ 672 nm的红光、量子效率高达 76% ,是一种优于 Ca S∶ Eu的光转换农膜添加剂 .而共掺 Eu2 +、Sm3+和 Cu+的 Ca S荧光粉有望成为一种性能优于光转换农膜添加剂 Ca S∶ Eu2 +,Cu+。

CaS∶Eu^(2+),Sm^(3+)的制备与表征

采用湿法工艺在还原气氛下制备了CaS∶Eu2+,Sm3+光存储材料。研究了灼烧温度和灼烧时间对样品性能的影响。XRD图谱表明,样品在700℃—1200℃均形成CaS晶格。光谱分析表明,在紫外光(295nm)激发后,用980nm半导体激光照射样品,具有光激励发光现象,发射光谱峰值波长为649nm。

电子俘获材料CaS:Eu,Sm可见光激发优势机理的研究

实验测定了电子俘获材料CaS :Eu,Sm的荧光激发谱、辐射谱以及红外上转换光激发光谱 ,发现可见光对红外上转换辐射光的激发灵敏度高达 5 0 % ,而紫外光只有 1 8% ,具有可见光激发的优势 .根据电子俘获材料的能级模型、电子俘获发光机理以及稀土离子在立方晶场中的能级结构 ,并结合光谱测试所提供的信息 ,分析了电子俘获材料CaS :Eu,Sm在光激发过程中的能量传递途径 ,阐明了电子俘获材料CaS :Eu,Sm可见光激发优势的机理 .

CaS:Eu^(2+),Sm^(3+)中Eu^(2+)的辐射寿命

采用电子俘获材料（ＥＴＭ－ＥｌｅｃｔｒｏｎＴｒａｐｐｉｎｇＭａｔｅｒｉａｌ）是由带隙宽为４～５ｅＶ的碱土金属硫化物（ＡＥＳ）和掺入其中的两种稀土离子组成的一类新型光学功能材料，即ＡＥＳ：Ｄ１，Ｄ２，其中作为主激活剂的稀土离子Ｄ１起发光中心作用，而作为...

Na2CaSiO4：Sm^3＋，Eu^3＋荧光粉的发光特性和能量传递

利用高温固相法合成Na_2CaSiO_4:Sm^(3+),Eu^(3+)系列荧光粉末,研究了Sm^(3+)和Eu^(3+)掺杂对Na_2CaSiO_4晶体结构的影响、材料发光特性以及存在的能量传递现象.X射线衍射结果表明Sm^(3+)和Eu^(3+)单掺及共掺样品均为单相的Na_2CaSiO_4结构,晶体结构没有改变.Na_2CaSiO_4:Sm^(3+)荧光样品在404 nm激发波长下呈现峰峰值为602 nm的橙红色荧光,来源于~4G_(5/2)→~6H_(7/2)跃迁.Na_2CaSiO_4:Eu^(3+)荧光样品在395 nm激发波长下发射出峰峰值为613 nm的红色荧光.对光谱和荧光寿命的测试和分析结果表明Sm^(3+)与Eu^(3+)之间存在能量传递,通过理论计算得到Sm^(3+)和Eu^(3+)之间的能量传递临界距离为1.36 nm,相互作用形式为电四极-电四极相互作用.随着Eu^(3+)掺杂浓度的增加,能量传递效率也逐渐提高至20.6%.