Color center and radiation center in Lu2SiO5:Ce crystal

Radiation damage of Lu2SiO5：Ce （LSO：Ce） crystals was investigated through intense UV light. An absorption band at 435 nm was observed in the transmission spectrum of the damaged LSO：Ce crystal, similar to that of absorption band caused by gamma ray irradiation. GDMS analysis for LSO：Ce crystals revealed the existence of impurities, such as Yb in the crystals. The impurities might be responsible for the optical absorption of the color center and the radiation center.     

Sm、Ce单掺以及Sm、Ce共掺CaO-B_2O_3-SiO_2玻璃中稀土离子的荧光性质研究

分别研究了单掺Sm2O3和CeO2以及共掺Sm2O3、CeO2的CaO-SiO2-B2O3玻璃的发光性质。单掺Sm2O3的CaO-SiO2-B2O3玻璃的光谱中出现典型的Sm3+的光谱性质;单掺CeO2的CaO-SiO2-B2O3玻璃的光谱中出现Ce3+的光谱性质,在332nm激发下,Ce3+发射蓝紫光,其发射光谱为一宽谱带,从350nm延展到500nm附近,主发射峰位于393nm,Stokes位移为61nm,只形成一个发光中心。当CaO-SiO2-B2O3玻璃共掺Sm2O3和CeO2时,出现Ce4+的发射峰,同时Sm3+的发光强度下降,说明作为一种新的激活剂Ce引入基质后,提高了Sm3+的局部对称性,Sm3+的f→f跃迁减弱,从而导致Sm3+的发光强度下降。在共掺Sm2O3、CeO2的CaO-SiO2-B2O3玻璃中Ce4+和Sm3+通过桥氧键相连。     

Lanthanum and boron co-doped BiVO4 with enhanced visible light photocatalytic activity for degradation of methyl orange

BiVO4 photocatalysts co-doped with La and B were prepared by sol-gel method using citric acid as chelate.The samples were characterized by X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),scanning electron microscopy(SEM),Brumauer-Emmett-Teller(BET),UV-Vis diffuse reflectance spectra(DRS) and the photocatalytic activity was investigated by photocatalytic degradation of methyl orange(MO).The results showed that boron and lanthanum ions incorporated into the lattice of BiVO4,and co-doping led to more surface oxygen vacancies,high specific surface areas,small crystallite size,narrow band gap and intense light absorbance in visible region.And the doped La(III) ions could help the separation of photogenerated electrons.Compared with BiVO4 and B-BiVO4,the photocatalytic activity of La-B co-doped BiVO4 was remarkably improved due to the synergistic effects of the co-doped ions.The degradation rate of MO in 60 min was 98.4% when La doping content was 0.05 mol.%,which was much higher than that of pure BiVO4(20%) and B-BiVO4(37%).     

Optical Spectroscopy of Er^3＋ and Er^3＋/Yb^3＋ Co-doped Bi2O3-GeO2-B2O3-ZnO Glasses

The （60 - x）Bi2O3 - xGeO2-30B2O3-10ZnO （x = 5, 10, 20, 30 molar percent） glasses doped with Er^3＋ and Er^3＋/Yb^3＋ were fabricated using the melting method. The thermal stability of the glasses was studied with their DTA curves. The results show that the difference between the glass transition temperature and the crystallization onset temperature increases with the increase of GeO2 content, indicating that the thermal stability of the glass has become better. The absorption spectra were recorded and the stimulated emission cross sections were calculated using the McCumber theory. The Ω2, O4, and Ω6 parameters,the transition probability, the radiative lifetime, and the fluorescence branch ratio of Er^3＋ for optical transition were calculated from their absorption spectra in terms of reduced matrix U^（t）（λ = 2, 4, 6） character for optical transitions. The infrared emission of Er^3＋ was measured upon excitation with 970 nm light and the full width at half-maximum （FWHM） was estimated from the emission spectra. The pumping efficiency and the intensity of the emission at the 1.54 μm band of Er^3＋ were enhanced considerably by co-doping Yb^3＋ .     

Nanostructured Yb：GGG polycrystalline powders via gel combustion method

Gadolinium gallium garnet (GGG) nanopowders doped with ytterbium ions (Yb:GGG) were synthesized with citric acid as a fuel via gel combustion method. The optimized conditions for preparing Yb3+:Gd3Ga5O12 nanopowders were discussed. The heat behavior, struc-ture and morphology of powders were analyzed with thermal analysis (TG-DTA), X-ray diffraction (XRD), infrared spectra (IR) and trans-mission electron microscope (TEM). TG-DTA analysis revealed that the weight loss of the precursor occured below 800 ℃ and its crystalli-zation temperature was 830.6 ℃. XRD and IR analysis showed that the precursor converted directly into pure GGG at a relatively lower tem-perature (900 ℃) without any other intermediate phase. The lattice constant was 1.2377 calculated by extrapolation method. TEM results in-dicated that the spherical powders showed good dispersity and had a relatively narrow size distribution with average particle size of approxi-mately 40-50 nm, which was favorable for good sinterability of Yb:GCG laser ceramic.     

Rate equation model analysis on the infrared and upconversion emission of Er/Yb co-doped borate-silicate glass

Er/Yb co-doped borate-silicate glasses with various Yb concentrations were fabricated by high-temperature solid-reaction method.The photoluminescence spectra around 1.55 μm and the visible upconversion spectra were measured.The radiative lifetime of Er-4I13/2,com-pared with the measured one,was obtained by Judd-Ofelt theory based on the absorption spectra.A rate equation model for Er/Yb co-doped system has been established based on the data obtained from the measurements,including the absorption and emissio...     

Growth, Optical Properties and Defects of High-Doped Yb∶YAl3(BO3)4 Crystal

High-doped Yb∶YAl3 (BO3)4 (Yb∶YAB) crystals were grown by the flux method using K2Mo3O10 as the flux. The efficient segregation coefficient was measured by using EPMA. The absorption and fluorescence spectra was measured at room temperature and compared the spectral parameters with Yb∶YAB of other Yb3 concentrations. With the increase of the Yb3 concentration, the main absorption and fluorescence peaks almost do not change, but the absorption coefficient and FWHM increase. The defects were investigated by using chemical etching method. The main defects are cracks, inclusions, dislocations and twins, which of them are more than low-doped crystals.     

Effect of Samarium on Mn Activated Zinc Borosilicate Storage Glasses

Electron-trapping materials (ETMs) are such kindof materials that can store the energy of incident lightrangingfromenergetic radiation to visible light that canbe releasedfromthetraps bythethermal or optical stim-ulationinthe formof thermoluminescence (TL) or opti-cally/photo stimulated luminescence (OSL/PSL) .ETMsare widely usedinthe filed of detectingradiation,infor-mation storage ,radiology,space exploring,indicator inthe dark and craft ,etc[1 ~6].In ETMs ,in additiontothe activation …     

Photocatalytic Activity of Nanosized TiO2 Enhanced by co-doping with Fe3+ and Nd3+ Ions

In this study, nanosized TiO2 co-doped with Fe3 and Nd3 ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3 ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400~500 nm, 565~600 nm and 730~765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3 content was 0.15% and Fe3 content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3 ion inhibited the recombination of photogenerated electron and hole, and Nd3 ion brought more surface carboxyl to promote the degradation reaction.     

Optical and magnetic properties of GaN epilayers implanted with ytterbium

We have studied the optical and magnetic properties of ytterbium implanted GaN epilayer grown on(0001)sapphire by metalorganic chemical vapor by deposition(MOCVD).Samples were implanted at room temperature with Yb ions at dose 4x1015 cm-2 and energy of 150 keV.The implanted samples were annealed at 1000 ℃ in N2 at atmospheric pressure to recover implantation damages.The photoluminescence (PL),PL excitation(PLE),and PL kinetics have been studied with continuous and pulse photo-excitations in 360-1100 nm spectral range at different temperatures.The characteristic Yb3+ion emission spectra were observed in the spectral range between 970-1050 nm.Theoretical fittings of the experimental PL temperature and PL kinetics data suggest that Yb3+ions are involved in at least two major luminescence centers.The PLE spectra indicate that excitation of the Yb3+ion occurs via electron-hole pair generation and complex processes.Magnetization versus magnetic field curves shows an enhancement of magnetic order for Yb-implanted samples in 5 K to 300 K temperature range.The Yb-implanted GaN sample showing weak ferromagnetic behavior was compared with the ferromagnetic in situ doped GaYbN material.     

卤化钾对硫掺杂ZnO荧光粉性能的影响

将ZnS与硫、卤化钾等化合物共混,在高温箱式炉中煅烧,得到了具有硫掺杂ZnO荧光发射特征的绿色荧光粉。XRD衍射表明合成荧光粉的主晶相为ZnO。研究了混合物配方、助熔剂种类及添加量和煅烧温度对发光强度和产物中硫含量的影响,证明助熔剂KX的加入明显提高了发光强度,认为X-的共掺杂能有效地强化发光,Cl-和Br-效果明显。Cl-的效果最佳,K+的掺杂有利于V*O的形成。灼烧温度在600～700℃时荧光强度最高,而此时产物中的硫含量较为稳定。     

Determination of enantiomeric purity of nicotine in pharmaceutical preparations by 13C-NMR in the presence of a chiral lanthanide shift reagent

A method for the determination of enantiomeric composition of nicotine samples, based on 13C-NMR spectroscopy in the presence of the chiral lanthanide shift reagent, tris[3-(trifluoromethylhydroxymethylene)-(+)-camphorato]ytte rbium [Yb(tfc)3], was developed. Observation at 100.6 MHz of the C2' resonance of nicotine in the presence of 0.15-0.20 mol of the ytterbium complex, either in ordinary 13C[1H]-NMR spectra or in carbon spectra enhanced by polarization transfer (refocused INEPT), allowed precise determination of the ratios of (S)- to (R)-nicotine. At least 1% of (R)-nicotine could be determined in samples of (S)-nicotine, milligram amounts being required for the analysis. Use of the 13C-NMR spectra is more advantageous than use of 1H-NMR spectra. Thus, Yb(tfc)3 induced separation of the proton resonances of the enantiomers of nicotine, and the shifted resonances of nicotine enantiomers could be assigned by use of 1H-13C heteronuclear chemical shift correlation, but the proton resonances were broad, their chemical shifts were sensitive to small variations of the ratio between Yb(tfc)3 and nicotine, and signals of the enantiomer present in small amounts were easily obscured by impurities. Therefore, although 13C-NMR is more time consuming, this method is more suitable for routine analysis. The method was applied for the determination of enantiomeric purity of (S)-nicotine in pharmaceutical formulations, including chewing gums, skin absorption patches, inhalators, and nasal sprays.     

Tm3+-doped tellurite glass with Yb3+ energy sensitized for broadband amplifier at 1400-1700 nm bands

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were per-fectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion proc-esses between Tm3+ and Yb3+ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm3+ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and inten-sity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping proc-ess. The potential advantages of Tm3+/Yb3+ co-doped tellurite glass as amplifier material were concluded.     

Synthesis,Luminescence and Magnetic Properties of YGa_(3-x)Cr_xB_4O_(12)

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Growth and Characteristics of Tunable Laser Crystals β-Ga2O3∶Cr

β-Ga2O3∶Cr single crystals have potential applications for tunable laser. In β-Ga2O3 crystal structure Cr3 ions are in octahedron other than tetrahedron. So the Cr3 ions are influenced by low field of β-Ga2O3 that results the 4T2 to 4A2 transition and show broad emission around 690 nm. β-Ga2O3 single crystals doped with different Cr3 concentrations were grown by floating zone technique. Their absorption spectra and fluorescence spectra were measured at room temperature. The values of field splitting parameter Dq and Racah parameter B were calculated based on the absorption spectra.     

火焰原子吸收光谱法测定铅锌矿尾矿矿渣中镉和铬

采用响应面法考察了火焰原子吸收光谱仪的几个工作参数间的相互作用和相互影响,对测定铅锌矿尾矿矿渣中Cd和Cr的工作条件进行了优化。采用Box-Behnken Design试验设计研究了灯电流、光谱通带、乙炔流量和燃烧器高度四个因素对铅锌矿尾矿矿渣中Cd和Cr吸光度的影响程度。用响应面法得出四个考察因素的最优工作参数如下：Cd,灯电流为1.02 mA,光谱通带为0.26 nm,乙炔流量为1 323.56 mL/min,燃烧器高度为8.13 mm;Cr,灯电流为1.65 mA,光谱通带为0.36 nm,乙炔流量为2 853.42 mL/min,燃烧器高度为6.62 mm。在火焰原子吸收光谱仪最优检测工作参数下,对铅锌矿尾矿矿渣样品中的Cd和Cr进行测定,Cd和Cr平均含量分别为6.9 μg/g和42.5 μg/g,加标回收率在96%～105%之间,RSD在0.39%～1.2%范围;对铅锌矿和铬铁矿标准物质进行测定,测定值与认定值一致,符合检测方法要求。     

Preparation of Long-Lasting Phosphorescence （LLP）Glass-Ceramic Materials

Three kinds of glass-ceramics, i.e., Mn^2 doped zinc borosilicate, Eu^2 , Dy^3 co-doped strontium aluminoborate and Eu^2 , Nd^3 co-doped calcium aluminoborate were prepared, whose phosphorescence emission band peaks at 525, 516 and 464 nm, respectively. In preparation of these glass-ceramics the base glasses were gained by heating the mixed starting materials at high temperature to get the transparent glasses; then those glasses were heat-treated and turned to opaque glass-ceramics. X-ray diffraction (XRD) shows that the crystallites are ZnSiO4, SrAl2O4 and α-CaAl2B2O7, respectively. It is a useful way to get new LLP materials by the method reported in this work that may be considered as “from glass to crystal”.     

The kinetics of reaction of zinc metal with selenium vapour

Abstract

The kinetics of reaction of coupons of zinc with selenium vapour have been investigated by the thermogravimetric technique at temperatures between 350 and 415°C and at selenium pressures between 0.05 and 0.8 Torr. Cubic zinc selenide (ZnSe) was the only reaction product observed under all experimental conditions. The selenization kinetics were essentially parabolic, although at higher temperatures initially linear reactions were sometimes observed. The apparent activation energy for the selenization of zinc metal was in the range 24 to 32 kcal/mole. The selenization rate varied inversely as the square root of the selenium pressure. It is postulated that the rate-controlling step of the selenization reaction is the outward diffusion of neutral zinc interstitials through a constantly thickening zinc selenide reaction scale.

Résumé

On a étudié la cinétique de la réaction entre des plaques de zinc et la vapeur de sélénium par la méthode de thermogravimétrie dans une gamme de température et de pression de sélénium comprise entre 350 et 415°C et 0.05 et 0.8 Torr. respectivement. Le séléniure de zinc de malie cubique (ZnSe) était Ie seul produit de la réaction obtenu dans toutes les conditions expérimentales. La cinétique de séléniuration était essentiellement de forme parabolique, bien qu'on ait observé parfois aux températures plus élevées des réactions initialement linéaires. L' énergie apparente d'activation pour la séléniuration du zinc métallique était comprise dans une gamme variant entre 24 et 32 kcal/mol. La vitesse de la séléniuration était inversement proportionnelle à la racine carrée de la pression du sélénium. On suggére que l' étape déterminante de la vitesse de reaction soit la diffusion vers l'extérieuI des interstitiels de zinc électriquement neuters à travers une couche de séléniure de zinc qui s'épaissit constamment.     

Bi3+ assisted luminescence in SrMoO4:Sm3+ red phosphors

In this paper, we report synthesis of pure SrMoO₄, Sm³⁺ (1 at%–5 at%) doped SrMoO₄ and Bi³⁺ (1 at%–3 at%) co-doped in 4 at% Sm³⁺ doped SrMoO₄ (SrMoO₄:4Sm³⁺) phosphors by solution combustion method. The X-ray diffraction (XRD) analysis reveals the tetragonal phase of all samples, also Bi³⁺ co-doping supports crystallite size growth and reduces lattice strain. Absorption analysis of Sm³⁺ doped SrMoO₄ ascertains a decrease in band gap and Bi³⁺ co-doping confirms the emergence of an absorbance peak at around 308 nm attributed to Bi³⁺ energy levels. Photoluminescence (PL) analysis ascertains an increase in emission peaks for Sm³⁺ doped SrMoO₄ up to 4% concentration, which are attributed to an electron transition from ⁴G_5/2 to ⁶H_J (J = 5/2, 7/2, 9/2, and 11/2) energy levels of Sm³⁺ ions. We have explained the effects of Bi³⁺ co-doping on the luminescence of Sm³⁺ doped SrMoO₄. The reduced microstrain and increased crystallinity of the phosphors as a result of Bi³⁺ co-doping and their correlation with the luminescence of Sm³⁺ ions are discussed.     

电感耦合等离子体原子发射光谱法测定La、Ce、Yb基体中痕量稀土杂质的多元光谱拟合校正限度

考察了La、Ce和Yb等基体元素对稀土杂质元素测定的光谱干扰。在杂质元素谱线窗口内,La、Ce和Yb所产生的干扰线总数量比文献报导的少,且当基体元素浓度增大时,在杂质元素谱线窗口内出现一些未曾报道过的谱线。经多元光谱拟合（MSF）法校正,基体元素的光谱干扰得到有效消除,杂质元素的检出限明显降低,但仍达不到没有La、Ce和Yb时的水平。当测定质量浓度为0100 μg/mL杂质元素时允许质量浓度为1 000～2 000 μg/mL基体元素存在,当被测的杂质浓度进一步降低时允许基体元素的最高浓度也随之降低。建立MSF模型时,应使建模溶液中杂质元素浓度是这些元素检出限的100倍,基体元素浓度接近实际样品中基体的存在量,MSF建模数据与样品测定数据还须在同一实验条件下完成。