南丰蜜桔中稀土元素与土壤的关系

南丰蜜桔是原产江西南丰地区的重要水果品种,但是对于该品种的稀土元素含量的研究还没有见到报道。借助ICP-MS/ICP-AES方法对南丰产的南丰蜜桔及其种植土壤中的稀土元素进行了全面分析,目的是研究南丰蜜桔中稀土元素的含量以及与土壤中稀土元素含量的关系。结果显示：南丰蜜桔仅仅能够测到10种稀土元素的存在,它们是La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho和Yb,它们的含量在0.63～0.01 ng·g-1之间。种植南丰蜜桔的土壤中上述十种稀土元素含量在29.36～0.07 μg·g-1之间,含量最多的三种元素是Ce, La和Nd,含量分别是29.36, 16.92和8.62 μg·g-1。南丰蜜桔中稀土元素含量与土壤中的稀土含量基本上成正相关：土壤中稀土元素含量越多,其在果实中的含量也越高。所以如果要通过稀土元素增加产量、提高品质,土施稀土元素效果也会非常明显。     

稀土元素对硫氧化镧铽发光性能的影响

本文研究了Ce、Pr、Nd、Sm、Eu、Dy Ho、Er、Tm、Yb十种稀土元素对La2O2S:Tb发光性能的影响.这些稀土元素特别是Ce+3、Pr+3、Eu+3和Yb+3,对La2O2S:Tb的发光亮度起猝灭作用.除了Eu+3和Pr+3以外,它们含量≤0.1%时对La2O2S:Tb的发光光谱和发光的颜色没有明显的影响.分别用阴极射线、X射线和254nm紫外线激发时,La2O2S:Tb发光性能变化的规律基本上相同.     

野生中药田基黄中稀土元素含量分析

中药材中的有效成分研究得到了人们的普遍关注。应用ICP-MS分析了中药材田基黄中稀土元素的含量。结果表明田基黄稀土元素La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Yb,Tm,Lu和Y的浓度在6～14 522 ng·g-1的范围之间。在上述稀土元素中,田基黄稀土元素含量超过2 000 ng·g-1的有La(4871.64), Ce(14 522.03)和Nd(2 064.94)。与粮食作物比,田基黄中稀土元素的含量是稻米、小麦、玉米和大麦等粮食的上千倍,这可能是田基黄具有肝病治疗效果的重要因素。稀土元素在田基黄中的分配除了自身的吸收分配特性以外,还要受土壤等环境因素的影响,分配机理还需要进一步研究。     

ICP-AES法分析猪肝、猪肉中痕量稀土元素

采用P507萃淋树脂预富集分离技术，用ICP－AES法测定猪肝，猪肉中痕量稀土元素La,Ce,Pr,Nd,Sm,Y的含量，本法排除了基体中Ca,P,Fe的干扰，检出限为0．33－0．74ng/g(鲜样），回收率为84．8％－109．1％，精密度为4．9－11％。     

用ICP-AES测定三烷基氧膦-煤油中的Ru,Rh和Pd元素

使用Ru,Rh和Pd水溶液标准,选取乙醇作为稀释液,用ICP-AES测定三烷基氧膦(trialkyl phos-phine oxide,TRPO)-煤油体系中Ru,Rh和Pd。研究了溶液配制中30%TRPO-煤油(v/v)比例、水溶液比例和硝酸浓度对测定Ru,Rh和Pd的影响。选取30%TRPO-煤油在溶液中的体积比为10%,水溶液体积比为5%和溶液的硝酸浓度为0.20mol.L-1时,配制的溶液呈均一溶液,处于稳定状态。根据上述条件,建立了ICP-AES测定有机相30%TRPO-煤油中的Ru,Rh和Pd的分析方法。Ru,Rh和Pd的检测限分别为0.057,0.025和0.118mg.L-1。方法的相对标准偏差小于3%。此方法不仅用于30%TRPO-煤油中Ru,Rh和Pd的测定,也可用于其他有机相体系中Ru,Rh和Pd的测定。     

ICP-AES法测定低纯钕(稀土)铁硼永磁合金中的镧、铈、镨、钕、铁、硼

本文研究了用ICP-AES对低纯钕(稀土)铁硼新型永磁材料主、次成分:La、Ce、Pr、Nd、Fe、B的测定方法。不用预先分离。选择了合适的分析线和内标线,研究了共存元素的相互干扰及其校正方法,测定了Sm、Eu、Gd、Tb、Ho、Er、Lu、Y、Sc对被测元素的光谱干扰。     

高能偏振能量色散X射线荧光光谱仪测定地质样品中稀土元素

由于稀土元素本身的特点及以往X射线荧光光谱仪的局限性,用XRF方法快速测定地质样品中稀土元素一直是个难点。探讨了有效解决该问题的途径。采用粉末压片制样,应用Epsilon 5型高能偏振X射线荧光光谱仪(HE-P-EDXRF)建立了土壤、岩石和水系沉积物中稀土元素La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu和Y的EDXRF分析方法,对分析线,二次靶,基体校正方法及校准曲线的回归等进行了探讨。结果表明,La,Ce,Pr,Nd和Y的校准曲线的相关系数r>0.99,其余元素的相关系数也均在0.969以上;Pr的检出限为4.09,其余元素的检出限在0.03~2.13之间;对岩石标准物质GBW07105连续测定10次,RSD在0.81%~8.35%;检验样本的EDXRF测定值与电感耦合等离子体质谱法(ICP-MS)测定值平均相对偏差在4.4%~15.4%之间,除Gd外其余元素的平均相对偏差均在15%以内,其中较好的为Y(4.4%),La(8.3%),Ce(8.3%),Nd(8.6%)。综上可知,本方法操作简单,能够实现大批量的岩石、土壤、水系沉积物中稀土元素的快速准确测定。     

应用ICP-MS测定野生肉苁蓉中的稀土元素

中药材中的微量元素含量引起人们的普遍关注。应用ICP-MS分析了新疆产野生肉苁蓉中稀土元素的含量, La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Yb,Lu,的浓度范围在1～260 ng·g-1之间,稀土元素之间含量差异比较大。在各种稀土元素中,新疆野生肉苁蓉含量超过100 ng·g-1的有三种,分别是La(144.89 ng·g-1,DW),Ce(259.75 ng·g-1,DW)和Nd(133.25 ng·g-1,DW);含量最少的三种是Eu(6.10 ng·g-1,DW),Ho(3.42 ng·g-1,DW)和Lu(1.15 ng·g-1,DW)。稀土元素在野生肉苁蓉中的分配除了自身的吸收分配特性以外,还要受土壤等环境因素的影响,分配机理需要进一步研究。     

P507萃取树脂色谱分离—ICP／AES法测定高纯La2O3中Ce,Pr,Nd和Sm

本文采用我院合成的P_(507)萃取树脂,在50℃恒温下,用0.055mol/L HCI-1 mol/L NH_4Cl淋洗体系,满意地解决了La与Ce、Pr、Nd和Sm的定量分离,用ICP-AES法测定了经分离富集的痕量稀土杂质元素。     

普里兹湾沉积物中稀土元素的测定及其配分模式分析

以HNO₃-H₂O₂-HF为消解体系,采用微波法对沉积物样品进行消解处理,利用电感耦合等离子质谱法测定了普里兹湾(Prydz Bay)沉积物中Sc, Y, La, Ce, Pr, Nd, Sm等16种稀土元素(rare earth elements,REEs)的含量,并进行了配分模式分析。从普里兹湾沉积物样品的分析数据和球粒陨石标准化配分模式可以看出：稀土总量(∑REEs)变化范围为117.35～348.63 μg·g-1,其中Ce含量较高,在总量中占了很大比例;各站位平均值为196.75 μg·g-1,总量最大值是最小值的2.97倍;各个站位稀土元素分布模式基本一致,轻重稀土元素之间有明显的分馏。该方法表明：各元素的线性关系良好,相关系数≥0.999 7;相对标准偏差(RSD)＜5.0%,相对误差＜10.0%;除了Sc的检出限稍高,其他元素的检出限均能达到ng·L-1。因此,该方法适用于沉积物中稀土元素的定量分析。     

Ba（n，x）~（134）Cs，~（134）Ba（n，2n）~（133）Ba，

用中子活化法相对于５４Ｆｅ（ｎ，Ｐ）５４Ｍｎ反应，在１３．５０—１４．８０ＭｅＶ中子能区测量了Ｂａ（ｎ，ｘ）１３４Ｃｓ，１３４Ｂａ（ｎ，２ｎ）１３３Ｂａ，１４０Ｃｅ（ｎ，２ｎ）１３９Ｃｅ，１４２Ｃｅ（ｎ，２ｎ）１４１Ｃｅ和２３Ｎａ（ｎ，２ｎ）２２Ｎａ的反应截面．并将所测的结果和其他作者的结果进行了比较，中子能量是用９０Ｚｒ（ｎ，２ｎ）８９ｍ＋ｇＺｒ反应和９３Ｎｂ（ｎ，２ｎ）９２ｍＮｂ反应截面比法测定的。     

高温高压密闭消解-ICP-MS测定垃圾焚烧残渣中重金属及稀土元素

采用高温高压密闭消解-电感耦合等离子体质谱(ICP-MS)测定了垃圾焚烧残渣中的Cr, Co, Ni, Cu, Zn, Zr, Cd, Ba和Pb共9种重金属元素及Sc, Y, La, Ce, Pr, Nd等16项稀土元素的含量。实验确定密闭消解罐中,以HF-HNO₃-HCl(1∶2∶1)三元混酸体系于185℃烘箱中12 h可完全消解垃圾焚烧残渣样品,同时对ICP-MS测试工作条件(包括雾室温度、雾化气流速、辅助气流速、冷却气体流速、采样深度等)进行了优化。采用Rh为内标元素进行信号漂移校正和基体补偿,得到25种分析元素标准曲线的线性相关系数(r)大于0.999 9,方法检出限在0.001～1.01 ng·g^-1,样品分析测试的相对标准偏差(RSD)小于4.5%(n=3)。测试结果表明本次分析的垃圾焚烧残渣样品中Cr, Cu, Zn, Zr, Cd, Ba和Pb元素含量偏高,其中Pb含量高达(1 459±8) mg·kg^-1,稀土元素平均总量为(199±2) mg·kg^-1,整体呈下降趋势,并显示相...     

A density-functional study of aluminium,iron, zirconium and cerium microclusters

The geometries and electronic structural properties of AB and ABC (A, B, C = Al, Fe, Zr, Ce) microclusters have been systematically investigated by using a hybrid density-functional method (B3LYP) approach. The spectroscopic constants of ground-state AB and ABC (A, B, C = Al, Fe, Zr, Ce) are obtained, and are found to be in agreement with other available experimental and theoretical results. The calculated gaps between highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO) are clearly changed when X is doped into the AB dimers (X = Al, Fe, Zr, Ce). The calculated results indicate that a triangular form with D_3h, C_2v or C_s symmetry is the most stable for the corresponding ABC trimers, and, in addition, the possible isomers (linear structure) with D_∞h or C_∞v symmetry of three-atom clusters were found to be of higher energies. We conclude that AlFe and Al₂Fe have the highest chemical stability of all the AB dimers and ABC trimers, respectively, due to the high HOMO-LUMO gap. We also find that the binding energy of Ce₃ is the largest in magnitude among all ABC (A, B, C = Al, Fe, Zr, Ce) trimers, as is the case with Ce₂ among all AB (A, B, C = Al, Fe, Zr, Ce) dimers. The most stable geometry, charge transfer and possible dissociation channels are also discussed.     

CexZr1-xO2固溶体储氧性能与结构的关系

采用加热回流技术制备了系列CexZr1-xO2(0.25≤x≤1)固溶体,通过N2物理吸附、XRD、Raman光谱、UV-Vis漫反射光谱表征了不同铈锆组成的铈锆复合氧化物结构对储氧性能的影响.结果表明,在铈锆组成比不同的样品之间,结构性质相差较大,随着载体中ZrO2 mol%的增加,载体结构从相对的有序经无序再回到相对的有序.Ce0.4Zr0.6O2样品具有最高的储氧性能,而Ce0.25Zr0.75O2样品具有较高的热稳定性.     

The effect of the chemical environment on theKβ/Kα X-ray intensity ratio

Summary Chemical effects on theKβ/Kα X-ray intensity ratios were investigated for different constitutions of Ti, V, Fe, Se, Br, Zr and Ce by a Ge(Li) X-ray detector. The vacancies were produced by heavily filtered²⁴¹Am gamma-rays. It is found that theKβ/Kα X-ray intensity ratios measured with compounds deviated up to 12% from the corresponding values of the pure elements (Ti, V, Fe) are larger than for the others (Se, Br, Zr and Ce).     

火焰原子吸收光谱法测定冬枣中的铁和锌

采用干法消解、湿法消解和非完全消解法3种方法多种体系处理冬枣样品,应用火焰原子吸收光谱法测定冬枣中铁和锌的含量.在选定的条件下,铁、锌的样品加标回收率在100.0％-101.3％之间,精密度（样品相对标准偏差RSD）均小于1.1％（n=11）.实验结果表明,湿法消解和非完全消解法的测定结果相差不大.其中非完全消解法简便、快捷,测定结果准确,更适用于冬枣中铁和锌的测定.     

Temperature-dependent structures of proton-conducting Ba(Zr(0.8-x)Ce(x)Y(0.2))O(2.9) ceramics by Raman scattering and x-ray diffraction

In situ temperature-dependent micro-Raman scattering and x-ray diffraction have been performed to study atomic vibration, lattice parameter and structural transition of proton-conducting Ba(Zr(0.8-x)Ce(x)Y(0.2))O(2.9) (BZCY) ceramics (x = 0.0-0.8) synthesized by the glycine-nitrate combustion process. The Raman vibrations have been identified and their frequencies increase with decreasing x as the heavier Ce(4+) ions are replaced by Zr(4+) ions. The main Raman vibrations of Ba(Ce(0.8)Y (0.2))O(2.9) appear near 305, 332, 352, 440 and 635 cm(-1). The X-O ( X=Ce, Zr, Y) stretching modes are sensitive to the variation of Ce/Zr ratio. A rhombohedral-cubic structural transition was observed for x = 0.5-0.8, in which the transition shifts toward higher temperature as cerium increases, except for Ba(Ce(0.8)Y(0.2))O(2.9). A minor monoclinic phase possibly coexists in the rhombohedral matrix for x = 0.5-0.8. The lower-cerium BZCYs (x = 0.0-0.4) ceramics do not exhibit any transition in the region of 20-900?°C, indicating a cubic phase at and above room temperature.     

FAAS法测定不同消化方法栽培桔梗中12种金属元素含量的研究

分别采用湿法、干法和先灰化再用硝酸-高氯酸(φ,4∶1)常压微沸条件下消解桔梗样品,用火焰原子吸收法测定栽培桔梗中的金属元素K,Mg,Ca,Cu,Zn,Mn,Fe,Co,Ni,Cd,Cr和Pb含量。研究了不同消化方法对测定栽培桔梗中的金属元素含量的影响以及测定不同元素的仪器最佳工作条件,并做了方法的准确度和精密度考察。结果表明,不同消化方法对测定Mg和Ca有显著影响,不同消化方法测定的栽培桔梗中K, Mg, Ca, Mn, Fe, Cu, Zn的平均含量分别为13 226.32, 922.57, 1 710.72, 9.23, 336.66, 8.75, 19.62 μg·g-1;Ni,Co,Cd,Cr和Pb未检出。方法的加标回收率为95.45%～105.50%, 相对标准偏差(n=9)为0.34%～5.78%。选择先灰化再用混酸消化测定栽培中药材金属元素含量,方法简单易行,结果令人满意。     

Luminescence and damage thresholds of cerium-doped LaF3 for ns-pulsed laser excitation at 248 nm

3 following excitation with 248 nm/14 ns laser pulses at room temperature for the two Ce concentrations 0.03 and [%mol]1. The relative intensities of the 5d-4f bands emitted from Ce³⁺ at regular and at perturbed lattice sites were found to vary linearly with time for the higher concentration and quadratically for the lower one. This can be explained by radiative energy transfer between the two sites and generation of new perturbed sites at a rate that only shows up for the low Ce concentration. Lifetimes of the respective emission bands were determined to be about 18 ns and 41 ns. Despite resonant absorption of the 5 eV photons, surprisingly high ablation thresholds – 16 J/cm² for 0.03% Ce, and 10 J/cm² for 1% Ce – were observed by the probe-beam deflection technique. The reason is the strong energy loss due to intense fluorescence and deposition of the nonradiative energy fraction in the bulk rather than at the surface. The depth of energy deposition was revealed by scanning electron microscopy in the form of distinctly different ablation morphologies for the two Ce concentrations. Received: 30 July 1998     

电感耦合等离子体质谱测定饲料中稀土元素镧和铈的研究

研究建立了应用电感耦合等离子体质谱(ICP-MS)同时测定饲料中稀土元素镧(La)和铈(Ce)的方法。优化了ICP-MS的操作条件,通过基体加入法和基体逐级稀释法研究了预混合饲料和配合饲料基体对La和Ce测定的影响,考察了硝酸浓度对La和Ce响应信号的抑制作用。在优化的条件下,以In(115)和Tb(159)为内标物,La和Ce检出限分别为26.2和6.47 ng·kg-1,线性相关系数为1.0000,动态线性范围达到3个数量级。将该方法用于预混合饲料和配合饲料样品中稀土元素La和Ce的测定,其回收率≥77.8%,相对标准偏差(RSD)≤8.5%,结果令人满意。