Simultaneous determination of light rare earths in monazite sand by densitometry on thin-layer chromatograms

The determination of individual light rare-earth metals in monazite sand is described, based on TLC with a mixture of di-isopropyl ether, diethyl ether, di(2-ethylhexyl)phosphate and nitric acid (8:8:0.4:0.07 v v ) as eluent. Linear densitometric calibration graphs are obtained for individual light rare-earths in the range 0.015-0.60 mug. The minimum detectable quantities of La. Ce, Pr, Nd and Sm are 9, 10, 20, 13 and 12 ng, respectively. The relative standard deviations for the determination of La, Ce, Pr, Nd and Sm in monazite sand were 1.8, 1.1, 5.9, 1.9 and 6.5%, respectively. Results were in good agreement with those obtained by spectrophotometry.     

Determination of Ce,Pr, Nd and Sm in High Purity La2O3 by Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

High purity lanthanum oxide was analysed to determine traces of Ce, Pr, Nd, and Sm by employing inductively coupled plasma atomic emission spectrometry (ICP-AES). Lanthanum oxide was dissolved in nitric acid and the solution was nebulized into the plasma generated by a RF generator (56 MHz; 1.5kW). Analytical lines of Ce, Pr, Nd, and Sm, which were free of interference from the spectral lines of both La and the other rare earths, were scanned on a Jobin-Yvon, Model JY-38 THR-1000 1m-Czerny-Turner monochromator. Standards containing the four analytes (Ce, Pr, Nd, and Sm) in the concentration range 0.01–0.2 μg/ml and La at 2 mg/ml were used for calibration. Detection limits ranged between 6 and 16 ng/ml for the four analytes in aqueous solution.     

Determination of rare earths in rare-earth concentrates by neutron activation analysis

Neutron activation analysis was applied to the determination of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Yb, Lu and Th in rare-earth concentrates resulting from minerals. High-resolution gamma-ray spectrometry with a Ge(Li) detector was used for the non-destructive determination, and a single comparator method using Co as flux monitor was applied.     

Matrix infrared spectroscopic and theoretical studies on the reactions of early lanthanoid atoms with nitrous oxide in excess argon

Reactions of laser-ablated early lanthanoid atoms (Ce, Pr, Nd, Sm, and Eu, except for radioactive Pm) with N 2O molecules in excess argon have been investigated using matrix-isolation infrared spectroscopy. Lanthanoid monoxide-dinitrogen complexes, OLn(N 2) (Ln = Ce, Pr, Nd, and Sm), are observed during sample deposition and identified on the basis of isotopic shifts, mixed isotopic splitting patterns, and CCl 4-doping experiments, whereas no new product is observed for Eu. The OLnNN (+) (Ln = Ce, Pr, Nd, and Sm) cations appear during sample deposition and increase visibly upon broadband irradiation (lambda > 250 nm) at the expense of the neutral OLn(N 2) complexes. Density functional theory calculations have been performed on the new products, which support identification of the OLn(N 2) and OLnNN (+) complexes from the matrix infrared spectra.     

Mg(OH)_2共沉淀和直接稀释联用ICP-MS法准确测定海水中的多种常量-微量元素

对海水中多种常量/微量元素分别用Mg(OH)_2共沉淀和直接稀释ICP-MS法进行方法比较研究,分别确定了这些元素适宜的准确分析方法,为海水中常量/微量元素的ICP-MS测定提供了实用的检测手段。结果表明,Mg(OH)_2共沉淀法能够实现对V,Cr,Mn,Co,Cd及稀土元素(La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu)等19种微量元素的分离富集和准确测定;10倍直接稀释法能够同时准确测定海水中B,Sr,Li,Rb,I,V,Cr,As,Cd,U,Mo,Cu,Mn 13种微量元素,但不适合Zn,Ni,Co和Pb,以及稀土元素等在海水中浓度过低元素的测定;两种方法对适宜测定的元素均操作简便快速,具有较高的准确度和精密度。这两种方法联用,就可用约50 mL的海水实现大洋和近海海水中Co,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu(这15个元素采用Mg(OH)_2共沉淀法)及B,Sr,Li,Rb,I,V,Cr,As,Cd,U,Mo,Cu,Mn(这13个元素采用10倍直接稀释法)等28种元素的准确测定。     

Quantitative analysis of trivalent uranium and lanthanides in a molten chloride by absorption spectrophotometry

As an analytical application for pyrochemical reprocessing using molten salts, quantitative analysis of uranium and lanthanides by UV/Vis/NIR absorption spectrophotometry was performed. Electronic absorption spectra of LiCl–KCl eutectic at 773 K including trivalent uranium and eight rare earth elements (Y, La, Ce, Pr, Nd, Sm, Eu, and Gd as fission product elements) were measured in the wavenumber region of 4,500–33,000 cm^?1. The composition of the solutes was simulated for a reductive extraction condition in a pyroreprocessing process for spent nuclear fuels, that is, about 2 wt% U and 0.1–2 wt% rare earth elements. Since U(III) possesses strong absorption bands due to f–d transitions, an optical quartz cell with short light path length of 1 mm was adopted in the analysis. The quantitative analysis of trivalent U, Nd, Pr, and Sm was possible with their f–f transition intensities in the NIR region. The analytical results agree with the prepared concentrations within 2σ experimental uncertainties.     

X-ray fluorescence analysis of rare earth elements in rocks using low dilution glass beads.

Major and trace elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe, Rb, Sr, Y, Zr, La, Ce, Pr, Nd, Sm, Gd, Dy, Th and U) in igneous rocks were assayed with fused lithium borate glass beads using X-ray fluorescence spectrometry. Low dilution glass beads, which had a 1:1 sample-to-flux ratio, were prepared for determination of rare earth elements. Complete vitrification of 1:1 mixture required heating twice at 1200 degrees C with agitation. Extra pure reagents containing determinants were used for calibrating standards instead of the rock standard. The calibration curves of the 23 elements showed good linearity. Furthermore, the lower limits of detection corresponding to three times the standard deviation for blank measurements were 26 mass ppm for Na2O, 6.7 for MgO, 4.5 for Al2O3, 4.5 for SiO2, 18 for P2O5, 1.1 for K2O, 4.0 for CaO, 3.9 for TiO2, 1.6 for MnO, 0.8 for Fe2O3, 0.5 for Rb, 0.2 for Sr, 0.4 for Y, 0.5 for Zr, 3.3 for La, 6.5 for Ce, 2.7 for Pr, 2.1 for Nd, 1.7 for Sm, 0.7 for Gd, 2.7 for Dy, 0.5 for Th, and 0.6 for U. Using the present method, we determined the contents of these 23 elements in four rhyolitic and granitic rocks from Japan.     

Rare-earth metal(III) oxide selenides M4O4Se[Se2] (M=La, Ce, Pr, Nd, Sm) with discrete diselenide units: crystal structures, magnetic frustration, and other properties

The rare-earth metal(III) oxide selenides of the formula La4O4Se[Se2], Ce4O4Se[Se2], Pr4O4Se[Se2], Nd4O4Se[Se2], and Sm4O4Se[Se2] were synthesized from a mixture of the elements with selenium dioxide as the oxygen source at 750 degrees C. Single crystal X-ray diffraction was used to determine their crystal structures. The isostructural compounds M4O4Se[Se2] (M=La, Ce, Pr, Nd, Sm) crystallize in the orthorhombic space group Amm2 with cell dimensions a=857.94(7), b=409.44(4), c=1316.49(8) pm for M=La; a=851.37(6), b=404.82(3), c=1296.83(9) pm for M=Ce; a=849.92(6), b=402.78(3), c=1292.57(9) pm for M=Pr; a=845.68(4), b=398.83(2), c=1282.45(7) pm for M=Nd; and a=840.08(5), b=394.04(3), c=1263.83(6) pm for M=Sm (Z=2). In their crystal structures, Se2- anions as well as [Se-Se]2- dumbbells interconnect {[M4O4]4+} infinity 2 layers. These layers are composed of three crystallographically different, distorted [OM4]10+ tetrahedra, which are linked via four common edges. The compounds exhibit strong Raman active modes at around 215 cm(-1), which can be assigned to the Se-Se stretching vibration. Optical band gaps for La4O4Se[Se2], Ce4O4Se[Se2], Pr4O4Se[Se2], Nd4O4Se[Se2], and Sm4O4Se[Se2] were derived from diffuse reflectance spectra. The energy values at which absorption takes place are typical for semiconducting materials. For the compounds M4O4Se[Se2] (M=La, Pr, Nd, Sm) the fundamental band gaps, caused by transitions from the valence band to the conduction band (VB-CB), lie around 1.9 eV, while for M=Ce an absorption edge occurs at around 1.7 eV, which can be assigned to f-d transitions of Ce3+. Magnetic susceptibility measurements of Ce4O4Se[Se2] and Nd4O4Se[Se2] show Curie-Weiss behavior above 150 K with derived experimental magnetic moments of 2.5 micro B/Ce and 3.7 micro B/Nd and Weiss constants of theta p=-64.9 K and theta p=-27.8 K for the cerium and neodymium compounds, respectively. Down to 1.8 K no long-range magnetic ordering could be detected. Thus, the large negative values for theta p indicate the presence of strong magnetic frustration within the compounds, which is due to the geometric arrangement of the magnetic sublattice in form of [OM4]10+ tetrahedra.     

Separation of rare earth,nuclear-fuel burn-up monitors in the 10−9 mole range by high-pressure liquid chromatography with UV-detection

Anion-exchange chromatography of the rare earth (Sm, Nd, Pr, Ce) ions in methanol-nitric acid-water media is performed using high-pressure liquid chromatography. The separation method is especially designed for determination of¹⁴⁸Nd in the nuclear fuel cycle in order to find precise burn-up values. The high-pressure liquid chromatography method presented here is very fast, gives high resolutions, and enables collection of selected fractions containing nmoles of rare earth by UV monitoring at 280 nm of the eluate.     

YAG∶Ce体系中稀土离子掺杂对Ce3+的光谱性能的影响

采用高温固相法合成了一系列的(Y0.95Ln0.01Ce0.04)3Al5O12(简称YAG∶Ce,Ln), 系统地研究了此体系中的Ln3+对Ce3+的发光强度的影响. 结果表明, 在YAG∶Ce的体系中, La3+, Gd3+, Lu3+等光学透明离子的少量掺杂对Ce3+的发光强度的影响不大; 掺入少量的Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+等稀土离子, 由于它们的能级与Ce3+的能级有交叠, 使它们之间存在着竞争吸收或能量转移, 对Ce3+的发光有较明显的变化, 其中, Pr3+和Sm3+的掺入使其在红光区有发射峰, 可以增加YAG∶Ce的红色成分以提高显色性; Nd3+, Eu3+和Yb3+对Ce3+的发光有严重的猝灭作用.     

Separation and gravimetric determination of rare earths with N-m-Tolyl-m-nitrobenzohydroxamic acid

N-m-Tolyl-m-nitrobenzohydroxamic acid is used as a reagent for separation and gravimetric determination of Ce(3+), La(3+), Pr(3+), Nd(3+), Sm(3+) and Gd(3+). By proper control of pH and use of masking agents these metal ions can be separated from several others and determined gravimetrically. The complexes can be weighed as (C(14)H(11)N(2)O(4))(3)M after drying.     

Determination of lanthanum, cerium, praseodymium and neodymium in alloy steels by inductively coupled plasma atomic-emission spectrometry

Inductively coupled plasma spectrometry has been applied to the determination of La, Ce, Pr and Nd in alloy steels. Spectral interference by other alloying elements as well as by the lanthanides themselves was studied. The influence of other lanthanides on the Pr and Nd lines could be dealt with by correction equations. It was found that within the range of concentrations corresponding to mild alloy steel, at least one of the lines selected for determining the lanthanides was free from interferences. The detection limits for La, Ce, Pr and Nd in steel were 5 x 10(-5), 1.5 x 10(-4), 1 x 10(-4) and 2.4 x 10(-4)% respectively. The procedure was tested on standard samples and by the standard-addition method.     

电感耦合等离子体原子发射光谱测定混合稀土铜合金中稀土和非稀土元素

本文提出了用电感耦合等离子体原子发射光谱(ICP—AES)法直接测定混合稀土铜合金中13个非稀土和稀土元素。选用了合适的分析线对及ICP光源的工作参数。探讨了观察高度、功率、酸度、载气和基体量的变化对被测元素谱线强度的影响。不用化学分离,可一次同时测定La、Ce、pr、Nd、Sm、Sn、Zn、Fe、Al、Ni、Pb,Mg和Mn。测定范围(％):La_2O_3:0.096～6.4;CeO_2:0.24～16;Pr_6O_(11):0.0384～2.56;Nd_2O_3:0.096～6.4;Sn:0.096～3.2;Mg、Mn、Fe,Sm_2O_3:0.024～1.6;Zn:0.396～6.7;Pb:0.092～6.4;Ni:0.096～3.2;Al:0.0384～1.28。相对标准偏差±3.0～9.1％;回收率85～116％满足冶炼上的要求,得到了满意的结果。     

Lanthanoid-based ionic liquids incorporating the dicyanonitrosomethanide anion

A series of low-melting-point salts with hexakisdicyanonitrosomethanidolanthanoidate anions has been synthesised and characterised: (C(2) mim)(3) [Ln(dcnm)(6)] (1?Ln; 1?Ln=1?La, 1?Ce, 1?Pr, 1?Nd), (C(2) C(1) mim)(3) [Pr(dcnm)(6)] (2?Pr), (C(4) C(1) pyr)(3) [Ce(dcnm)(6)] (3?Ce), (N(1114))(3) [Ln(dcnm)(6)] (4?Ln; 4?Ln=4?La, 4?Ce, 4?Pr, 4?Nd, 4?Sm, 4?Gd), and (N(1112OH) )(3) [Ce(dcnm)(6)] (5?Ce) (C(2) mim=1-ethyl-3-methylimidazolium, C(2) C(1) mim=1-ethyl-2,3-dimethylimidazolium, C(4) C(1) py=N-butyl-4-methylpyridinium, N(1114) =butyltrimethylammonium, N(1112OH) =2-(hydroxyethyl)trimethylammonium=choline). X-ray crystallography was used to determine the structures of complexes 1?La, 2?Pr, and 5?Ce, all of which contain [Ln(dcnm)(6)](3-) ions. Complexes 1?Ln and 2?Pr were all ionic liquids (ILs), with complex 3?Ce melting at 38.1?°C, the lowest melting point of any known complex containing the [Ln(dcnm)(6)](3-) trianion. The ammonium-based cations proved to be less suitable for forming ILs, with complexes 4?Sm and 4?Gd being the only salts with the N(1114) cation to have melting points below 100?°C. The choline-containing complex 5?Ce did not melt up to 160?°C, with the increase in melting point possibly being due to extensive hydrogen bonding, which could be inferred from the crystal structure of the complex.     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定板栗中的矿物元素及稀土元素

为了准确测定板栗中矿物元素和稀土元素的含量水平,采用冷冻干燥方式预处理样品,选用硝酸和过氧化氢体系微波消解样品,结合电感耦合等离子体质谱技术,建立了板栗中钠(Na)、钾(K)、镁(Mg)、锰(Mn)、铁(Fe)、钒(V)、钴(Co)等19种矿物元素及镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)、钇(Y)等15种稀土元素的同时分析测定方法。方法检出限为0.0027~0.78μg/L,相对标准偏差为1.4%~6.3%。通过国家标准物质GBW10019苹果的准确度实验验证,测定结果均在标准证书值范围内。实验结果表明,方法适用于板栗中矿物元素及稀土元素的同时测定。     

Determination of light rare earths and other elements in Cuban soils

The objective of the present study was the elaboration of a procedure for the determination of Y, La, Ce, Pr and Nd in soils by spectrophotometry with Arsenazo III preceded by a separation-concentration stage, which includes coprecipitation and ion exchange. Multielement analysis by energy dispersive X-ray fluorescence (including Y, La, Ce and Nd) and flame atomic absorption spectrophotometry was carried out simultaneously in order to obtain a general characterization of the soil samples. Certified reference materials and statistical intercomparison of the obtained results were used to evaluate the accuracy of the methods. The precision was examined by analyzing replicate samples.     

Studies on the Redox Properties of Rare Earth Heteropoly Tungstoarsenate K_17[Ln(As_2W_17O_61)_2]·xH_2O

The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.     

稀土—4—（2—吡啶偶氮）间苯二酚螯合物的高效液相色谱分离和测定

本文讨论了反相离子对液相色谱法分离和检测稀土-4-(2-吡啶偶氮)间苯二酚螯合物的各种条件,在12 min内完成了9种稀土螫合物的分离,校正曲线的线性范围是(ppm):La(0.01～3.20),Ce(0.03～2.8),Pr(0.06～3.5),Nd(0.05～3.8),Sm(0.01～3.0),Eu(0.05～3.4),Tb(0.02～3.0),Ho(0.01～3.4),Er(0.06～4.0).变异系数小于1.2％.     

The spectrochemical determination of La,Ce, Pr,Nd, Sm,Gd and Dy in sodium rare earth sulphates

A DC-arc spectrochemical procedure is described for the analysis of La, Ce, Pr, Nd, Sm, Gd and Dy in sodium rare earth sulphates derived from monazites.     

Crystal structures and stability of NaLnF(4) (Ln = La, Ce, Pr, Nd, Sm and Gd) studied with synchrotron single-crystal and powder diffraction

Crystal structures of the NaLnF(4) materials (Ln = La, Ce, Pr, Nd, Sm or Gd) were studied with synchrotron single-crystal and powder diffraction. The materials with Ln = La, Ce, Nd, Sm and Gd have the average β structure (P6[combining macron], Z = 1) with partial ordering of the cations. A new type of a superstructure due to ordering of the cations and vacancies was found in NaPrF(4) (P3, Z = 6). It could be described using the group-subgroup relationships P6[combining macron]?P3. Our observations suggest that the β structure is unstable and that the ordering is a slow process at ambient conditions. Upon compression, β-NaNdF(4), β-NaGdF(4) and the superstructure NaPrF(4) are stable to at least 8 GPa with no evidence for any pressure-induced disorder-order phenomena.