稀土精矿检测方法

综述了近年来稀土精矿中稀土总量、15种稀土氧化物配分量以及非稀土杂质含量分析测定的国家标准以及最新方法。电感耦合等离子体原子发射光谱法精密度高,检测速度快,为测定稀土精矿中稀土总量的常用方法。电感耦合等离子体质谱法不受基体干扰,更适用于痕量和超痕量稀土元素含量的测定,满足中、重稀土精矿的测定需求。分光光度法测定稀土精矿中非稀土杂质Th,Ti含量准确度高。对稀土精矿分析检测发展趋势进行了展望。     

Determination of rare earths in selected rare earth matrices by spark source mass spectrometry

Three methods of preparing rare earth samples for mass spectrographic analysis are presented. Techniques for adding appropriate internal standards are described and relative sensitivity factors for rare earth impurities in rare earths, lanthanum, yttrium and scandium matrices are presented. Although indium has some value as an internal standard in rare earth samples, best analytical results are obtained when selected rare earths are used as internal standards.     

Neutron activation analysis of rare earth impurities in europium oxide

A neutron activation analysis method for determining Yb, Dy, Ho, Sm and La impurities in europium oxide with sensitivities of 10^?5 to 10^?7% is described. The method is based on a preliminary concentration of the rare earth elements by reducing europium(III) with zinc to europium(II), and separating the trivalent rare earth elements by extraction chromatography. After neutron irradiation, the individual radioisotopes of the rare earth elements are separated by using KU-2 cation exchange resin and ammonium α-hydroxyisobutyrate solution as the eluant.     

Neutron activation analysis of rare earth impurities in metallic uranium

A method with a sensitivity of 2·10⁻⁷ to 1·10⁻¹⁰% has been developed for determining Yb, Ho, Dy, Gd, Eu, Sm and La impurities in metallic uranium by means of neutron activation. The method is based on a preliminary chromatographic separation of the total amount of rare earth elements from uranium by passing the solution in sulphuric acid through KU-2 cation exchange resin and eluting the traces of uranium retained by the resin with a solution of ascorbic acid. The rare earth impurities are then eluted from the resin with 4–5N HCl, evaporated, and irradiated for 20 hours with a neutron flux of 1.2·10¹³ n·cm⁻²·sec⁻¹. Subsequently the traces of the rare earth elements are co-precipitated with Fe(OH)₃, dissolved in concentrated HCl and separated from the iron and other impurities by passing the solution through Dowex 1X8 anion exchange resin in the chloride form. The individual rare earth elements are then separated from each other using KU-2 cation exchange resin and a solution of ammonium α-hydroxyisobutyrate as the eluant.     

Determination of traces of rare earths in high-purity thorium dioxide by neutron activation analysis

The use of thorium dioxide as a nuclear fuel requires the determination of individual rare earth impurities at 0.08–1 mg kg^?1 levels. Neutron activation is sufficiently sensitive but separation from the matrix is essential. In the proposed method, thorium dioxide (5–20 g) is dissolved in concentrated nitric acid with a little hydrofluoric acid; after evaporation, thorium is complexed with ammonium carbonate and the solution is passed through a small column of Chelex-100 resin which retains the rare earths quantitatively without retaining thorium. The rare earth elements are eluted with dilute nitric acid, concentrated, and irradiated with standards; after irradiation the rare earth are collected on a lanthanum carrier and measured by γ-ray spectrometry. The recoveries of rare earths were checked with tracers and by standard addition to thorium dioxide matrices. The reproducibility for La, Eu and Dy was satisfactory at 0.01, 0.003 and 0.002 mg kg^?1, respectively; as was the reproducibility for all rare earths added to thorium dioxide (1–4 μg/5 g). Limits of detection are adequate for certification of nuclear-grade material.     

Nanocomposites based on opal matrices and silica sols doped with rare earth compounds

Ordered 3D composites based on opal matrices and silica sols doped with rare earth elements have been prepared using colloidal chemistry methods. A uniform distribution of rare earth elements (which is important for avoiding luminescence concentration quenching) was achieved by means of repeated filling of the opal matrix interstitial space with silica sols doped with salts or oxides of rare earth elements. Trace amounts (10–30 ppm) of europium in a composite were shown to strongly affect optical properties of the material.     

辉光放电质谱法测定稀土矿中的15种稀土元素

利用高纯铜粉与稀土矿石粉末均匀混合压片制样.混合15种高纯稀土氧化物制样建立标准工作曲线,校正15种稀土元素相对灵敏度因子,再进行定量分析.结果 表明,稀土元素工作曲线的线性方程相关系数R2均大于0.996,相对标准偏差(RSD)小于5％,满足定量分析要求.测定结果与电感耦合等离子体质谱法(ICP-MS)和电感耦合等离...     

X-Ray fluorescence analysis of thulium oxide for rare earth impurities

A wavelength dispersive X-ray fluorescence spectrometric method has been developed for the analysis of thulium oxide to determine the neighbouring rare earth impurities. The sample is taken in oxalate form and the analysis is done on a Philips PW 1220 spectrometer with a LiF (200) crystal. The detection limit for holmium, lutetium and yttrium is 0.002%, for dysprosium and erbium 0.005% and for, ytterbium it is 0.01%. The precision at each concentration of the standards and the theoretical detection limits have been calculated. Intensity correction factors for the line overlaps have been determined.     

Relative sensitivity of rare earth elements in spark-source mass spectrometry

A method for calculating the relative sensitivity factors for the rare earth elements in geological material is outlined. A close correlation is found between the relative sensitivity factors calculated and isotopic mass and the first ionization potential for the elements. The points are grouped in the vicinity of a regression line, which may be used to determine the relative sensitivity factors for all the rare earth elements.     

In-situ vaporization and matrix removal for the determination of rare earth impurities in zirconium dioxide by electrothermal vaporization inductively coupled plasma atomic emission spectrometry

A novel method for the determination of trace rare earth impurities in ZrO₂ powder has been developed based on electrothermal vaporization inductively coupled plasma atomic emission spectrometry. A polytetrafluoroethylene slurry was used as a fluorinating reagent to convert both the matrix (Zr) and the analytes (rare earth elements) into fluorides with different volatilities at a high temperature in a graphite furnace. The more volatile ZrF₄ was removed in-situ by selective vaporization prior to the determination of the analytes, removing matrix spectral interferences. Under optimum operating conditions, the absolute detection limits of the analytes varied from 0.04 ng (Yb) to 0.50 ng (Pr) with relative standard deviations less than 5%. The recommended approach has been successfully applied to the determination of trace rare earth impurities (La, Pr, Eu, Gd, Ho and Yb) in ZrO₂ powder and the results were in good agreement with those obtained by pneumatic nebulization inductively coupled plasma atomic emission spectrometry after the separation of the matrix using a solvent extraction procedure.     

Separation of rare earth elements by high-speed counter-current chromatography

Besides being widely used in electronic and glass industries, rare earth elements have recently been found to have important biological effects including the ability to stabilize and enhance interferon activity [J.J. Sedmak and S.E. Grossberg, J. Gen. Virol, 52 (1981) 195]. In this paper, the rare earth elements have been separated using a high-speed counter-current chromatography (HSCCC) centrifuge equipped with three multilayer coils connected in series. Two-phase solvent systems were composed of n-heptane containing di-(2-ethylhexyl)phosphoric acid (stationary phase) and dilute hydrochloric acid (mobile phase) where the partition coefficient of each can be optimized by selecting the proper hydrochloric acid concentration. The mobile phase was eluted through the column at a flow-rate of 5 ml/min, while the apparatus was rotated at 900 rpm. Continuous detection of the rare earth elements was effected by means of a post-column reaction with arsenazo III and the elution curve was obtained by on-line monitoring at 650 nm. Excellent isocratic separations of closely related rare earth elements were achieved at high partition efficiencies up to several thousand theoretical plates. Versatility of the present method was demonstrated in an exponential gradient elution of hydrochloric acid concentration where fourteen rare earth elements were all resolved in about 4.5 h.     

Determination of rare earth impurities in high purity gadolinium oxide by inductively coupled plasma mass spectrometry after 2-ethylhexylhydrogen-ethylhexy phosphonate extraction chromatographic separation

A method was developed for the determination of rare earth impurities in high purity Gd(2)O(3) by inductively coupled plasma mass spectrometry (ICP-MS). The matrix suppression effect of Gd(2)O(3) on signals of rare earth impurities was compensated for by Re internal standardization. The spectra overlap interferences from GdH, GdO, GdOH(n) (n=1-3) on Tb, Tm, Yb and Lu were eliminated by 2-thylhexylhydrogen-2-ethylhexy phosphonate (EHEHP) extraction chromatographic separation. The detection limits for REEs were 0.005-0.017 ng ml(-1) in solution and 0.002-0.05 mug g(-1) in solid. Recoveries of spiked sample for REEs were from 88 to 121% with the precision of 1.0-7.5% RSD. Determination of trace REEs in two Gd(2)O(3) samples were performed. The method can be applied to analysis of 99.99-99.9999% high purity Gd(2)O(3).     

稀土萃取分离技术方法研究

稀土在工业诸多领域中发挥着关键作用,在增材制造材料和介电材料等高新技术领域均显示出可期的应用前景。稀土元素的分离是衔接稀土资源与高性能稀土功能材料的关键过程,所以高效提纯稀土元素变得尤为重要。本文梳理了化学沉淀法、离子交换与吸附法、萃取色层法、溶剂萃取法、液膜分离法这些经典方法和化学气相传输法、氧化还原法、萃取沉淀法、微生物法、非平衡溶剂萃取法这些新技术方法的优缺点和适用性,侧重分析了这些技术方法在节能减排方面的最新研究情况,并展望了稀土分离提纯领域的重点发展方向,以期为稀土资源的绿色高效开发利用提供依据和借鉴。     

High-resolution spectra of selected rare earth elements and spectral interferences studied by inductively coupled plasma-atomic emission spectroscopy (ICP-AES)

The rare earth elements (REEs) play very important roles in industrial manufacturing, technology development and biological processes. Due to their complex emission spectra, trace levels of REEs are difficult to analyze by conventional ICP-AES techniques. The present study investigates possible spectral interferences of matrices (rare earth oxides of Ce, Pr, Nd, Sm and Dy) on the analytical lines (± 0.1 nm) of a target REE. Detailed and well-resolved spectra for selected REEs are presented, and procedures used to rectify the problem of spectral interferences caused by REE matrices are discussed. A computer-assisted system (CAS) for spectral recognition has been developed and used to assist in the study of matrix interference. To determine directly trace rare earth elements in REE matrices without sample pre-separation, the application potential is demonstrated with a one meter sequential instrument retrofitted with a 3600 grooves/mm grating.     

Treatment of fluorophosphate rare earth concentrate

Methods for primary processing of fluorophosphate rare earth concentrate precipitated from phosphoric acid of dihydrate process by introduction of fluoride ion were examined. Separation of rare earth cations from phosphorus, fluorine, and an appreciable part of the impurity cations by interaction of the concentrate with sulfonic cation resin in sulfuric acid was suggested. Further processing of sulfonic cation resin containing rare earth elements was possible by known methods.     

Synthesis of rare earth monoxides

The standard Gibbs energy changes for the formation of an ionic or metallic monoxide from rare earth metal and sesquioxide have been calculated. Under high pressures ionic ytterbium monoxide and lighter rare earth metallic monoxides should be obtained, which is confirmed by experiments in a belt-type apparatus in the range 15–80 kbar and 500-1200°C. For Ln =La, Ce, Pr, Nd, Sm, a face-centered cubic compound is obtained from each reaction. The cell parameters are respectively 5.144, 5.089, 5.031, 4.994, and 4.943 ± 0.005A?. The compounds appear golden yellow with a metallic luster. From chemical analyses and cell parameter consideration it is concluded that these compounds are the rare earth monoxides. For Ln =Gd, Dy, Tm, no reaction is observed at 50 kbar and 1000°C. The rare earth monoxides show a variety of properties: LaO, CeO, PrO, and NdO are metallic with the rare earth in the trivalent state; EuO and YbO are semiconductors with the rare earth in the divalent state; SmO is metallic with samarium in an intermediate valence state close to 3.     

膜去溶-ICP-MS法测定高纯Eu_2O_3中14种痕量稀土杂质

研究了不需基体分离,膜去溶-ICP-MS法直接测定高纯Eu2O3中的14种痕量稀土杂质的分析方法。讨论了Eu基体产生的多原子离子对被测元素的质谱干扰。使用膜去溶后,待测元素灵敏度提高3倍左右,EuO/Eu产率从去溶前的0.016%降低为0.0007%。建立了Tm的数学校正方程,通过膜去溶结合数学校正可将Eu基体对Tm干扰完全消除。14种稀土杂质的检出限和(∑RE)为70 ng/L,测定下限和(∑RE)为0.54μg/g。对6N高纯Eu2O3样品进行了分析,样品回收率为96%~109%,RSD小于10%。所建立的方法对Eu2O3标准样品的测定结果与国家标准方法测定结果相一致。     

Identification and determination of natural radioactive impurities in rare earth chlorides

²²⁷Ac,²²⁸Th,²²⁶Ra,²¹⁰Po and²¹⁰Pb can be present at rare earth chlorides. A radiochemical procedure is presented for the identification and determination of natural radioactive impurities in rare earth chlorides. The determination limits for these radionuclides were 1.5·10^–4 to 3·10^–1 Bq/g. The relative standard deviations for determining 10^–2 Bq/g radionuclides were usually less than ±7%.     

电感耦合等离子体质谱法测定三水铝土矿中的15种有效稀土元素

建立电感耦合等离子体质谱法测定三水铝土矿中15种有效稀土元素的分析方法。参考三水铝土矿中有效铝的概念,提出了有效稀土元素的概念,并对三水铝土矿中稀土元素的回收利用的可行性进行了评价。模拟低温拜耳法生产氧化铝的工艺,对三水铝土矿中稀土元素溶出过程中的氢氧化钠浓度、溶出温度及时间等条件进行了试验,采用90 g/L氢氧化钠结合微波消解技术对三水铝土矿进行分解,用ICP-MS法测定有效稀土元素,有效稀土元素测定结果的相对标准偏差为0.92%~7.40%(n=7),回收率为98.6%~101.2%。该方法可用于测定三水铝土矿中有效稀土元素,能够对三水铝土矿中稀土元素的回收利用价值进行评价。     

稀土配合物杂化发光材料的组装及光物理性质研究进展

稀土配合物兼具无机物稳定性好以及有机物荧光量子效率高的优点,而且具有可设计性,制备简便,容易修饰,荧光性质优异（发射谱带窄、色纯度高、荧光寿命长、量子产率高以及发射光谱范围覆盖可见和近红外光区等）．但配合物的光、热、化学稳定性和机械加工性能相对较差,因而限制了其在很多领域中的实际应用．近年来的研究表明,将稀土配合物引入到各种基质材料中可以改善其稳定性及机械加工性能,并对其光物理性质产生调制作用．根据基质材料的不同,杂化材料可分为无机基质、无机／有机复合基质及有机基质杂化材料．本文综述了这些不同基质稀土配合物杂化发光材料的研究进展,探讨了主客体间相互作用对杂化材料光物理性质及稳定性的影响,为实现稀土配合物杂化发光材料在光学器件领域（LED照明、光纤维、光学放大器及激光等）及生命分析领域的应用提供了重要的理论依据．