Determination Of Nd Research Articles

Concept of a new Thermal Isotope Mass Spectrometer

New applications in scientific geological work centering around the exact isotopic analysis of Nd and Sr challenges the capabilities of the existing mass spectrometers. The new instrument equipped with 11 detectors for simultaneous measurements of isotope ratios has been designed for the purpose of improving the accuracy of the determination of Nd and Sr isotope ratios to 2 ppm. Following the idea that the accuracy mainly depends on the quality of the detector system immediately leads to a design in which oversized static Faraday-cups are combined with a variable mass dispersion of the analyzer. This will be achieved by using two quadrupole doublets in front of and behind a straight through ion optical element like the well known Wien Filter. The Wien Filter consists basically of a magnetic field B and a superimposed electrostatic field E, arranged perpendicular to each other. Ions of arbitrary mass and charge can move along the straight z axis if their velocity equals v{sub 0} = E{sub 0}/B{sub 0}. Since the velocity of the ions depends on their charge, mass and the potential in the ion source, one concludes, that mass scanning is possible by varying the electrostatic field, keeping the magnetic field constant. Thus,more » rapid scanning is possible. In addition, their is no high mass limitation, contrary to magnetic sector field mass spectrometry.« less

Direct spectrophotometric determination of Nd in mixed rare earths with semi-xylenol orange and cetylpyridinium chloride

The derivative absorption spectra of the neodymium complex with Semi-Xylenol Orange and cetylpyridinium chloride has been investigated. The characteristic absorption of the complex is ∼ 350 times that of neodymium chloride. The fourth-order derivative spectrum has been used to eliminate the interference of the other lanthanides, and to increase the sensitivity by a further factor of 6. Beer's law is obeyed for 0–7.5 μg of Nd in 25 ml of solution. The relative standard deviation for 7 determinations of 1.8 μg/25 ml neodymium was 1.3%. The detection limits were 5.8 ng/ml in the absence of lanthanum and 11.2 ng/ml in the presence of 44 ng/ml lanthanum (or 36 ng/ml yttrium). The method has been used for the determination of neodymium in mixed rare earths, with satisfactory results.

Direct spectrophotometric determination of Nd and Er in mixed rare earths with 8-hydroxyquinoline-5-sulphonic acid and cetylpyridinium chloride

Neodymium and erbium can form stable ternary complexes with 8-hydroxyquinoline-5-sulphonic acid and cetylpyridinium chloride, but a photometric method based on this does not give high enough sensitivity and is subject to interference by cerium. Use of the third derivative spectra, however, eliminates the interference by cerium and increases the sensitivity.

Spectrophotometric study and analytical applications of lanthanide-kojic acid complexes: Direct determination of Nd, Ho and Er in mixtures of rare earths

The complexes of the rare-earth metals with kojic acid in weakly alkaline solution are reported. The characteristic absorbances of neodymium, holmium and erbium can be increased by factors of 4.3, 11.0 and 6.4 respectively, compared with those of the chlorides. The third-derivative spectra have been used to eliminate the interference of Ce, La and Y, and the sensitivities are again increased, by a factor of 6–9.

Micellar systems in flow injection for the spectrophotometric determination of neodymium in glasses

Neodymium (0.03–21 µg ml–1) can be determined at a sampling rate of 120 h–1 by injection at pH 2.7 in the presence of 0.4 M NaNO3 into a carrier containing 1.6 × 10–3M 1-(2-pyridylazo)-2-naphthol (PAN)(0.15 g of Triton X-100 plus 1 mg of PAN) buffered at pH 9.2 [HBO2+ NaBO2(0.04 M)] and monitoring the absorbance at 560 nm. The influence of the presence of electrolytes in the matrix on peak height was studied. The interferences produced by heavy metals were eliminated by extracting their diethyldithiocarbamates into chloroform-ethyl actate (1 + 1). The method was applied to the determination of Nd in a commercial glass.

Determination of Nd, Ho, Er, Tm and Y in Solutions by Hollow Cathode Discharge with Copper Cathodes

Abstract A hollow cathode discharge has been applied to the determination of Nd, Ho, Er, Tm and Y in solutions using copper cathodes and argon as a carrier gas. The solutions were evaporated to dryness in the cathodes without a pretreatment. Absolute detection limits for the elements studied here were found to be lower in the copper cathode by about one order than those obtained in previous studies in graphite hollow cathodes.

Noncontact doping level determination in GaAs using photoreflectance spectroscopy

Shifts of the band edge in GaAs layers as measured by photoreflectance (PR) spectroscopy have been accurately calibrated to the N-type doping level (Nd). Samples produced by controlled Si-doping experiments using ion implantation of GaAs substrates and GaAs doped with Si to known levels during growth by molecular-beam expitaxy have been investigated with this technique. A measurable change in the location of the band gap (E) determined from PR directly correlates with the maximum N-type doping level as determined via C-V for both types of samples with a change of band gap δE/δNd=5.8±0.5×10−20 eV cm3 for 1×1016 cm−3 ≤Nd≤8×1017 cm−3. Correlations were also made to sheet carrier concentration (Hall measurements). This method is shown to be fast, accurate, and easily applicable to uniformity studies and a viable alternative to either C-V or Hall measurements for nondestructive determination of Nd.

Determination of donor and acceptor impurity concentrations in n-InP and n-GaAs

The Hall mobility of semiconducting materials is generally computed without accounting for the Hall factor,r H. It is shown that for low magnetic fields this may lead to considerable errors in the calculation of the impurity concentrations,N D andN A, in both n-GaAs and n-InP of reasonable purity. Tables allowing the determination ofN D andN A under low magnetic field conditions are computed at room and liquid nitrogen temperatures. They account forr H and for the inelastic nature of collisions with polar optical phonons without assuming Matthiessen's rule.

Determination of neodymium isotopes as burnup indicator of highly irradiated (U, Pu)O2 lmfbr fuel

For the determination of fission product Nd as a burnup indicator of nuclear fuel, a method is proposed. The procedure involves the fuel dissolution in HNO3−HF mixture, the Nd separation on an anion exchange column of Dowex 1-X4 and PbO2, purification on two extraction chromatography columns and determination of the Nd by mass spectrometry. The calculation of the possible contamination with natural Nd and its correction, determination of the average weighted fission yield and the calculation of the atom percent burnup are also described.

Spectrographic determination of Nd, Sm, Gd, Tb and Dy in high purity europium oxide

Nd, Sm, Gd, Tb and Dy have been determined spectrographically in europium oxide of high purity within the concentration range of 0.005 to 0.1%. The sample is mixed with graphite powder in the ratio 1∶1 and amounts of 10 mg are excited in the 15 A d.c. arc for 25 sec. The spectra were recorded with a 3.4 m Jarrell-Ash grating spectrograph with a reciprocal linear dispersion of 1.2 A/mm. Eu 3649.8 and Eu 4064.5 were employed as internal standard lines. The variation coefficient was between 10 and 18%.

Determination of rare earths in silicate rocks by epithermal neutron activation and a simple group separation

The determination of nine rare earth elements in rock samples by epithermal neutron activation, followed by a simple group-separation procedure and Ge(Li) γ-ray spectrometry, is described. This method is found to be advantageous for the determination of Nd, Gd, Ho, Er and Lu by means of the short-lived nuclides149Nd,159Gd,166Ho,171Er and176mLu. Precision for La, Sm and Eu is similar to that of thermal neutron activation, that for Dy is worse. Samples of the standard rocks, basalt BCR-1 and granite G-2, were analyzed by this procedure and the results obtained are compared with previously reported data.

Empirical Relationships between the Partial Dispersions of the Ordinary Types of Optical Glasses*

Three empirical relationships have been derived between reciprocals of pairs of partial dispersions of the ordinary optical glasses. The relationships are of the form X=a+b Y+cY2 where X and Y are variable and a, b, and c the empirical constants. a, b, and c were determined by least squares making use of the data on sixteen optical glasses manufactured by The Bausch and Lomb Optical Company. The fit obtained appears to hold within the 5th place experimental error of the index determinations. Determination of ND and Nh and the use of the three empirical relationships quoted above allows calculation of NF, NC, NG′, and V in a simple manner. These relationships, however, do not apply to the barium glasses.