Susceptibility of rare earth bromates between 1 and 4.2 K

AC magneitic susceptibilities measured between 1 and 4.2 K are reported for a series of rare earth bromate hydrates, RE(BrO₃)₃ · 9H₂O, for the rare earths Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Yb. Results for Pr, Tb, Dy, and Er are in good agreement with a previous determination. New results are reported for Nd, Sm, Gd, Ho, and Yb, some of which show interesting differences from the structurally similar rare earth ethylsulfates and anhydrous trichlorides.     

Extraction of rare-earth elements from nitric acid solutions with polyalkylphosphonitrilic acid

The distribution of microamounts of La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO₃ solutions and solutions of polyalkylphosphonitrilic acid in a fluorinated alcohol was studied. The stoichiometry of the extractable REE complexes was determined. An increase in the concentration of fluorinated alcohol in the organic phase leads to a decrease in the REE distribution ratios, which is due to solvation of the extractant with the alcohol molecules.     

Extraction of Am(III) and Lanthanides from Nitric Acid Solutions with Polyfunctional Organophosphorus Acids

Extraction of microamounts of Am, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu nitrates from aqueous HNO₃ with solutions of (diphenylphosphinylmethyl)phenylphosphinic, (di-p-tolylphosphinylmethyl)phenylphosphinic, (di-p-anisylphosphinylmethyl)phenylphosphinic, and (dioctylphosphinylmethyl)phenylphosphinic acids and of butyl hydrogen (diphenylphosphinylmethyl)phosphonate in toluene was studied. The metal : extractant ratio in the extractable species was determined.     

Extraction of Rare-Earth Elements from Nitric Acid Solutions with Bidentate Phosphoryl-containing Compounds and Their Mixtures

Extraction of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu from HNO₃ solutions with neutral bidentate phosphoryl-containing compounds was studied. Extraction with tetraphenylmethylenediphosphine dioxide increases in going from Lu to La, and extraction with methyleneoxyphenyldiphosphine dioxides increases in the opposite direction. The anomalous aryl strengthening effect varies in the same direction. Extraction with mixtures of diphosphine dioxides allows efficient concentration of the sum of rare-earth elements from nitric acid solutions.     

Extraction of Rare-Earth Elements from Nitric Acid Solutions with Ethylenediphosphine Dioxides

Extraction of microamounts of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu from HNO₃ aqueous solutions with ethylenediphosphine dioxides in organic diluents was studied. The effect of the dioxide structure on its extractive power and selectivity was considered. The stoichiometry of extractable solvates was determined.     

Extraction of Am(III) and Rare-Earth Elements from Nitric Acid Solutions with Dibutyl Diphenylphosphinylmethylphosphonate

Extraction of HNO₃ and trace amounts of Am, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu nitrates from aqueous HNO₃ with solutions of dibutyl diphenylphosphinylmethylphosphonate in dichloroethane was studied. The stoichiometry of the extractable solvates was determined, and the apparent extraction constants were calculated.     

Extraction of Am(III) and Rare-Earth Elements from Nitric Acid Solutions with (Diphenylphosphinylmethyl)phenylphosphinic Acid

Extraction of microamounts of Am, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu nitrates from aqueous HNO₃ with solutions of (diphenylphosphinylmethyl)phenylphosphinic acid in dichloroethane was studied. The stoichiometry of the extractable complexes was determined. Synergistic enhancement of the extraction of rare-earth elements in the presence of tetraphenylmethylenediphosphine dioxide was revealed.     

Recovery of rare-earth elements from nitric acid solutions by fullerene black impregnated with diphenyl(dibutylcarbamoylmethyl)phosphine oxide

The distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO₃ solutions and fullerene black impregnated with diphenyl(dibutylcarbamoylmethyl)phosphine oxide (L) was studied. The influence exerted on the efficiency of REE recovery by the HNO₃ concentration in the aqueous phase and concentration of L in the sorbent phase was examined. The degree of REE recovery increases on adding HClO₄ to the aqueous phase.     

Synthesis and Study of Uranates of Rare-Earth Elements of Compositions LnU3O10.5·6H2O (Ln = La,Ce, Pr,Nd, Sm), LnU6O19.5·10H2O (Ln = Nd,Sm, Eu,Gd, Tb,Dy), and LnU2O7.5 (Ln = Dy,Ho, Er,Tm, Yb,Lu)

Radiochemistry - The interaction of synthetic skupite UO3·2.25H2O with aqueous solutions of La, Ce, Pr, Nd, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu nitrates under hydrothermal conditions at a...     

Extraction of Am and Rare-Earth Elements from Nitric Acid Solutions with Ethyl Bis(diphenylphosphinylmethyl)phosphinate

Extraction of HNO₃ and microamounts of Am, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO₃ solutions with solutions of ethyl bis(diphenylphosphinylmethyl)phosphinate in dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the effective extraction constants of HNO₃ and Am were calculated. With increasing number of phosphoryl groups in the extractant molecule, the extraction of Am(III) and rare-earth elements from HNO₃ solutions increases.     

Influence of Rare-Earth Elements on ElectricalProperties of Pd

The influence of RE (RE = La, Ce. Pr. Nd, Sm, Eu, Gd. Tb. Dy, Er, Yb) additives with dilute concentrations on the electrical properties of Pd has been studied. All RE elements increase the specific resistivity (ρ) and decrease the resistance temperature coefficient (α) of Pd. and (ρ.α) Pd-RE ls equal to (ρ· α)Pd.The RE elements before Gd reduce the thermo-emf of Pd on Cu. other heavy RE enhance the thermo-emf.The experimental data of normalized Pd-0.1 at.-%RE alloys indicate that the effect of light RE additives on the specific resistivity of Pd is larger than that of heavy RE and Ce. Eu and Yb show anomalous strong effect. The valence and atomic size are main factors influencing the electrical properties.     

Extraction of Rare-Earth Elements and Americium from Nitric Acid Solutions with Polyphosphine Oxides

Extraction of HNO₃ and microamounts of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Am from solutions of NH₄NO₃ and HNO₃ with solutions of polyphosphine oxides containing o-oxyphenylenemethylene fragments in dichloroethane was studied. The stoichiometry of the extractable complexes was determined, and the apparent extraction constants were calculated. As the number of phosphoryl groups in the extractant molecule is increased, the extraction of cerium-group lanthanides increases and that of yttrium-group lanthanides decreases.     

Reactions of hydrogen with R3Ni8Al intermetallides (R = Y,Pr, Nd,Gd, Tb,Dy, Ho,Er) with the Ce3Co8Si type of structure

Summary X-ray phase analysis, DTA, and volumetry have been applied to the reactions with hydrogen shown by R₃Ni₈Al compounds with structures of Ce₃Co₈Si type, where R = Y, Pr, Nd, Gd, Tb, Dy, Ho and Er. The R₃Ni₈Al react with hydrogen at room temperature and pressures below 0.1 MPa. Hydrides of composition R₃Ni₈AlH_x are obtained, where x=9.3 for Y, 10.3 for Pr, 11.4 for Nd, 8.7 for Gd, 6.9 for Tb, 5.7 for Dy, 5.4 for Ho, and 2.7 for Er. Hydride formation is accompanied by an increase in unit-cell volume by 5.7–18.2% without change in the initial hexagonal symmetry. Most of the hydrides decompose on heating at moderate temperatures up to 470 K. The main interest among these hydrides is in the Y₃Ni₅AlH_8.3, which can be recommended as a low-pressure hydrogen absorber.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 3, pp. 37–44, May–June, 1992.     

A study on the phase transition and characteristics of rare earth elements doped BaTiO3

Non-reducible dielectric composition satisfying X8R specifications (−55 to 150°C, ±15%) for automotive applications was investigated in a BaTiO₃-MgCO₃-MnO₂-rare earth elements (La, Pr, Gd, Tb, Dy, Ho, Er, Yb, Lu) system. In the cases of Er, Yb, Lu-substituted samples, a transition of the Curie point shifted to a higher temperature was observed. The peak shift toward higher temperatures indicated that the tetragonal phase became more stable at the high temperature. The ionic radius of rare earth elements was found to be an important factor in controlling the temperature dependency of the dielectric properties. Especially, smaller ionic radii of rare earth elements such as Yb and Lu were effective dopants to meet the X8R temperature-capacitance characteristics.     

不同稀土元素掺杂对钛酸钡陶瓷导电性的影响

采用溶胶－凝胶法制备了１４种稀土掺杂的ＢａＴｉＯ３超细粉体（ＲＥ＝Ｙ，Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｙｂ，Ｌｕ），用一般陶瓷工艺将这些超细粉体分别烧成了１４种稀土掺杂的ＢａＴｉＯ３陶瓷，测得了这些陶瓷体的电阻率并对Ｅｕ和Ｙｂ掺杂的ＢａＴｉＯ３陶瓷成绝缘体的原因进行了初步讨论。     

Extraction of rare-earth elements from nitric acid solutions with bis(dioctylphosphinylmethyl)phosphinic acid

The distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO₃ solutions and solutions of bis(dioctylphosphinylmethyl)phosphinic acid in organic diluents was studied. The stoichiometry of the extractable complexes was determined, and the diluent effect on the efficiency of extraction of rare-earth elements from nitric acid solutions was examined. Addition of a neutral solvating component, tetraphenylmethylenediphosphine dioxide, to the organic phase enhances the extraction of rare-earth elements, exerting a synergistic effect.     

Synthesis,order-disorder transition and magnetic properties of LiLnS2, LiLnSe2, NaLnS2 and NaLnSe2 (Ln=Lanthanides)

Ternary chalcogenides LiLnS₂, LiLnSe₂, NaLnS₂, and NaLnSe₂ (Ln-La, Ce, Nd, Sm, Gd, Tb, Dy, Ho, Er, or Y) were prepared by heating the mixtures of elements. DTA(differential thermal analysis) measurements showed the first order transitions at high temperatures above 600 °C in LiLnS₂ (Ln=Dy, Ho, Er, Y), LiLnSe₂ (Ln=Gd to Er), NaNdS₂, and NaCeSe₂, which are considered order-disorder transitions between a NaCl and an α-NaFeO₂ structure. This is consistent with X-ray diffraction measurements. Magnetic susceptibility measurements revealed that all the lanthanides ions are in trivalent state.     

Thermal conductivity and Lorenz number of the heavy rare-earth metals

A detailed investigation of the thermal conductivity of pure, heavy rare-earth metals has been made in the range of temperatures 0.3–4.2 K. The results obtained on the 10 samples investigated (Gd, Dy, Ho, Er, Yb, and Tb) show that the thermal conductivity can be readily separated into a linear and a quadratic term in temperature. The linear term, when related to the residual electrical resistivity, gives Lorenz numbers which are remarkably close to the theoretical value and this indicates an electronic linear contribution to the thermal conductivity; the experimental evidence available suggests that the quadratic term is due to a phonon contribution. Interesting information on the scattering mechanisms for electrons and phonons is also obtained.This work was in part supported by the Calouste Gulbenkian Foundation and Instituto de Alta Cultura, Portugal (J.B.S.) and a Rhodes Scholarship (R.R.).     

Crystal structure and magnetic properties of new rare earth ternary equiatomic silicides RERhSi

New ternary silicides RERhSi (RE=Y, Gd, Tb, Dy, Ho, Er) have been prepared by arc melting from the elements and annealed for for several days at 800°C. Single crystal studies show these materials to be of orthorhombic symmetry and isostructural with TiNiSi (anti-PbCl₂ structure). Gd, Tb and Dy compounds show a spontaneous magnetization and their ordering consists probably of a non-colinear arrangement of the moments. HoRhSi and ErRhSi order antiferromagnetically at 8K and 7.5K respectively. At 4.2K HoRhSi undergoes a metamagnetic transition above 6kOe. A field transition appears also at 4.2K for ErRhSi above 12kOe.     

Thermal conductivities and Lorenz functions of the heavy rare-earth metals between 90 and 300 K

The thermal conductivities and electrical resistivities of Tb, Dy, Gd, Ho, Er, and Yb polycrystals were measured as a function of temperature between 90 and 300 K. The results confirm the anomalies at the magnetic transition temperatures. The thermal conductivity of polycrystalline ytterbium was found to increase with temperature, agreeing with the estimated values of Powell and Ho, and not temperature independent as predicted by Aliev and Volkenshtein. The Lorenz functions were calculated from the experimental results, and they were anomalously high. These large deviations indicate the presence of heat mechanisms other than the usual dominant electronic contribution. The additional contribution to the thermal conductivity is likely to be due to the bipolar mechanism.