15832-34-5Relevant articles and documents
Liquid-liquid solvent extraction of rare earths from chloride medium with sec-nonylphenoxy acetic acid and its mixtures with neutral organophosphorus extractants
Xiao, Pengfei,Bao, Changli,Song, Naizhong,Li, Cui,Jia, Qiong
, p. 1157 - 1161 (2011/10/18)
In the present study, sec-nonylphenoxy acetic acid (CA100) and its mixtures with four neutral organophosphorus extractants, tri-butyl-phosphate (TBP), 2-ethylhexyl phosphonic acid di-2-ethyl ester (DEHEHP), Cyanex923, and Cyanex925 have been applied to the extraction of rare earths. Results show that all the four mixing systems do not have evident synergistic effects on the extraction of rare earths. The different extraction effects have been considered to the separation of rare earths. The four mixtures may be applied to the separation of yttrium from some certain lanthanoids at proper mole fractions of CA100. Pleiades Publishing, Ltd., 2011.
Synthesis, crystal and electronic structures of new narrow-band-gap semiconducting antimonide oxides RE3SbO3 and RE 8Sb3-δO8, with RE = La, Sm, Gd, and Ho
Wang, Peng,Forbes, Scott,Kolodiazhnyi, Taras,Kosuda, Kosuke,Mozharivskyj, Yurij
, p. 8795 - 8803 (2010/08/06)
In the search for high-temperature thermoelectric materials, two families of novel, narrow-band-gap semiconducting antimonide oxides with the compositions RE3SbO3 and RE8Sb3-δO 8 (RE = La, Sm, Gd, Ho) have been discovered. Their synthesis was motivated by attempts to open a band gap in the semimetallic RESb binaries through a chemical fusion of RESb and corresponding insulating RE 2O3. Temperatures of 1350 °C or higher are required to obtain these phases. Both RE3SbO3 and RE 8Sb3-δO8 adopt new monoclinic structures with the C2/m space group and feature similar REO frameworks composed of RE4O tetrahedral units. In both structures, the Sb atoms occupy the empty channels within the REO sublattice. High-purity bulk Sm and Ho samples were prepared and subjected to electrical resistivity measurements. Both the RE3SbO3 and RE8Sb 3-δO8 (RE = Sm, Ho) phases exhibit a semiconductor-type electrical behavior. While a small band gap in RE 3SbO3 results from the separation of the valence and conduction bands, a band gap in RE8Sb3-δO 8 appears to result from the Anderson localization of electrons. The relationship among the composition, crystal structures, and electrical resistivity is analyzed using electronic structure calculations.
Effect of the 18-crown-6 and benzo-18-crown-6 on the solvent extraction and separation of lanthanide(III) ions with 8-hydroxyquinoline
Atanassova
, p. 1304 - 1311 (2008/10/09)
The synergistic solvent extraction of 13 lanthanides with mixtures of 8-hydroxyquinoline (HQ) and the crown ethers (S) 18-crown-6 (18C6) or benzo-18-crown-6 (B18C6) in 1,2-dichloroethane has been studied. The composition of the extracted species has been
Electrodeposition of Ho and electrochemical formation of Ho-Al alloys from the eutectic LiCl-KCl
Castrillejo,Bermejo,Barrado,Medina,Martinez
, p. C713-C721 (2008/10/09)
The electrochemistry of a LiCl-KCl-HoCl3 melt at inert and reactive electrodes has been studied at temperatures between 673 and 823 K. At a W electrode the electroreduction of Ho(III) proceeds in a single step and electrocrystallization plays an important role. Experimental current-time transients followed the theoretical models based on instantaneous nucleation with three-dimensional growth of the nuclei whatever the applied overpotential. Mass transport toward the electrode is a diffusion process, and the validity of the Arrhenius law was verified. For an Al electrode, the electroreduction of Ho(III) takes place at less cathodic potential values than at the inert W electrode which indicated the formation of Ho-Al intermetallic compounds. Ho-Al alloy films were obtained by potentiostatic electrolysis, and the samples were characterized by X-ray diffraction and scanning electron microscopy. The activity of Ho in the aluminium phase as well as the standard Gibbs energy of formation for Al3Ho were estimated from open-circuit chronopotentiometric measurements.
Temperature-Dependent Rate Constants for the Reactions of Gas-Phase Lanthanides with O2
Campbell, Mark L.
, p. 7274 - 7279 (2007/10/03)
The reactivity of the gas-phase lanthanide atoms Ln (Ln = La-Yb with the exception of Pm) with O2 is reported. Lanthanide atoms were produced by the photodissociation of [Ln(TMHD)3] and detected by laser-induced fluorescence. For all the lanthanides studied with the exception of Yb, the reaction mechanism is bimolecular abstraction of an oxygen atom. The bimolecular rate constants (in molecule-1 cm3 s-1) are described in Arrhenius form by k[Ce(1G4)] = (3.0 ± 0.4) × 10-10 exp(-3.4 ± 1.3 kJ mol-1/RT); Pr(4I9/2), (3.1 ± 0.7) × 10-10 exp(-5.3 ± 1.5 kJ mol-1/RT); Nd(5I4), (3.6 ± 0.3) × 10-10 exp(-6.2 ± 0.4 kJ mol-1/RT); Sm(7F0), (2.4 ± 0.4) × 10-10 exp(-6.2 ± 1.5 kJ mol-1/RT); Eu(8S7/2), (1.7 ± 0.3) × 10-10 exp(-9.6 ± 0.7 kJ mol-1/RT); Gd(9D2), (2.7 ± 0.3) × 10-10 exp(-5.2 ± 0.8 kJ mol-1/RT); Tb(6H15/2), (3.5 ± 0.6) × 10-10 exp(-7.2 ± 0.8 kJ mol-1/RT); Dy(5I8), (2.8 ± 0.6) × 10-10 exp(-9.1 ± 0.9 kJ mol-1/RT); Ho(4I15/2), (2.4 ± 0.4) × 10-10 exp(-9.4 ± 0.8 kJ mol-1/RT); Er(3H6), (3.0 ± 0.8) × 10-10 exp(-10.6 ± 1.1 kJ mol-1/RT); Tm(2F7/2), (2.9 ± 0.2) × 10-10 exp(-11.1 ± 0.4 kJ mol-1/RT), where the uncertainties represent ±2σ. The reaction barriers are found to correlate to the energy required to promote an electron out of the 6s subshell. The reaction of Yb(1S0) with O2 reacts through a termolecular mechanism. The limiting low-pressure third-order rate constants are described in Arrhenius form by k0[Yb(1S0)] = (2.0 ± 1.3) × 10-28 exp(-9.5 ± 2.8 kJ mol-1/RT) molecule-2 cm6 s-1.
Temperature dependent rate constants for the reactions of gas phase lanthanides with N2O
Campbell, Mark L.
, p. 562 - 566 (2007/10/03)
The reactivity of gas phase lanthanide (Ln) atoms (Ln=La-Yb with the exception of Pm) with N2O from 298 to 623 K is reported. Lanthanide atoms were produced by the photodissociation of Ln(TMHD)3 (TMHD=2,2,6,6-tetramethyl-3,5-heptanat
Acid Solvolysis Kinetics of Lanthanide Porphyrins
Haye, Shirleyanne,Hambright, Peter
, p. 666 - 668 (2007/10/02)
The kinetics of the acid solvolysis reactions of twelve water-soluble lanthanide tetrakis(N-methyl-4-pyridyl)porphyrins (Ln-P) follow rate = k1+>2/ (k-1/k2) + +>> at 25 deg C, I = 0.8M (LiNO3/HNO3) indicating that two protons are required for solvolysis, and since log (k1k2/k-1) = 45.0R0 - 39.4 (R0 is the ionic radius in Angstroem), a 0.1 Angstroem change in radius has a 32000 fold rate effect.
