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Neutron scattering lengths of the isotopes of thulium, ytterbium and lutetium
1986-03-01
Coherent neutron scattering lengths and total cross sections have been measured on samples of ordinary Tm, Yb and Lu and on isotopically enriched compounds. From the experimental data for 0.57 meV neutron energy the following data were obtained: - the coherent scattering lengths (in fm) of the bound atoms /sup 169/Tm (7.07+0.03); /sup 170/Yb (6.8+-0.1); /sup 171/Yb (9.7+-0.1); /sup 172/Yb (9.5+-0.1); /sup 173/Yb (9.56+-0.10); /sup 174/Yb (19.2+-0.1); /sup 176/Yb (8.7+-0.1); Yb (12.41+-0.03); /sup 175/Lu (7.28+-0.09); /sup 176/Lu (6.3+-0.2) and Lu (7.21+-0.03); - the thermal absorption cross sections (in barn) for /sup 169/Tm (100+-2); Yb (34.8+-0.8) and Lu (74+-2). In combination with the resonance parameters the measured coherent scattering lengths allowed the determination of potential scattering radii R' which are of particular interest for the permanently deformed and deformable nuclei in the rare-earth region. (orig.).
1984-06-01
The ternary germanides RNiGe and RCoGe (R=Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were produced by arc melting from the elements and annealed for 720 h at 1070 K. X-ray studies show these materials to be of orthorhombic crystalline structure isomorphic to that of TiNiSi. The temperature dependence of magnetic susceptibility has been measured by the Faraday method within the range of 77-300 K. The compounds with R=Gd, Tb, Dy, Ho, Er, Tm and Yb are the Curie-Weiss-type paramagnetics, the magnetic moments corresponding to R/sup 3 +/ ions. Electrical resistance and thermo- emf of some compounds are measured within the range of 300-1000 K and 400-1000 K, respectively.
Nuclear orientation of /sup 171/Lu and /sup 173/Lu
1983-12-01
The decays of /sup 171/Lu and /sup 173/Lu have been studied by means of nuclear orientation. External perturbations of two /sup 171/Yb levels have been observed. Unambiguous spin assignments have been made for several levels in /sup 171/Yb and mixing ratios of the transitions in /sup 171/Yb and /sup 173/Yb have been deduced. The properties of the /sup 171/Yb and /sup 173/Yb rotational bands have been studied using the quasiparticle-phonon model including a Coriolis interaction.
Direct observation of Fe spin reorientation in single crystalline YbFe6Ge6
2005-08-22
We have grown single crystals of YbFe6Ge6 and LuFe6Ge6 and characterized their anisotropic behaviour through low field magnetic susceptibility, field-dependent magnetization, resistivity and heat capacity measurements. The Yb+3 valency is confirmed by LIII XANES measurements. YbFe6Ge6 crystals exhibit a field-dependent, sudden reorientation of the Fe spins at about 63 K, a unique effect in the RFe6Ge6 family (R = rare earths) where the Fe ions order anti-ferromagnetically with Neel temperatures above 450 K and the R ions' magnetism appears to behave independently. The possible origins of this unusual behaviour of the ordered Fe moments in this compound are discussed.
Physical phenomena of the cage compounds RE3Pd20Si6 (RE=Yb, Lu)
2009-01-01
Features of atomic rattling motion (anharmonic thermal vibrations), a phenomenon that relates to a new route for devising materials for thermoelectric applications of complex metal alloys, have been detected in certain members of the RE3Pd20X6 (RE=rare-earth element, X=Si or Ge) series of compounds relating to details of their particular crystal structure. In this work, thermal properties of Yb3Pd20Si6 and Lu3Pd20Si6 are reported as a first account of their position with respect to atomic rattling in an attempt to demystify the conditions that favour this dynamic materials property.
X-ray absorption spectroscopic studies of RCu2Si2 and RCu2Ge2 intermetallic compounds
1983-01-01
L3 absorption edges of rare earths, R, in RCu2Si2(except for R = La, Ce, Eu, Er and Lu) and in RCu2Ge2(except for R = La, Ce, Er and Lu) intermetallic compounds are recorded. Shifts in energy of the L3 edge in these systems with respect to corresponding rare-earth metal edge position are measured. It is found that the rare-earth ions exist in a trivalent state except for Eu and Yb. The divalent state of Eu in EuCu2Ge2 and that of Yb in YbCu2Ge2 are established. Shifts in energy of the K absorption edge of Cu in RCu2Si2 and RCu2Ge2(except for Ho and Lu) are also measured. The present results on the K edge shifts of Cu in RCu2Ge2 and RCu2Sii2 are, in general, ...
1992-06-01
Experimental results showing the temperature dependence of the conductivity of a variety of Pr-RE-Ba-Cu-O (RE=Er, Yb, Lu, and Tm) compounds are presented. The semiconducting behavior of the conductivity observed is analysed using ln [sigma][proportional to]T[sup -2/5] and ln [sigma][proportional to]T[sup -1/4] laws suggested, using the small-polaron hopping model by Triberis et al., for the high- and low-temperature regime, respectively. The agreement of the experimental data with these models is very satisfactory, giving a meaningful interpretation of the transport mechanism of these materials. (orig.).
Crystal structure of the R{sub 2}PbS{sub 4} (R = Yb and Lu) compounds
2008-04-03
The crystal structure of the R{sub 2}PbS{sub 4} (R = Yb and Lu) compounds (space group Pnma, Pearson symbol oP28, a = 1.1899(2) nm, b = 0.39015(8) nm, c = 1.4127(2) nm, R1 = 0.0349 for Yb{sub 2}PbS{sub 4} and a = 1.1919(2) nm, b = 0.38890(8) nm, c = 1.4103(3) nm, R1 = 0.0343 for Lu{sub 2}PbS{sub 4}) was investigated by means of X-ray single crystal diffraction. The R atoms are surrounded by octahedra, the Pb atoms by trigonal prisms with one additional atom.
2007-05-15
The luminescence of Yb{sup 3+} in the oxyborate Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} is reported. At low temperature, in addition to the usual ytterbium infrared emission, this phosphor presents an emission in the ultraviolet ({lambda}{sub max}=345nm) which corresponds to the transition from the charge transfer state (O-Yb) to the 4f levels of Yb{sup 3+}. The temperature quenching Tq50% is equal to 120K. The infrared emission studied at room temperature is located between 950 and 1100nm. Europium emission quenching in the Li{sub 2}Yb{sub 5}O{sub 4}(BO{sub 3}){sub 3} phase is related to Eu->Yb transfer by cross-relaxation. The reverse Yb->Eu transfer by cooperative sensitization is highlighted in the codoped Li{sub 2}Lu{sub 5}O{sub 4}(BO{sub 3}){sub 3} compound.
Yb-Yb correlations and crystal-field effects in the Kondo insulator YbB12 and its solid solutions
2003-10-17
We have studied the effect of Lu substitution on the spin dynamics of the Kondo insulator YbB12 to clarify the origin of the spin-gap response previously observed at low temperature in this material. Inelastic neutron spectra have been measured in Yb1-xLuxB12 compounds for four Lu concentrations x = 0, 0.25, 0.90 and 1.0. The data indicate that the disruption of coherence on the Yb sublattice primarily affects the narrow peak structure occurring near 15-20 meV in pure YbB12, whereas the spin gap and the broad magnetic signal around 38 meV remain almost unaffected. It is inferred that the latter features reflect mainly local, single-site processes, and may be reminiscent of the inelastic magnetic response reported for mixed-valence intermetallic compounds. On the other hand, the lower component at 15 meV is most likely due to dynamic short-range magnetic correlations. The crystal-field splitting in YbB12 estimated from the Er3+ transitions measured in a Yb0.9Er0.1B12 sample, has the same order of magnitude as other relevant energy scales of the system and is thus likely to play a role in the form of the magnetic spectral response.
2007-01-01
Yb3+ (2.7%):Na4Y6F22 and Yb3+(1%):LiLuF4 crystals are grown by the Bridgman-Stockbarger technique. Temperature dependences of the thermal conductivity coefficients and absorption spectra are determined. The radiative lifetime of Yb3+ ions is measured to be 1.94 and 2.13 ms for Yb:NYF and Yb:LLF, respectively, and the spectra of the cross-sections of stimulated emission are calculated. (authors)
Investigation of Anderson lattice behavior in Yb1-xLuxAl3
Measurements of magnetic susceptibility {chi}(T), specific heat C(T), Hall coefficient R{sub H}(T), and Yb valence {nu} = 2 + n{sub f} [f-occupation number n{sub f} (T) determined from Yb L{sub 3} x-ray absorption measurements] were carried out on single crystals of Yb{sub 1-x}Lu{sub x}Al{sub 3}. The low temperature anomalies observed in {chi}(T) and C(T) corresponding to an energy scale T{sub coh} {approx} 40 K in the intermediate valence, Kondo lattice compound YbAl{sub 3} are suppressed by Lu concentrations as small as 5% suggesting these low-T anomalies are extremely sensitive to disorder and, therefore, are a true coherence effect. By comparing the temperature dependence of various physical quantities to the predictions of the Anderson Impurity Model, the slow crossover behavior observed in YbAl{sub 3}, in which the data evolve from a low-temperature coherent, Fermi-liquid regime to a high temperature local moment regime more gradually than predicted by the Anderson Impurity Model, appears to evolve to fast crossover behavior at x {approx} 0.7 where the evolution is more rapid than predicted. These two phenomena found in Yb{sub 1-x}Lu{sub x}Al{sub 3}, i.e., the low-T anomalies and the slow/fast crossover behavior are discussed in relation to recent theories of the Anderson lattice.
RARE-EARTH COMPOUNDS AS HIGH-TEMPERATURE REFRACTORIES. A Bibliography
References (216) are given to journals, reports, and patents published from 1949 to 1960. The elements included are: Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Th, Tm, U, and Yb. A subject index is also given. (P.C.H.)
Magnetic and Moessbauer studies on rare-earth-containing Heusler alloys Pd2RSn (R = Tb--Yb)
1985-01-01
Magnetic susceptibility and 119Sn Moessbauer studies have been carried out on a new series of rare-earth-containing Heusler alloys having the formula Pd2RSn (R = Tb--Yb). The Tm and Yb compounds in this series along with Lu, Sc, and Y compounds are superconducting. The magnetic susceptibility of Pd2TmSn and Pd2YbSn deviates from the Curie-Weiss behavior at low temperatures indicating that crystalline electric field effects are appreciable. Analysis of the magnetic susceptibility data in terms of crystalline electric fields shows that the ground state of the Tm3+ ion is nonmagnetic which, therefore, does not affect the superconducting state. The susceptibility of Yb3+ ions at low temperatures is also reduced from the free-ion value due to the crystalline electric field interaction. The Tb- and ...
1979-01-01
The potential energy curve in different electronic states of LuF, YbF, HoF, TbF, LuH, YbH, LuD, YbD, LuO and PrO have been calculated using RKR method. The dissociation energy of these molecules in their ground state has also been calculated using an empirical electronegativity potential function. The dissociation energy thus obtained has been compared with the other values reported in literature. (author)
4,4'-dipyridyl complexes of rare-earth thiocyanates
1984-01-01
4,4'-Dipyridyl complexes of rare-earth thiocyanates of the formula Ln(4-dipy)/sub 2/(NCS)/sub 3/.5H/sub 2/O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 4-dipy = 4,4'-dipyridyl) have been synthesized. The IR spectra of these compounds and other physical properties are discussed. The thermal decomposition of some compounds (in the order Gd as appropriate Lu) has been investigated.
2008-01-01
Following the strategy of using bifunctional phosphonic acids for the synthesis of new metal phosphonates, the flexible ligand 2-phosphonoethanesulfonic acid, H2O3P-C2H4-SO3H (H3L), was used in a high-throughput (HT) and microwave investigation of rare earth phosphonatoethanesulfonates. The HT-investigation led to six isotypic compounds Ln(O3P-C2H4-SO3) with Ln=Ho (1), Er (2), Tm (3), Yb (4), Lu (5) and Y (6). The syntheses were scaled-up in glass reactor tubes in order to obtain larger amounts for a detailed characterization. Based on these results all compounds could be also synthesized by microwave-assisted heating and the influence of reaction time and stirring rate during the synthesis was established. For compound 2 the crystal ...
Myriad of correlated electron effects found in the RT2Zn20 family
2008-01-01
The dilute, rare earth bearing family of RT2Zn20 (R = rare earth, T transition metal) intermetallic compounds can be tuned to a nearly ferromagnetic Fermi liquid that is closer to the Stoner limit than Pd (for R = Y, Lu and T = Fe). The submersion of moment bearing rare earths (Gd-Tm) into this highly polarizable matrix gives rise to exceptionally high temperature ferromagnetism (e.g. TC=86K for GdFe2Zn20) for a compound with only one moment bearing ion out of 23 in the formula unit. In addition to this d-shell correlated electron behavior, 4f hybridization gives rise to six, new, Yb-based heavy fermion compounds: YbT2Zn20 (T = Fe, Ru, Os, Co, Rh, Ir). These half dozen compounds manifest a range of Yb ion degeneracy values (N) for TapproxTK, ranging from N=4-8. Not only do ...
2010-01-01
Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce-Pd-B and Yb-Pd-B at 850 deg. C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively, employing X-ray single crystal and powder diffraction. Phase relations in the Ce-Pd-B system at 850 deg. C are governed by formation of extended homogeneity fields, tau2-CePd8B2-x (0.10tau3-Ce3Pd25-xB8-y (1.063Bx (03. Crystallographic parameters for the new structure type tau2-CePd8B2-x (space group C2/c, a=1.78104(4) nm, b=1.03723(3) nm, c=1.16314(3), ...
Process for producing a cycloolefin
1987-07-07
A process is described for producing a cycloolefin which comprises partially hydrogenating a monocyclic aromatic hydrocarbon in the presence of water, an alkaline agent and a ruthenium catalyst composed of a solid carrier and a ruthenium component supported thereon. The solid carrier consists essentially of at least one rare earth element compound, the rare earth element being selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y. The carrier supports 0.01 to 10 wt. % of the ruthenium component, based on the solid carrier.
Iodides of hexaantipyryllanthanides
1982-01-01
The data on the study of phase equilibrium in the systems LnI/sub 3/- AP-H/sub 2/O, (Ln=Gd, Yb, Lu) AP-antipyrine at 0 deg C are presented. It is shown, that complete replacement of water in aquo-cations of lanthanides by antipyrine takes place. At that, the properties of the initial LnI/sub 3/x9H/sub 2/O and compounds formed (Ln(AP)/sub 6/)I/sub 3/ differ sharply.
1981-01-01
Using the methods of solubility and spectrophotometry interaction of La3+ and Ln3+ (Pr3+, Nd3+, Gd3+, Tb3+, Er3+, Yb3+ and Lu3+) ions with electroneutral oxidized riboflavin (RF) in the aqueous solution is studied. It is established that lanthanides (3) form with RF complex compounds with one and two Ln(3) ions in a molecule. Stability constants of the complexes are determined and the assumption is made on the places of binding of lanthanides with RF molecule
2006-01-01
Texture peculiarities (preferred orientation of nanometric structural blocks) are studied of cationic and anionic constituents of structures of phosphate compounds forming in the Ln2O3-P2O5 (Ln=Er, Tm, Yb, Lu) systems. It is shown that nanostructuring during phosphate formation is regulated by two contrary vector processes of fragmentation of corresponding endless cationic and anionic elements right up to [LnOn] polyhedrons and [PO4] tetrahedrons
2009-01-01
Activation cross sections of the natYb(p,xn)169Lu reaction have been measured for the first time up to 70 MeV to investigate the production possibility of the radionuclide 169Yb through decay of its parent 169Lu. The cross sections were measured using the stacked foil irradiation technique and gamma spectrometry. The experimental data were compared with the results of the ALICE-IPPE theoretical model code. Different production routes were compared for the internal radiotherapy related radioisotope 169Yb. Above 30 MeV proton energy the integral yield of the natYb(p,xn)169Lu reaction is higher than that of the earlier investigated 169Tm(p,n)169Yb, 169Tm(d,2n)169Yb, ...
2008-01-01
Complex sulfides with the SrS: Ln2S3 ratio equal to 3:1, 1:3, or 1:4 for Ln = Y or Lu have been predicted on the basis of thermodynamic analysis of previously designed SrS-Ln2S3 (Ln = Tb, Dy, or Er) phase diagrams. Phase diagrams for the SrS-Ln2S3 (Ln = Tm, Lu, or Sc) systems have been designed for the first time. These systems form congruently melting compounds SrLn2S4 (CaFe2O4 type structure, orthorhombic crystal system). Unit cell parameters, heats of melting, and microhardness have been determined. For SrTm2S4, the respective values are as follows: a=1.181 nm, b=1.421 nm, c=0.396 nm, 2040 K, DELTAH m=188 kJ/mol, 3500 MPa. For SrLu2S4: a=1.187 nm, b=1.416 nm, c=0.392 nm, ...
2010-01-01
Solid-state Ln(L)3 compounds, where Ln stands for trivalent Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, and L is 3-methoxybenzoate, have been synthesized. X-ray powder diffractometry, infrared spectroscopy, complexometry and elemental analysis were used to characterize the compounds. In order to study the thermal behaviour of these compounds simultaneous thermogravimetry and differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC) were used. The results provided information on the composition, dehydration, polymorphic transformation, thermal stability and thermal decomposition of the synthesized compounds.
Excitation functions of alpha-particle induced nuclear reactions on natural ytterbium
2008-01-01
Excitation functions of the reactions natYb(alpha,xn)170,171,173,175,177m2Hf, natYb(alpha,x)171g,172g,177g,178mLu and natYb(alpha,x)169g,177gYb have been measured up to 39 MeV, among them seven (170,171,173,177m2Hf, 177g,178mLu, 177gYb) are reported for the first time. The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE and to the only data-set found in the literature. Yields of different production routes of the therapeutically relevant 177Lu are compared
2010-01-01
Polycrystalline uranium-bearing compounds Y6U1O12, Gd6U1O12, Ho6U1O12, Yb6U1O12, and Lu6U1O12 samples were irradiated with various ions species (300 keV Kr++, 400 keV Ne++, and 100 keV He+) at cryogenic temperature (approx100 K), and the microstructures were examined following irradiation using grazing incidence X-ray diffraction and transmission electron microscopy. The pristine samples are characterized by an ordered, fluorite derivative structure, known as the delta phase. This structure possesses rhombohedral symmetry. Amorphization was not observed in any of the irradiated samples, even at the highest dose ...
2008-01-01
Spectroscopic properties of Yb3+-doped MI3MIII(PO4)2 and (MI=an alkali metal: Na, Rb; MIII=trivalent cation Lu or Y) are reported. In order to study their optical characteristics, the absorption, emission and luminescence excitation spectra have been measured at 4, 10 and 293K in the VUV to IR range. Systematic comparison of the absorption spectra, intensity of the f-f transitions and emission efficiency of ytterbium in all the types of the investigated compounds have been made. Luminescence of the samples has been excited using various excitation lines, including the synchrotron radiation. Strong fundamental 2F5/22F7/2 emission in the IR range has been observed. The double peak spectrum typical for the Yb3+ charge transfer (CT) luminescence has been recorded after synchrotron radiation ex...
4,4'-dipyridyl and 2,2'-dipyridyl complexes of rare-earth perchlorates
1982-01-01
4,4'-dipyridyl and 2,2'-dipyridyl complexes of rare-earth perchlorates of the formula Ln(4-dipy)/sub 8/(ClO/sub 4/)/sub 3/HClO/sub 4/.4 H/sub 2/O (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 4-dipy = 4,4'-dipyridyl) and Ln(2-dipy)/sub 3/(ClO/sub 4/)/sub 3/.6 H/sub 2/O (Ln = Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Y, 2-dipy = 2,2'-dipyridyl) have been synthesized. The IR spectra of these compounds and other physical properties are discussed.
1983-03-20
L/sub 3/ absorption edges of rare earths, R, in RCu/sub 2/Si/sub 2/(except for R = La, Ce, Eu, Er and Lu) and in RCu/sub 2/Ge/sub 2/(except for R = La, Ce, Er and Lu) intermetallic compounds are recorded. Shifts in energy of the L/sub 3/ edge in these systems with respect to corresponding rare-earth metal edge position are measured. It is found that the rare-earth ions exist in a trivalent state except for Eu and Yb. The divalent state of Eu in EuCu/sub 2/Ge/sub 2/ and that of Yb in YbCu/sub 2/Ge/sub 2/ are established. Shifts in energy of the K absorption edge of Cu in RCu/sub 2/Si/sub 2/ and RCu/sub 2/Ge/sub 2/(except for Ho and Lu) are also measured. The present results on the K edge shifts of Cu in RCu/sub 2/Ge/sub 2/ and RCu/sub 2/Sii/sub 2/ are, in general, consistent with the available NMR measurements on the same systems.
1975-01-01
The subject is covered in chapters entitled: nuclear magnetic resonance spectroscopy. Nuclear quadrupole resonance spectroscopy. Microwave spectroscopy. Vibrational spectra of small symmetric species and of single crystals. Characteristic vibrational frequencies of compounds containing main-group elements. Vibrational spectra of transition-element compounds. Vibrational spectra of some co-ordinated ligands, Moessbauer spectroscopy. References are made to the following elements of nuclear interest: Cs, Be, Sr, Sc, Zr, Nb, Ta, Mo, W, Re, Ru, Cd, I, V, Te, B, In, Y, Hf, Am, Np, Pu, Pa, Th, U, Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, Yb, as well as some general references to lanthanides and actinides. (U.K.)
2009-01-01
A novel tridentate neutral organophosphorus compound, tetra-(p-tolyl)[(o-phenylene)oxymethylene] diphosphine dioxide (I) has been synthesized and its extracting ability for microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 and NH4NO3 aqueous solutions has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes and conditional extraction constants of Ln(III) have been determined. The extraction behavior of compound I is compared with that of the diglycolamide ligand TODGA. The potentialities of polymeric resin impregnated with compound I for the preconcentration of lanthanides(III) from ...
Computer modeling of Ba2RE3+NbO6 (RE3+ = rare-earth and Y) compounds
2009-01-01
In this work we have performed atomistic simulations in Ba2RE3+NbO6 (RE3+ = La, Ce, Nd, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) compounds in order to predict their physical properties and behavior under lanthanide substitutions. The potential model adopted describes very well the structural and dielectric properties of these materials. The dependence of the tolerance factor on their physical properties was investigated and the results indicate that the lattice energy, sound velocities and bulk modulus do not show morphotropic phase boundaries between the three phases in which these compounds crystallize. These observables have a linear dependence on the tolerance factor. Only the elastic constant shows morphotropic phase boundaries
An inelastic neutron scattering study of the spin dynamics of Yb{sub 1-x}Lu{sub x}Al{sub 3}.
1998-09-11
We present the results of a systematic inelastic neutron scattering study of the spin dynamics of the mixed valent compound YbAl{sub 3} doped with nonmagnetic lutetium. The aim of the investigation is to clarify the origin of the unusual gap-like magnetic response observed in YbAl{sub 3}, which can be modeled by two inelastic peaks: a narrow peak at 34 meV with HWHM, r = 6.4 {+-} 0.8 meV and a broad peak at 44 meV with {Lambda} = 30 {+-} 1 meV. Lutetium substitution leads to a substantial increase in the linewidth ({Lambda} = 9 {+-} 1 meV at x = 0.1) and a decrease in the intensity (down by 60% at x = 0.1) of the narrow component, with a negligible effect on the broad inelastic peak. This trend is confirmed with higher doping resulting in the complete suppression of the narrow peak at x {ge} 0.35. The results indicate that the narrow component arises from coherent excitation processes within the hybridized 4f-band, which are destroyed by disorder, while the broad component is not so sensitive to the loss of coherence.
1991-05-01
Ammonium lanthanide double sulphate dihydrates NH{sub 4}Ln(SO{sub 4}){sub 2}.2H{sub 2}O (Ln=Er, Tm, Yb, Lu and Y) were synthesized and characterized by chemical, infrared, thermal and X-ray diffraction methods. The X-ray data showed that the crystals are monoclinic, space group P2{sub 1}/c, with four formula units per unit cell. The compounds are structurally isomorphous with KLu(SO{sub 4}){sub 2}.2H{sub 2}O reported in the literature, and the metal ion is coordinated to eight oxygen atoms. The infrared spectra suggested that both water molecules are coordinated to the metal ion. The compounds lost both water molecules between 120 and 225deg C. The heat of dehydration was calculated from measurements of the peak area under the differential thermal analysis curve, recorded during thermal dehydration of the compounds. It showed satisfactory agreement with the heat of dehydration obtained by the solution calorimetric method for NH{sub 4}Lu(SO{sub 4}){sub 2}.2H{sub 2}O. (orig.).
1984-01-01
Values or limits are provided for the Gibbs free energies of formation of A/sub n/B/sub m/ intermetallic compounds for 84 binary systems. A elements are: Li, Be, Mg, Ca, Sr, Ba, Al, Si, Sc, Ti, V, Mn, Fe, Co, Ni, Y, Zr, Nb, Hf, Ta, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U, and Pu. B elements are Fe, Co, Ni, Ru, Rh, Pd, Ag, Re, Os, Ir, Pt, and Au. The significance and applications of this information are discussed.
Benzohydroxamates of rare earths. Benzgidroksamaty redkozemel'nykh ehlementov
1984-01-01
Benzohydroxamates of the composition M(C6H5CONMO)3, M(C6H5CONHO)3x3Phen, where M-La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y as Well as Na2[M(C6H5CONHO)3EDTA].x5H2O, where M=REE are synthesized By the method of X-ray phase analysis individuality of isolated compounds is shown. On the basis of physicochemical properties (solubility, molar conductivity) of the compounds and their IR spectrum data bidentate cyclic coordination of benzohydroxamate-ion is shown
Benzohydroxamates of rare earths
1984-01-01
Benzohydroxamates of the composition M(C/sub 6/H/sub 5/CONMO)/sub 3/, M(C/sub 6/H/sub 5/CONHO)/sub 3/x3Phen, where M-La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y as well as Na/sub 2/(M(C/sub 6/H/sub 5/CONHO)/sub 3/EDTA).x5H/sub 2/O, where M=REE are synthesized by the method of X-ray phase analysis individuality of isolated compounds is shown. On the basis of physicochemical properties (solubility, molar conductivity) of the compounds and their IR spectrum data bidentate cyclic coordination of benzohydroxamate-ion is shown.
2003-08-01
The EPR g factors g {sub parallel} and g {sub perpendicular} {sub to} of Yb{sup 3+} and the hyperfine structure constants A {sub parallel} and A {sub perpendicular} {sub to} of {sup 171}Yb{sup 3+} and {sup 173}Yb{sup 3+} in crystals of the zircon-structure orthophosphates YPO{sub 4}, LuPO{sub 4}, and ScPO{sub 4} are calculated from the calculation formulas of the EPR parameters for a 4f{sup 13} ion in tetragonal symmetry. In these formulas, the contributions to the EPR parameters from the J-mixing between the ground {sup 2}F{sub 7/2} and excited {sup 2}F{sub 5/2} states, the admixtures between the lowest Kramers doublet {gamma}{gamma} and the other 6 Kramers doublets (or irreducible representations) via the crystal-field and orbital angular momentum (or hyperfine structure) interactions and the covalency reduction effect are included. The calculated values agree with the observed ones. In the calculations, the superposition model is used to estimate the crystal-field parameters. It is found intrinsic parameters A(R{sub 0}) that the superposition model with the same R{sub 0} for Yb{sup 3+} in various zircon-type compounds obtained by considering local lattice relaxation are not scattered as those obtained by using the structural data of pure zircon-type compounds. It appears that, in order to obtain suitable superposition model parameters, the local lattice relaxation should be taken in to account. (orig.)
Hydrothermal synthesis and luminescence properties of Yb3+ doped rare earth stannates
2009-01-01
Yb3+ doped rare earth stannate [Ln2Sn2O7 (Ln = La, Y, Lu, Gd)] nanocrystals were successfully prepared by a simple hydrothermal method. All the products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which revealed that they are pyrochlore-type rare earth stannate nanocrystals with the diameter of about 15 nm. Room temperature photoluminescence spectra showed that the Y2Sn2O7:Yb3+ and Lu2Sn2O7:Yb3+ nanocrystals exhibited strong broad emission bands centered at about 532 and 500 nm which was reported for the first time, while no obvious luminescence properties were found in the La2Sn2O7:Yb3+ and ...
2008-07-01
Excitation functions of the reactions {sup nat}Er({alpha},x){sup 167,169}Yb, {sup nat}Er({alpha},x){sup 172,173}Tm, {sup nat}Yb({alpha},x){sup 170,173,175,177m2}Hf, {sup nat}Yb({alpha},x){sup 171,172,177g,178m}Lu and {sup nat}Yb({alpha},x){sup 169,177}Yb were measured up to 38 MeV for application purposes (medical isotope production and charged particle activation analysis). The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE. The literature is very poor regarding cross section measurements on erbium or ytterbium irradiated with alpha particles. Yields of different production routes (proton-, deuteron- and alpha-irradiation) of {sup 169}Yb and {sup 177}Lu are compared. We can conclude that the production of {sup 169}Yb and {sup 177}Lu by using an alpha-beam on natural erbium and natural ytterbium targets is not a defendable alternative.
Magnetic Ordering and Superconductivity in the RE$_2$Ir$_3$Ge$_5$ (RE = Y, La-Tm, Lu) System
2003-11-19
We find that the compounds for RE = Y, La-Dy, crystallize in the tetragonal Ibam (U$_2$Co$_3$Si$_5$ type) structure whereas the compounds for RE = Er-Lu, crystallize in a new orthorhombic structure with a space group Pmmn. Samples of Ho$_2$Ir$_3$Ge$_5$ were always found to be multiphase. The compounds for RE = Y to Dy which adopt the Ibam type structure show a metallic resistivity whereas the compounds with RE = Er, Tm and Lu show an anomalous behavior in the resistivity with a semiconducting increase in $\\rho$ as we go down in temperature from 300K. Interestingly we had earlier found a positive temperature coefficient of resistivity for the Yb sample in the same temperature range. We will compare this behavior with similar observations in the compounds RE$_3$Ru$_4$Ge$_{13}$ and REBiPt. La$_2$Ir$_3$Ge$_5$ and Y$_2$Ir$_3$Ge$_5$ show bulk superconductivity below 1.8K and 2.5K respectively. Our results confirm that Ce$_2$Ir$_3$Ge$_5$ shows a Kondo lattice behavior and undergoes antiferromagnetic ordering below 8.5K. Most of the other compounds containing magnetic rare-earth elements undergo a single antiferromagnetic transition at low temperatures (T$\\leq$12K) while Gd$_2$Ir$_3$Ge$_5$, Dy$_2$Ir$_3$Ge$_5$ and Nd$_2$Ir$_3$Ge$_5$ show multiple transitions. The T$_N$'s for most of the compounds roughly scale with the de Gennes factor. which suggests that the chief mechanism of interaction leading to the magnetic ordering of the magnetic moments may be the RKKY interaction.
Thermal Conductivity in Magnetic Superconductors
2003-01-14
We present here an overview of thermal conductivity behavior in magnetic superconductors: rare-earth nickel borocarbide intermetallic compounds, RNi_{2}B_{2}C, and the 2122 rare-earth rutheno-cuprates. The borocarbide family of intermetallics exhibits the large variety of phenomena - only superconductivity (R = Y, Lu), coexistence of superconductivity and magnetic order (R = Tm, Er, Ho, Lu), only magnetic order (R = Tb, Gd), and heavy fermion behavior (R = Yb) - within the same crystal structure. The rutheno-cuprate Eu_{1.5}Ce_{0.5}RuSr_2Cu_{2}O_{10-\\delta} exhibits coexistence of weak ferromagnetism and superconductivity at a surprisingly high temperature (\\approx 45 K) and onset of antiferromagnetic order near 200 K. We demonstrate how coexistence of superconductivity and magnetic order in these compounds is releaved by the thermal conductivity studies.
Rare earth orotates. Orotaty redkozemel'nykh ehlementov
1978-01-01
Rare earth orotates of the Ln(C5H3N2O4)xnH2O composition, where Ln=Y, La, Pr, Nd, Eu, Gd, Ho, Er, Tm, Yb, Lu, are synthesized, and some of their properties investigated. The synthesis was carried out by dissolving rare earth carbonates in boiling saturated solution of orotic acid in the mole ratio of 1:3. The obtained compounds are barely soluble in water. Their solubility decreases along the La-Lu series. The orotate density, determined picnometrically, varies from 1.62 to 2.24. The compounds are not thermostable and decompose without melting. The thermal analysis of orotates was carried out by the derivatographical method. The infrared spectra investigation showed levelling of bonds of C-0 carboxyl group. The carbonyl group of ring did not participate in coordination of rare earth ion
2008-01-01
By means of the mass spectrometry and using a binary two-temperature effusion cell one investigated into La(hfa)3, Nd(hfa)3, Sm(hfa)3, Gd(hfa)3, Dy(hfa)3, Ho(hfa)3, Yb(hfa)3, Lu(hfa)3 overheated vapors to determine the type of the molecular forms occurring within the vapor at its various overheating values and to determine the temperature of the full dissociation of the compounds. In case of the equal temperature within the effusion cell upper and lower chambers, as well as, in case of an insignificant overheating, the vapors of the listed compounds are strongly oligomerized (one revealed mono-, di- and trimeric forms). The vapor overheating demonstrates the low thermal stability of the oligomeric forms, the stability of which decreases within La-Lu chain. One ...
2010-01-01
A series of aminopyridinate-stabilized dialkyl-lanthanoid complexes has been synthesized and characterized. The complexes were prepared by alkane elimination reacting [Ln(CH2SiMe3)3(thf)2] (Ln = Er, Yb, Lu) or [Ln(CH2Ph)3(thf)3] (Ln = Y, Er, Lu) with one equivalent of the bulky aminopyridine (2,6-diisopropylphenyl)-[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine . Single-crystal X-ray analyses were carried out for all of the benzyl derivatives. The reaction of these compounds with ammonium borate leads to the elimination of one of the two alkyl functions and affords organolanthanoid cations. The aminopyridinate-stabilized dialkyl-lanthanoid compounds can initiate the polymerization of isoprene after activation with perfluorinated tetraphenyl borates. The obtained polymers have a 3,4-conten...
2004-01-01
We investigated the effect of spin polarization on the structural properties and the electric field gradient (EFG) on Sn, In, and Cd impurities in RSn3 (R=Sm, Eu, Gd) and RIn3 (R=Tm, Yb, Lu) compounds. The calculations were performed self-consistently using the scalar-relativistic full potential linearized augmented plane wave method. The local density approximations and generalized gradient approximation (GGA) without spin polarization and with spin polarization (GGA+SP) to density functional theory were applied. In addition to that we performed some calculations within open core treatment (GGA+open core). It is clearly seen that GGA+SP is successful in predicting the larger lattice parameter and the dramatic drop of EFG for R=(Eu, Yb) relative to other rare-earth compounds
2002-12-02
We investigated the effect of spin polarization on the structural properties and gradient of electric field (EFG) on Sn, In, and Cd impurity in RSn$_3$ (R=Sm, Eu, Gd) and RIn$_3$ (R=Tm, Yb, Lu) compounds. The calculations were performed self-consistently using the scalar-relativistic full potential linearized augmented plane wave method. The local density approximations (LDA) and generalized gradient approximation without spin polarization (GGA) and with spin polarization (GGA+SP) to density functional theory were applied. In addition to that we performed some calculations within open core treatment (GGA+open core). It is clearly seen that GGA+SP is successful in predicting the larger lattice parameter and the dramatic drop of EFG for R=(Eu, Yb) relative to other rare earth compounds. This is an indication that spin splitting generated by spin polarization without any modification, is capable of treating properly the highly correlated f electrons in these systems.
2004-06-15
We investigated the effect of spin polarization on the structural properties and the electric field gradient (EFG) on Sn, In, and Cd impurities in RSn{sub 3} (R=Sm, Eu, Gd) and RIn{sub 3} (R=Tm, Yb, Lu) compounds. The calculations were performed self-consistently using the scalar-relativistic full potential linearized augmented plane wave method. The local density approximations and generalized gradient approximation (GGA) without spin polarization and with spin polarization (GGA+SP) to density functional theory were applied. In addition to that we performed some calculations within open core treatment (GGA+open core). It is clearly seen that GGA+SP is successful in predicting the larger lattice parameter and the dramatic drop of EFG for R=(Eu, Yb) relative to other rare-earth compounds.
2007-01-23
We investigated the effect of spin polarization on the structural properties and gradient of electric field (EFG) on Sn, In, and Cd impurity in RSn$_3$ (R=Sm, Eu, Gd) and RIn$_3$ (R=Tm, Yb, Lu) compounds. The calculations were performed self-consistently using the scalar-relativistic full potential linearized augmented plane wave method. The local density approximations (LDA) and generalized gradient approximation without spin polarization (GGA) and with spin polarization (GGA+SP) to density functional theory were applied. In addition to that we performed some calculations within open core treatment (GGA+open core). It is clearly seen that GGA+SP is successful in predicting the larger lattice parameter and the dramatic drop of EFG for R=(Eu, Yb) relative to other rare earth compounds. This is an indication that spin splitting generated by spin polarization without any modification, is capable of treating properly the highly correlated f electrons in these systems.
The first high resolution direct NMR observation of an f-block element
1989-04-26
The last decade has seen a dramatic increase in the importance of the organometallic chemistry of the lanthanide elements. In particular, iodides, cyclopentadienyls, and bis(trimethylsilyl)amides of Sm(II), Eu(II), or Yb(II), due to their unique reactivity (e.g., as selective reducing agents), have attracted much attention. Yet high resolution, solution-state NMR, one of the organometallic chemists most informative tools, has not previously been applied to the direct observation of an f-block element, excluding complexes of the f{sup 0} La(III). The reason for this neglect is probably because the majority of complexes (except those of La(III), Yb(II), and Lu(III)) are paramagnetic, and many of the NMR-active f-block nuclei have large quadrupole moments. Yet for certain of these elements spin-{1/2} isotopes exist, and the range of diamagnetic compounds is rapidly increasing. As a case in point, {sup 171}Yb is a spin-{1/2}nucleus, with a natural abundance of 14.27% and a moderately sized, positive gyromagnetic ratio (4.4712 {times} 10{sup 7} rad T{sup {minus}1} s{sup {minus}1}); these features combine to give a receptivity four times greater than that of {sup 13}C. Three solid-state, wide-line studies of this nucleus have appeared. The authors now report {sup 171}Yb chemical shift solution NMR data for the series of Yb(II) complexes.
Spectral properties of Yb^3^+ ions in Lu3ScAl4O12 single crystal
2010-01-01
In this paper, a Yb^3^+ doped Lu3ScAl4O12 single crystal has been grown by the Czochralski method. The cell parameters were analyzed with X-ray diffraction (XRD). The absorption spectrum, emission spectrum and fluorescence lifetime of Yb:Lu3ScAl4O12 crystal were measured at room temperature. The absorption bandwidth, emission bandwidth, absorption cross-section, emission cross-section and fluorescence lifetime have been estimated as 25nm, 12.6nm, 0.54x10^-^2^0cm^2, 1.47x10^-^2^0cm^2 and 1.43ms. The spectral properties of Yb:Lu3ScAl4O12 crystal were compared with those of Yb:Lu3Al5O12 (Yb:LuAG) crystal. The results indicate that Yb:Lu3ScAl4O12 crystal should be a potential candidate used for generating short pulses in mode-locking operation.
2009-01-01
The structure and phase evolution of nanocrystalline Ce1 x Ln x O2 x/2 (Ln=Yb, Lu, x=01) oxides upon heating in H2 was studied for the first time. Up to 950C the samples were single-phase, with structure changing smoothly with x from fluorite type (F) to bixbyite type (C). For the Lu-doped samples heated at 1100C in the air and H2, phase separation into coexisting F- and C-type structures was observed for ~0.40xx3+ and Yb3+ strongly hinders the crystallite growth of ceria during heat treatment at 800 and 950C in both atmospheres. Valency of Ce and Yb in Ce0.1Lu0.9O1.55 and Ce0.95Yb0.05O1.975 samples heated at 1100C was studied by XANES and magnetic measurements. In the former Ce was dominated by Ce4+, with small contribution of Ce3+...
1975-01-01
The distribution of the lanthanides in the extraction of their nitrates, chlorides, and thiocyanates by neutral oxygen-containing extraction reagents (in 12 systems) was studied. In all the systems on the curves of the distribution coefficient versus atomic number of the element, four subgroups of the elements (four tetrads) appear: La, Ce, Pr, Nd; Pm, Sm, Eu, Gd; Gd, Tb, Dy, Ho; and Er, Tm, Yb, Lu. Between Nd and Pm there is a junction of the first and second tetrads, and between Ho and Er that of the third and fourth. The second and third tetrads are in contact on Gd, and moreover, Gd is the last element of the second tetrad and simultaneously the first element of the third tetrad.
1986-01-01
Rare earth compounds with sulfamic acid are sunthesized and their composition, corresponding to the formula M(NH2SO3)3xnH2O, where M-La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Er, Tm, Yb, and Lu. N=2, 3, is established. Rare earth sulfamates, isolated in solid state, are studied using the methods of IR sectroscopy, thermography and X-ray diffraction. Solubility of rare earth sulfamates in water, depending on temperature, is studied. It is found, that all the salts are characterized by exclusively high solubility in water, increasing with the temperature increase
2010-01-01
In this study, possibilities of heavy lanthanides (Ho3+, Er3+, Tm3+, Yb3+, and Lu3+) separation on Nucleosil 100-5-SA, an ion-exchange column, was investigated. Separation of lanthanides was carried out using an isocratic program of ?-hydroxyisobutyric acid (HIBA) eluent. Fast Fourier transform continuous cyclic voltammetry (FFT-CCV) at a gold microelectrode was used as the detection method. Simplicity, high precision and accuracy, time efficiency, and being economic are advantages of the developed technique in comparison with the previous reported ones. In addition, removal of oxygen from the test solution is not required, the detection limit is suitable and the technique is fast enough for determination of compounds in a wide variety of chromatographic methods. The waveform potential was...
Raman investigations of rare-earth arsenate single crystals
2010-01-01
Polarized Raman spectroscopy was used to investigate the room-temperature phonon characteristics of a series of rare-earth arsenate (REAsO4, RE = Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) single crystals. The Raman data were interpreted in a systematic manner based on the known tetragonal zircon structure of these compounds, and assignments and correlations were made for the observed bands. We found that the wavenumbers of the internal modes of the AsO4 tetrahedron increased with increasing atomic number. This increase seems to be correlated to the contraction of the RE-O bond length. For three out of four lattice wavenumbers observed, this tendency was not nearly so marked as in the case of the internal mode wavenumber. Copyright Copyright 2009 John Wiley & Sons, Ltd.
Raman Investigations of Rare Earth Arsenate Single Crystals 5-8-2009
2009-01-01
Polarized Raman Spectroscopy was used to investigate the room-temperature phonon characteristics of a series of rare-earth arsenate (REAsO4, RE = Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) single crystals. The Raman data were interpreted in a systematic manner based on the known tetragonal zircon structure of these compounds, and assignments and correlations were made for the observed bands. We found that the wavenumber of the internal modes of the AsO4 tetrahedron increased with increasing atomic number, and for three out of four lattice wavenumbers observed, this tendency was not nearly so marked as in the case of the internal mode wavenumber
2008-01-01
The partition of microamounts of rare earth chlorides (RE = La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) between aqueous HCl and organic solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoylmethyl)phosphine oxide, and dibutyl(diethylcarbamoylmethyl)phosphine oxide was studied in the presence of ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The stoichiometry of extracted complexes was determined. The effect of the aqueous HCl concentration, the nature of the extractant, and the organic diluent on the efficiency of rare earth extraction was studied
1986-01-01
Synthesis conditions of compact ceramics on the basis of a new group of complex oxides K3Ln(VO4)2 (Ln - La, Pr, Md, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu) are studied using the method of hot pressing, investigation results and certain physico-chemical properties of the samples prepared are presented. It is shown that the new ceramics has a high density, fine-grain structure and according to the values of specific resistance (109-1010 Ohmxcm) it can be assigned to the class of dielectrics. It is characterized by a good mechanical strength. Melting agrees with the corresponding temperatures of individual compounds
Stuffed Rare Earth Pyrochlore Solid Solutions
2006-03-28
Synthesis and crystal structures are described for the compounds Ln2(Ti2-xLnx)O7-x/2, where Ln = Tb, Dy, Ho, Er, Tm, Yb, Lu, and x ranges from 0 to 0.67. Rietveld refinements on X-ray powder diffraction data indicate that in Tb and Dy titanate pyrochlores, extra Ln3+ cations mix mainly on the Ti4+ site with little disorder on the original Ln3+ site. For the smaller rare earths (Ho-Lu), stuffing additional lanthanide ions results in a pyrochlore to defect fluorite transition, where the Ln3+ and Ti4+ ions become completely randomized at the maximum (x=0.67). In all of these Ln-Ti-O pyrochlores, the addition of magnetic Ln3+ in place of nonmagnetic Ti4+ adds edge sharing tetrahedral spin interactions to a normally corner sharing tetrahedral network of spins. The increase in spin connectivity in this family of solid solutions represents a new avenue for investigating geometrical magnetic frustration in the rare earth titanate pyrochlores.
2009-01-01
The existence of further metal-rich condensed cluster compounds in R-Z-Te systems has been synthetically explored for R = Sc, Y, Pr, Dy, Er, Tm, Yb, Lu and, mainly, Z = Ru, Rh, Pd, Ag, Ir, Pt, Au. Ten new examples of orthorhombic Er7Ni2Te2-type (Imm2) have been identified and that for Dy7Ir2Te2 has been refined. Seven new examples of other ternary structure types plus X-ray powder pattern evidence for 14 unknown phases have also been identified. To date the family of ternary R-Z-Te phases appears to be limited to those for R = Sc, Y, and Dy-Lu, a trend that is parallel to but more emphatic than those variations found among parallel cluster halide systems. Stability trends among the halide and especially the telluride series follow the I1 + I2 sums for the R elements well, the larger values...
Crystal structures and magnetic properties of fluorite-related oxides Ln3NbO7 (Ln=lanthanides)
2009-01-01
Crystal structures and magnetic properties of the ternary oxides Ln3NbO7 (Ln=La, Pr, Nd, Sm-Lu) are reported. Their powder X-ray diffraction measurements and Rietveld analyzes show that they have the fluorite-related structures with space group Pnma (Ln=La, Pr, Nd), C2221 (Ln=Sm-Tb), or Fm-3m (Ln=Dy-Lu). Magnetic susceptibility measurements were carried out from 1.8 to 400 K. The Ln3NbO7 compounds for Ln=Pr, Gd, Dy-Yb show Curie-Weiss paramagnetic behavior, and Sm3NbO7 and Eu3NbO7 show van Vleck paramagnetism. On the other hand, two magnetic anomalies were observed for both Nd3NbO7 (0.6 and 2.7 K) and Tb3NbO7 (2.0 and 3.2 K). From the results of specific heat measurements, it was found that these ...
2009-01-01
The effect of anisotropy on the low-field electron spin resonance in the Kondo lattice compounds YbRh2Si2 and YbIr2Si2 is assessed. It is shown that the g-shift in YbRh2Si2 is a consequence of the anisotropy in the Yb-Yb interactions as mirrored in the molecular field parameters characterizing the resonant susceptibility. It is also pointed out that the large residual linewidth for YbIr2Si2 results from the modification of the Korringa contribution that occurs when the Curie susceptibility of the isolated ion is replaced by the resonant susceptibility with an experimentally determined molecular field parameter. (fast track communication)
Photoemission and the electronic properties of heavy fermions -- limitations of the Kondo model
The electronic properties of Yb-based heavy fermions have been investigated by means of high resolution synchrotron radiation photoemission and compared with predictions of the Kondo model. The Yb heavy fermion photoemission spectra show massive disagreement with the Kondo model predictions (as calculated within the Gunnarsson-Schonhammer computational method). Moreover, the Yb heavy fermion photoemission spectra give very strong indications of core-like characteristics and compare favorable to purely divalent Yb metal and core-like Lu 4f levels. The heavy fermions YbCu{sub 2}Si{sub 2}, YbAgCu{sub 4} and YbAl{sub 3} were measured and shown to have lineshapes much broader and deeper in binding energy than predicted by the Kondo model. The lineshape of the bulk component of the 4f emission for these three heavy fermion materials was compared with that from Yb metal and the Lu 4f levels in LuAl{sub 3}, the heavy fermion materials show no substantive spectroscopic differences from simple 4f levels observed in Yb metal and LuAl{sub 3}. Also, the variation with temperature of the 4f fineshape was measured for Yb metal and clearly demonstrates that phonon broadening plays a major role in 4f level lineshape analysis and must be accounted for before considerations of correlated electron resonance effects are presumed to be at work.
Photoemission and the electronic properties of heavy fermions -- limitations of the Kondo model
1993-09-01
The electronic properties of Yb-based heavy fermions have been investigated by means of high resolution synchrotron radiation photoemission and compared with predictions of the Kondo model. The Yb heavy fermion photoemission spectra show massive disagreement with the Kondo model predictions (as calculated within the Gunnarsson-Schonhammer computational method). Moreover, the Yb heavy fermion photoemission spectra give very strong indications of core-like characteristics and compare favorable to purely divalent Yb metal and core-like Lu 4f levels. The heavy fermions YbCu{sub 2}Si{sub 2}, YbAgCu{sub 4} and YbAl{sub 3} were measured and shown to have lineshapes much broader and deeper in binding energy than predicted by the Kondo model. The lineshape of the bulk component of the 4f emission for these three heavy fermion materials was compared with that from Yb metal and the Lu 4f levels in LuAl{sub 3}, the heavy fermion materials show no substantive spectroscopic differences from simple 4f levels observed in Yb metal and LuAl{sub 3}. Also, the variation with temperature of the 4f fineshape was measured for Yb metal and clearly demonstrates that phonon broadening plays a major role in 4f level lineshape analysis and must be accounted for before considerations of correlated electron resonance effects are presumed to be at work.
Study on the /sup 171/Lu decay
1984-02-01
The /sup 171/Lu decay schemes are specified and supplemented. Energies and intensities of ..gamma..-transitions accompanying /sup 171/Lu ..-->.. /sup 171/Yb decay are presented along with coefficients of electron internal conversion and transition multipolarity. ..gamma..-transition suppression factors are also presented. A scheme of /sup 171/Lu ..-->.. /sup 171/Yb decay is proposed on the base of the analysis of the data obtained with the use of information on e..gamma..-coincidences and in nuclear reactions. This scheme is presented in a table form with indication of energies and transition multipolarities, spin-parities and log ft levels. 23 transition (from 88) can not be described by the scheme, that accounts for 0.24% of the decay total intensity.
Solar abundance of 176Lu and s-process nucleosynthesis
2006-01-01
The isotopic composition of lutetium has been measured with high precision using a thermal ionization mass spectrometer whose linearity was verified by measuring an isotopically certified reference material for potassium prepared by the National Institute of Standards and Technology (NIST 985). The abundance sensitivity of the mass spectrometer for the measured ion beams of Lu+ was examined to ensure the absence of tailing effects and interfering ion beams. The isotope fractionation of the measured 176Lu/175Lu ratio was estimated with reference to the isotope fractionation of ytterbium (whose isotopes are in the same mass region as lutetium), which was recently measured in this laboratory using gravimetrically prepared solutions of the enriched isotopes 171Yb and 176Yb. This is the first reported ...
Preparation of micrograms of 173,174Lu
2007-01-01
In order to measure the decay data of 173,174Lu, a procedure for separation of micro- grams of 173,174Lu from grams of Yb is needed. Cation exchange column chromatography was used to separate 173,174Lu from irradiated natural Yb target with polystyrene sulfonate ion ex- change resins (type 002 x 8, grain size 40-50 mum) as the fixed phase and aqueous solution of alpha- HIBA (alpha-hydroxyisobutyric acid) as the eluent. The effects of temperature and carrier amounts on the separation were studied. A series of methods for removal of alpha-HIBA from the eluate were studied and compared, including decomposition with concentrated HClO4-HNO3, cation exchange chromatography, hydroxide precipitation, solvent extraction with HDEHP, and HDEHP extraction ...
Electronic structure and bulk properties of MB6 and MB12 borides
2008-01-01
Ab initio band structure calculations are carried out for the higher borides MB6 and MB1-2. High-precision measurements of the elastic constants are performed for the compounds ZrB12, HoB12, ErB12, TmB12, LuB12, YB6 and LaB6 at low temperatures. The bulk properties of the borides are analyzed on the basis of the calculated equations of states and balanced crystal orbital overlap populations. Our calculations indicate that hexaborides with divalent metals, CaB6, SrB6, BaB6, and YbB6, are semiconductors with small energy gaps. The metallic MB6 hexaborides with trivalent M atoms are found to possess larger bulk moduli values. For dodecaborides the bulk moduli are found to be higher for ...
Electron spin resonance of dense Yb-based heavy-fermion compounds: New experimental data
2009-01-01
We report the more recent advances in electron spin resonance (ESR) of few undoped Yb-based intermetallic compounds with heavy fermions (HF). The X-band ESR spectra of the Kondo lattices YbBiPt, YbRh2Pb, and YbT2Zn20 (T = Fe, Co) are presented. A comparison with earlier ESR studies in YbRh2Si2 and YbIr2Si2 shows that the exchange interactions between the Yb 4f electrons and relevant conduction electron (d-, s-, or p-like) bands as well as the hybridization crystalline electric field (CEF) effects should be taken into account in order to develop a reliable model of spin dynamics in the Yb-based HF systems
Structure, charge ordering and physical properties of Yb2Fe3O7
2010-01-01
The structural and physical properties of the layered Yb2Fe3O7 have been extensively investigated. Transmission electron microscopy (TEM) observations at room temperature reveal the presence of diffuse zigzag-type streaks at 1/3(hhl) running along the c* axis direction, suggesting the presence of a charge ordered state with a shorter coherence length in comparison with that in Lu2Fe3O7. The measurements of magnetization demonstrate that the replacement of Lu3+ by the magnetic Yb3+ ion in this layered system could result in visible effects on the low-temperature magnetic properties: the ferrimagnetic phase transition temperature decreases and an additional magnetic anomaly possibly attributed to antiferromagnetic coupling between Yb and Fe layers appears at around 50K. Analysis of the...
Trapping and self-trapping in ytterbium-doped oxides with charge transfer luminescence
2009-01-01
Temperature dependence of the charge transfer luminescence (CTL) of Yb-doped yttrium aluminum garnet Y3Al5O12-Yb (YAG-Yb) and Yb-doped lutetium aluminum perovskite LuAlO3-Yb (LuAP-Yb) crystals under X-ray excitation and their thermostimulated luminescence are investigated in the temperature range 30-350 K and compared to those of undoped crystals. Simulation using a set of kinetic equations describing the processes of creation of excitons, electron-hole pairs, their trapping and self-trapping, radiative relaxation and quenching is presented for the systems under investigation to analyze qualitatively two different types of experimentally observed temperature dependences: CTL yield decline with the temperature decrease below 110 K as in case of YAG-Yb and constant yield in the same temperature range as in ...
High resolution in-beam. gamma. -spectroscopy
1985-03-15
The authors describe a crystal spectrometer installed at the SIN cyclotron to measure in-beam gamma spectra. Results are presented of the prompt gamma spectra from the /sup 176/Yb(p,3n..gamma..)/sup 174/Lu reaction.
Experimental determinations of the mineral/liquid partition coefficients of REE (La, Sm, Eu, Gd, Tb, Yb and Lu), Sc and Sr are reported for the minerals perovskite, spinel and melilite in synthetic systems. Perovskite ...
Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce-Pd-B and Yb-Pd-B at 850 C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively, employing X-ray single crystal and powder diffraction. Phase relations in the Ce-Pd-B system at 850 C are governed by formation of extended homogeneity fields, ?2-CePd8B2?x (0.10<x<0.48); ?3-Ce3Pd25?xB8?y (1.06<x<1.87; 2.20<y<0.05), and CePd3Bx (0<x<0.65) the latter arising from binary CePd3. Crystallographic parameters for the new structure type ?2-CePd8B2?x (space group C2/c, a=1.78104(4) nm, b=1.03723(3) nm, c=1.16314(3), ?=118.515(1) for x=0.46) were established from X-ray single crystal diffraction. The crystal structures of ?2-CePd8B2?x and ?3-Ce3Pd25?xB3?y are connected in a crystallographic group-subgroup relationship. Due to the lack of suitable single crystals, the novel structure of ?1-Ce6Pd47?xB6 (x=0.2, C2/m space group, a=1.03594(2) nm, b=1.80782(3) nm, c=1.01997(2) nm, ?=108.321(1)) was determined from Rietveld refinement of X-ray powder diffraction data applying the structural model obtained from single crystals of homologous La6Pd47?xB6 (x=0.19) (X-ray single crystal diffraction, new structure type, space group C2/m, a=1.03988(2) nm, b=1.81941(5) nm, c=1.02418(2) nm, ?=108.168(1)). The Yb-Pd-B system is characterized by one ternary compound, ?1-Yb2Pd14B5, forming equilibria with extended solution YbPd3Bx, YbB6, Pd5B2 and Pd3B. The crystal structures of both Yb2Pd14B5 and isotypic Lu2Pd14B5 were determined from X-ray Rietveld refinements and found to be closely related to the Y2Pd14B5-type (I41/amd). The crystal structure of binary Yb5Pd2?x (Mn5C2-type) was confirmed from X-ray single crystal data and a slight defect on the Pd site (x=0.06) was established. The three structures ?1-Ce6Pd47?xB6, ?2-CePd8B2?x and ?3-Ce3Pd25?xB8?y are related and can be considered as the packings of fragments observed in Nd2Fe14B structure with different stacking of common structural blocks. Physical properties for Yb2Pd13.6B5 (temperature dependent specific heat, electrical resistivity and magnetization) yielded a predominantly Yb-4f13 electronic configuration, presumably related with a magnetic instability below 2 K. Kondo interaction and crystalline electric field effects control the paramagnetic temperature domain.
1992-01-01
Synergic extraction of Yb(III) and Lu(III) has been carried out with thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) in chloroform from aqueous perchlorate media from pH 1 to 6. The results demonstrate antisynergic effect from pH 3 to 6 in the extracton of Lu(III). The stoichiometric composition at pH 3 was established to be M(TTA)[sub 3]x3TBA, where M=Yb(III) and Lu(III). However, the composition of synergic adducts at pH 6 was Yb(TTa)[sub 3]x3TBA and Lu(TTA)[sub 3]xTBA. The change in the coordination number of the synergic adduct of Lu(III) at different pHs was further investigated through thermodynamic functions like enthalpy, entropy and Gibbs free energy. The mechanism of synergism and antisynergism of the synergic adducts at pH 3 and 6 has been discussed. The formation and stability constants have been determined. (orig.).
1992-01-01
Synergic extraction of Yb(III) and Lu(III) has been carried out with thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) in chloroform from aqueous perchlorate media from pH 1 to 6. The results demonstrate antisynergic effect from pH 3 to 6 in the extracton of Lu(III). The stoichiometric composition at pH 3 was established to be M(TTA)3x3TBA, where M=Yb(III) and Lu(III). However, the composition of synergic adducts at pH 6 was Yb(TTa)3x3TBA and Lu(TTA)3xTBA. The change in the coordination number of the synergic adduct of Lu(III) at different pHs was further investigated through thermodynamic functions like enthalpy, entropy and Gibbs free energy. The mechanism of synergism and antisynergism of the synergic adducts at pH 3 and 6 has been discussed. The formation and stability constants have been determined. (orig.)
1979-01-01
The conditions of thermal decomposition of La, Ce, Pr Nd, Sm, Eu, Gd, Ho, Er, Yb, Lu, and Y anisates were studied. The results showed that hydrated anisates of La, and Ce lost their water of crystalization, formed anhydrous salts and, then decomposed into oxides. Anhydrous anisates of La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Ho, Yb, Lu, and Y decomposed into oxides at a temperature of 973-1093 K. The values of the activation energy of dehydration reactions of lanthanum and cerium anisates have been determined. (author)
Thermal decomposition of rare earths anisates
1979-01-01
The conditions of thermal decomposition of La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Er, Yb, Lu, and Y anisates were studied. The results showed that hydrated anisates of La, and Ce lost their water of crystalization, formed anhydrous salts and, then decomposed into oxides. Anhydrous anisates of La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Ho, Yb, Lu, and Y decomposed into oxides at a temperature of 973-1093 K. The values of the activation energy of dehydration reactions of lanthanum and cerium anisates have been determined.
Coordination of lanthanide nitrates with N,N,N{prime},N{prime}-tetramethylsuccinamide
1999-10-04
Two compound classes have been identified from the reaction of trivalent lanthanide nitrates with tetramethylsuccinamide (TMSA). The nature of these Ln-TMSA compounds has been examined in the solid phase by thermogravimetric analysis (TGA) and single-crystal X-ray diffraction and in solution by infrared spectroscopy. Isostructural, 10-coordinate compounds with a 2:1 TMSA:Ln stoichiometry were found for the lanthanides La and Ce. Single-crystal X-ray diffraction analysis of the Ln-TMSA nitrate compounds, Ln = La and Ce, reveals a polymeric structure with each metal center containing one chelating bidentate succinamide and two bridging bidentate succinamides. For the remaining lanthanides Pr, Nd, Gd, Yb, and Lu, a series of isostructural, 9-coordinate compounds containing a 3:2 TMSA:Ln ratio were formed. Single-crystal X-ray diffraction analysis of the Ln-TMSA products, Ln = Ce, Pr, Nd, Gd, and Yb, reveals these compounds to be dimeric, with each metal center containing one chelating bidentate succinamide and two bridging bidentate succinamides. The solution stoichiometries were examined in acetonitrile-water mixtures and support the stoichiometries observed in the solid-state structures. Cerium nitrate appears to be a special (and transitional) lanthanide in its reaction with TMSA. Although infrared and TGA analyses indicate a 2:1 ligand-to-metal product, crystals for both the 2:1 and 3:2 compounds were isolated. No evidence for such multiple forms was found with any of the other lanthanides.
1987-01-01
Yb-based Kondo lattice systems (YbAgCu/sub 4/, YbCu/sub 2/Si/sub 2/, YbRh/sub 2/Si/sub 2/) represent an interesting class of materials in which it is possible to study systematically the development of heavy electron behavior through the application of pressure. Certainly, additional experiments are required to determine to what extent Yb compounds are mirror images of their Ce counterparts. Finally, pressure reveals the presence of competing interactions for which a simple model exists that qualitatively accounts for the pressure response observed in a large number of Ce, U and Yb-based Kondo lattice systems.
2005-03-28
The electronic structure and selected zone-center phonons in Yb graphite intercalation compound (YbC6) are investigated {theoretically} using density functional calculations and LDA+U approximation for Coulomb correlations in the f shell, and experimentally using angle-resolved photoemission. We find that both in LDA and LDA+U approach the Yb f states are fully occupied providing no evidence for mixed-valent behavior. The obtained theoretical results are in good agreement with photoemission experiments. The 4f states are considerably hybridized both with the Yb 5d and C 2p states resulting in a substantial admixture of Yb f at the Fermi level. Soft Yb phonons, given a noticeable presence of the Yb states at the Fermi level, are probably responsible for the superconductivity recently reported in YbC6.
2010-01-01
The interphase distribution of microamounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc perchlorates between aqueous HClO4 solutions and solutions of bidentate phosphorylmethyl-substituted butylphenylphosphinates Oct2P(O)CH2P(O)Ph(OBu) (compound I) and Ph2P(O)CH2P(O)Ph(OBu) (compound II) in 1,2-dichloroethane is studied. The stoichiometry of extracted complexes is determined, and the efficiency of metal ion extraction into the organic phase is considered as a function of the HClO4 concentration in the aqueous phase and the nature of the organic solvent. The possibility of concentrating rare-earth elements (REE)(III) and scandium(III) from HClO4 solutions with the complexing sorbent synthesized by noncovalent immobilization of I and II compounds on a macroporuos pol...
Preparation and quality control of lutetium-177 bleomycin as a possible therapeutic agent
2010-01-01
Due to interesting therapeutic properties of 177Lu and antineoblastic antibiotic, bleomycin (BLM), 177Lu-bleomycin (177Lu-BLM) was developed as a possible therapeutic compound. Lu-177 of 2.6-3 GBq/mg specific activity was obtained by irradiation of a natural Lu2O3 sample with a thermal neutron flux of 4 centre dot 1013 n centre dot cm-2 centre dot s-1. The product was converted into chloride form which was further used for labeling of BLM. In optimized conditions a radiochemical purity of 98% was obtained for 177Lu-BLM shown by instant thin-layer chromatography (ITLC) (specific activity, 740 GBq/mmole). Biodistribution studies of Lu-177 chloride and 177Lu-BLM were performed in wild-type rats. The ...
Scintillation mechanisms in rare earth orthophosphates
1994-12-31
In this Communication we present results of our studies on scintillation properties of rare earth orthophosphates. Despite of the PO{sub 4} group high frequency vibrations, which limit the conversion efficiency in orthophosphate lattices, some of them are very promising, as evidenced by the exceptionally good scintillation properties of LuPO{sub 4}:Ce. We have studied the following orthophosphate crystals: YbPO{sub 4}:Ce, YbPO{sub 4}, and Lu{sub x}Yb{sup 1-x}PO{sub 4}:Ce. Both Ce and Yb ions scintillate (through d-f transition and charge transfer state decay, respectively) but, unfortunately, they also show strong tendency toward mutual quenching. We propose that nonradiative Yb-Ce energy transfer and the nonradiative decay of the (Yb{sup 2+} + Ce{sup 4+}) charge transfer state are responsible for the observed effect. Therefore ytterbium does not provide cheaper substitute for the optically inactive RE ion (lutetium) in the orthophosphate lattice, on the contrary, it has to be carefully avoided whenever a Ce-activation is used.
Hexagonal Yb[sub 6]Cr[sub 4+[chiAl[sub 43-[chi]]([chi]=1. 76) with a new structure type]]
1994-10-15
The title compound contains one Yb, two Cr and seven Al sites, one of which is about half occupied by Cr. The coordination polyhedron of Yb has the composition [Cr(Al,Cr)[sub 2]Al[sub 13]Yb], while those around Cr are [Al[sub 10]YB[sub 2 and [Al[sub 12]], and that around the mixed site is [Al[sub 9]Yb[sub 3]]. (orig.).]]
2009-01-01
Rare earth basic nitrate hydrates (LnBN) of the general formula [Ln6(m6-O)(m3-OH)8(H2O)12(2-NO3)6](NO3)2xH2O, (Ln=Y, Sm, Eu, Gd. Tb, Dy, Ho, Er, Tm, Yb, Lu; x=3, 4, 5, 6) exist at least in seven different structure types (AI-D). The present paper describes and discusses their synthesis and structure determination. The basal building unit, common to all these compounds, is a [Ln6(m6-O)(m3-OH)8(H2O)12(2-NO3)6]2+ cluster of idealized symmetry -32/m. The stoichiometry is completed by non-coordinated (NO3)1- anions and H2O molecules in interstices.
2010-01-01
A series of novel yttrium- and lanthanide-containing heteropolyoxopalladates have been prepared and isolated as hydrated sodium salts, Na5[XIIIPdII12(AsPh)8O32]sy H2O (X=Y (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10), Tm (11), Yb (12), Lu (13); y=15-27). The polyanions [XIIIPdII12(AsPh)8O32]5- consist of a cuboid framework of twelve PdII ions with eight phenylarsonate heterogroups located at the vertices and a central guest ion X. The compounds 1-13 have been prepared in a simple one-pot self-assembly reaction of Pd(CH3COO)2, phenylarsonic acid and the respective salt of the element X in 0.5 M aqueous sodium acetate solution (pH 6.9), and characterized in the solid state by single-crystal X-ray diffraction, elemental and thermogravimetric (TGA) analyses, and...
2001-01-01
The chromatographic techniques of separation and concentration permitting preparation of high pure ytterbium and measure of Lu content with the sensitivity 0.3 - 0.1 ppb were described. The procedure based on elution complexing chromatography with the use of EDTA and cation exchanger KU-2 x 8M was developed. Used concentrations of EDTA were equal to 0.05 and 0.025 mol/l, elution rate was equal to 4 ml/cm2 min. It is shown that the procedure makes possible 350-fold purification of Yb from Lu, it permits concentration of the sample by Lu approx in 300 times and provides the effective method for separation of the purified Yb from rare earth concentrates
Search for an [ital M]0 transition in [sup 170]Yb
1993-05-01
We have examined the suggestion that an [ital M]0 transition occurs between the 2819.6-keV 0[sup [minus level of [sup 170]Yb and the 0[sup +] ground state by internal-conversion electron emission. Gamma rays, internal-conversion electrons, and internal [ital e][sup +][ital e[minus]] pairs were detected from the [beta][sup +] and electron capture decay of two-day [sup 170]Lu (0[sup +]). At an upper limit of 2[times]10[sup [minus]8] electron per [sup 170]Lu decay, no evidence was obtained for [ital M]0 decay of the 2819.6-keV level of [sup 170]Yb by single-electron emission.]]
Structural and Magnetothermal Properties of Compounds: Yb5SixGe4-x,Sm5SixGe4-x, EuO, and Eu3O4
The family of R{sub 5}Si{sub x}Ge{sub 4-x} alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R{sub 5}Si{sub x}Ge{sub 4-x} systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R{sub 5}Si{sub x}Ge{sub 4-x} systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb{sub 5}Si{sub x}Ge{sub 4-x} and Sm{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys with 0 {le} x {le} 4 have been examined by using single crystal and powder x-ray diffraction at room temperature, and dc magnetization and heat capacity measurements between 1.8 K and 400 K in magnetic fields ranging from 0 to 7 T. Unlike the majority of R{sub 5}Si{sub x}Ge{sub 4-x} systems studied to date, where R is the rare earth metal, all Yb-based germanide-silicides with the 5:4 stoichiometry crystallize in the same Gd{sub 5}Si{sub 4}-type structure. The magnetic properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} materials are nearly composition-independent, reflecting the persistence of the same crystal structure over the whole range of x from 0 to 4. Both the crystallographic and magnetic property data indicate that Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys are mixed valence systems, in which the majority (60%) of Yb atoms is divalent, while the minority (40%) is trivalent. This finding is supported by recent Moessbauer spectroscopy data.
Structural and Magnetothermal Properties of Compounds: Yb5SixGe4-x,Sm5SixGe4-x, EuO, and Eu3O4
The family of R{sub 5}Si{sub x}Ge{sub 4-x} alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R{sub 5}Si{sub x}Ge{sub 4-x} systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R{sub 5}Si{sub x}Ge{sub 4-x} systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb{sub 5}Si{sub x}Ge{sub 4-x} and Sm{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys with 0 {le} x {le} 4 have been examined by using single crystal and powder x-ray diffraction at room temperature, and dc magnetization and heat capacity measurements between 1.8 K and 400 K in magnetic fields ranging from 0 to 7 T. Unlike the majority of R{sub 5}Si{sub x}Ge{sub 4-x} systems studied to date, where R is the rare earth metal, all Yb-based germanide-silicides with the 5:4 stoichiometry crystallize in the same Gd{sub 5}Si{sub 4}-type structure. The magnetic properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} materials are nearly composition-independent, reflecting the persistence of the same crystal structure over the whole range of x from 0 to 4. Both the crystallographic and magnetic property data indicate that Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys are mixed valence systems, in which the majority (60%) of Yb atoms is divalent, while the minority (40%) is trivalent. This finding is supported by recent Moessbauer spectroscopy data.
Structural and Magnetothermal Properties of Compounds: Yb5SixGe4-x,Sm5SixGe4-x, EuO, and Eu3O4
2007-05-09
The family of R{sub 5}Si{sub x}Ge{sub 4-x} alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R{sub 5}Si{sub x}Ge{sub 4-x} systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R{sub 5}Si{sub x}Ge{sub 4-x} systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb{sub 5}Si{sub x}Ge{sub 4-x} and Sm{sub 5}Si{sub x}Ge{sub 4-x} pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys with 0 {le} x {le} 4 have been examined by using single crystal and powder x-ray diffraction at room temperature, and dc magnetization and heat capacity measurements between 1.8 K and 400 K in magnetic fields ranging from 0 to 7 T. Unlike the majority of R{sub 5}Si{sub x}Ge{sub 4-x} systems studied to date, where R is the rare earth metal, all Yb-based germanide-silicides with the 5:4 stoichiometry crystallize in the same Gd{sub 5}Si{sub 4}-type structure. The magnetic properties of Yb{sub 5}Si{sub x}Ge{sub 4-x} materials are nearly composition-independent, reflecting the persistence of the same crystal structure over the whole range of x from 0 to 4. Both the crystallographic and magnetic property data indicate that Yb{sub 5}Si{sub x}Ge{sub 4-x} alloys are mixed valence systems, in which the majority (60%) of Yb atoms is divalent, while the minority (40%) is trivalent. This finding is supported by recent Moessbauer spectroscopy data.
2009-01-01
Synthesis, structures, and magnetic properties of ternary rare earth oxides ALnO2 (A=Cu or Ag. Ln=rare earths) have been investigated. CuLnO2 (Ln=La, Pr, Nd, Sm, Eu) were synthesized by the direct solid state reaction of Cu2O and Ln2O3, and AgLnO2 (Ln=Tm, Yb, Lu) were obtained by the cation-exchange reaction of NaLnO2 and AgNO3 in a KNO3 flux. These compounds crystallized in the delafossite-type structure with the rhombohedral 3R type (space group: R-3m). Magnetic susceptibility measurements showed that these compounds are paramagnetic down to 1.8 K. Specific heat measurements down to 0.4 K indicated that CuNdO2 ordered antiferromagnetically at 0.8 K. - Graphical abstract: Ternary rare earth oxides ALnO2 (A=Cu or Ag. Ln=rare ...
Structural and thermal properties of rare earth complexes with 2,2-biphenyldicarboxylic acid
2010-01-01
Rare earth complexes with 2,2-biphenyldicarboxylic acid (diphenic acid=H2dpa) were obtained as hydrated precipitates of the general formula Ln2(C14H8O4)3nH2O, where n=3 for the of Y(III) and Ce(III)Er(III) and n=6 for La(III), Tm(III), Yb(III) and Lu(III) complexes. On heating in air atmosphere complexes lose all water molecules in the temperature range 30210C in one step and form anhydrous compounds, which are stable up to 315370C. During further heating they decompose to oxides. The trihydrated compounds are crystalline powders whereas the hexahydrated are amorphous solids. The trihydrated complexes crystallize in the monoclinic (Pr(III) and Ce(III) complexes) and triclinic (Y(III) and Nd(III)Er(III) complexes) crystal systems.
A Bismuth-Stabilized Metal-Rich Telluride Lu9Bi1.0Te1.0 - Synthesis and Characterization
2010-01-01
Synthetic reactions aimed at bismuth incorporation into rare-earth-metal-rich tellurides yielded Lu9Bi1.00Te1.00 over a small range of compositions, but no analogues with Gd, Tb, Er, or Y. A single-crystal X-ray diffraction analysis gave the composition Lu9Bi0.99(3)Te1.01 in the acentric orthorhombic space group Cmc21 at ambient temperature. This is isostructural with the re-refined Sc9Te2 earlier reported in a monoclinic Cc structure. Lu9Bi1.00Te1.00 represents the first ternary compound in this structure type and the third lutetium-richest compound after Lu8Te and Lu7Te. The structure contains 3 x 3 columns of Lu in the form of condensed distorted trans-edge-sharing octahedral chains along a. The Te and Bi anions lie within tricapped trigonal prisms of Lu. Generally shorter Lu-Lu interac...
1984-08-01
The neutron capture cross sections and solar abundances of /sup 160,161/Dy, /sup 170,171/Yb, /sup 175,176/Lu, and /sup 176,177/Hf have been measured. With this data base s-process studies have been carried out to determine the s-process neutron density and temperature and to investigate the s-process nucleosynthesis of the /sup 176/Lu clock. From various branchings the neutron density was found to be (0.8--1.8) x 10/sup 8/ neutrons per cm/sup 3/ and the temperature kT to be 18--28 keV. On the basis of the present data, /sup 176/Lu proved not to be applicable as a cosmic clock because of the temperature sensitivity of the /sup 176/Lu half-life but can be used instead as a stellar thermometer. Constraints for the s-process temperature (kT = 20--28 keV) were found to be in good agreement with the investigated branchings.
1999-01-01
Experiences with the new palliative agent Lu-177 EDTMP are summarized. The production of primary 177Lu by the 176Lu(n,gamma) 177Lu reaction and the synthesis of the radioactive complex are described as well as the procedures used for the control of the radionuclidic and the radiochemical purity. The stability of the compound has been also studied. The in vivo essays with rats and the use of the radiopharmaceutical, after a careful dose evaluation, in a patient with bone metastases from a breast cancer, show that the behaviour of Lu-177 EDTMP is similar to that of the analogue Sm-153 EDTMP. (author)
Phase Equilibria and Crystal Growth for LiREF4 Scheelite Crystals
2009-02-10
The scheelite type laser crystals LiREF4 melt congruently only for RE being one of the elements Er, Tm, Yb, Lu, or possibly Y, respectively. For RE = Eu, Gd, Tb, Dy, or Ho the corresponding scheelites undergo a peritectic melting under the formation of the corresponding rare earth fluoride. The melting behavior of LiREF4 mixed crystals with two or more RE is not yet known well. If RE is a mixture of Gd and Lu, Gd rich solid solutions melt peritectically under formation of (Gd,Lu)F3 and Lu rich solid solutions melt directly without formation of other solid phases.
Measurement of radioactive isotope 173Lu and 174Lu with Yb isobars by ID-TIMS
2007-01-01
When more than two elements on the filament of a thermal ionization mass spectrometer (TIMS) are vaporized, the element ratios in the vapor depend on the filament temperature. The ion current ratios of different mass numbers vary with the temperature, which is dominated by the filament current. With the presence of isobaric interference, the method of isotopic analysis by TIMS is established in the present paper and applied to determine the natural lutetium abundance in the solutions, in which ytterbium and lutetium are mixed by ratio of 1000 : 1. The measured isotope ratio of lutetium is in good agreement with the standard value. Likewise, the concentrations of 173Lu and 174Lu in the real samples produced through bombardment of ytterbium target by proton beam are determined by ID-TIMS. The relative uncertainties of concentrations are 0.45% and 1.1%, ...
XPS studies of the intermediate valence state of Yb in (YbS)1.25CrS2
2008-01-01
This paper presents clear evidences for valence fluctuation of Yb in (YbS)1.25CrS2. The X-ray photoelectron spectroscopy (XPS) spectra of Yb 4f, 5p, 4d and 4p have been measured. They reveal the multiplet structures of Yb2+ and Yb3+, indicating that it is a 'homogeneous' mixed-valence misfit-layer compound like (EuS)1.173NbS2 while keeping non-metallic properties. Yb 4f, 4d and 4p spectra are deconvoluted into the components of Yb2+ and Yb3+, from the relative areal intensities of which an intermediate valence has been estimated to be 2.89 in average. This result indicates that about 1.11 electrons per chemical formula are transferred from a YbS layer. On the other hand, the Cr 2p spectrum shows the spin-orbit (s.o.)-split peaks of Cr3+, implying that an ...
1991-05-01
Inelastic neutron scattering has been employed to study the crystalline electric field (CEF) of the ytterbium monopnictides YbX (X=N, P, As, Sb). The CEF potential is essentially governed by the fourth order term with the CEF level scheme to be {Gamma}{sub 6}-{Gamma}{sub 8}-{Gamma}{sub 7} for all compounds. The overall CEF splitting {Delta}{sub CEF} is gradually decreasing from about 81 meV for YbN to about 39 meV for YbSb, in rough agreement with the proportionality {Delta}{sub CEF} {proportional to} a{sup -5} expected from geometrical coordination, where a is the lattice parameter. The observed CEF transitions have large line widths; for YbP{sub 0.84} the line shapes are found to be asymmetric at T=10 K due to nonstoichiometry, and for YbN and YbSb the CEF transitions are even split into two components probably due to interaction with phonons. (orig.).
Selective separation of yttrium by CA-100 in the presence of a complexing agent
2006-02-09
The selective separation of Y from yttrium solution containing small heavy rare earth (HRE) impurities (Ho, Er, Tm, Yb, Lu) by liquid-liquid extraction using CA-100 in the presence of a water-soluble complexing agent of ethylenediaminetetraacetic acid (EDTA) was experimentally studied at 298 K. Experiments were carried out in two feeds, Feed-I: [RE]{sub f} = 4.94 x 10{sup -3} M, Y = 98.5%, HRE (Ho, Er, Tm, Yb, Lu) = 1.5%; Feed-II: [RE]{sub f} = 4.94 x 10{sup -3} M, Y = 99.9%, HRE (Ho, Er, Tm, Yb, Lu) = 0.1%, as a function of equilibrium pH (pH{sub eq}), the concentration ratio of [EDTA]:[HRE impurities]. It was shown that the extraction of HRE in the presence of EDTA was suppressed when compared to that of Y because of the masking effect, while the selective extraction of Y was enhanced and the separation factors increased to maximum at appropriate condition for Feed-I: Y/Ho = 1.53, Y/Er 3.09, Y/Tm = 5.61, Y/Yb = 12.04, Y/Lu = 27.51 at pH 4.37 and [EDTA]:[HRE impurities] = 4:1, for Feed-II: Y/Ho = 1.32, Y/Er = 1.91, Y/Tm = 2.00, Y/Yb 3.05, Y/Lu = 3.33 at pH 4.42 and [EDTA]:[HRE impurities] = 8:1. The separation and purification of Y by this method was discussed.
2006-02-09
Yb 4f electronic structure of YbXCu{sub 4} (X = Cd, Mg, Zn and Sn) has been investigated by means of high-resolution soft X-ray photoemission spectroscopy (SX-PES) with the excitation energy of h{nu} = 800 eV, in comparison with the results of the valence transition compound YbInCu{sub 4}. The SX-PES spectra of YbCdCu{sub 4} exhibit the temperature dependence similar to YbInCu{sub 4}, while those of the other YbXCu{sub 4} compounds almost no temperature dependence. The X-dependence of the Yb 4f states suggests that the low In 5p density of states is important for the valence transition of YbInCu{sub 4}.
Preparation of 177Lu-DOTA/DTPA-Bz-Cys-RGD dimer and biodistribution evaluation in normal mice
2008-01-01
177Lu-DOTA-Bz-Cys-RGD dimer and 177Lu-DTPA-Bz-Cys-RGD dimer were prepared, and the in vitro and in vivo properties were compared. TLC and HPLC show that the labeling yields of two radiolabeled compounds are more than 95% under optimal conditions (pH=5.0, reacting at 100 degree C for 15-20 min), and the two radiolabeled compounds show pretty good in vitro stability. HPLC analyses and lg P values reveal that lipophilicity of 177Lu-DOTA-Bz-Cys- RGD dimer is higher than 177Lu-DTPA-Bz-Cys-RGD dimer. The uptake of 177Lu-DTPA-Bz-Cys- RGD dimer in other tissues is significantly higher than that of 177Lu-DOTA-Bz-Cys-RGD dimer at 4 h postinjection, except for blood and spleen. The in vivo stability of 177Lu-DOTA-Bz-Cys-RGD dimer is much better than 177Lu-DTPA-Bz-Cys-RGD ...
Syntheses and crystal structures of rare earth basic nitrates hydrates
2009-01-01
Rare earth basic nitrate hydrates (LnBN) of the general formula [Ln6(mu6-O)(mu3-OH)8(H2O)12(eta2-NO3)6](NO3)2.xH2O, (Ln = Y, Sm, Eu, Gd. Tb, Dy, Ho, Er, Tm, Yb, Lu. X = 3, 4, 5, 6) exist at least in seven different structure types (AI-D). The present paper describes and discusses their synthesis and structure determination. The basal building unit, common to all these compounds, is a [Ln6(mu6-O)(mu3-OH)8(H2O)12(eta2-NO3)6]2+ cluster of idealized symmetry -32/m. The stoichiometry is completed by ...
2004-01-01
The time-differential perturbed-angular-correlation technique (TDPAC) was applied to the study of the internal electric-field gradient (EFG) in Eu-, Ho-, and Tm-sesquioxides in their cubic bixbyite phase. These new results as well as previous characterizations of the EFG at $^{181}$Ta sites in bixbyite-structure compounds were compared to those obtained in experiments using $^{111}$Cd as probe and to point-charge model predictions. The cumulated EFG data obtained with $^{181}$Ta in binary oxides enables a first attempt to investigate the dependence of the non-ionic contributions to the EFG on the electronic configuration of the probe-atom. A factorization of the EFG as a function of the electronic characteristics of the probe and the geometry of the cation coordination with its nearest and next-near neighbors is proposed. This factorization let us to interpret the behavior of the EFG at $^{181}$Ta/$^{111}$Cd sites in bixbyites and is in qualitative agreement with a simplified decomposition of the EFG valence contribution coming from {\\it ab initio} calculations in pure systems and with very recent calculations at impurity sites in binary oxides.
2008-01-01
Partition of trace amounts of metal (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc) perchlorates was studied between aqueous HClO4 solutions and dichloroethane solutions of phosphorus podands bearing two Ph2P(O)CH2C(O)NH-terminal groups linked via di-and triethylene glycol spacers. The stoichiometry of extracted complexes was determined. The efficiency of metal ion recovery to the organic phase was studied as a function of aqueous HClO4 concentration and nature of the organic solvent. The compounds synthesized have higher metal extraction capacities in HClO4 solutions than (dibutylcarbamoyl)diphenylphoshine oxide. The utility of macroporous polymer sorbents impregnated by these podands for extracting and concentrating rare earth(III) and scandium(III) ions from aqueous ...
2008-01-01
Interphase distribution of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,Y and Sc perchlorate trace amounts between HClO4 aqueous solutions and phosphorus-containing podands with two end groups Ph2P(O)CH2C(O)NH- connected by di- and triethylene glycol chain in dichlorethane has been studied. Stoichiometry of extracted complexes is determined, effect of HClO4 concentration in aqueous phase and nature of organic solvent on the efficiency of metal ion transitions in organic phase are treated. Studied compounds reveal higher extraction ability regarding to metal ions in HClO4 solutions as compared with the same ability of (dibutylcarbamoylmethyl)diphenylphosphine oxide. Possibility for the using macroporous polymer sorbents impregnated by studied podands for the separation and concentration of ...
2010-01-01
Novel polyfunctional neutral organophosphorus compounds, namely bis(diphenylphosphoryl-methylcarbamoyl)alkanes of general formula [Ph2P(O)CH2C(O)NH]2(CH2)n (I-III; n = 3, 5, 8), were synthesized and studied as extractants for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from perchloric acid solutions. The influence of both of HClO4 concentration in the aqueous phase and that of the extractant in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. Bis(diphenylphosphorylmethylcarbamoyl)alkanes II and III possess a higher extraction efficiency towards Ln(III) than their monoanalogue Ph2P(O)CH2C(O)NHC9H19. The potentialities of polymeric resin impregnated with bis(diphenylphosphorylmethylcarbamoyl)p...
2009-01-01
Using the method to synthesize rare-earth metal(III) fluoride sulfides MFS (M=Y, La, Ce-Lu), in some cases we were able to obtain mixed-valent compounds such as Yb3F4S2 instead. With Eu3F4S2 another isotypic representative has now been synthesized. Eu3F4S2 (tetragonal, I4/mmm, a=400.34(2), c=1928.17(9) pm, Z=2) is obtained from the reaction of metallic europium, elemental sulfur, and europium trifluoride in a molar ratio of 5:6:4 within seven days at 850 deg. C in silica-jacketed gas-tightly sealed platinum ampoules. The single-phase product consists of black plate-shaped single crystals with a square cross section, which can be obtained from a flux using equimolar amounts of NaCl as fluxing agent. The crystal structure is best described as an ...
Estimation of thermochemical behavior of spallation products in mercury target
2002-01-01
In order to examine the radiation safety of a spallation mercury target system, especially source term evaluation, it is necessary to clarify the chemical forms of spallation products generated by spallation reaction with proton beam. As for the chemical forms of spallation products in mercury that involves large amounts of spallation products, these forms were estimated by using the binary phase diagrams and the thermochemical equilibrium calculation based on the amounts of spallation product. Calculation results showed that the mercury would dissolve Al, As, B, Be, Bi, C, Co, Cr, Fe, Ga, Ge, Ir, Mo, Nb, Os, Re, Ru, Sb, Si, Ta, Tc, V and W in the element state, and Ag, Au, Ba, Br, Ca, Cd, Ce, Cl, Cs, Cu, Dy, Er, Eu, F, Gd, Hf, Ho, I, In, K, La, Li, Lu, Mg, Mn, Na, Nd, Ni, O, Pb, Pd, Pr, Pt, Rb, Rh, S, Sc, Se, Sm, Sn, Sr, Tb, Te, Ti, Tl, Tm, Y, Yb, Zn and Zr in the form of inorganic mercury compounds. As ...
2008-01-01
The level density and radiative strength functions obtained for the compound nuclei 40K, 60Co, 71,74Ge, 80Br, 114Cd, 118Sn, 124,125Te, 128I, 137,138,139Ba, 140La, 150Sm, 156,158Gd, 160Tb, 163,164,165Dy, 166Ho, 168Er, 170Tm, 174Yb, 176,177Lu, 181Hf, 182Ta, 183,184,185,187W, 188,190,191,193Os, 192Ir, 196Pt, 198Au, 200Hg precisely reproduce the intensities of two-step cascades, density and total radiation widths of neutron resonance. For 21 nuclei cascade populating ability approx 100 of their excited ...
Separation of rare earth elements by microorganisms
2005-01-01
The selective accumulation of rare earth elements in Gram-positive bacteria and actinomycetes was examined. The resting cells of 18 strains having high capacities to accumulate rare earth elements were screened for selectivity using a solution containing 5 elements: Y, La, Sm, Er, and Lu. Among the strains tested, Bacillus megaterium accumulated Sm, Streptomyces albus accumulated Lu, and Arthrobacter nicotianae accumulated both Sm and Lu in higher quantities than the other metals. Similar results were also obtained from a solution containing Y and 14 rare elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). The amount of Sm accumulated in B. megaterium and that of Lu accumulated in S. albus increased as the initial metal concentration increased. S. albus and B. megaterium cells show the highest capacity to accumulate Lu and Sm, respectively, from a solution ...
1980-07-01
Ordered perovskites with octahedral vacancies have been obtained for a new series of composition A/sub 12//sup 2 +/B/sub 6//sup 3 +/M/sub 5//sup 6 +/ square O/sub 36/ identical with A/sub 2//sup 2 +/B/sup 3 +/M/sub 5/6//sup 6 +/square /sub 1/6/O/sub 6/ for M/sup 6 +/ = U and A/sup 2 +/ = Ba; B/sup 3 +/ = Sm-Lu, Sc, Y or A/sup 2 +/ = Sr; B/sup 3 +/ = Yb, Lu. With the exception of the cubic 1:1 ordered Ba/sub 12/Sc/sub 6/U/sub 5/ square O/sub 36/ the perovskites crystallize in distorted orthorhombic structures. For the type A/sub 12//sup 2 +/B/sub 6//sup 3 +/M/sub 5//sup 6 +/ square O/sub 36/ the cation/vacancy ratio (for the octahedral sites) is 11:1. This value integrates into the scheme of perovskites with octahedral vacancies and cubic stacking of the AO/sub 3/ sheets, where compounds with a cation/vacancy ratio of 5:1, 7:1, 9:1, and 15:1 are already known.
Interaction of the components in Dy-Ni-Sn ternary system and crystal structure of new compounds
2009-01-01
The phase diagram of the Dy-Ni-Sn ternary system was constructed at 870 K (0-50 at.% Sn) and 770 K (more than 50 at.% Sn) using X-ray analysis and scanning electron microscopy. The interaction of the elements results the formation of 11 ternary compounds-Dy6Ni2Sn (Ho6Co2Ga-type), DyNi5Sn (CeCu4.38In1.62-type), DyNiSn2 (LuNiSn2-type), DyNiSn (TiNiSi-type), Dy2Ni2Sn (W2CoB2-type), DyNiSn4 (LuNiSn4-type), DyNi3Sn2 (HoGa2.4Ni2.6-type), Dy2Ni7Sn3 (own structure type), DyNi2-xSn (YbNi2-xSn-type), Dy3Ni4Sn6 ...
1999-12-20
YbNi{sub 2}B{sub 2}C has been found to be a heavy fermion metal with neither superconductivity nor magnetic order in contrast to the other members of the borocarbide family. LuNi{sub 2}B{sub 2}C is a superconductor with {Tc} {approximately} 16.3 K no magnetic order. Transport studies on single crystal Yb{sub x}Lu{sub (1{minus}x)}Ni{sub 2}B{sub 2}C show a systematic change from a heavy fermion system to a moderately high-temperature superconductor. A giant thermopower is observed for small x to x=1, i.e., in the transition region from a Kondo alloy to a heavy fermion metal. Measurements of H{sub c2}(T,x) are also reported for x < 0.15.
1990-12-01
The structures of the 211 or green phases, Yb{sub 2}BaCuO{sub 5} and Lu{sub 2}BaCuO{sub 5}, have been refined from time-of-flight powder neutron diffraction data. Both crystallize in the orthorhombic system, space group Pnma, with lattice parameters a = 12.0588(1) {angstrom}, b = 5.6123(1) {angstrom}, c = 7.0535(1) {angstrom}, and a = 12.0314(1) {angstrom}, b = 5.5989(1) {angstrom}, c = 7.0380(1) {angstrom}, respectively. The phases are isostructural with Y{sub 2}BaCuO{sub 5}, consisting of a three-dimensional framework of MO{sub 7} units (M = Yb, Lu) enclosing cavities occupied by the Ba and Cu atoms. Ba is 11-coordinate and Cu 5-coordinate, in a distorted square-pyramidal environment.
1985-09-01
The first profiles of Pr, Tb, Ho, Tm and Lu in the Pacific Ocean, as well as profiles of La, Ce, Nd, Sm, Eu, Gd and Yb are reported. Concentrations of REE (except Ce) in the deep water are two to three times higher than those observed in the deep Atlantic Ocean. Surface water concentrations are typically lower than in the Atlantic Ocean, especially for the heavier elements Ho,Tm,Yb and Lu. Cerium is strongly depleted in the Pacific water column, but less so in the oxygen minimum zone. The distribution of the REE group is consistent with two simultaneous processes: (1) cycling similar to that of opal and calcium carbonate, and (2) adsorptive scavenging by settling particles and possibly by uptake at ocean boundaries. However, the first process can probably not be sustained by the low REE contents of shells, unless additional adsorption on surfaces is invoked. The second process, adsorptive scavenging, largely controls the oceanic distribution and typical seawater pattern of the rare earths. (author).
1968-06-01
The experimental results obtained in the study of the (d,p) reactions, at E{sub d} = 12 MeV, on the three even-even deformed nuclei {sup 170}Yb, {sup 172}Yb and {sup 174}Yb have been analysed in terms of DWBA calculations. The spectroscopic information relative to the odd final nuclei have been compared with the predictions of the collective model and of the Nilsson's model. The effect of various parameters used in the DWBA analysis (form factors, optical wave functions) has been carefully studied. The observed differences between the three final nuclei are qualitatively reproduced in the experimental study of resonances, seen in excitation functions of elastically and inelastically scattered protons on the same target nuclei, and corresponding to analogue states in the three nuclei {sup 171}Lu, {sup 173}Lu and {sup 175}Lu. (author) [French] Les resultats experimentaux de l'etude des reactions (d.p) a E{sub d} = 12 MeV, sur les noyaux deformes pairs-pairs {sup 170}Yb, {sup 172}Yb et {sup 174}Yb ont ete interpretes dans le cadre de l'approximation de Born des ondes deformees. Les informations spectroscopiques relatives aux noyaux impairs finals ont ete comparees aux predictions du modele collectif et du modele de Nilsson, apres avoir examine avec soin l'influence des differents parametres (facteurs de forme, fonctions d'onde 'optiques') utilises lors de l'analyse. Les differences observees entre les trois noyaux finals sont qualitativement reproduites par les resultats experimentaux de l'etude de resonances dans les fonctions d'excitation de diffusion elastique et inelastique de protons sur les memes noyaux-cibles, lors de la recherche d'etats analogues dans les noyaux {sup 171}Lu, {sup 173}Lu et {sup 175}Lu. (auteur)
Proton transfer studies of /sup 172/Lu
1976-08-01
The level structure of the odd-odd nuclide /sup 172/Lu has been studied by means of the (/sup 3/He, d) and (..cap alpha.., t) proton transfer reactions on /sup 171/Yb. The spectrum has been interpreted in terms of two-quasiparticle states formed by coupling the transferred proton with the 1/2/sup -/(521) neutron in the target ground state. Assignments have been proposed for the bands arising by parallel and antiparallel coupling of the target neutron with protons in the 7/2/sup +/(404), 1/2/sup -/(541), and 5/2/sup +/(402) Nilsson orbitals. Some evidence is also presented for the assignment of the )1/2/sup -/(521)/subn/ +- 9/2/sup -/(514)/subp/closing-brace levels. The Q value of the /sup 171/Yb(/sup 3/He, d)/sup 172/Lu reaction is measured to be -792 +- 34 keV, yielding a mass excess of -56700 +- 37 keV for /sup 172/Lu. (AIP)
2008-01-01
Excitation functions of the reactions natEr(alpha,x)167,169Yb, natEr(alpha,x)172,173Tm, natYb(alpha,x)170,173,175,177m2Hf, natYb(alpha,x)171,172,177g,178mLu and natYb(alpha,x)169,177Yb were measured up to 38 MeV for application purposes (medical isotope production and charged particle activation analysis). The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE. The literature is very poor regarding cross section measurements on erbium or ytterbium irradiated with alpha particles. Yields of different production routes (proton-, deuteron- and alpha-irradiation) of 169Yb and ...
1982-06-01
The bottleneck phenomena in YbAl/sub 2/:Gd and YbAl/sub 2/:Eu is used to extract the conduction electrons' spin-flip relaxation to the lattice, deltasub(eL)sup((0)). The values observed are compared with those observed in the other dialuminides, XAl/sub 2/:Gd (X = Sc, Y, La, Lu). A correlation between deltasub(eL)sup((0)) and the atomic number of the host X atom is clearly demonstrated, and is similar to that found by others for rare-earth beryllides. A simple model is suggested to explain this observed phenomenon. The ESR isothermal limit of the R ion in YbAl/sub 2/ enables one to extract the dependence of the ion-conduction electron exchange coupling on the 4f occupation number. Results can shed some light on the nature of the Yb ions in YbAl/sub 2/ at low temperatures.
1998-01-01
Unusual REE compounds with mixed oxoanions are discovered by studying phase equilibria in a subsolidus area of ternary systems with participation of two acid oxides. The above compounds are thermoresistant, however they oxides as a rule in a limited area of the La-Lu series. Their structures are often unique noncentrisymmetrical, not liable to polymorphism and adaptive morphotropy. Effect of crystallochemical factors, including coordination numbers, on the possibility of existence and stability of these compounds is discussed
Superconducting properties of Lu2Fe3Si5 with non-magnetic impurities
2009-01-01
Ternary iron-silicide Lu2Fe3Si5 is a superconductor with the high transition temperature Tc = 6.0 K despite the inclusion of Fe elements. Recent experimental reports strongly suggest the exotic superconductivity in this compound. We investigate the effect of non-magnetic impurities on the superconducting properties of Lu2Fe3Si5 in order to verify the possibility of non-s-wave superconductivity. We examined the superconducting properties of (Lu1-xScx)2Fe3Si2 and (Lu1xYx)2Fe3Si2 in polycrystalline samples. The substitution of Lu for Sc or Y exhibits rapid suppression of Tc where the x = 0.1 substitution lowers ...
2006-01-01
Using X-ray absorption spectroscopy we have investigated the local structure of Yb2O3 and Lu2O3 thin films deposited on Si(1 0 0) by means of atomic layer deposition. These two oxides, as well as those of the other rare earth elements, are considered among the high dielectric constant materials candidates to substitute SiO2 in ultra-scaled CMOS devices. We find that the films maintain the overall bixbyite structure of the bulk oxides, but exhibit significant distortions of the local structure depending on thickness and thermal treatment
2009-01-01
Attenuation of the x rays and gamma rays in the 22Ti, 41Nb, 69Tm, 70Yb, and 71Lu elements have been measured with special emphasis for the x ray energies (Ein) in lower vicinity of the K shell ionization threshold (BK) of the element. The incident photon beam is obtained from decay of the 55Fe, 241Am, and 57Co radioisotopes, and fluorescence of the 23V, 70Yb, 71Lu, 74W, 76Os, and 90Th targets excited by the x rays and gamma rays from the radioisotopes. The measurements were performed using energy dispersive setups involving Ge detectors. The measured attenuation coefficients agree with the available theoretical values except at the photon energies ...
O-toluilates of heavy lanthanides
1980-01-01
The formation conditions of o-toluilates of Eu, Gd, Dy, Ho, Er, Yb and Lu, their quantitative composition and solubilities in water at room temperature were studied. The o-toluilates of Eu, Gd, Dy and Yb were obtained as hydrated salts with general formula Ln(CH/sub 3/C/sub 6/H/sub 4/COO)/sub 3/ . nH/sub 2/O, where n = 1, 5; 2. The o-toluilates Ho, Er and Lu are obtained as anhydrous salts. Their solubility is in the range of 10/sup -3/ M/dm/sup 3/.
Nuclear Data Sheets for A = 169
2008-01-01
Experimental data pertaining to all nuclei with mass number A = 169 (Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt) have been evaluated. Level schemes from both radioactive decay and reaction studies are presented, along with associated tables of experimental data and adopted properties for levels and gamma rays. These include data from several recent high-precision measurements of intensities for gamma rays emitted in 169Yb epsilon decay. These are of special interest because of their use as calibration standards. Excited-state information is newly available for Re, Os, Ir and Pt, and heavy-ion reaction studies have significantly expanded our knowledge of excited states in Lu through Ta. More extensive work on epsilon decay from W is needed and new experimental work will be required to resolve a discrepancy ...
Nuclear Data Sheets for A = 151
1988-10-01
The 1976 version of A = 151 mass chain (76Ha35) has been revised. The evaluated experimental data are presented for 14 known nuclides of A = 151 (Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu). Except for their isotopic identification, nothing much is known about 3 nuclides in this mass chain (Ce, Pr, and Lu) which are far off the stability line. High spin excitations are known for 9 nuclides (Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb). Particle transfer data are available for 5 nuclides (Nd, Pm, Sm, Eu and Gd). The neutron capture data are available for /sup 151/Sm and /sup 151/Nd. In terms of a variety of experimental studies, the /sup 151/Sm and /sup 151/Eu nuclides are the ones most extensively studied. copyright 1988 Academic Press, Inc.
2008-01-01
Phases of variable composition K1x A1x R1+x (MoO4)3) (0 x 0.20.6), where A = Ni, Mg, Co, or Mn and R = Yb, Lu, or Sc, which crystallize in a NASICON-type structure (space group R Formula Not Shown c) were synthesized by solid-phase reactions. Their crystal parameters were calculated, and IR and Raman spectra described.
Measurements of Coster-Kronig enhancement factors for Yb, Lu, Os and Pt elements
2009-01-01
In this work X-ray production cross-sections' measurements, Liota, Lalpha, Lbeta and Lgamma, of Yb, Lu, Os and Pt elements have been studied at energies in the range 9.572-14.384 keV and the effect of Coster-Kronig transitions on fluorescence cross-sections for L X-ray line has been obtained. From these studies absolute values of L X-ray cross-sections have been calculated with incorporation of the enhancement due to the Coster-Kronig effect. The experimental enhancement factors tend to be smaller than those predicted by theory
Elemental content in ground and soluble/instant coffee
2002-01-01
The concentration of thirty-four elements in twelve coffee brands has been measured using instrumental neutron activation analysis. The samples investigated included four brands of commercially available ground coffee and eight brands of soluble/instant coffee. The elements measured were Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Gd, Hf, K, La, Lu, Mg, Mn, Na, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, Tm, U, V, Yb and Zn. Twenty four elements were found to be below the detection limit in one or more samples. These elements were Ce, Cr, Fe, V, As, Eu, Ba, Dy, Gd, Hf, La, Lu, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Ti, Yb, Tm, and U. (author)
Optical properties and electronic structure of single crystals of LuAl{sub 2} and YbAl{sub 2}
2000-04-15
The optical conductivities of single crystals of LuAl{sub 2} and YbAl{sub 2} were measured by spectroscopic ellipsometry in the energy range of 1.4-5.5 eV for LuAl{sub 2} and 1.4-5.2 eV for YbAl{sub 2}. The optical conductivity spectra of LuAl{sub 2} and YbAl{sub 2} show similar features except for a difference in magnitude. Both have peaks near 1.8-2.1 eV and broad shoulders between 3.0 and 4.0 eV. The shoulder is weaker in YbAl{sub 2}. The band structure, density of states, and optical conductivity were calculated with the tight-binding linear muffin-tin orbital method in the atomic sphere approximation. The calculated optical conductivity with the inclusion of energy-dependent broadening agrees well with the experimental data. Oxidation effects on the surface of the sample were modeled using a three-phase model. The calculated optical conductivity of the clean surface is enhanced over that of the oxidized surface. (c) 2000 The American Physical Society.
2006-01-01
Phase diagrams of liquid binary systems RED-1 diluent-tri-n-butyl phosphate solvates of rare-earth element(III) (neodymium, gadolinium, yttrium, ytterbium, lutetium) nitrates were studied, and the binodal curves in the ternary systems [Ln(NO3)3(TBP)3] (Ln = Nd and Yb)-RED-1-Escaid 100 were determined at various temperatures.
Field Tuning and Quantum Criticality in Ytterbium Based Heavy Electron Compounds
2010-01-01
We review here the results of magnetization, specific heat, and inelastic neutron scattering measurements conducted on Yb3Pt4, Yb2Pt2Pb, Yb5Pt9, and YbRh2Pb, which indicate that the Yb moments in these heavy electron compounds are appreciably localized, at least in their paramagnetic states. The magnetic ground states in each are isolated magnetic doublets, and we show that magnetic fields suppress long ranged magnetic order and lead to a characteristic magnetic field-temperature phase diagram where order vanishes suddenly above a critical value for the field. We argue that the stability of magnetic order in these compounds arises from the competition between the Zeeman splitting g B H of the ground state doublet, which favors a spin polarized state with minimal entropy and without long ...
1983-01-01
Ceramic materials based on the lanthanide orthophosphate series of compounds are known to be highly stable both chemically and physically. These characteristics have recently led to an extensive evaluation of these substances as potential primary containment media for the disposal of high-level radioactive wastes. Since one important class of high-level nuclear waste (i.e., reprocessed light water reactor spent fuel) contains a relatively high concentration of various lanthanides, the solid state chemical properties of the mixed rare-earth and actinide-doped orthophosphates are of considerable practical interest. The Kramers' ions Ce/sup 3 +/, Nd/sup 3 +/, Dy/sup 3 +/, Er/sup 3 +/, Yb/sup 3 +/, and U/sup 3 +/ have been incorporated in single crystals of the tetragonal symmetry hosts ScPO/sub 4/, YPO/sub 4/, and LuPO/sub 4/, and EPR spectroscopy has been used to verify the substitutional behavior of these ions and to investigate their electronic ground state properties. Principal axial spectroscopic splitting factors and hyperfine parameters were determined. These results are compared to those obtained for the same paramagnetic ions in other hosts characterized by crystal fields with tetragonal symmetry at the impurity-ion site.
Magnetic properties of YbNi5 from 170Yb Mssbauer and magnetisation measurements
2007-01-01
Abstract. From Yb170 Mssbauer measurements on YbNi5, we establish: the Yb3+ ground state Kramers doublet is well isolated and has uniaxial anisotropy, the compound magnetically orders at 0.55K, the Yb3+ moments are aligned along the hexagonal axis, they have a saturated value of 3.9B and a thermal variation close to a mean field S = 1/2 law. We obtain the strength of the Yb3+Yb3+ coupling which we find is considerably smaller than that between the rare earths (R3+) in the other RNi5. From a study of the spin dynamics, we find that dynamic short range order is present just above the ordering temperature and that above 2K, the relaxation rate of the paramagnetic Yb3+ spins follows a T-linear Korringa law with a relatively pronounced slope which we link to a high density of states ...
2009-01-01
Tm- and Yb-doped gadolinium tungstate, (GdxTmyYb1-x-y)2(WO4)3 (x=0.7-0.9. Y=0.001-0.01), have been prepared by the polymerized complex method to achieve a homogeneous dispersion of dopants and to stabilize the host structure. Decomposition (900 deg. C 5 h) of the precursors with x=0.8-0.9 yielded a pure monoclinic phase, while that of x=0.7 resulted in formation of an orthorhombic impurity. The monoclinic phase exhibits bright up-converted blue emission due to the 1G4-
Ultrasonic study of the Yb-based heavy fermion compound YbRh2Zn20
2009-01-01
We report ultrasonic measurements on the high quality single crystal of the Yb-based heavy fermion compound YbRh2Zn20 over a temperature range from 200 K to 0.5 K. A shallow, but clear minimum was observed in the temperature dependent elastic constants C11, (C11 - C12)/2 and C44 around 15 K, probably attributed to the ground state and low-lying excited states of Yb3 in the cubic CEF. We discuss the low-temperature elastic properties and possible energy level scheme of localized 4f state of Yb3 ions in YbRh2Zn20. CEF ground state developed at the low temperatures and physical parameters relating to a quadrupolar moment in YbRh2Zn20
Quantum phase transition in the heavy-fermion compound YbIr$_2$Si$_2$
2006-10-04
We investigate the pressure-temperature phase diagram of YbIr$_2$Si$_2$ by measuring the electrical resistivity $\\rho(T)$. In contrast to the widely investigated YbRh$_2$Si$_2$, YbIr$_2$Si$_2$ is a paramagnetic metal below $p_c\\simeq 8$ GPa. Interestingly, a first-order, presumably ferromagnetic, transition develops at $p_c$. Similar magnetic properties were also observed in YbRh$_2$Si$_2$ and YbCu$_2$Si$_2$ at sufficiently high pressures, suggesting a uniform picture for these Yb compounds. The ground state of YbIr$_2$Si$_2$ under pressure can be described by Landau Fermi-liquid (LFL) theory, in agreement with the nearly ferromagnetic Fermi-liquid (NFFL) model. Moreover, evidence of a weak valence transition, characterized by a jump of the Kadowaki-Woods (KW) ratio as well as an enhancement of the residual resistivity $\\rho_0$ and of the quasiparticle-quasiparticle scattering cross section, is observed around 6 GPa.
Yb-based heavy fermion compounds and field tuned quantum chemistry
The motivation of this dissertation was to advance the study of Yb-based heavy fermion (HF) compounds especially ones related to quantum phase transitions. One of the topics of this work was the investigation of the interaction between the Kondo and crystalline electric field (CEF) energy scales in Yb-based HF systems by means of thermoelectric power (TEP) measurements. In these systems, the Kondo interaction and CEF excitations generally give rise to large anomalies such as maxima in {rho}(T) and as minima in S(T). The TEP data were use to determine the evolution of Kondo and CEF energy scales upon varying transition metals for YbT{sub 2}Zn{sub 20} (T = Fe, Ru, Os, Ir, Rh, and Co) compounds and applying magnetic fields for YbAgGe and YbPtBi. For YbT{sub 2}Zn{sub 20} and YbPtBi, the Kondo and CEF energy scales could not be well separated in S(T), presumably because of small CEF level splittings. A similar effect was observed for the magnetic contribution to the resistivity. For YbAgGe, S(T) has been successfully applied to determine the Kondo and CEF energy scales due to the clear separation between the ground state and thermally excited CEF states. The Kondo temperature, T{sub K}, inferred from the local maximum in S(T), remains finite as magnetic field increases up to 140 kOe. In this dissertation we have examined the heavy quasi-particle behavior, found near the field tuned AFM quantum critical point (QCP), with YbAgGe and YbPtBi. Although the observed nFL behaviors in the vicinity of the QCP are different between YbAgGe and YbPtBi, the constructed H-T phase diagram including the two crossovers are similar. For both YbAgGe and YbPtBi, the details of the quantum criticality turn out to be complicated. We expect that YbPtBi will provide an additional example of field tuned quantum criticality, but clearly there are further experimental investigations left and more ideas needed to understand the basic physics of field-induced quantum criticality in Yb-based systems.
YbT2Zn20 (T = Fe, Co, Ru, Rh, Os, Ir): six closely related heavy fermion compounds
2006-08-18
We introduce six, Yb-based, heavy fermion compounds in the YbT2Zn20 family (T = Fe, Co, Ru, Rh, Os, Ir). These compounds are isostructural and, given they are dilute, rare earth bearing, intermetallic compounds, the local environment of the Yb sites is only weakly affected by changes in T. For T = Fe, Ru, Rh, Os, Ir the thermodynamic data associated with each compound are qualitatively similar and consistent with Kondo temperatures 10 K < T_K < 30 K. On the other hand the transport data, specifically the T^2 coefficient of the resistivity, vary dramatically. By taking advantage of the systematics that five, related compounds offer, we have been able to argue that the differences in resistivity are associated with differences in the low temperature degeneracy of the Yb ion for T ~ T_K. YbCo2Zn20 appears to have a lower T_K < 5 K and seems to be very close to a quantum critical point.
2007-03-28
We have synthesized single crystals of a new intermetallic compound with a distorted Heusler structure, YbRh$_{2}$Pb. We present a study of the magnetic, thermal, and transport properties. Heat capacity measurements revealed that YbRh$_{2}$Pb orders magnetically below T$_{N}$=0.57 K from a paramagnetic state with substantial crystal electric field splitting. Magnetic field further splits the ground state, which leads to the suppression of magnetic order in YbRh$_{2}$Pb.
1987-03-15
Solvent extraction behavior of Eu(III), Yb(III), and Lu(III) has been investigated by using thenoyltrifluoroacetone (TTA) as extractant in the presence of 1,7-diaza-4,10,13-trioxacyclopentadecane-N,N'-diacetic acid (DAPDA) and 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N'-diacetic acid (DACDA) as macrocyclic ionophores. DAPDA and DACDA were chosen in this work in view of their unique complexation toward lanthanides. It was observed that in the presence of DAPDA (L), Eu(III) extracted predominantly as ternary complex (Eu(L)(TTA)), whereas Yb(III) and Lu(III) were extracted as mixed, binary Ln(TTA)/sub 3/ and ternary (Ln(L)(TTA)) complexes. On the other hand, in the presence of DACDA, Eu(III) formed mixed binary and ternary complexes in the organic phase, whereas Yb(III) and Lu(III) formed predominantly binary complexes. In contrast to the extraction in the presence of DAPDA/DACDA, heavier lanthanides, i.e., Yb(III) and Lu(III), were extracted much less compared to lighter lanthanides, i.e., La(III) and Nd(III), in the presence of ethylenediamine-N,N'-diacetic acid (EDDA), a structurally analogous noncyclic polyaminopolycarboyxlic acid.
Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments
Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were ...
Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments
Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured ...
Rare Earth Element Partition Coefficients from Enstatite/Melt Synthesis Experiments
Enstatite (En(80)Fs(19)Wo(01)) was synthesized from a hypersthene normative basaltic melt doped at the same time with La, Ce, Nd, Sm, Eu, Dy, Er, Yb and Lu. The rare earth element concentrations were measured in both ...
1987-01-01
Effect of environment and dietary habits on trace element contents in human scalp hair has been investigated in the present work. Trace elements were detected with neutron activation technique. It was found that diet and environment contribute largely towards the trace elements in the human body. Further trace elements Te, Lu, Ba, Cs, Yb, Re, Hf, In and Ir were detected for the first time in human scalp hair.
Lightweight high performance ceramic material
A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.
Lightweight high performance ceramic material
A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.
Lightweight high performance ceramic material
A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.
Growth-induced anisotropy in bismuth - Rare-earth iron garnets
The bismuth-doped rare-earth iron garnets, (R3-x-yBixPby)Fe5O12 (Bi:RIG, R = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), were prepared under constant growth conditions to investigate the ...
1977-01-01
The general quadratic force constants, compilance constants and coriolis coupling constants for eight pyramidal molecules of the type XY3(X= La, Ce, Nd, Eu, Gd, Ho, Yb or Lu. Y = F) have been evaluated using recent vibrational data. The results have been briefly discussed. (author)
Distribution patterns of rare earth elements in various plant species
1997-09-01
The elements La, Ce, Nd, Sm, Eu, Gd, Tb, Yb and Lu have been determined in 6 different plant species by neutron activation analysis. When the concentrations of each species were normalized to Norway spruce, smooth curves were obtained which revealed systematic inter-species differences. (author) 3 figs., 4 refs.
Anomalous conversion of the 19. 38-keV E1 transition in /sup 171/Yb
1975-01-01
Measurements on the electron conversion spectra of /sup 171/Lu were performed. The observed anomaly in L/sub I//L/sub II/, L/sub I//L/sub III/, M/sub I//M/sub II/, and M/sub I//M/sub III/ ratios is discussed considering possible explanations and their validity.
2008-01-01
In this paper, we focus on the mechanism of non-Fermi liquid phenomena in the vicinity of the magnetic field-tuned quantum critical point in Yb-based heavy fermion compounds YbAuCu4, YbRh2Si2 and YbFe4P12. A comparative study of YbAuCu4 and YbPdCu4 with differently magnetically ordered ground states of antiferromagnetic (AFM) and ferromagnetic (FM) indicates that the competition between the field-destabilized AFM and field-stabilized FM correlations plays an important role on the field-tuned quantum critical behavior. The non-integer valence of these compounds leads to a consideration that the experimental susceptibility is dominated by the weakly broadened 4f hole level above the Fermi sea that extends to the cf hybridized band located at the Fermi level. Whilst, the ...
Nuclear orientation study of the decay of /sup 171/Lu
1985-07-08
The levels and ..gamma..-ray transitions in /sup 171/Yb have been studied by radioactive decay of oriented /sup 171/Lu. The orientation was produced using the hyperfine field in ferromagnetic gadolinium to polarize an ensemble of /sup 171/Lu nuclei at a temperature of 14 mK. The directional distribution of the ..gamma..-rays was measured using high-resolution Ge(Li) detectors. Anisotropies of 30 ..gamma..-rays in /sup 171/Yb were measured. Multipole mixing ratios were deduced for most of the mixed ..gamma..-ray transitions and unambiguous spin assignments were made for several levels. The energy and structure of the rotational band levels, reduced E2 and M1 transition probabilities and E2/M1 mixing ratios were calculated using the semi-microscopic quasiparticle-phonon model with a Coriolis interaction. In general, good agreement is obtained between the theoretical predictions and experimental results.
Magnetism and Transport in YbMn2Sb2
2005-01-19
A new ternary intermetallic compound, namely, YbMn2Sb2, has been synthesized and its magnetic and electrical transport properties have been studied in the temperature range of 2 to 300 K. This compound crystallizes in a trigonal, La2O2S type structure (space group P3bm1, No. 164) and is found to be ferromagnetically ordered at room temperature. The magnetism is attributed to the ordering of Mn sublattice. M5 xray absorption spectrum of YbMn2Sb2 obtained at room temperature suggests that the valency of Yb in this compound is close to 2. Electrical resistivity of this compound is metal like and a positive magnetoresistance of 13 percent is observed at 5 K in an applied field of 9T. Key words Rare earth intermetallics and alloys, Magnetic properties, Xray absorption spectroscopy, Electrical transport.
1989-06-01
Determination of the rare earth elements (REE's) in acidic hot spring and crater lake waters by the neutron activation analysis (NAA) in which activation was performed mostly by epithermal neutrons (epithermal NAA) was investigated. Nine REE's, La, Ce, Sm, Eu, Tb, Ho, Tm, Yb and Lu, out of fourteen naturally existing REE's were determined at ppb levels with satisfactory precision. The epithermal NAA was found to be more effective in the determination of Sm, Tb, Ho and Yb than the normal NAA in which activation was performed mainly by thermal neutrons. Combined use of the epithermal and normal NAA's enabled the determination of eleven REE's, La, Ce, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb and Lu. (author).
Spectrophotometric studies in complexing of lutetium with phthalexone-S and semiphthalexone-S
1980-06-01
The spectrophotometric method has been used to investigate complexing of lutetium with phthalexone -S(PT-S) and semiphthalexone-S(SPT-S), separated from the industrial compounds of these reagents, using helium filtration. pH effect is studied. It is found that PT-S and Lu form monoprotonated complex of equimolecular composition (LuH/sub 2/R)/sup -/. The two complexes: (LuHR) and ((LuOH)R)/sup 2 -/ are form in system Lu-SPT-S. The stability constants of the forming complexes are determined and their structural formulae are proposed.
Magnetic and structural properties of Lu2(Fe, Mn)17Hy hydrides
2009-01-01
The Lu2Fe17-xMnxHy, x = 0-2, y = 0-3, hydrides with the Th2Ni17-type crystal structure were prepared and their structural and magnetic parameters were studied. The lattice parameters measured at room temperature increase smoothly with H content. The magnetic measurements indicate that the Lu2Fe17Hy hydrides (with y up to 1.77) are antiferromagnets at high temperatures and ferromagnets at low temperatures. The Lu2Fe16.5Mn0.5 compound also has a high temperature antiferromagnetic state, but its hydrides are ferromagnets only. The Lu2Fe17-xMnxHy hydrides, with x = 0.7 and 2, are ferromagnets with Tc monotonically increasing with H content. The ...
Determination of chemical purity and specific activity of 177g,mLuCl3 by INAA and ET-AAS
2008-01-01
Radioactive solutions of 177g,mLuIIICl3 are used for labeling organic compounds for metabolic radiotherapy and radioimmunotherapy. The labeling process involves Lu in III oxidation state, so the presence of other stable impurities in the same oxidation state could result in an isomorphous dilution of radioactive 177gLu. Samples of 177gLuCl3 were analyzed to quantify the chemical impurities with a special regard for trivalent elements with instrumental neutron activation analysis (INAA), carried out in the research nuclear reactor TRIGA MARK II (GA, USA) of the Universit degli Studi di Pavia, and electrothermal atomic absorption spectroscopy (ET-AAS) (Varian, USA) at LASA.
2001-07-01
In this work, we perform spectroscopic studies to characterize the energy transfer processes occurring in rare-earth doped lithium fluoride systems, aiming the optimization of the population inversion of these media. Yb{sup 3+} ion was used in order to probe the electron-phonon coupling in LiYF{sub 4}, LiGdF{sub 4} and LiLuF{sub 4} matrices. In these systems it was obtained the average phononenergy, the vibronic transition probability and Huang-Rhys coupling constant. These parameters are dependent on the crystal host and the LiLuF{sub 4} system presents excluded correlation effects, an electronic repulsion that weakens the vibronic coupling. The Tm:Ho:LiYF{sub 4} system was studied under diode laser pumping at 796 nm, aiming the 2 {mu}m emission optimization. The ideal conditions of concentration and laser power were determined favouring the latter emission. Upconversion processes of two photons were identified besides the energy transfer among ions. The dynamic processes of luminescence of donors and acceptors allowed one to classify the energy transfer process as an energy transfer process assisted by fast diffusion among donors. The spectroscopic study of the Yb:Tm:LiYF{sub 4} allowed the determination of efficient non resonant transfer mechanisms between ({sup 2}F{sub 5/2}) Ytterbium level and ({sup 3}H{sub 5}) Thulium level, assisted by two phonon with hopping migration among donors ( Foerster-Burshtein model). The repopulation process of the Yb donor level is due to a cooperative sensitization between Yb-Tm pairs followed by an energy transfer process. (author)
Thermoelectric transport in rare-earth compounds
2007-07-01
This work focuses on the thermoelectric transport in rare-earth compounds. The measurements of the thermal conductivity, thermopower, and Nernst coefficient are supplemented by investigations of other quantities as magnetic susceptibility and specific heat. Chapter 2 provides an introduction to the relevant physical concepts. Section 1 of that chapter summarizes the characteristic properties of rare-earth systems; section 2 gives an overview on thermoelectric transport processes in magnetic fields. The applied experimental techniques as well as the new experimental setup are described in detail in Chapter 3. The experimental results are presented in Chapter 4-6, of which each concentrates on a different subject. In Chapter 4, various Eu clathrates and the skutterudite-like Ce{sub 3}Rh{sub 4}Sn{sub 13} are presented, which have been investigated as potential thermoelectric materials for applications. Chapter 5 focusses on the study of the energy scales in the heavy-fermion series Lu{sub 1-x}Yb{sub x}Rh{sub 2}Si{sub 2} and Ce{sub x}La{sub 1-x}Ni{sub 2}Ge{sub 2} by means of thermopower investigations. Chapter 6 is dedicated to the thermoelectric transport properties of the correlated semimetal CeNiSn with special emphasis on the Nernst coefficient of this compound. (orig.)
Carrier relaxation dynamics in heavy fermion compounds
2002-01-01
The first femtosecond carrier relaxation dynamics studies in heavy fermion compounds are presented. The carrier relaxation time shows a dramatic hundred-fold increase below the Kondo temperature revealing a dramatic sensitivity to the electronic density of states near the Fermi level. Femtosecond time-resolved optical spectroscopy is an excellent experimental alternative to conventional spectroscopic methods that probe the low energy electronic structure in strongly correlated electron systems. In particular, it has been shown that carrier relaxation dynamics are very sensitive to changes in the low energy density of states (e.g. associated with the formation of a low energy gap or pseudogap) providing new insights into the low energy electronic structure in these materials. In this report we present the first studies of carrier relaxation dynamics in heavy fermion (HF) systems by means of femtosecond time-resolved optical spectroscopy. Our results show that the carrier relaxation dynamics, below the Kondo temperature (T{sub K}), are extremely sensitive to the low energy density of states (DOS) near the Ferini level to which localized f-moments contribute. Specifically, we have performed measurements of the photoinduced reflectivity {Delta}R/R dynamics as a function of temperature and excitation intensity on the series of HF compounds YbXCu{sub 4} (X = Ag, Cd, In) in comparison to their non-magnetic counterparts LuXCu{sub 4}.
2007-06-12
Full Text Available.Heavy fermion compounds represent one of the most strongly correlated forms of electronic matter and give rise to low temperature states that range from small moment ordering to exotic superconductivity, both of which are often in close proximity to quantum critical points. These strong electronic correlations are associated with the transfer of entropy from the local moment degrees of freedom to the conduction electrons, and, as such, are intimately related to the low temperature degeneracy of the (originally) moment bearing ion. Here we report the discovery of six closely related Yb-based heavy fermion compounds, YbT
1998-01-01
Methods of X-ray diffraction analysis were applied to study phase equilibria in Eu-Mn-Ga and Yb-Mn-Ga system alloys. Isothermal sections of phase diagrams at 500 deg C are built. One ternary intermetallic compounds in the first system and four compounds of similar type in the second one are revealed and their crystal structure is determined
Synthesis and Properties of YbB2
2002-11-14
We report temperature and field dependent measurements of the magnetic susceptibility, specific heat and resistivity of sintered YbB2 pellets, prepared via two distinct reaction routes, utilizing different temperatures, pressures and sintering times. Sample behavior is affected by the preparation procedure, as a consequence of different secondary phases, most of which were identified via x-ray diffraction. These experiments show that YbB2 is a metal with the Yb atoms in or very close to their 3+ state. YbB2 appears to order anti-ferromagnetically at TN ~ 5.6 K, which can be considered a relatively high ordering temperature for an ytterbium-based intermetallic compound.
Single crystal growth of a new YB{sub 50} family compound: YB{sub 44}Si{sub 1.0}
1997-10-01
Single crystals of a new yttrium borosilicide of YB{sub 44}Si{sub 1.0} have been grown by the floating zone method using a xenon lamp image furnace. X-ray powder diffraction, precession photography, and chemical analyses showed that the crystal obtained is a new YB{sub 50} family yttrium borosilicide which has a composition of YB{sub 44.4}Si{sub 1.04} in the middle part of the crystal and an orthorhombic crystal structure with space group Pbam or Pba2.
Intercalant-Driven Superconductivity in YbC$_{6}$ and CaC$_{6}$
2005-04-06
Recently deiscovered superconductivity in YbC$_6$ and CaC$_6$ at temperatures substantially higher than previously known for intercalated graphites, raised several new questions: (1) Is the mechanism considerably different from the previously known intercalated graphites? (2) If superconductivity is conventional, what are the relevant phonons? (3) Given extreme similarity between YbC$_6$ and CaCa$_6$, why their critical temperatures are so different? We address these questions on the basis of first-principles calculations and conclude that coupling with intercalant phonons is likely to be the main force for superconductivity in YbC$_6$ and CaC$_6$, but not in alkaline-intercalated compounds, and explain the difference in $T_c$ by the ``isotope effect'' due to the difference in Yb and Ca atomic masses.
Anisotropic exchange in frustrated pyrochlore Yb2Ti2O7
2009-01-01
The local Yb3+ magnetic susceptibility tensor was recently measured in the frustrated pyrochlore compound Yb2Ti2O7 by means of in-field polarized neutron scattering in a single crystal. A very anisotropic effective exchange tensor was derived for the Yb3+ ion. Using this result, we reinterpret here the data for the powder susceptibility in Yb2Ti2O7. We show that, in the case of a well-isolated Kramers doublet with anisotropic g and exchange tensors, the inverse susceptibility for a powder sample does not strictly obey a Curie-Weiss law at low temperature. We discuss the consequences regarding the paramagnetic Curie temperature, usually taken as a measure of the exchange/dipolar interaction, and the exotic 'slow fluctuation' ground state of ...
Hf isotopic analyses of zircons in combination with U-Pb age information is a powerful tool for constraining the formation and evolution of the continental lithosphere. A rapidly growing data-set of in-situ Hf isotopic measurements by LA-MC-ICP-MS has accumulated since the introduction of the 2nd generation instruments in the early 2000s. All of the in-situ analyses are performed with on-line Lu and Yb isobaric interference corrections. In order to assess the viability of the typical isobaric corrections on the Hf isotopic measurements we prepared a set of synthetic zircons with variable amounts of REE. Analyses of these zircons and homogeneous, gem-quality zircons clearly show that accuracy and precision of Hf isotopic measurements in zircons decrease systematically with increasing REE/Hf ratios. The synthetic zircon experiments indicate that at Lu-Yb/Hf ratios resulting in around 20 percent or less difference between uncorrected and Lu-Yb corrected ratios, we can routinely obtain accurate and precise Hf isotopic data (better than +/- 1 epsilon Hf at 2 sd). Grain to grain reproducibility increases to +/-4 epsilon units at corrections of 60 percent in these relatively homogeneous grains; accuracy suffers slightly as well. At corrections of around 80 percent, the grain to grain reproducibility is +/- 9 epsilon units and the 176Hf/177Hf ratios are highly inaccurate. Most probably this is a result of the formation of REE oxides and possibly Y dimers, which directly interfere with all masses of interest during the Hf isotopic analyses. As a result, the Lu-Yb peak stripping becomes an inadequate proxy for all isobaric interferences. The threshold for retaining around 1 epsilon unit error at 2 sd level for the Hf isotope ratios cannot be stated specifically because: 1) oxide formation is a common phenomenon for all ICP-MS, but is instrument and analysis specific and 2) precision and accuracy are affected by the heterogeneity of the REE distribution and/or variation in 176Hf/177Hf. In order to better assess these effects in natural zircons, we analyzed a number of zircon standards, including 91500, BR266, MAD, SAME, FC-1, and R33. These results indicate FC-1 as the standard with the highest Lu-Yb/Hf ratios (14+/-8 percent difference between uncorrected and Lu-Yb corrected ratios) that yields accurate and precise Hf isotope ratios (better than +/- 1 epsilon Hf, 2 sd). The highest REE/Hf standard from the above suite was R33 (22+/-9 percent difference between uncorrected and Lu-Yb corrected ratios). Both accuracy and precision suffered in R33 compared to FC-1, yet we were still able to obtain relatively accurate, but less precise (+/- 2 epsilon units Hf, 2 sd), which we attribute to spatial heterogeneity in REE contents and/or 176Hf/177Hf. Overall, our experiments indicate that we can obtain accurate and precise Hf isotopic data for natural zircons with REE/Hf ratio resulting in 20 percent or less difference between Lu-Yb uncorrected and corrected ratios. A tentative strategy for obtaining high-quality, in-situ Hf isotopic ratios would be to use zircon standards with variable REE/Hf ratios to evaluate the instrument REE oxide/Y-dimer formation during the experiment. LA-MC-ICP-MS Hf isotopic data can be regarded as accurate only for zircons with REE/Hf equal or less than the highest REE/Hf zircon standard used during a given experiment that yields accurate data.
1988-08-01
Time dependent formation processes of LnBa/sub 2/Cu/sub 3/O/sub x/ (Ln = La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu) from mixtures of Ln/sub 2/O/sub 3/, BaCO/sub 3/ and CuO have been investigated by means of X-ray diffraction. It is shown that intermediate by-products formed during the formation of LnBa/sub 2/Cu/sub 3/O/sub x/ are classified into two types of Ln. Ln/sub 2/CuO/sub 4/ and BaCuO/sub 2/ are formed for Ln = La, Nd, Sm, Eu and Gd, while Ln/sub 2/Cu/sub 2/O/sub 5/, Ln/sub 2/BaCuO/sub 5/ and BaCuO/sub 2/ are formed as intermediate by-products for Ln = Dy, Ho, Er, Tm, Yb and Lu. These data include the determination of lattice constants of a group of materials, Ln/sub 2/BaCuO/sub 5/.
2010-01-01
X-ray powder data for YbCu2Ge2, YbAg2Si2 and YbAg2Ge2 confirmed the atom order of the ThCr2Si2 type (ordered BaAl4 type) as reported earlier. YbCu2Ge2 is an intermediate valence system with the Yb ions valence close to +2 at low temperatures, whereas the other two compounds are weakly temperature-dependent paramagnets. All these ternaries show metallic character of their electrical conductivity. The structure of Yb(Cu1-xZnx)2Si2 (x=0.65, 0.77) was found to correspond to the BaAl4 type, assuming a random distribution of Cu and Zn atoms over the positions 4d (0, 1/2, 1/4). The Si atoms were found in the sites 4e (0, 0, z). These two pseudoternary compounds are diamagnetic. A novel phase with the composition Yb(Ag0.18Si0.82)2 crystallizes in the ThSi2-type on the verge to a symmetry reduction...
Thermodynamic optimization of the Mg-Tb and Mg-Yb systems
2006-01-01
The two Mg-RE systems, Mg-Tb and Mg-Yb, have been critically assessed by means of the CALculation of PHAse Diagram (CALPHAD) technique. The solution phases (liquid, body-centered cubic, face-centered cubic and hexagonal close-packed) were modeled with the Redlich-Kister equation. The intermetallic compounds Mg24Tb5 and Mg5Tb were treated as stoichiometric. The compounds, Mg2Tb and Mg3Tb in Mg-Tb system and Mg2Yb in Mg-Yb system, which have a homogeneity range, were modeled using two sublattices Mg2(Mg, Tb), Mg3(Mg, Tb) and (Mg, Yb)2(Mg, Yb), respectively. A three-sublattice model (Mg, Tb)0.5(Mg, Tb)0.5Va3 was applied to describe the intermediate B2 compound (MgTb) in order to cope with the order-disorder ...
Unusual Ground State Properties of the Kondo-Lattice Compound Yb2Ir3Ge5
2003-03-29
We report sample preparation, structure, electrical resistivity, magnetic susceptibility and heat capacity studies of a new compound Yb$_2$Ir$_3$Ge$_5$. We find that this compound crystallizes in an orthorhombic structure with a space group PMMN unlike the compound Ce$_2$Ir$_3$Ge$_5$ which crystallizes in the tetragonal IBAM (U$_2$Co$_3$Si$_5$ type) structure. Our resistivity measurements indicate that the compound Yb$_2$Ir$_3$Ge$_5$ behaves like a typical Kondo lattice system with no ordering down to 0.4 K. However, a Curie-Weiss fit of the inverse magnetic susceptibility above 100 K gives an effective moment of only 3.66 $\\mu
2005-06-15
Low-energy excited photoemission spectra of YbXCu{sub 4} (X = Cd, Mg, Zn) with high-energy resolution have been measured, in comparison with those of the valence transition compound YbInCu{sub 4}. The energy position of the peak due to the conduction-band states hybridized with the Yb{sup 2+} 4f{sub 7/2} states, qualitatively reflects the X-dependent Kondo temperature. A comparison between the PES spectra of YbInCu{sub 4} and YbCdCu{sub 4}, suggests the In 5p states play an important role for the valence transition of YbInCu{sub 4}.
2008-01-01
A synthetic route was introduced to speed up the preparation of high performance nanostructured Yb0.3Co4Sb12+y (y=0.3 and 0.6) compounds. Compared with the samples prepared by a traditional method, the processing time is reduced from the typical 10 days to less than 40 h, the Yb filling fraction limit increases, and the resulting thermoelectric transport properties are improved significantly. As a consequence, the dimensionless figure of merit of our bulk nanostructured Yb0.3Co4Sb12.3 reaches 1.3 at 800 K. The enhanced thermoelectric performance coupled with the dramatically reduced processing time will be of considerable significance to the commercial-scale production of skutterudite-based thermoelectric materials
2010-01-01
Polycrystalline nonstoichiometric Yb14MnSb11 compounds have been successfully prepared by modified induction melting and spark plasma sintering. The carrier concentration was finely tuned by changing the elemental ratio of Mn to Sb. Excess Mn decreases the electrical conductivity and increases the Seebeck coefficient. The thermal conductivity of all samples was less than 1.0 W m-1 K-1. The maximum ZT value is 0.35 K at 673 K for Yb14Mn1.05Sb11, significantly higher than that of the stoichiometric Yb14MnSb11 polycrystalline sample. (Copyright 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
2010-04-15
Heavy-fermion compounds YbIr2Si2 and YbRh2Si2 were studied by means of angle-resolved photoemission (PE). The splittings and dispersions of the 4f13 bulk and surface PE signals in the region of the expected energy crossings of the 4f final states and the valence bands in the Brillouin zone are observed. The experimental results are explained in terms of a simplified periodic Anderson model by a momentum dependence of the electron hopping matrix element between the 4f and valence-band states.
The use of rare earths in photovoltaics
1982-01-01
This chapter discusses the use of the metal-insulator semiconductor (MIS) junction as an alternative solar cell. Topics considered include the choice of the barrier forming metal, the thin film properties of the alternative barrier metals, and the junction and photovoltaic properties of alternative barrier metals. The properties of the new solar cell barrier metals Sc, Y, Lu and Yb are compared with other barrier metals such as Be, Hf, and Cr. The alternative barrier metals are compared under realistic conditions (e.g., chemically etched surfaces, thermally evaporated barrier metals in an oil free high vacuum). The results indicate that Sc and Lu are superior both in their transparency and in their barrier forming abilities. Open circuit voltages can be obtained that approximate the theoretical maximum Voc, according to the simple diffusion theory. It is determined that ...
Micro-pulling-down: a viable approach to the crystal growth of refractory rare-earth sesquioxides
2007-01-01
The RE2O3 (RE = Y, Lu, Sc) sesquioxides are promising host materials for solid-state lasers owing to their low phonon energy and high thermal conductivity. Our results demonstrate that the micro-pulling-down method is a viable approach to the single-crystal growth of refractory rare-earth sesquioxides with melting points over 2400 deg C. The method yields chemically homogeneous single-crystal rods of high crystallinity. We also present thermal conductivity data for Yb-doped Y2O3, Lu2O3, and Tm-doped Y2O3
1989-01-01
The use of a cellulose ion-exchanger (Hyphan) for the isolation of the rare earth elements (REE's) yttrium and scandium from aqueous solution is described. After preconcentration, the cations under investigation were determined using a wall stabilized plasma arc in atomic emission spectroscopy (DCP-OAES). The detection limits for Sc, Y, La, Nd, Gd, Yb and Lu were determined (0.02-0.31 mugml-1). The distribution coefficient for the investigated cations were determined as a function of pH. The order of selectivity is the following sequences, Yb
A REVIEW OF THE RARE-EARTH HYDRIDES
Some of the properties of rare earth hydrides are reviewed. Information on the hydrides of Tm, Lu, Tb, and Ho is not included because no work has been done on these elements. Eu and Yb are different from other rare earths in that MH/sub 2/ is their highest hydride and the crystal structures of EuH/sub 2/ and YbH/sub 2/ are orthorhombic. ra, Ce, Pr, and Nd form a dihydride which will take hydrogen into solid solution up to MH/sub 3/ without a change in crystal structure. The heavy rare earths form the same type of dihydride as the light, but as the hydrogen content increases from MH/sub 2/ the cubic structure becomes unstable and is replaced by a hexagonal structare. With increasing atomic number, thermal stability and hydrogen deusity increase. (J.R.D.)
2009-01-01
We succeeded in growing high-quality single crystals of a valence fluctuating compound YbCu2Si2 and a divalent compound YbCu2Ge2. The magnetic susceptibility of YbCu2Si2 follows the Curie-Weiss law with Yb3+ at high temperatures, but reveals a broad peak around 40 K for H parallel [100], which is due to the formation of a 4f-itinerant heavy fermion state at lower temperatures. This is also reflected in the temperature dependence of Hall coefficient, thermoelectric power and thermal expansion. The corresponding de Haas-van Alphen (dHvA) branches are approximately explained by the 4f-itinerant LDA band model, and the 4f-itinerant LDA+U model is found to be much applicable to the dHvA data. The cyclotron effective masses of main Fermi surfaces are relatively large, being 30-40 ...
Two new layered oxohalides in the system Cu-Yb-Te-O-Cl
2010-01-01
Two complex lanthanide(III) transition metal(II) tellurium(IV) oxyhalides, Cu3Yb2(TeO3)4Cl4 and Cu3Yb3(TeO3)4Cl6 have been synthesized and the crystal structures were determined by single-crystal X-ray diffraction. Both compounds are layered with only weak connections in between the layers. The layers are made up of [YbO8], [TeO3] and [CuOxCly] polyhedra. In both compounds the strong Lewis acid cations Yb3+ and Te4+ only form bonds to oxygen while Cu2+ form bonds to both oxygen and chlorine. This leads the Cl- ions to be expelled from the bonding volumes of the crystal structures and protrude from the layers. Magnetic susceptibility measurements were performed on a powder sample of Cu3Yb2(TeO3)4Cl4. The Curie-Weiss law found at low temperatures indicates a Curie-Weiss temperature of ca. -5...
1990-11-01
19 intermetallic compounds with the general formula RMX (R = Ca, Sr, Ba, Eu, Yb; M = Cu, Ag, Au; X = Sb, Bi) were synthesized and structurally studied by X-ray methods on powders and single crystals. The ternary phases crystallize in four ordered structural types: ZrBeSi, LiGaGe, TiNiSi and MgAgAs. Some comments are given on the parameters controlling the structure of these phases, and the volume effects are calculated. (orig.).
Deviation from the Kadowaki-Woods relation in Yb-based intermediate-valence systems
The T sup 2 -coefficient of the electrical resistivity, A, is compared with the electronic specific heat coefficient, gamma, for a number of Yb-based compounds. It is revealed that many systems, including YbCuAl, YbInCu sub 4 , YbAl sub 3 , and YbCu sub 5 , show A/gamma sup 2 values close to 0.4 x 10 sup - sup 6 mu OMEGA cm mol sup 2 K sup 2 mJ sup - sup 2 , which are remarkably small compared to those obtained from an expression known as the Kadowaki-Woods relation: A/gamma sup 2 = 1.0 x 10 sup - sup 5 mu OMEGA cm mol sup 2 K sup 2 mJ sup - sup 2. Empirically, the compounds with the smaller A/gamma sup 2 values appear to show weak intersite magnetic correlation and/or to have almost fully degenerate (J = 5/2 or 7/2) ground states.
Electrical and optical properties of the mixed-valence misfit-layer compound (YbS)1.25CrS2
2008-01-01
The crystals of the new misfit-layer compound (YbS)1.25CrS2 were grown by chemical transport reaction in a closed silica ampoule. This compound is built up of alternately stacking of YbS and CrS2 layers. The dimensions of a unit cell are a1 = 5.31 A, b1 = 5.75 A, and c1 = 10.63 A for the YbS sublattice and a2 = 3.32 A, b2 = 5.75 A, and c2 = 10.63 A for the CrS2 sublattice. Both layers are incommensurate along the a-axis and the incommensurability parameter, which is defined by alpha = a2/a1, is about 0.625. It is found from the comparison of lattice parameters among a series of lanthanide misfit-layer compounds and lanthanide monosulfides that Yb is in an intermediate valence state close to trivalency rather than divalency ...
Structural Stability of Vacancy-ordered $Yb_{2.75}C_{60}$
1997-09-19
The fcc-based structure of Yb2.75C60 is unique among metal-doped fullerene compounds, exhibiting long-range-ordered vacancies, significantly off-centered divalent Yb cations, and distorted, crystallographically inequivalent, orientationally ordered C60 anions. A simple electrostatic-energy analysis, which models the constituents using point charges, is shown to provide insight into how each of these features stabilizes this unusual crystal structure. The results have general implications for a variety of other intercalated metal fullerides.
1997-01-01
A solution of metallic ytterbium in liquid ammonia reacts readily with various metal carbonyls to from the corresponding metalcarbonylates. The reaction of an excess of Yb in liquid NH3 with [CpFe(CO)2]2 gives (THF)4Yb[Fe(CO)2Cp]2 in 42% yield. The compound seems to contains two equivalent Yb-Fe bonds
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