Lu Samples Research Articles

Formation of bound dineutrons in the 175Lu (n, 2n) 174gLu nuclear reaction and its cross-section

The dineutron as a bound chargeless nucleus of two identical nucleons has been attracting attention for many decades. In addition to the study of the formation of a bound dineutron in the outgoing channel of specific nuclear reactions, cross-section estimates have been gaining interest as research targets. We used a traditional neutron activation technique to irradiate Lu samples followed by measurements of the induced activity with HPGe spectrometer in order to detect gamma-peaks of the 175Lu (n, 2n)174gLu reaction product when this reaction channel is not open for incident neutron energies. Based on two measurements of the instrumental gamma-ray spectra of Lu samples we reliably identified the presence of the 174gLu isotope in the outgoing channel of the 175Lu (n, 2n)174gLu nuclear reaction. Also, the cross-section for this nuclear reaction was obtained and to be equal 33.5−6.7+7.0 mb. For the first time, the dineutron as a nuclear reaction product was indirectly detected via statistically significant observation of the induced activity of 174gLu with a corresponding cross-section estimate.

Half-life of the nuclear cosmochronometer 176Lu measured with a windowless 4π solid angle scintillation detector

The 176Lu-176Hf nuclear decay is a powerful tool to measure the age of astrophysical and geological events and has been used as a “cosmochronometer”. However, the half-life values of 176Lu measured with various experiments differ significantly. Furthermore, the half-life values evaluated from Lu-Hf isochrons in meteorites and terrestrial rocks with known ages show two different values. Here we report half-life measurements using a method that is almost independent of various uncertainties. To the best of our knowledge this is the most accurate value of 176Lu half-life. We measure the total energy released from 176Lu decay using a windowless 4π solid angle detector based upon bismuth germanate (BGO) scintillation crystals, where a natural Lu sample is located inside of the detector. The measured half-life of (3.719 ± 0.007) × 1010 yr corresponding to a decay constant of (1.864 ± 0.003) × 10−11 yr−1 is consistent with that obtained from the analysis of terrestrial rocks within the uncertainty.

Neutron capture cross section measurements for <sup>nat</sup>Lu with different thickness

The C<sub>6</sub>D<sub>6</sub> detection system coupling with the pulse height weighting technique is widely used for experimentally measuring the neutron capture cross section. The thickness of sample used in the experiment directly affects the neutron beam time and the reliability of the experimental data. In the present work, we compare the lutetium (Lu) neutron capture reaction cross sections among the samles with different thickness, obtained by the C<sub>6</sub>D<sub>6</sub> detection system of the back-streaming white neutron beam line at China spallation Neutron Source (CSNS back-n). The light response of the detection system is simulated with the consideration of the sample thickness by GEANT4 Monte Carlo simulation code. The 4<sup>th</sup> order polynomial pulse weight functions for different samples are determined by using the above light response function. In the experiment, the high precision capture yield distributions in the resonance energy region are obtained by measuring the longer flight distance and background. The experimental resonance parameters are deduced by analyzing the capture yield distribution with the R-matrix theory. The comparisons of the results of capture yield and the resonance parameters between the two groups show that the resonance curve of 1.06mm <sup>nat</sup>Lu sample changes due to its thickness effect, and there is a large difference between the experimental resonance parameters and ENDF/B-VIII.0 database. However, the experimental results of 0.207mm <sup>nat</sup>Lu sample can well accord with the ENDF/B-VIII. 0 data.

Effects of hydrothermal aging, thermal cycling, and water storage on the mechanical properties of a machinable resin-based composite containing nano-zirconia fillers

ObjectivesThis study aimed to investigate the effects of hydrothermal aging, thermal cycling, and water storage on the mechanical properties of a machinable resin-based composite containing nano-zirconia fillers. Materials and methodsA machinable resin-based composite containing nano-zirconia fillers (Lava Ultimate, LU) and a resin-based composite with a similar resin matrix-to-filler ratio but without zirconia fillers (Tetric N-Ceram, TNC) were prepared into bars and assigned into four groups based on the type of aging treatment (hydrothermal aging, thermal cycling, water storage, or no aging). The phase transformations of the zirconia fillers in LU after aging were evaluated by X-ray diffraction. The flexural strength, Weibull modulus, flexural modulus, and Vickers hardness of each group were investigated. The fracture surface morphologies of both resin-based composites before and after aging were observed by a scanning electron microscopy (SEM). ResultsOnly Tetragonal zirconia was detected in the LU samples. Both before and after aging, the flexural strength, flexural modulus, and Vickers hardness values of LU were significantly higher than those of TNC (p < 0.05) with the exception of the flexural modulus of LU, which showed no difference with that of TNC after water storage (p = 0.68). Hydrothermal aging, thermal cycling, and water storage had no significant effects on the surface Vickers hardnesses of LU or TNC (p > 0.05). Hydrothermal aging significantly improved the flexural strength of LU (p = 0.00). Thermal cycling (p = 0.00) and water storage (p = 0.00) significantly decreased the flexural strength of LU. The flexural strength of TNC was not decreased by hydrothermal aging (p = 0.82) or water storage (p = 0.36), while it was decreased by thermal cycling (p = 0.00). The hydrothermal aging group of LU exhibited the highest Weibull modulus. ConclusionsThe machinable resin-based composite containing nano-zirconia fillers provides superior flexural strength, flexural modulus, and Vickers hardness compared to the direct-filling resin-based composite with a similar resin matrix-to-filler ratio, although it fails to provide better aging resistance.

Synchrotron X-ray diffraction study of double perovskites Sr2RNbO6 (R = Sm, Gd, Dy, Ho, Y, Tm, and Lu)

A series of double-perovskite oxides, Sr2RNbO6 (R = Sm, Gd, Dy, Ho, Y, Tm, and Lu) were prepared and their crystal structure and powder diffraction reference patterns were determined using the Rietveld analysis technique. The crystal structure of each of the Sr2RNbO6 phase is reported in this paper. The R = Gd, Ho, and Lu samples were studied using synchrotron radiation, while R = Sm, Dy, Y, and Tm samples were studied using laboratory X-ray diffraction. Members of Sr2RNbO6 are monoclinic with a space group of P21/n and are isostructural with each other. Following the trend of “lanthanide contraction”, from R = Sm to Lu, the lattice parameters “a” of these compounds decreases from 5.84672(10) to 5.78100(3) Å, b from 5.93192(13) to 5.80977(3) Å, c from 8.3142(2) to 8.18957(5) Å, and V decreases from 288.355(11) to 275.057(2) Å3. In this double-perovskite series, the R3+ and Nb5+ ions are structurally ordered. The average Nb–O bond length is nearly constant, while the average R–O bond length decreases with the decreasing ionic radius of R3+. Powder diffraction patterns for these compounds have been submitted to the Powder Diffraction File (PDF).

Magnetic order and magnetoelectric properties of R2CoMnO6 perovskites ( R=Ho , Tm, Yb, and Lu)

We present a detailed study on the magnetic structure and magnetoelectric properties of several double perovskites ${R}_{2}\mathrm{CoMn}{\mathrm{O}}_{6}$ ($R=\mathrm{Ho}$, Tm, Yb, and Lu). All of these samples show an almost perfect $(\ensuremath{\sim}94%)$ ordering of $\mathrm{C}{\mathrm{o}}^{2+}$ and $\mathrm{M}{\mathrm{n}}^{4+}$ cations in the unit cell. Our research reveals that the magnetic ground state strongly depends on the $R$ size. For samples with larger $R$ (Ho and Tm), the ground state is formed by a ferromagnetic order ($F$ type) of $\mathrm{C}{\mathrm{o}}^{2+}$ and $\mathrm{M}{\mathrm{n}}^{4+}$ moments, while $R$ either remains mainly disordered (Ho) or is coupled antiferromagnetically (Tm) to the Co/Mn sublattice. For samples with smaller $R$ (Yb or Lu), competitive interactions lead to the formation of an $E$-type arrangement for the $\mathrm{C}{\mathrm{o}}^{2+}$ and $\mathrm{M}{\mathrm{n}}^{4+}$ moments with a large amount of extended defects such as stacking faults. The $\mathrm{Y}{\mathrm{b}}^{3+}$ is partly ordered at very low temperature. The latter samples undergo a metamagnetic transition from the $E$ into the $F$ type, which is coupled to a negative magnetodielectric effect. Actually, the real part of dielectric permittivity shows an anomaly at the magnetic transition for the samples exhibiting an $E$-type order. This anomaly is absent in samples with $F$-type order, and, accordingly, it vanishes coupled to the metamagnetic transition for $R=\mathrm{Yb}$ or Lu samples. At room temperature, the huge values of the dielectric constant reveal the presence of Maxwell-Wagner depletion layers. Pyroelectric measurements reveal a high polarization at low temperature, but the onset of pyroelectric current is neither correlated to the kind of magnetic ordering nor to the magnetic transition. Our study identified the pyroelectric current as thermally stimulated depolarization current and electric-field polarization curves show a linear behavior at low temperature. Therefore, no clear ferroelectric transition occurs in these compounds.

Frustrated spin- 12 molecular magnetism in the mixed-valence antiferromagnets Ba3MRu2O9(M=In , Y, Lu)

We have performed magnetic susceptibility, heat capacity, muon spin relaxation, and neutron scattering measurements on three members of the family Ba3MRu2O9, where M = In, Y and Lu. These systems consist of mixed-valence Ru dimers on a triangular lattice with antiferromagnetic interdimer exchange. Although previous work has argued that charge order within the dimers or intradimer double exchange plays an important role in determining the magnetic properties, our results suggest that the dimers are better described as molecular units due to significant orbital hybridization, resulting in one spin-1/2 moment distributed equally over the two Ru sites. These molecular building blocks form a frustrated, quasi-two-dimensional triangular lattice. Our zero and longitudinal field muSR results indicate that the molecular moments develop a collective, static magnetic ground state, with oscillations of the zero field muon spin polarization indicative of long-range magnetic order in the Lu sample. The static magnetism is much more disordered in the Y and In samples, but they do not appear to be conventional spin glasses.

Novel Lu-doped Bi2WO6 nanosheets: Synthesis, growth mechanisms and enhanced photocatalytic activity under UV-light irradiation

Polycrystalline systems of lutetium doped bismuth tungstates Bi2WO6: Lu (Lu at% 0, 2, 5 and 8) were synthesized using the coprecipitation method, followed by thermal treatment at 500°C. The Bi2WO6:Lu samples were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-Ray analysis (EDS) and UV–vis diffuse reflectance spectra (DRS). The XRD and SEM analyses showed that the as-prepared samples crystallized in the same orthorhombic structure and consist of agglomerated nanosheets. To characterize the photocatalytic activities, UV–visible spectrometry was used to analyze the evolution of Rhodamine B photodegradation in presence of the Bi2WO6: Lu photocatalysts. The characteristic absorption band of Rhodamine B at 554nm shifted to lower wavelengths under UV irradiation. The pure Bi2WO6 and the 5% Lu doped Bi2WO6 photocatalysts presented the lowest and highest efficiencies, respectively. An interpretation of improved photocatalytic efficiencies was proposed.

Lutentium incorporation influence on ZnO thin films coated via a sol–gel route: spin coating technique

Pure and lutetium (Lu) incorporated zinc oxide (ZnO) thin films were deposited by a sol–gel route. The effect of Lu contribution on the properties of ZnO was examined in detail by means of XRD, AFM, SEM, UV–Vis spectrophotometer, and I–V measurements. The nano-sized ZnO:Lu samples had hexagonal wurtzite structure with c-axis (002) preferential orientation. The pure ZnO nano-particles homogeneously scattered on the film surface and this homogeneous particle distribution was deteriorated with Lu incorporation. Ohmic contacts to the ZnO:Lu films were formed using gold (Au) metallization schemes. As-deposited Au contacts exhibited linear current–voltage characteristics. The optical band gap for pure ZnO went up from 3.281 to 3.303 eV with low Lu contribution level up to 3 at.%, then it decreased with more Lu level. The Urbach energy was also studied and it was found that Eu depended on Lu incorporation level.

Geochemistry of the Görcsöny Ridge amphibolites (Tisza Unit, SW Hungary) and its geodynamic consequences

The Gorcsony Ridge is part of the complicated Variscan metamorphic basement of the SW Tisza plate. It was penetrated by several wells, one of which (Baksa-2) explored 1200 m borecore available for petrological examination. Amphibolite samples of this core are of two different sorts: one sort contains biotite, rutile, and garnet, while the other contains ilmenite and is free of garnet. The two rock types occur separately along the borehole, defining a lower and an upper unit (LU, UU). Based on their major and trace element compositions, LU samples are within-plate (WP) tholeiites which assimilated pelagic sediments, while those of the UU represent WP alkali basalts. Thermobarometric calculations suggest that the difference in chemical composition itself does not explain the above differences in mineralogy, so the two units must also differ in their metamorphic histories. Consequently, the crystalline basement of the Gorcsony Ridge possibly consists of amalgamated fragments of different origins and evolutions which became juxtaposed during the Variscan collisional orogeny.

Improved in situ Hf isotope ratio analysis of zircon using newly designed X skimmer cone and jet sample cone in combination with the addition of nitrogen by laser ablation multiple collector ICP-MS

The effect of three different cone combinations on the performance of laser ablation MC-ICP-MS (Neptune plus) for the in situ Hf isotope analysis of zircon were investigated. The signal sensitivities of Hf, Yb and Lu were improved by a factor of 1.4 and 2.5, respectively, with using the X skimmer cone + standard sampler cone and the X skimmer cone + Jet sample cone compared to the standard arrangement (H skimmer cone + standard sample cone). However, when using the high-sensitivity Jet sample cone, the instrumental mass fractionation for hafnium displayed a large non-linear component that could not be corrected using the normal mass fractionation laws. The magnitude of this non-linear mass fractionation was strongly related to the central gas flow rate. The in situ Hf isotope analysis of zircon standards 91500 and Mud Tank using the Jet cone displayed large deviations (410–470 ppm) at the optimum central gas flow rate for Hf, which seriously deteriorated the performance of the Jet cone. The addition of 4 ml min−1 nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to not only increase the sensitivity of Hf by a factor of 2.1, but also suppress this non-linear mass fractionation. The determined Yb/Hf and Lu/Hf ratios at their corresponding optimum makeup gas flow rates for Hf intensity were found to be reduced by factors of 2 and 1.3 in the presence of nitrogen, respectively, which would benefit the accurate in situ determination of Hf isotopes in high-content Yb and Lu samples. Compared to the standard arrangement, the corresponding precision (2σ) of 176Hf/177Hf for single spot analysis of zircon standard 91500 was improved from 224 ppm to 50 ppm by using the newly designed X-skimmer cone and Jet sample cone in combination with the nitrogen addition technique. The determined 176Hf/177Hf ratios are in excellent agreement with published values in five reference zircon standards (91500, GJ-1, Mud Tank, Penglai and Plesovice). Our first Hf isotopic results from zircon standard M257 (0.281544 ± 0.000018; 2SD, n = 151) showed that it was fairly homogeneous in Hf isotopes. These results clearly demonstrate that the present analytical method has the potential to become an important tool for the pursuit of high-quality in situ Hf isotope data for zircons.

Sample of minor merger of galaxies: Optical CCD surface photometry and HII region properties

We present the results of the B, V and I photometry of eleven southern minor mergers. The total apparent B magni- tude, integrated B−V and V − I colours were measured. We built B, V ,a ndI equivalent profiles for each galaxy and decomposed them into bulge and disk components when possible. From Hα+N(II) images we have estimated the basic photometric param- eters of the HII regions, such as position, size, B − V and V − I colours, Hα+(NII) luminosity and EW(Hα + (NII)) equivalent width. Primary components have blue absolute magnitudes in the range −22 < MB < −18, with a peak at MB = −22. The magnitudes of the secondary components are in the range −22 < MB < −16 with a maximum at MB = −19. Most pairs have ∆MB ∼ 2, which means that in luminosity the primary galaxy is on average about 6 times brighter than the secondary. We found a linear correlation between the luminosity ratios of the components and their ratio of major diameters, leading to mass ratios between 0.04 < Msecondary/M primary < 0.2, suggesting indeed that our sample is formed by minor mergers. On average the galaxies have colours bluer than those of isolated galaxies with the same morphological type. Most of the HII regions and evolved star-forming regions of the sample were formed between 3.6 to 13.7 Myr ago with an average of (6.3 ± 0.7) Myr. The HII region properties, luminosity, sizes and ages are similar in both components. The HII regions have log (Hα+(NII)) lumi- nosity between 38.6 and 41.7. The HII region luminosity function for the whole sample fits a power law of index α = -1.33. The linear correlation between the luminosity L(Hα+(NII)) and the size of the HII regions has slope of 2.12 ± 0.06. We found that the disk of the primary component is more luminous than those of Lu's sample, while the disk of the secondary is smaller and fainter. A plot of the disk parameters does not change with colour. This indicates that the different stellar populations in the disks were affected in the same way.

Rotational bands and isomeric states inLu175

Rotational bands in $^{175}\mathrm{Lu}$ have been extended through investigation with the $(n,{n}^{\ensuremath{'}}\ensuremath{\gamma})$ reaction. Spallation neutrons bombarded Lu samples, and the resulting $\ensuremath{\gamma}$ rays were detected in a large-scale Compton-suppressed Ge detector array. Prompt- and delayed-$\ensuremath{\gamma}\ensuremath{\gamma}$ coincidences have been used to extend the $5∕{2}^{+}[402]$ band to spin $17∕2$, the $3∕{2}^{+}[411]$ band to spin $11∕2$, the $1∕{2}^{+}[411]$ band to spin $15∕2$, and the $1∕{2}^{\ensuremath{-}}[541]$ and $9∕{2}^{\ensuremath{-}}[514]$ bands to spin $21∕2$. A new band, based on the $7∕{2}^{\ensuremath{-}}[523]$ configuration, is tentatively assigned from its bandhead to spin $13∕2$. The three-quasiparticle ${K}^{\ensuremath{\pi}}=19∕{2}^{+}$ isomer is confirmed and its half-life determined to be $984\ifmmode\pm\else\textpm\fi{}13(\text{stat}.)\ifmmode\pm\else\textpm\fi{}30(\text{sys}.)$ $\ensuremath{\mu}\mathrm{s}$, in agreement with previous results.

Superconducting rare earth transition metal borocarbides

We present an overview of selected properties of quaternary intermetallic rare earth transition metal borocarbides and related boronitride compounds, as well as of theoretical calculations with possible relevance to the mechanism of superconductivity. The interplay of superconductivity and magnetism for compounds with pure and mixed rare earth components is considered. We suggest that the incommensurate magnetic structure modulated along the a-axis is responsible for the pair breaking in Ho x R 1− x Ni 2B 2C; R=Y, Lu samples. The effect of doping (Cu, Co) at the transition metal site is considered experimentally and theoretically. The possible role of correlation effects due to the presence of the transition metal component in determining the electronic structure is discussed comparing the band structure calculation results with various electronic spectroscopies as well as de Haas–van Alphen data. Important thermodynamic properties of these systems are analyzed within multiband Eliashberg theory with special emphasis on the upper critical field H c2( T) and the specific heat. In particular, the unusual positive curvature of H c2( T) near T c observed for high-quality single crystals, polycrystalline samples of YNi 2B 2C, LuNi 2B 2C as well as to a somewhat reduced extent also for the mixed system Y 1− x Lu x Ni 2B 2C is explained microscopically. It is shown that in these well-defined samples the clean limit of type II superconductors is achieved. The values of H c2( T) and of its positive curvature near T c (as determined both resistively and from magnetization as well as from specific heat measurements is an intrinsic quantity generic for such samples) decrease with growing impurity content. Both quantities thus provide a direct measure of the sample quality.

A new nickel(III) oxide family: MSr3NiO6 (M = Sc, In, Tm, Yb and Lu)

AbstractThe new phases MIIISr3NiIIIO6 have been prepared for M = Sc, In, Tm, Yb and Lu. Thermogravimetric analysis indicates that these phases are stoichiometric nickel(III) oxides. Rietveld refinement of their crystal structures from powder X‐ray diffraction data confirms that they adopt the rhombohedral K4CdCl6‐ type structure (space group R\documentclass{article}\pagestyle{empty}\begin{document}$ \bar 3 $\end{document}c, a = 9.6595 (2) and c = 10.8546 (3) Å for ScSr3NiO6). The M site is fully occupied for M = Sc and In, but a deficiency of scattering for M = Tm, Yb and Lu is shown to be due to Ni substitution through a simultaneous refinement of the YbSr3NiO6 structure using X‐ray and time‐of‐flight neutron diffraction data. The refined composition is (Yb0.83Ni0.17)‐Sr3NiO6. The magnetic susceptibilities of the M = Sc, In and Lu samples show Curie–Weiss behaviour down to 6K; however, ScSr3NiO6 shows a broad transition between 250 and 290 K, with Curie–Weiss behaviour above and below this anomaly. This transition is thought to be between the statically and dynamically Jahn–Teller distorted regimes of octahedrally coordinated, low‐spin Ni3+.

ULTRASONIC ATTENUATION MEASUREMENTS ON LuBa2Cu3O7 AND HoBa2Cu3O7

HoBa 2 Cu 3 O 7 and LuBa 2 Cu 3 O 7 show very different ultrasonic attenuation behavior at temperatures below 220 K. The Ho sample exhibits a broad maximum in attenuation at around 220 K, while the Lu sample shows a minimum followed by a plateau below 140 K. At T c , the Ho sample shows a decrease in attenuation; there is no evidence for such a change in the Lu sample.

Specific Heat of Lutetium Metal Between 0.38 and 4°K

The specific heat of lutetium metal has been measured in a ${\mathrm{He}}^{3}$ cryostat. Between 0.38 and 4\ifmmode^\circ\else\textdegree\fi{}K (in mJ/mole \ifmmode^\circ\else\textdegree\fi{}K) ${C}_{p}=0.210{T}^{3}+11.27T+0.094{T}^{\ensuremath{-}2}$. Scatter of individual points from this curve is, except in a few isolated cases, less than 0.5%. The lattice specific heat corresponds to a Debye characteristic temperature $\ensuremath{\theta}=210\ifmmode^\circ\else\textdegree\fi{}$K, which is considerably higher than $\ensuremath{\theta}'\mathrm{s}$ previously assigned to rare earths. The discrepancy is probably due to difficulties in determining $\ensuremath{\theta}$ accurately for those lanthanides which have large magnetic contributions to ${C}_{p}$. On the basis of this and other researches it is suggested that for all trivalent rare earths, $\ensuremath{\theta}$ can be calculated by linear interpolation, as a function of the atomic number, between $\ensuremath{\theta}=210\ifmmode^\circ\else\textdegree\fi{}$K for Lu and $\ensuremath{\theta}=142\ifmmode^\circ\else\textdegree\fi{}$K for La. An accuracy of \ifmmode\pm\else\textpm\fi{}5\ifmmode^\circ\else\textdegree\fi{}K may be expected. The present value for the coefficient in the electronic specific heat ${C}_{E}$ for Lu and previous measurements on La, Sc, and Y suggest that within \ifmmode\pm\else\textpm\fi{}7% accuracy we may write for all trivalent lanthanides ${C}_{E}=10.5T$. The small ${T}^{\ensuremath{-}2}$ term in ${C}_{p}$ could be caused by interaction of the nuclear quadrupole moment with the crystalline field gradient or it may be due to long-range exchange-type coupling between the electronic moments of rare-earth impurities in our Lu sample. If the former interpretation is accepted, the electric field gradient, along the symmetry axis, becomes 2.2\ifmmode\times\else\texttimes\fi{}${10}^{24}$ ${\mathrm{cm}}^{\ensuremath{-}3}$.