12008-33-2Relevant articles and documents
Semiconductor-insulator transition in a YbB6 nanowire with boron vacancy
Han, Wei,Wang, Zhen,Li, Qidong,Lian, Xin,Liu, Xudong,Fan, Qinghua,Zhao, Yanming
, p. 244 - 250 (2018)
In this paper, we report the study of transport and magnetic properties of ytterbium hexaboride (YbB6) nanowires grown by a low trigger-temperature (200–240 °C) solid state method. The temperature dependence of resistivity shows that the YbBsu
On phase equilibria and crystal structures in the systems Ce-Pd-B and Yb-Pd-B. Physical properties of R2Pd13.6B5 (R=Yb, Lu)
Sologub, Oksana,Rogl, Peter,Salamakha, Leonid,Bauer, Ernst,Hilscher, Gerfried,Michor, Herwig,Giester, Gerald
, p. 1013 - 1037 (2010/08/05)
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, τ2-CePd8B2-x (0.103-Ce3Pd25-xB8-y (1.063Bx (03. Crystallographic parameters for the new structure type τ2-CePd8B2-x (space group C2/c, a=1.78104(4) nm, b=1.03723(3) nm, c=1.16314(3), β=118.515(1)° for x=0.46) were established from X-ray single crystal diffraction. The crystal structures of τ2-CePd8B2-x and τ3-Ce3Pd25-xB3-y are connected in a crystallographic group-subgroup relationship. Due to the lack of suitable single crystals, the novel structure of τ1-Ce6Pd47-xB6 (x=0.2, C2/m space group, a=1.03594(2) nm, b=1.80782(3) nm, c=1.01997(2) nm, β=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, β=108.168(1)°). The Yb-Pd-B system is characterized by one ternary compound, τ1-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 τ1-Ce6Pd47-xB6, τ2-CePd8B2-x and τ3-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.
Thermoelectric properties of some metal borides
Takeda, Masatoshi,Fukuda, Tadahiro,Domingo, Ferrer,Miura, Takahiro
, p. 471 - 475 (2008/10/09)
Polycrystalline AlMgB14 and some hexaborides (CaB6, SrB6, YbB6, SmB6, and CeB6) were synthesized to examine their thermoelectric properties. Single phase of orthorhombic AlMgB14, which contains B12 icosahedral clusters as building blocks, was obtained at sintering temperatures between 1573 and 1823K. Seebeck coefficient (α) and electrical conductivity (σ) of the phase were about 500μV/K and 10-11/Ωm at room temperature, respectively. These values are comparable to those of metal-doped β-rhombohedral boron. On the other hand, metal hexaborides with divalent cation possessed large negative α ranging from -100 to -270μV/K at 1073K. Calculated power factors of CaB6 and SrB 6 exceeded 10-3W/K2m within the entire range of temperature measured. As a result, they can be thought as promising candidates for n-type thermoelectric material.
Raman scattering investigation of RB6 (R = Ca, La, Ce, Pr, Sm, Gd, Dy, and Yb)
Ogita, Norio,Nagai, Shinji,Okamoto, Naoki,Udagawa, Masayuki,Iga, Fumitoshi,et al.
, p. 1 - 9 (2008/10/09)
The excitation-energy, polarization, and temperature dependeces of Raman scattering spectra have been measured for the RB6 crystals (R=Ca 2+, La3+, Ce3+, Pr3+, Sm 2.6+, Gd3+, Dy3+, and Yb2+). In the divalent crystals of CaB6 and YbB6, the Eg phonon shows doublet, while the line shape is a broad single peak for the trivalent case. In the trivalent crystals, two kinds of the extra peaks have been clearly observed at around 200 cm-1 and at around 1400 cm -1 in addition to the Raman-active phonons and crystal electric-field (CEF) excitations. The peak intensities at around 200 cm -1 show the anomalous decrease with decreasing temperature, and this temperature dependence correlates with that of the mean-square displacement of the R ion. Furthermore, their energies decrease with the increase of the cage space due to B6. These peaks are originated from the second-order excitation of acoustic phonons. The broad peak at around 1400 cm-1 is assigned as the second-order excitation of the T2g phonon. For the T2g phonon, the energy difference and its line-shape change between the trivalent and divalent crystals suggests the existence of electron-phonon interaction. We have observed the CEF excitation in PrB 6 and have obtained the Lea, Leask, and Wolf parameters with x=0.94 and W=9.2 K.
Evidence for a ferromagnetic transition in Yb1-xLaxB6 (0≤x≤0.006)
Iga, Fumitoshi,Ueda, Yuki,Takabatake, Toshiro,Suzuki, Takashi,Higemoto, Wataru,et al.
, p. 1 - 4 (2008/10/08)
Magnetization and muon spin relaxation (μSR)in Yb1-xLaxB6 have been measured to study whether ferromagnetic moments appear as in La-doped CaB6. Magnetization processes of polycrystalline samples for 0≤x≤0.006 have revealed ferromagnetic hysteresis with a saturation moment of 1 × 10-4μB/f.u. On cooling below 150 K, an increase of the internal field up to 0.6 mT has been observed by zero-field/μSR measurements on both polycrystals and single crystals. These results indicate a ferromagnetic transition at 150 K in this system.
Complexes of divalent lanthanides (Yb(II), Eu(II), Sm(II)) with decaborates
White III, James P.,Shore, Sheldon G.
, p. 2756 - 2761 (2008/10/08)
Decaborate complexes of divalent lanthanides are prepared through the reduction of B10H14 by elemental lamhanides in liquid NH3. The products are insoluble in liquid NH3. Extraction with CH3CN yields the complexes (CH3CN)6Yb[B10H14] and (CH3CN)xEu[B10H14], in which the boron cage is bound to the lanthanide dianion through Ln-H-B bonds. Solvent-separated decaborate anions [B10H13]- and [B10H15] are also observed in the CH3CN extracts. Reductions of B10H14 by lanthanide amalgams, Ln(Hg) (Ln = Sm, Yb), in 1,2-dimethoxyethane (DME) produce small amounts of the DME-solublc salts containing the solvent-separated decaborate anions [B10H13]- and [B10H15]-. The major reaction product is insoluble in DME, but extraction with CH3CN yields salts with the solvent-separated [B10H13]- and [B10H15]. Solvent-free Eu[B10B10] and Yb[B10B10] are prepared by decomposing in vacuum at 200°C NH3- and also CH3CN-solvated salts of Eu[B10H14] and Yb[B10H14]. Further decomposition of Yb[B10H10] at temperatures above 600°C in vacuum leads to the formation of YbB6.
11B NUCLEAR QUADRUPOLE INTERACTION IN METAL HEXABORIDES (MB6).
Aono,Kawai
, p. 797 - 802 (2008/10/09)
The objective of this work is to discuss the bonding nature of the hexaborides on the basis of the experimental results on the **1**1B nuclear electric quadrupole interaction.
