12008-32-1

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Chemical Properties

-325 mesh 10μm or less with 99.9% purity; refractory material [CER91] [KIR78]

InChI:InChI=1/6BH2.Y/h6*1H2;/q6*+1;-6/rB6H12Y/c1-7(2,3,4,5)6/h1-6H2

Upstream product

• 7440-67-7 zirconium 

Relevant academic research and scientific papers

Characterization of the electronic properties of YB4 and YB 6 using 11B NMR and first-principles calculations

Two compounds, tetragonal YB4 and cubic YB6, have been investigated by electric-field gradient (EFG) and Knight shift measurements at the boron sites using the 11B nuclear magnetic resonance (NMR) technique and by performing first-principles calculations. In YB6 11B (I=3/2) NMR spectra reveal patterns typical for an axially symmetric field gradient with a quadrupole coupling frequency of νQ=600±15kHz. In the second boride (YB4) three different EFGs were observed corresponding to the three inequivalent crystallographic sites for the boron atoms (4h, 4e, and 8j). They correspond to: νQ(4h)=700±30kHz with an asymmetry parameter η=0.02±0.02, νQ(4e)=515±30kHz, η=0.00+0.02/-0.00, and νQ(8j)=515±40kHz, η=0.46±0.08. The Knight shifts measured by magic-angle spinning (MAS) NMR at room temperature are very small being 0.6±8 and -1±8ppm for YB4 and YB6, respectively. For the theoretical calculations structure optimizations were performed as a first step. For the obtained structural parameters the EFGs were computed within the local-density approximation. Very satisfactory agreement between experimental and theoretical results is obtained both for the structural parameters and the B EFGs, thus confirming the underlying structural models. In addition to the EFGs, band structures, densities of states, and valence-electron densities are presented and the bonding situation in the two yttrium borides is discussed. The band-structure results are compatible with the very low values for the Knight shifts mentioned above.

Synthesis of pure YB4powder via the reaction of Y 2O3with B4C

Pure YB4powder was synthesized via the reaction of Y 2O3with B4C under a vacuum pressure within the range of 20-50 Pa using spark plasma sintering (SPS) route. The effect of temperature and the molar ratio of the starting materials was studied. The role of the YBO3, an intermediate product, in the synthesis of YB 4was investigated. For preparation of high purity YB4, the molar proportion of B4C to Y2O3should not be higher than the stoichiometric ratio (15/7). YBO3can be removed through decomposing to Y2O3and B2O 3or reacting with B4C to form YB4and B 2O3at a temperature above 1650°C. The little residual impurities, such as Y2O3and YBO3, can be removed by hydrochloric acid washing. Thus, a high purity YB4powder has been synthesized. The oxygen content of the obtained YB4is about 0.007% and the particle size is in the range of 3-10 μm.

Synthesis and Characterization of Single-Phase Metal Dodecaboride Solid Solutions: Zr1- xYxB12 and Zr1- xUxB12

Single-phase metal dodecaboride solid solutions, Zr0.5Y0.5B12 and Zr0.5U0.5B12, were prepared by arc melting from pure elements. The phase purity and composition were established by powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and 10B and 11B solid-state nuclear magnetic resonance (NMR) spectroscopy. The effects of carbon addition to Zr1-xYxB12 were studied and it was found that carbon causes fast cooling and as a result rapid nucleation of grains, as well as "templating" and patterning effects of the surface morphology. The hardness of the Zr0.5Y0.5B12 phase is 47.6 ± 1.7 GPa at 0.49 N load, which is ～17% higher than that of its parent compounds, ZrB12 and YB12, with hardness values of 41.6 ± 2.6 and 37.5 ± 4.3 GPa, respectively. The hardness of Zr0.5U0.5B12 is ～54% higher than that of its UB12 parent. The dodecaborides were confirmed to be metallic by band structure calculations, diffuse reflectance UV-vis, and solid-state NMR spectroscopies. The nature of the dodecaboride colors - violet for ZrB12 and blue for YB12 - can be attributed to charge-transfer. XPS indicates that the metals are in the following oxidation states: Y3+, Zr4+, and U5+/6+. The superconducting transition temperatures (Tc) of the dodecaborides were determined to be 4.5 and 6.0 K for YB12 and ZrB12, respectively, as shown by resistivity and superconducting quantum interference device (SQUID) measurements. The Tc of the Zr0.5Y0.5B12 solid solution was suppressed to 2.5 K.

The ternary RE-Si-B systems (RE = Dy, Ho, Er and Y) at 1270 K: Solid state phase equilibria and magnetic properties of the solid solution REB2-xSix (RE = Dy and Ho)

The solid state phase equilibria in the ternary RE-Si-B diagrams (RE = Dy, Ho, Er and Y) were determined at 1270 K using experimental techniques such as X-ray diffraction, scanning electron microscopy and electron probe microanalysis. In general, three ternary phases were obtained for each diagram: the line compound RE5Si2B8 with tetragonal symmetry, the boron-inserted Nowotny phase RE5Si3Bx of Mn5Si3-type and the solid solution REB2-xSix of AlB2-type. Prior to this work, the binary systems RE-Si and RE-B, which form the boundary of each diagram, were also re-investigated. In addition to the structures of RE5Si3 (Mn5Si3-type, RE = Dy, Ho and Y) and Dy3Si4 (Ho3Si4-type) which were previously reported or will be presented in a forthcoming paper, the X-ray single crystal structures of RE5Si4 (Sm5Ge4-type, RE = Dy and Ho), DySi (CrB-type) and HoSi in both polymorphic modifications, i.e. the FeB- (high temperature) and CrB- (low temperature) types, were determined and are described herein. Structural relationships between members of the same series on one side, and between both forms of HoSi on the other side, are also discussed in terms of coordination polyhedra and interatomic distances. Finally, magnetic measurements were performed on the alloys REB2-xSix, which in case of RE = Dy exhibit a marked increase of the magneto-crystalline anisotropy, whereas for RE = Ho a change from ferromagnetic to antiferromagnetic behaviour with increasing silicon content is encountered.

Large crystal structure distortion in DyB6 studied by X-ray diffraction

A large magnetoelastic coupling induces a lattice distortion of a rhombohedral type in DyB6. Below the quadrupolar ordering temperature TQ=31K the cubic and the distorted phases coexist. The cubic phase disappears at 23K, which was identified as the magnetic ordering point TN. In the magnetic phase the distortion (dl/l)111 increases monotonically with decreasing temperature and reaches the value of 9 × 10-3 at 8 K, which is one of the largest value known for cubic compounds.

Single Crystal Growth and Properties of Incongruently Melting TbB6, DyB6, HoB6, and YB6

Details of the single crystal growth of incongruently melting TbB6, DyB6, HoB6, and YB6using a crucible-free vertical floating zone method are reported. Magnetic susceptibility is reported and discussed. It is suggested that antiferro-quadrupolar ordering occurs in DyB6between 30 and 25.6 K.