Structural differences between single crystal and polycrystalline UBe₁₃

Journal Article · 16 May 2018 · Philosophical Magazine (2003, Print)

DOI: https://doi.org/10.1080/14786435.2018.1468578 · OSTI ID:1440472

Volz, Heather Michelle ^[1]; Vogel, Sven C.  ^[1]; Smith, Alice Iulia  ^[1]; Smith, James L. ^[1]; Fisk, Zachary ^[2]; Winkler, Bjorn ^[3]; Dirmyer, Matthew R. ^[1]; Judge, Elizabeth  ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of California, Irvine, CA (United States)
3. Goethe Univ., Frankfurt (Germany)

Here, we report on observations of structural and chemical differences between samples of UBe₁₃ that were synthesised using two different methods. Unexplained discrepancies in properties between samples with differing synthesis had previously been found in this heavy fermion superconductor. A polycrystalline UBe₁₃ sample was made by arc-melting the constituents. Single crystals were grown using an aluminium flux and had a consistently slightly larger lattice parameter than the polycrystals, which merited further study. Neutron diffraction data were collected at the Lujan Center at LANSCE on the HIPPO diffractometer. Aluminium was detected by inductively coupled plasma mass spectrometry (ICP-MS) in the flux-grown single crystal (0.803 wt%), and small amounts (~0.2 wt%) of thorium were detected in the UBe₁₃ polycrystalline sample. In order to probe the implications of the presence of Al, calculations by spin-polarised DFT-GGA+U show that the incorporation of Al onto the 96i site (the lowest symmetry site in the structure) is energetically more favourable than on other sites. In general, the trends calculated by DFT for bond lengths and lattice parameter increases are consistent with bond lengths experimentally observed by neutron diffraction, but specific percentage changes with aluminium incorporation may be obscured by the unexpected thorium in the polycrystalline sample. The aggregate of our initial observations suggests that incorporation of aluminium from the flux into single crystal UBe₁₃ is significant.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1440472
• Report Number(s): LA-UR--17-21717
• Journal Information: Philosophical Magazine (2003, Print), Journal Name: Philosophical Magazine (2003, Print) Journal Issue: 22 Vol. 98; ISSN 1478-6435
• Publisher: Taylor & FrancisCopyright Statement
• Country of Publication: United States
• Language: English