Abstract
In this study we reported the synthesis of three polycrystalline uranium borides UB1.78±0.02, UB3.61±0.041, and UB11.19±0.13 and their analyses using chemical analysis, X-ray diffraction, SQUID magnetometry, solid-state NMR, and Fourier transformed infrared spectroscopy. We discuss the effects of stoichiometry deviations on the lattice parameters and magnetic properties. We also provide their static and MAS-NMR spectra showing the effects of the 5f-electrons on the 11B shifts. Finally, the FTIR measurements showed the presence of a local disorder.
Highlights
Structures and Physical Properties of Borides have been studied for their properties such as hardness, stability to radiolytic decay, chemical inertness, and magnetism
We present the synthesis of UB1.78±0.02, UB3.61±0.041, and UB11.19±0.13 by arc melting, their room temperature crystal structure by XRD and low temperature single crystal XRD (100 K to 300 K), and their magnetic susceptibility and their local structure determined by 11 B nuclear magnetic resonance (NMR) and Fourier transformed infrared the Uranium Borides UB1.78±0.02, UB3.61±0.041 and UB11.19±0.13
Excess of 5 to 10 wt% in boron is added to reach a pure stoichiometry but, as the different phase structure exists within a range of composition of U/B ratio [6], we did not compensate for the boron loss
Summary
Structures and Physical Properties of Borides have been studied for their properties such as hardness, stability to radiolytic decay, chemical inertness, and magnetism. In the uranium-boron phase diagram, three compounds have been reported to exist: UB2 , UB4 , and UB12 [4,5]. They are mostly synthesized by arc-melting elemental uranium and boron in stoichiometric amounts. Due to boron evaporation, non-stoichiometric UBX (X = 2 ± x, 4 ± x, or 12 ± x) phases and additional UBX or UO2 phases are often detected. The magnetic properties of the UBX (X = 2, 4, 12) are intensively studied in the literature. UB2−x is a Pauli paramagnet and a compensated metal with closed Fermi surfaces [7]. UB4−x is a magnetic compensated metal, and a moderate heavy fermion where a cross-over is observed between itinerant
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