Electrochemical Formation of Elemental Boron in LiCl–KCl–KBF4 at 723 K

The electrochemical reduction behavior of B(III) ions was investigated in LiCl–KCl–KBF4 at 723 K. The results of cyclic voltammetry using Mo, Ag, and Ni electrodes suggested the reduction of B(III) to B(0) at potentials of 1.5 V or at a more negative potential (vs. Li+/Li). Spherical electrodeposits were observed after potentiostatic electrolysis at 1.1–1.5 V. From the results of X-ray photoelectron spectroscopy, scanning transmission electron microscope/energy-dispersive X-ray spectroscopy (STEM/EDX), and selected area electron diffraction, it was concluded that the spherical electrodeposits obtained at 1.1 V were elemental amorphous boron. The purity of the products was 85 wt% boron, as determined by STEM/EDX analysis. The current efficiency of elemental B electrodeposition was 96.2% in this system. The formation of Ni2B at 1.1–1.9 V was indicated by X-ray diffraction, although it was not the main product. These results indicate that the presence of B(III) ions in a melt causes a fatal adverse effect on the recycling process of Nd–Fe–B magnets due to the reduction of B(III) ions. Further, the possibility of reducing the energy and cost of the elemental boron production process was discussed.

A new class of high-entropy M3B4 borides

A new class of high-entropy M3B4 borides of the Ta3B4-prototyped orthorhombic structure has been synthesized in the bulk form for the first time. Specimens with compositions of (V0.2Cr0.2Nb0.2Mo0.2Ta0.2)3B4 and (V0.2Cr0.2Nb0.2Ta0.2W0.2)3B4 were fabricated via reactive spark plasma sintering of high-energy-ball-milled elemental boron and metal precursors. The sintered specimens were ∼98.7% in relative densities with virtually no oxide contamination, albeit the presence of minor (4–5 vol%) secondary high-entropy M5B6 phases. Despite that Mo3B4 or W3B4 are not stable phase, 20% of Mo3B4 and W3B4 can be stabilized into the high-entropy M3B4 borides. Vickers hardness was measured to be 18.6 and 19.8 GPa at a standard load of 9.8 N. This work has further expanded the family of different structures of high-entropy ceramics reported to date.

Use of LA-ICP-MS for determination of elemental concentrations of boron in preservative treated solid wood and engineered wood panels

This study has been completed to review the applicability and benefits of using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as an analytical tool for analysis of preservative concentration and penetration across boron treated solid wood and engineered wood products. LA-ICP-MS is shown to be effective at evaluating the penetration while simultaneously measuring the elemental boron concentration profile continuously across a sample.