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The quinary members in the solid solution Hf₂Fe_1−δRu_5−xIr_x+δB₂(x=1–4, VE=63–66) have been investigated experimentally and computationally. They were synthesized via arc‐melting and analyzed by EDX and X‐ray diffraction. Density functional theory (DFT) calculations predicted a preference for magnetic ordering in all members, but with a strong competition between ferro‐ and antiferromagnetism arising from interchain Fe−Fe interactions. The spin exchange and magnetic anisotropy energies predicted the lowest magnetic hardness forx=1 and 3 and the highest forx=2. Magnetization measurements confirm the DFT predictions and demonstrate that the antiferromagnetic ordering (T_N=55–70 K) found at low magnetic fields changed to ferromagnetic (T_C=150–750 K) at higher fields, suggesting metamagnetic behavior for all samples. As predicted, Hf₂FeRu₃Ir₂B₂has the highest intrinsic coercivity (H_c=74 kA/m) reported to date for Ti₃Co₅B₂‐type phases. Furthermore, all coercivities outperform that of ferromagnetic Hf₂FeIr₅B₂, indicating the importance of AFM interactions in enhancing magnetic anisotropy in these materials. Importantly, two members (x=1 and 4) maintain intrinsic coercivities in the semi‐hard range at room temperature. This study opens an avenue for controlling magnetic hardness by modulating antagonistic AFM and FM interactions in low‐dimensional rare‐earth‐free magnetic materials.

Raman scattering is performed on Fe₃GeTe₂(FGT) at temperatures from 8 to 300 K and under pressures from the ambient pressure to 9.43 GPa. Temperature‐dependent and pressure‐dependent Raman spectra are reported. The results reveal respective anomalous softening and moderate stiffening of the two Raman active modes as a result of the increase of pressure. The anomalous softening suggests anharmonic phonon dynamics and strong spin–phonon coupling. Pressure‐dependent density functional theory and phonon calculations are conducted and used to study the magnetic properties of FGT and assign the observed Raman modes,and. The calculations proved the strong spin–phonon coupling for themode. In addition, a synergistic interplay of pressure‐induced reduction of spin exchange interactions and spin–orbit coupling effect accounts for the softening of themode as pressure increases.

Transition‐metal borides (TMBs) containing B_n‐fragment (n>3) have recently gained interest for their ability to enable exciting magnetic materials. Herein, we show that the B₄‐containing TiFe_0.64(1)Os_2.36(1)B₂is a new ferromagnetic TMB with a Curie temperature of 523(2) K and a Weiss constant of 554(3) K, originating from the chain ofM₃‐triangles (M=64 %Fe+36 %Os). The new phase was synthesized from the elements by arc‐melting, and its structure was elucidated by single‐crystal X‐ray diffraction. It belongs to the Ti_1+xOs_2−xRuB₂‐type structure (space groupP2 m, no. 189) and contains trigonal‐planar B₄boron fragments [B−B distance of 1.87(4) Å] interacting withM₃‐triangles [M–Mdistances of 2.637(8) Å and 3.0199(2) Å]. The experimental results were supported by computational calculations based on the ideal TiFeOs₂B₂composition, which revealed strong ferromagnetic interactions within and between the Fe₃‐triangles. This discovery represents the first magnetically ordered Os‐rich TMB, thus it will help expand our knowledge of the role of Os in low‐dimensional magnetism of intermetallics and enable the design of such materials in the future.

Most nanomaterials, such as transition metal carbides, phosphides, nitrides, chalcogenides, etc., have been extensively studied for their various properties in recent years. The similarly attractive transition metal borides, on the contrary, have seen little interest from the materials science community, mainly because nanomaterials are notoriously difficult to synthesize. Herein, a simple, general synthetic method toward crystalline transition metal boride nanomaterials is proposed. This new method takes advantage of the redox chemistry of Sn/SnCl₂, the volatility and recrystallization of SnCl₂at the synthesis conditions, as well as the immiscibility of tin with boron, to produce crystalline phases of 3d, 4d, and 5d transition metal nanoborides with different morphologies (nanorods, nanosheets, nanoprisms, nanoplates, nanoparticles, etc.). Importantly, this method allows flexibility in the choice of the transition metal, as well as the ability to target several compositions within the same binary phase diagram (e.g., Mo₂B, α‐MoB, MoB₂, Mo₂B₄). The simplicity and wide applicability of the method should enable the fulfillment of the great potential of this understudied class of materials, which show a variety of excellent chemical, electrochemical, and physical properties at the microscale.

Transition‐metal borides (TMBs) have recently attracted attention as excellent hydrogen evolution (HER) electrocatalysts in bulk crystalline materials. Herein, we show for the first time that VB and V₃B₄have high electrocatalytic HER activity. Furthermore, we show that the HER activity (in 0.5 mH₂SO₄) increases with increasing boron chain condensation in vanadium borides: Using a −23 mV overpotential decrement derived from −0.296 mV (for VB at −10 mA cm⁻²current density) and −0.273 mV (for V₃B₄) we accurately predict the overpotential of VB₂(−0.204 mV) as well as that of unstudied V₂B₃(−0.250 mV) and hypothetical “V₅B₈” (−0.227 mV). We then derived an exponential equation that predicts the overpotentials of known and hypothetical V_xB_yphases containing at least a boron chain. These results provide a direct correlation between crystal structure and HER activity, thus paving the way for the design of even better electrocatalytic materials through structure–activity relationships.

Transition‐metal borides (TMBs) have recently attracted attention as excellent hydrogen evolution (HER) electrocatalysts in bulk crystalline materials. Herein, we show for the first time that VB and V₃B₄have high electrocatalytic HER activity. Furthermore, we show that the HER activity (in 0.5 mH₂SO₄) increases with increasing boron chain condensation in vanadium borides: Using a −23 mV overpotential decrement derived from −0.296 mV (for VB at −10 mA cm⁻²current density) and −0.273 mV (for V₃B₄) we accurately predict the overpotential of VB₂(−0.204 mV) as well as that of unstudied V₂B₃(−0.250 mV) and hypothetical “V₅B₈” (−0.227 mV). We then derived an exponential equation that predicts the overpotentials of known and hypothetical V_xB_yphases containing at least a boron chain. These results provide a direct correlation between crystal structure and HER activity, thus paving the way for the design of even better electrocatalytic materials through structure–activity relationships.

Abundant transition metal borides are emerging as substitute electrochemical hydrogen evolution reaction (HER) catalysts for noble metals. Herein, an unusual canonic‐like behavior of theclattice parameter in the AlB₂‐type solid solution Cr_1–xMo_xB₂(x= 0, 0.25, 0.4, 0.5, 0.6, 0.75, 1) and its direct correlation to the HER activity in 0.5 M H₂SO₄solution are reported. The activity increases with increasingx, reaching its maximum atx= 0.6 before decreasing again. At high current densities, Cr_0.4Mo_0.6B₂outperforms Pt/C, as it needs 180 mV less overpotential to drive an 800 mA cm⁻²current density. Cr_0.4Mo_0.6B₂has excellent long‐term stability and durability showing no significant activity loss after 5000 cycles and 25 h of operation in acid. First‐principles calculations have correctly reproduced the nonlinear dependence of theclattice parameter and have shown that the mixed metal/B layers, such as (110), promote hydrogen evolution more efficiently forx= 0.6, supporting the experimental results.