ZrB , with a high symmetrical cubic structure, possesses both high hardness ≈27.0 GPa and ultralow electrical resistivity ≈18 µΩ cm at room temperature. Both the superior conductivity and hardness of ZrB are associated with the extended BB 3D covalent bonding network as it is not only favorable for achieving high hardness, but also provides conducting channels for transporting electrons.

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In this work, tungsten triboride (WB3) was successfully synthesized at high pressure and high temperature. The structure was reconfirmed to be WB3 (P63 mmc), and some part has a tungsten atomic defect according to the measurement results of X-ray diffraction, high-resolution transmission electron microscopy, and Rietveld refinement. The asymptotic Vickers hardness that had eliminated influence of excess boron is 25.5 GPa for WB3. This value is in good agreement with the previous theoretic results. Proof of novel electron transfer between the tungsten atom and the boron atom was found. A deficient amount of transfer electron induces distorted sp2 hybridization of B–B bonds in WB3. The weakly directional sp2 hybridization of B–B bonds is an essential factor that can influence the hardness of WB3. Our results are helpful to design new hard and superhard materials of transition metal borides.

An effective approach to enhance the thermoelectric performance (ZT) of polycrystalline In4Se3 based samples by crystallographic and microstructural engineering is proposed and demonstrated. Cu intercalation, Br substitution at selenium sites, and incorporation of dispersed hierarchical nanoparticles are discussed. An improved ZT of 1.1 at 723 K is achieved in CuBr2 doped In4Se2.5.

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