Ternary Mg3(Bi,Sb)2 single crystals showing high thermoelectric performance are for the first time grown by the Mg flux method.

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The emerging class of topological materials provides a platform to engineer exotic electronic structures for a variety of applications. As complex band structures and Fermi surfaces can directly benefit thermoelectric performance it is important to identify the role of featured topological bands in thermoelectrics particularly when there are coexisting classic regular bands. In this work, the contribution of Dirac bands to thermoelectric performance and their ability to concurrently achieve large thermopower and low resistivity in novel semimetals is investigated. By examining the YbMnSb2 nodal line semimetal as an example, the Dirac bands appear to provide a low resistivity along the direction in which they are highly dispersive. Moreover, because of the regular‐band‐provided density of states, a large Seebeck coefficient over 160 µV K−1 at 300 K is achieved in both directions, which is very high for a semimetal with high carrier concentration. The combined highly dispersive Dirac and regular bands lead to ten times increase in power factor, reaching a value of 2.1 mW m−1 K−2 at 300 K. The present work highlights the potential of such novel semimetals for unusual electronic transport properties and guides strategies towards high thermoelectric performance.

The discovery of a tenfold increase in magnetostriction of Fe by alloying nonmagnetic Ga was a breakthrough in magnetostrictive materials. The large magnetostriction is attributed to tetragonal nanoheterogeneities dispersed in the bcc matrix. A further remarkable fivefold increase is achieved by trace rare earth doping (<1 at%) up to a value of ≈1500 ppm, more than 50 times that of pure iron. However, it remains a mystery why trace rare earth dopants can induce such giant magnetostriction. Here, it is found that interaction of rare earth dopants with the nanoheterogeneities produces the giant magnetostriction, through a combination of experimental studies, firstprinciples calculation and phase field simulations. The dopants tend to enter the nanoheterogeneities, increasing their distortion thereby creating a larger tetragonal distortion of the matrix as well as increased magnetocrystalline anisotropy. A mesoscopic model is developed using phase field simulation showing that the bulk tetragonal distortion arises mainly from those nanoheterogeneities with fixed Ga-Ga pairs parallel to the applied magnetic field. Increased tetragonal distortion of the doped nanoheterogeneities leads to further distortion of the matrix. The results deepen the understanding of heterogeneous magnetostriction, and will guide the search for new magnetic materials with giant magnetostriction.

Accurate estimation of the state of charge (SOC) of batteries is crucial in a battery management system. Many studies on battery SOC estimation have been investigated recently. Temperature is an important factor that affects the SOC estimation accuracy while it is still not adequately addressed at present. This paper proposes a SOC estimator based on a new temperature-compensated model with extended Kalman Filter (EKF). The open circuit voltage (OCV), capacity, and resistance and capacitance (RC) parameters in the estimator are temperature dependent so that the estimator can maintain high accuracy at various temperatures. The estimation accuracy decreases when applied in high current continuous discharge, because the equivalent polarization resistance decreases as the discharge current increases. Therefore, a polarization resistance correction coefficient is proposed to tackle this problem. The estimator also demonstrates a good performance in dynamic operating conditions. However, the equivalent circuit model shows huge uncertainty in the low SOC region, so measurement noise variation is proposed to improve the estimation accuracy there.

Boron solids exhibit a fascinating geometric and electronic structure. The properties of alpha-rhombohedral boron can be significantly changed by the addition of other atomic constituents. It is found that Pauling's bond valence principle plays an important role in designing boron-rich semiconductors. We have designed the novel boron-rich phases B12N2X (X = Zn, Cd, Be) with the boron carbide type structure by combining Pauling's bond valence principle with first-principles techniques. Their energy gaps, bulk moduli, microhardnesses, and total energies have been calculated. The results show that they are new superhard materials and potential semiconductors. It has been elucidated why B12N2 is metallic but B12N2Be is a semiconductor. This should open up new potential areas for predicting novel boron-rich compounds for industrial applications.

Boron-rich phases with icosahedral symmetry are quite intriguing. It is important to understand the origin of hardness of boron-rich materials. By starting from a chemical bond viewpoint, a simple method for evaluating hardness of boron-rich phases is presented. This method has been applied to some materials such as R-B 12 , B 13 C 2 , and B 12 X 2 (X ) O, P, As), and the predicted hardnesses are in agreement with available experimental values. The results show that this approach provides a powerful tool for predicting superhardness when searching for novel superhard materials in boron-rich phases by first principles.

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