Entropy-engineered materials are garnering considerable attention owing to their excellent mechanical and transport properties, such as their high thermoelectric performance. However, understanding the effect of entropy on thermoelectrics remains a challenge. In this study, we used the PbGeSnCd x Te3+x family as a model system to systematically investigate the impact of entropy engineering on its crystal structure, microstructure evolution, and transport behavior. We observed that PbGeSnTe3 crystallizes in a rhombohedral structure at room temperature with complex domain structures and transforms into a high-temperature cubic structure at ∼373 K. By alloying CdTe with PbGeSnTe3, the increased configurational entropy lowers the phase-transition temperature and stabilizes PbGeSnCd x Te3+x in the cubic structure at room temperature, and the domain structures vanish accordingly. The high-entropy effect results in increased atomic disorder and consequently a low lattice thermal conductivity of 0.76 W m–1 K–1 in the material owing to enhanced phonon scattering. Notably, the increased crystal symmetry is conducive to band convergence, which results in a high-power factor of 22.4 μW cm–1 K–1. As a collective consequence of these factors, a maximum ZT of 1.63 at 875 K and an average ZT of 1.02 in the temperature range of 300–875 K were obtained for PbGeSnCd0.08Te3.08. This study highlights that the high-entropy effect can induce a complex microstructure and band structure evolution in materials, which offers a new route for the search for high-performance thermoelectrics in entropy-engineered materials.

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In free-space optical (FSO) communication, high-precision pointing is a critical technology required for rapid acquisition to reduce link establishment time and increase communication time. FSO communication on a motion platform is necessary to expand the communication area and to promote the establishment of a global communication network. However, the pointing accuracy of an optical communication terminal on a motion platform is low due to numerous error sources and error coupling. This paper evaluates the error sources and proposes a pointing model to avoid problems resulting from error coupling. This proposed pointing model was designed to improve the pointing accuracy of a gimbals-type optical communication terminal (GOCT) on a motion platform. The effectiveness of the proposed pointing model was verified by tracking star experiments. The modified residual error of the proposed point model was 94.8 μrad compared to 1324.2 μrad without correction. Additionally, the modified residual error was 94.8 μrad of the proposed pointing model compared to 140.2 μrad of the existing model. The actual open-loop pointing error was reduced from 150.4 μrad of the existing model to 101.3 μrad of the proposed model. Thus, the pointing accuracy of a GOCT on a motion platform was significantly improved after correction by the proposed pointing model.

Intermetallic compounds have attracted considerable attention as advanced structure materials with special properties. While a range of powder metallurgy methods have been developed to synthesize intermetallics, these approaches typically feature slow heating rates and therefore sluggish interdiffusion between the precursor powders, ending up with multiphase products with different metallic ratios. However, single-phase intermetallics offer more controllable properties for materials design yet remain difficult to achieve because of the synthetic limits. Herein, we report a target-sintering approach to synthesize a range of single-phase intermetallics, the stoichiometry of which is simply dictated by the chemical composition of the used precursors without any intermediate phase formation. This unique process is enabled by an ultrafast high-temperature sintering (UHS) method, which crucially offers fast temperature ramping (up to 103–104 °C/min vs. 101–102 °C/min in the conventional methods) to avoid phase impurity, as well as short sintering time to limit elemental loss. As a proof-of-concept demonstration, we synthesized, for the first time, a range of single-phase Ti–Al intermetallics, such as Ti3Al (phase fraction of 99.5%) and TiAl3 (phase fraction of 91.8%). This approach is promising for application to other intermetallic and alloy systems where target-sintering can be used to achieve a variety of single-phase materials.

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