GeTe, as a p-type semiconductor, has been intensively studied in recent years as a promising lead-free midtemperature-range thermoelectric (TE) material. Herein, we report an improved energy conversion efficiency (η) using a two-step TE properties optimization in Mn−Sb co-doped GeTe by engineering electronic structure and lattice dynamics. Mn−Sb co-doping enhances the TE properties of GeTe, as evidenced from both experiments and first-principles-based theoretical calculations. The density functional theory (DFT) calculations indicate that Mn−Sb co-doping improves the band convergence and optimizes the Fermi level position. This in turn helps in enhancing the Seebeck coefficient (α). As a result of the optimized Seebeck coefficient and electrical conductivity (σ), an enhanced power factor (α 2 σ) is obtained for the Mn−Sb co-doped system. Moreover, a significant reduction in the phonon (lattice) thermal conductivity (κ ph ∼ 0.753 W/mK) at 748 K is observed for Ge 0.87 Mn 0.05 Sb 0.08 Te, attributed to the point-defect scattering and reduced phonon group velocity. The synergistic improvement in α and reduction in κ ph result in a maximum figure-of-merit (zT) of 1.67 at 773 K, with an average zT (zT av ) of ∼ 0.9 for Ge 0.87 Mn 0.05 Sb 0.08 Te over a temperature range of 300−773 K, leading to an η of ∼12.7%.

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Neutron diffraction and magnetometric data show that hexagonal (LiGaGe-type crystal structure) RAuSn compounds (R = Pr, Nd, Gd, Tb, Dy, Ho) order antiferromagnetically at low temperatures. Their magnetic structures are described by the wavevector k = [ 1 2 , 0, 0]; the magnetic moments are normal to the hexagonal axis in TbAuSn and DyAuSn, parallel to it in PrAuSn and HoAuSn and make an angle of 30 • in NdAuSn. ErAuSn is cubic (space group F 43m). At T = 1.6 K only a broad peak corresponding to short-range ordering is observed. The observed Néel points range from 2.8 K in PrAuSn to 24 K in GdAuSn. In all title compounds the magnitudes of ordered magnetic moments at 1.6 K derived from neutron diffraction experiments are smaller than the respective free R 3+ ion values, indicating a strong effect of the crystalline electric field. * Dedicated to Professor Henryk Szymczak on the occasion of his 60th birthday.

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Magnetic molecules known as molecular nanomagnets (MNMs) may be the key to ultra-high density data storage. Thus, novel strategies on how to design MNMs are desirable. Here, inspired by the hexagonal structure of the hardest intermetallic magnet SmCo5, we have synthesized a nanomagnetic molecule where the central lanthanide (Ln) ErIII is coordinated solely by three transition metal ions (TM) in a perfectly trigonal planar fashion. This intermetallic molecule [ErIII(ReICp2)3] (ErRe3) starts a family of molecular nanomagnets (MNM) with unsupported Ln-TM bonds and paves the way towards molecular intermetallics with strong direct magnetic exchange interactions—a promising route towards high-performance single-molecule magnets.