Not your usual superconductor: Most superconductors have only one superconducting phase. Khim et al . measured the magnetic susceptibility of the heavy fermion material CeRh ₂ As ₂ to reveal the presence of two distinct superconducting phases, one of which emerges from the other when an external magnetic field is applied (see the Perspective by Pourret and Knebel). The researchers ascribe the unusual properties of CeRh ₂ As ₂ to its crystal structure, which is globally centrosymmetric but consists of noncentrosymmetric layers. —JS

This paper presents tables of key thermoelectric properties, which define thermoelectric conversion efficiency, for a wide range of inorganic materials. The twelve families of materials included in these tables are primarily selected on the basis of well established, internationally-recognized performance and promise for current and future applications: tellurides, skutterudites, half Heuslers, Zintls, Mg–Sb antimonides, clathrates, FeGa₃-type materials, actinides and lanthanides, oxides, sulfides, selenides, silicides, borides and carbides. As thermoelectric properties vary with temperature, data are presented at room temperature to enable ready comparison, and also at a higher temperature appropriate to peak performance. An individual table of data and commentary are provided for each family of materials plus source references for all the data.

Cu‐based argyrodites have attracted attention as thermoelectric materials for energy harvesting. However, phase transitions and low energy conversion performance limit their applications.This work explores the great thermoelectric performance of Cu ₈ SiS _x Se _{6‐ x} argyrodite with stabilized high‐symmetry cubic phase at above 282 K. The suppression of the phase transition below room temperature is realized due to the increase of the configurational entropy caused by the substitution of Se by S in Cu ₈ SiS _x Se _{6‐ x} . As a result, a significant enhancement of weighted mobility is achieved for materials without the phase transition due to clean grain boundary contacts. In turn, samples with disordered or dirty grain boundaries lead to a lower and increasing trend of weighted mobility for materials with phase transition in the operating temperature range. The developed argyrodites exhibit excellent thermoelectric performance due to the improved power factor of up to 4.2 µWcm ⁻¹ K ⁻² and ultralow lattice thermal conductivity of 0.18 Wm ⁻¹ K ⁻¹ at 773 K, which is derived from the peculiar chemical bonding with a large number of different Si‐Se, Se‐Cu, and Cu‐Cu interactions. The dimensionless thermoelectric figure of merit zT for Cu ₈ SiS ₃ Se ₃ argyrodite reaches a value of 1.24, offering this material as a low‐cost and Te‐free alternative for thermoelectric energy conversion applications.

The antimonides Ce₂Ir₃Sb₄, La₂Ir₃Sb₄, and Ce₂Rh₃Sb₄were synthesized by solid state reaction from the elements. The crystal structures of these compounds were determined from single crystal X-ray diffraction data. Ce₂Ir₃Sb₄crystallises in a new structure type in the space groupPnma(no. 62) witha= 16.1510(8) Å,b= 4.5600(3) Å,c= 10.9463(5) Å. La₂Ir₃Sb₄and Ce₂Rh₃Sb₄crystallise in the Ce₂Ir₃Sb₄structure type as well witha= 16.2659(10) Å,b= 4.5896(3) Å,c= 10.9996(7) Å) anda= 16.2293(8) Å,b= 4.5604(2) Å,c= 10.9804(5) Å, respectively. The four- and five-bonded transition metal atoms and three- and four-bounded Sb atoms form a 3D-network with the rare-earth metal embedded in its cavities, resembling the topology of Ca in the CaBe₂Ge₂or Th in ThCr₂Si₂type. Magnetic susceptibility and X-ray absorption near edge spectroscopy data indicate a stable trivalent state for Ce in the Ce₂Ir₃Sb₄compound.

The crystal structures of low- (α) and high-temperature (β) modifications of In₂Te₃ are refined for the first time.