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Topological superconducting systems are expected to exhibit a range of exotic physics which are particularly useful for application in quantum computing technologies. Here, the authors report the synthesis of LaNiGa2 which exhibits both topological and superconducting features originating from its nonsymmorphic crystal structure.

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.

Single crystals of Ce3(Ni/Al/Ga)11 were obtained from an Al flux reaction. Single crystals of the title compound crystallizing in the orthorhombic space group Immm (No. 71, Z = 2) with a = 436.38(14), b = 1004.5(3) and c = 1293.4(4) pm. This is a standardized unit cell of the previously published La3Al11 structure type. Wavelength dispersive microprobe provides the composition of Ce3.11(1)Ni0.03(1)Al8.95(1)Ga1.90(1). Single crystal refinement provides the composition Ce3Ni0.08Al9.13Ga1.78 with substitution of the Ni and Ga on the Al1 and Al4 sites with the Al2 and Al3 solely occupied by Al. Magnetic susceptibility measurements reveal antiferromagnetic ordering with TN = 4.8 K and there is no evidence for a ferromagnetic ordering that has been reported for Ce3Al11. The effective magnetic moment was found to be μeff = 1.9μB/Ce, which is lower than the expected value for trivalent Ce (2.54μB/Ce).

Single crystals of Y b14−xCexMnSb11 were grown from tin metal as a flux solvent with a maximum Ce incorporation of 0.6. The phases with x ∼ 0.1–0.6 crystallize in the tetragonal Ca14AlSb11 structure type with I41/acd space group. In this structure type, there are 4 crystallographically unique Yb sites and the structure can be described according to the Zintl concept as containing 14Y b2+ + [MnSb4]9− + [Sb3]7− + 4Sb3−. For x > 0.3, Ce is incorporated on specific Yb sites in the structure as a function of x, initially at x = 0.3 on the Yb(2) site followed by Yb(4) at higher values of x. These sites have the largest volume as indicated by Hirshfeld surface analysis of chemical bonding. As Ce content is increased, the ferromagnetic ordering temperatures decrease and effective paramagnetic moments increase. The magnetic ordering temperatures decrease from the undoped TC of 50 K until x ∼ 0.4, where the lowest TC of 39 K is reached. As the additional electron introduced by Ce3+ fills the hole associated with [MnSb4]9−, the screening of the Mn moments is reduced. This leads to an increase in overall moment attributed to Mn in addition to the moment from the Ce3+ f electron. Increasing Ce content also leads to an increase in electrical resistivity, an expected effect from reducing the carrier concentration.

The description of the two types of layers in our article is inaccurate. All the [M2Pn2] and [M2Ch2] (M = d-metal; Pn = pnictogen; Ch = chalcogen) layers, which were described as 'fluorite-type', consist of square nets of M atoms coordinated tetrahedrally by Pn (anion) or Ch (anion) alternately above and below the net centers. This arrangement of cations and anions is actually anti-fluorite type, not fluorite-type. Similarly, all the [Ln2O2] (Ln = rare earth atom) layers that were originally described as 'anti-fluorite-type' consist of square nets of O (anion) coordinated tetrahedrally by Ln (cation) alternately above and below the net centers. This arrangement is actually fluorite-type, not anti-fluorite-type. The schematics of the structures are correct. The authors regret the error.

Chemical hydrides are compounds that can potentially uptake and release hydrogen without the use of hydrogen gas. Nanostructure silicon may have great potential as a chemical hydride. The surface can be capped by hydride and dihydride, and hydrogen can be thermally desorbed from the surface. We have prepared large-scale (1−2 g) samples of hydrogen-capped silicon nanoparticles with average diameters of 60, 10, 5, and 4 nm via a low-temperature chemical method to explore the release of hydrogen from the surface as a function of size. The 60- and 10-nm-diameter particles have only hydrogen on the surface. The 60-nm-diameter particles are crystalline, and the 10-nm-diameter particles are amorphous according to powder X-ray diffraction (XRD). The 5- and 4-nm-diameter particles have both hydrogen and solvent capped on the surface. The 4-nm-diameter particles are amorphous and the 5-nm-diameter particles are crystalline by powder XRD. Weight percentages of ∼3.5% at 350 °C are observed for the 10-nm-diameter particles. The largest weight loss is observed for the amorphous 4-nm-diameter particles, which show a weight loss of ∼4.5%, which is attributed primarily to hydrogen. The products have been investigated by powder XRD, scanning electron microscopy (SEM), transmission electron microscopy (TEM), solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR), Fourier transform infrared (FTIR) analysis, thermogravimetry/differential scanning calorimetry (TG/DSC), and thermogravimetry/mass spectroscopy (TG/MS). [ABSTRACT FROM AUTHOR]

Na4Si4and Na4Ge4are ideal chemical precursors for inorganic clathrate structures, clusters, and nanocrystals. The monoclinic Zintl phases, Na4Si4and Na4Ge4, contain isolated homo-tetrahedranide [Si4]4−and [Ge4]4−clusters surrounded by alkali metal cations. In this study, a simple scalable route has been applied to prepare Zintl phases of composition Na4Si4and Na4Ge4using the reaction between NaH and Si or Ge at low temperature (420 °C for Na4Si4and 270 °C for Na4Ge4). The method was also applied to K4Ge4, using KH and Ge as raw materials, to show the versatility of this approach. The influence of specific reaction conditions on the purity of these Zintl phases has been studied by controlling five factors: the method of reagent mixing (manual or ball milled), the stoichiometry between raw materials, the reaction temperature, the heating time and the gas flow rate. Moderate ball-milling and excess NaH or KH facilitate the formation of pure Na4Si4, Na4Ge4or K4Ge4at 420 °C (Na4Si4) or 270 °C (both M4Ge4compounds, M = Na, K). TG/DSC analysis of the reaction of NaH and Ge indicates that ball milling reduces the temperature for reaction and confirms the formation temperature. This method provides large quantities of high quality Na4Si4and Na4Ge4without the need for specialized laboratory equipment, such as Schlenk lines, niobium/tantalum containers, or an arc welder, thereby expanding the accessibility and chemical utility of these phases by making them more convenient to prepare. This new synthetic method may also be extended to lithium-containing Zintl phases (LiH is commercially available) as well as to alkali metal-tetrel Zintl compounds of other compositions, e.g.K4Ge9. [ABSTRACT FROM AUTHOR]

By converting waste heat into electricity and improving the efficiency of refrigeration systems, thermoelectric devices could play a significant role in solving today's energy problems. Increasing the thermoelectric efficiency (as measured by the thermoelectric material's figure-of-merit, zT) is critical to the development of this technology. Complex Zintl phases, in particular, make ideal candidates for thermoelectric materials because the necessary “electron–crystal, phonon–glass” properties can be engineered with an understanding of the Zintl chemistry. A recent example is the discovery that Yb14MnSb11, a transition metal Zintl compound, has twice the zT as the material currently in use at NASA. This perspective outlines a strategy to discover new high zT materials in Zintl phases, and presents results pointing towards the success of this approach. [ABSTRACT FROM AUTHOR]

Capped boron nanoparticles have been synthesized at room temperature by a simple route that does not involve the use of flammable boranes. [ABSTRACT FROM AUTHOR]