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High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

Polycrystalline LiGa 2 Ir has been prepared by a solid state reaction method. A Rietveld refinement of powder x-ray diffraction data confirms a previously reported Heusler-type crystal structure (space group Fm-3m , No. 225) with lattice parameter a  = 6.0322(1) Å. The normal and superconducting state properties were studied by magnetic susceptibility, heat capacity, and electrical resistivity techniques. A bulk superconductivity with T c  = 2.94 K was confirmed by detailed heat capacity studies. The measurements indicate that LiGa 2 Ir is a weak-coupling type-II superconductor ( λ e–p  = 0.57, Δ C/ γ T c  = 1.4). Electronic structure, lattice dynamics, and the electron–phonon interaction are studied from first principles calculations. Ir and two Ga atoms equally contribute to the Fermi surface with a minor contribution from Li. The phonon spectrum contains separated high frequency Li modes, which are seen clearly as an Einstein-like contribution in the specific heat. The calculated electron–phonon coupling constant λ e–p  = 0.68 confirms the electron–phonon mechanism for the superconductivity. LiGa 2 Ir and recently reported isoelectronic LiGa 2 Rh are the only two known representatives of the Heusler superconductors with the valence electron count VEC = 16.

We have successfully synthesized three osmium-based hexagonal Laves compounds R Os 2 ( R  = Sc, Y, Lu), and discussed their physical properties. LeBail refinement of pXRD data confirms that all compounds crystallize in the hexagonal centrosymmetric MgZn 2 -type structure ( P6 3 /mmc , No. 194). The refined lattice parameters are a  =  b  = 5.1791(1) Å and c  = 8.4841(2) Å for ScOs 2 , a  =  b  = 5.2571(3) Å and c  = 8.6613(2) Å for LuOs 2 and a  =  b  = 5.3067(6) Å and c  = 8.7904(1) Å for YOs 2 . R Os 2 Laves phases can be viewed as a stacking of kagome nets interleaved with triangular layers. Temperature-dependent magnetic susceptibility, resistivity and heat capacity measurements confirm bulk superconductivity at critical temperatures, T c , of 5.36, 4.55, and 3.47 K for ScOs 2 , YOs 2 , and LuOs 2 , respectively. We have shown that all investigated Laves compounds are weakly-coupled type-II superconductors. DFT calculations revealed that the band structure of R Os 2 is intricate due to multiple interacting d orbitals of Os and R . Nonetheless, the kagome-derived bands maintain their overall shape, and the Fermi level crosses a number of bands that originate from the kagome flat bands, broadened by interlayer interaction. As a result, R Os 2 can be classified as (breathing) kagome metal superconductors.

We have synthesized and characterized the physical properties of a layered, mixed valent oxypnictide via magnetization, electrical resistivity, and specific heat measurements. Although does not exhibit superconductivity down to T = 0.5 K, it demonstrates an intriguing resistivity minimum observed at = 13.7 K. Disappearance of the resistivity minimum under an applied magnetic field of H = 9 T together with the negative magnetoresistance at low and positive at high temperatures are observed, which are typical for both Kondo-like spin-dependent scattering and 3D weak localization. We argue that the Kondo scattering is a more plausible explanation due to the low-temperature deviation from the Curie-Weiss law observed in the magnetic susceptibility, consistent with the presence of magnetic interactions between paramagnetic ions and Kondo screening of these moments. We supplemented the experimental characterization with a detailed description of chemical bonding, employing density functional theory (DFT) calculations and crystal orbital Hamilton population (COHP) analysis for and isostructural , which is a superconductor with K. Based on the calculations performed, we present the difference between and in the character of electronic states at the Fermi level. This discrepancy impacts structural stability and may cause a lack of superconductivity in down to T = 0.5 K.

We present transition metal-embedded (T@Gan) endohedral Ga-clusters as a favorable structural motif for superconductivity and develop empirical, molecule-based, electron counting rules that govern the hierarchical architectures that the clusters assume in binary phases. Among the binary T@Gan endohedral cluster systems, Mo8Ga41, Mo6Ga31, Rh2Ga9, and Ir2Ga9 are all previously known superconductors. The well-known exotic superconductor PuCoGa5 and related phases are also members of this endohedral gallide cluster family. We show that electron-deficient compounds like Mo8Ga41 prefer architectures with vertex-sharing gallium clusters, whereas electron-rich compounds, like PdGa5, prefer edge-sharing cluster architectures. The superconducting transition temperatures are highest for the electron-poor, corner-sharing architectures. Based on this analysis, the previously unknown endohedral cluster compound ReGa5 is postulated to exist at an intermediate electron count and a mix of corner sharing and edge sharing cluster architectures. The empirical prediction is shown to be correct and leads to the discovery of superconductivity in ReGa5. The Fermi levels for endohedral gallide cluster compounds are located in deep pseudogaps in the electronic densities of states, an important factor in determining their chemical stability, while at the same time limiting their superconducting transition temperatures.

The modifications in the electronic properties induced by the thickness and size of an individual flake of transition-metal halides on different substrates (silicon oxide or In-doped tin oxide) are of particular technological interest, even more in the case of chromium trihalides (CrX3, X = Cl, Br, and I), whose longer lifetime under ambient conditions is particularly intriguing. By using synchrotron-based scanning photoelectron microscopy with a resolution of 0.1 μm and Kelvin probe force microscopy, we evaluated the surface modification reaction and the surface potential. Our results established the correlations of the two latter properties with the thickness of flakes, observing a natural tendency to preserve their characteristic when the flakes have significantly less thickness. This is in contrast to thicker flakes, which show alteration patterns similar to those observed in bulk-cleaved samples (Kazim, S.; Mastrippolito, D.; Moras, P.; Jugovac, M.; Klimczuk, T.; Ali, M.; Ottaviano, L.; Gunnella, R. Phys. Chem. Chem. Phys.2023, 25, 3806–3814. https://doi.org/10.1039%2FD2CP04586A%29. This preliminary study investigates interfaces made by dry transfer of CrCl3 flakes in an atmospheric environment. Cl vacancies and the formation of O/CrCl3 are induced, serving as dissociation centers that facilitate the migration of Cl vacancies between the top and bottom surfaces. By manipulating 2D atomic layers via surface oxidation or the introduction of surface vacancies, a novel and versatile approach is unveiled for the development of low-dimensional multifunctional nanodevices.

We report the experimental and theoretical investigation of structure, chemical bonding interactions, and physical properties of new ternary stannides AIrSn2 (A = Sr and Ba). AIrSn2 (A = Sr and Ba) crystallizes in the orthorhombic Re3B-type structure with the space group Cmcm (No. 64). According to single-crystal X-ray diffraction results, the structure of AIrSn2 (A = Sr and Ba) can be considered as a Zintl-type compound with heterogeneous polyanionic [IrSn2]2− and A2+. The specific heat down to 1.8 K shows no evidence for bulk superconductivity in either SrIrSn2 or BaIrSn2. Electronic structure calculations, especially chemical bonding interactions in SrIrSn2 and BaIrSn2, match well with the observed structural stability and metallic nature.

We report the synthesis and physical properties of a hexagonal boride YRu3B2, which was previously predicted to show superconductivity [N.K. Nepal, L.-L. Wang, arXiv:2409.18441 (2024)]. A polycrystalline sample was synthesized by arc-melting a pre-reacted YB2 and metallic Ru. Phase and elemental composition were characterized by means of powder x-ray diffraction and scanning electron microcopy. Our resistivity and heat capacity measurements indicate that YRu3B2 is a weakly coupled superconductor, with a critical temperature Tc = 0.63 K and an upper critical field μ0Hc2(0)=0.11 T. Isovalent substitution of Y with 5 at% and 10 at% of Sc resulted in a slight enhancement of the critical temperature up to ca. 0.8 K. Density functional theory calculations together with chemical-bonding analysis, reveal that the electronic states at and near the Fermi energy level are dominated by the Ru kagome sublattice.

Biofilm-related infections, especially those associated with medical devices like catheters, pose significant clinical challenges due to their resistance to conventional treatments. This study investigates a green chemistry-based approach to synthesize silver nanoparticles (AgNPs) stabilized with trans-cinnamaldehyde ( -CA) and evaluates their potential for combating microbial biofilms and based on novel mechanism of action. Silver nanoparticles ( -CA-AgNPs) were synthesized using -CA as both a reducing and stabilizing agent. The NPs were then thoroughly characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), electron microscopy (TEM, SEM, STEM), and dynamic light scattering (DLS). We evaluated its antimicrobial potential against the most prevalence biofilm-forming pathogens including and using minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) assays. Moreover, we investigated the mechanism of action of -CA-AgNPs underlying biofilm inhibition. Biofilm formation and structure were verified by SEM imagining. DLS analysis confirmed that -CA-AgNPs had an average particle diameter of 2.5 nm, coupled with a notably negative zeta potential (-45 mV), indicative of good colloidal stability. -CA-AgNPs displayed potent antimicrobial properties, with MIC values ranging from 26 to 412 µg/mL and MBC values from 103 to 825 µg/mL. Biofilm formation inhibitory properties reached 88.74% of inhibition for and 70.60% for . Moreover, we found potent metal ion-chelating capabilities, importantly, in binding and reducing ferrous ions, the crucial factor of biofilm formation. Furthermore, -CA-AgNPs substantially impaired biofilm development on catheter surfaces, underscoring their robust antibiofilm potential. Presented here -CA-AgNPs exhibit significant antimicrobial and antibiofilm activity. By effectively targeting critical elements in biofilm formation, such as ferrous ions, coupled with antimicrobial potential of both active compounds, these green-synthesized NPs have potential applications in significantly improving the safety and effectiveness of medical devices. However, further studies are needed to ensure their efficacy in clinical use.

Single semiconductors such as KTaO3, CdS MoS2 or their precursor solutions were combined to form novel binary and ternary semiconductor nanocomposites by the calcination or by the hydro/solvothermal mixed solutions methods, respectively. The aim of this work was to study the influence of preparation method as well as type and amount of the composite components on the surface properties and photocatalytic activity of the new semiconducting photoactive materials. We presented different binary and ternary combinations of the above semiconductors for phenol and toluene photocatalytic degradation and characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) specific surface area and porosity. The results showed that loading MoS2 onto CdS as well as loading CdS onto KTaO3 significantly enhanced absorption properties as compared with single semiconductors. The highest photocatalytic activity in phenol degradation reaction under both UV-Vis and visible light irradiation and very good stability in toluene removal was observed for ternary hybrid obtained by calcination of KTaO3, CdS, MoS2 powders at the 10:5:1 molar ratio. Enhanced photoactivity could be related to the two-photon excitation in KTaO3-CdS-MoS2 composite under UV-Vis and/or to additional presence of CdMoO4 working as co-catalyst.