In this work, we investigate the transition metal oxide spinel Fe3V3O8 using combined X-ray and neutron powder diffraction techniques to elucidate its crystal and magnetic structures. The results indicate that the compound retains a tetragonal crystal structure with space group I41/amd throughout the temperature range from 3.3 K to 475 K. The magnetic structure is described by the magnetic space group I41'/am'd, and no structural or magnetic phase transition is observed within this temperature window. At low temperatures, the system exhibits a canted antiferromagnetic ordering. Magnetization measurements reveal anomalies near 30 K and 100 K, corresponding to the μy component exceeding μz and reaching its maximum value, respectively. A pronounced magnetic hysteresis associated with magnetic domain formation is observed at 2 K, which becomes significantly suppressed above 300 K. Specific-heat measurements reveal a weak and broad anomaly around 180 K, likely associated with spin-glass-like behavior.

The development of cost-effective and sustainable sodium-ion batteries (SIBs) requires optimized hard carbon (HC) anodes. This study investigates honeycomb-like porous carbons derived from black soldier fly (BSF) frass, an abundant biomass waste, calcinated from 800 degrees C to 1400 degrees C. Among the samples, BSF-1200 exhibited the best electrochemical performance. Structural characterization (SEM, HRTEM) showed that BSF-1200 possesses a highly porous, sponge-like architecture that enhances electrolyte penetration and ion transport. Electrochemical tests revealed that BSF-1200 delivers a reversible capacity of 215.1 mAh g- 1 after 200 cycles at 0.2 A g- 1, along with an initial Coulombic efficiency of 68.26 %, low charge-transfer resistance, a high Na+ diffusion coefficient, and excellent rate capability. These improvements arise from its hierarchical porous structure, which facilitates efficient sodium storage. This work demonstrates a sustainable, low-cost approach for producing highperformance carbon anodes from insect-derived biomass. It offers valuable guidance for designing porous carbons for next-generation SIBs.

In this work, we investigate the transition metal oxide spinel $\text{Fe}_{2.99} \mathrm{V}_{3.01} \mathrm{O}_{8}$ using combined X-ray and neutron powder diffraction techniques to elucidate its crystal and magnetic structures. The results indicate that the compound retains a tetragonal crystal structure with space group $\mathbf{I 4}_{\mathbf{1}} /$ amd throughout the temperature range from 3.3 K to 475 K. The magnetic structure is described by the magnetic space group $I 4_{1}{ }^{\prime} / a m^{\prime} d$, and no structural or magnetic phase transition is observed within this temperature window. At low temperatures, the system exhibits a canted antiferromagnetic ordering. Magnetization measurements reveal anomalies near 30 K and 100 K, corresponding to the $\mu_{y}$ component exceeding $\mu_{z}$ and reaching its maximum value, respectively. A pronounced magnetic hysteresis associated with magnetic domain formation is observed at 2 K, which is significantly suppressed above 300 K. Specific heat measurements show a weak and broad anomaly around 180 K, which is likely associated with subtle lattice distortions rather than magnetic ordering.

Fundamentally understanding lattice dynamics and thermal transport behavior in liquid‐like, partially occupied compounds remains a long‐standing challenge in condensed matter physics. Here, the microscopic mechanisms are investigated underlying the ultralow thermal conductivity in ordered/liquid‐like Cu 3 BiS 3 by combining experimental methods with first‐principles calculations. The ordered structure and liquid‐like are first experimentally synthesized and characterized, partially Cu‐atom occupied Cu 3 BiS 3 structure with increasing temperature. Selfconsistent phonon calculations are then combined, including bubble‐diagram corrections, with the Wigner transport equation, considering both phonon propagation and diffuson contributions, to evaluate the anharmonic lattice dynamics and thermal conductivity in phase‐change Cu 3 BiS 3 . The theoretical model predicts an ultralow thermal conductivity of 0.34 W m −1 K −1 at 400 K, dominated by diffuson contributions, which accurately reproduces and explains the experimental data. Importantly, the machine‐learning‐based molecular dynamics (MD) simulations not only reproduced the partially Cu‐atom occupied Cu 3 BiS 3 structure with the space group Pnma but also successfully replicated the thermal conductivity obtained from experiments and Wigner transport calculations. This observation highlights the negligible impact of ionic mobility arising from partially occupied Cu sites on the thermal conductivity in diffuson‐dominated thermal transport compounds. This work sheds light on the minimal impact of ionic mobility on ultralow thermal conductivity in phase‐change materials. It demonstrates that the Wigner transport equation accurately describes thermal transport behavior in partially occupied phases with diffuson‐dominant thermal transport.

Fundamentally understanding lattice dynamics and thermal transport behavior in liquid-like, partially occupied compounds remains a long-standing challenge in condensed matter physics. Here, the microscopic mechanisms are investigated underlying the ultralow thermal conductivity in ordered/liquid-like Cu3BiS3 by combining experimental methods with first-principles calculations. The ordered structure and liquid-like are first experimentally synthesized and characterized, partially Cu-atom occupied Cu3BiS3 structure with increasing temperature. Selfconsistent phonon calculations are then combined, including bubble-diagram corrections, with the Wigner transport equation, considering both phonon propagation and diffuson contributions, to evaluate the anharmonic lattice dynamics and thermal conductivity in phase-change Cu3BiS3. The theoretical model predicts an ultralow thermal conductivity of 0.34 W m-1 K-1 at 400 K, dominated by diffuson contributions, which accurately reproduces and explains the experimental data. Importantly, the machine-learning-based molecular dynamics (MD) simulations not only reproduced the partially Cu-atom occupied Cu3BiS3 structure with the space group Pnma but also successfully replicated the thermal conductivity obtained from experiments and Wigner transport calculations. This observation highlights the negligible impact of ionic mobility arising from partially occupied Cu sites on the thermal conductivity in diffuson-dominated thermal transport compounds. This work sheds light on the minimal impact of ionic mobility on ultralow thermal conductivity in phase-change materials. It demonstrates that the Wigner transport equation accurately describes thermal transport behavior in partially occupied phases with diffuson-dominant thermal transport.

Metal-organic frameworks (MOFs) are a versatile class of porous crystalline materials whose properties can be finely tuned through reticular chemistry. Isoreticular expansion, a powerful strategy for increasing pore size without altering framework topology, has enabled the design of MOFs with hierarchical porosity and enhanced functionality. In this study, we report the scalable synthesis and structural characterization of a new aluminum-based MOF, designated AlDMDA-68, constructed using an imine-based dicarboxylate linker 4,4 '-(hydrazine-1,2-iylidenebis(methanylylidene))dibenzoic (H2DMDA). The framework exhibits a rad net analogous to MIL-68(Al), featuring dual-channel architectures with pore diameters up to 3.16 nm. Optimization of reaction parameters, including metal-to-ligand (M/L) ratio, yielded phase-pure materials with rod-like morphology. Powder X-ray diffraction and 27Al MAS NMR confirmed framework formation and the presence of coordination defects, respectively. Nitrogen sorption measurements revealed a high Brunauer-Emmett-Teller (BET) surface area of 1866 m2 g-1 and substantial uptake, indicating a hierarchical microporous-mesoporous structure. The material also demonstrated high thermal stability (similar to 350 degrees C) and excellent scalability, achieving a fivefold increase in yield without compromising structural integrity. These findings highlight AlDMDA-68 as a promising candidate for various applications and establish elongated imine-based linkers as effective building blocks for designing mesoporous Al-MOFs with tunable functionality.

This study investigates the structure, microstructure, and transport properties of off-stoichiometric GeTe (offGeTe). In a narrow range of 50-53 at% Te, both the rhombohedral a-GeTe and orthorhombic g-GeTe phases coexist. Despite their similar chemical composition, GeTe and off-GeTe alloys exhibit distinct microstructural and thermal/electronic properties. Theoretical density functional theory (DFT) calculations were employed to verify that changes in the Ge/Te ratios influence the concentration of Ge vacancies, leading to a significant alteration in transport properties despite minor variations in chemical compositions. The off-GeTe alloy, which is free of Ge precipitates, displays defective domain boundaries, showcasing a non-typical herringbone nanostructure that is unprecedented for GeTe-based materials. Notably, the phase transition temperature of off-GeTe, at 620K, differs from its peak zT temperature of 698K. Moreover, a TE device incorporating off-GeTe demonstrates superior interfacial stability and higher energy conversion efficiency compared to its stoichiometric GeTe counterpart. Consequently, off-GeTe demonstrates superior TE performance and enhanced interfacial stability compared to stoichiometric GeTe. The addition of Sb to off-GeTe further improves its potential for TE applications by lifting the single-leg conversion efficiency greater than 3%.

The transition from disorder to order and structural transformation are distinctive metal-organic framework (MOF) features. How to adapt or control both behaviors in MOF has rarely been studied. In this case, we demonstrate that our successful synthesis of [Al(OH)(PDA)]n (AlPDA-53-DEF, AlPDA-53-H, and AlPDA-68) with H2PDA=4,4 '-[1,4-phenylenebis(ethyne-2,1-diyl)]-di benzoic acid has shown the intricate world of Aluminum Metal-Organic Frameworks (Al-MOFs). It offers profound insights into defect structures to order and transformations. AlPDA-53-DEF, in particular, revealed a fascinating interplay of various pore sizes within both micro and mesoporous regions, unveiling a unique lattice rearrangement phenomenon upon solvent desorption. Defects and disorders emerged as crucial impacts of transforming AlPDA-53-DEF, with its initially imperfect crystallinity, into the highly crystalline, hierarchically porous AlPDA-53-H. The synthesis of AlPDA-53-DEF, AlPDA-53-H, and AlPDA-68 with insights into Aluminum Metal-Organic Frameworks (Al-MOFs), their defect structures, lattice rearrangement, and the role of defects and disorders in the transformation from AlPDA-53-DEF to AlPDA-53-H. image

Co- and Ni-free disordered rocksalt cathodes utilize oxygen redox to increase the energy density of lithium-ion batteries, but it is challenging to achieve good cycle life at high voltages >4.5 V (versus Li/Li+). Here we report a family of Li-excess Mn-rich cathodes that integrates rocksalt- and polyanion-type structures. Following design rules for cation filling and ordering, we demonstrate the bulk incorporation of polyanion groups into the rocksalt lattice. This integration bridges the two primary families of lithium-ion battery cathodes-layered/spinel and phosphate oxides-dramatically enhancing the cycling stability of disordered rocksalt cathodes with 4.8 V upper cut-off voltage. The cathode exhibits high gravimetric energy densities above 1,100 Wh kg(-1) and >70% retention over 100 cycles. This study opens up a broad compositional space for developing battery cathodes using earth-abundant elements such as Mn and Fe.

AbstractDue to their amorphous‐like ultralow lattice thermal conductivity both below and above the superionic phase transition, crystalline Cu‐ and Ag‐based superionic argyrodites have garnered widespread attention as promising thermoelectric materials. However, despite their intriguing properties, quantifying their lattice thermal conductivities and a comprehensive understanding of the microscopic dynamics that drive these extraordinary properties are still lacking. Here, an integrated experimental and theoretical approach is adopted to reveal the presence of Cu‐dominated low‐energy optical phonons in the Cu‐based argyrodite Cu7PS6. These phonons yield strong acoustic‐optical phonon scattering through avoided crossing, enabling ultralow lattice thermal conductivity. The Unified Theory of thermal transport is employed to analyze heat conduction and successfully reproduce the experimental amorphous‐like ultralow lattice thermal conductivities, ranging from 0.43 to 0.58 W m−1 K−1, in the temperature range of 100–400 K. The study reveals that the amorphous‐like ultralow thermal conductivity of Cu7PS6 stems from a significantly dominant wave‐like conduction mechanism. Moreover, the simulations elucidate the wave‐like thermal transport mainly results from the contribution of Cu‐associated low‐energy overlapping optical phonons. This study highlights the crucial role of low‐energy and overlapping optical modes in facilitating amorphous‐like ultralow thermal transport, providing a thorough understanding of the underlying complex dynamics of argyrodites.

This study highlights the extremely low in-plane thermal conductivity of the two-dimensional organic-inorganic hybrid perovskite (OIHP) EA(2)PbI(4) single crystal, which approaches its amorphous limit near 300 K. To elucidate the mechanism underlying this ultralow thermal conductivity, phonon dispersion relations of EA(2)PbI(4) were directly measured using inelastic neutron scattering. Additionally, the Debye temperature (theta(D)) of EA(2)PbI(4) was 284 K, corresponding to an average phonon group velocity of 2284 m s(-1). The suppressed thermal transport efficiency is then attributed to the exceptionally short phonon mean free paths, which approach the bond lengths in the PbI6 framework. Moreover, a low Einstein temperature (theta E) of 45 K was identified through heat capacity fitting, indicating the presence of low-lying optical vibrational modes as revealed by detailed Raman scattering measurements. These softened phonons can readily engage with acoustic ones, creating a more complex scattering environment. This study also reports exceptionally low exciton binding energies of 5.3-6.4 meV in high-quality EA(2)PbI(4) single crystals, the lowest among OIHPs. These findings not only unveil the distinctive thermal transport behavior and optical properties of EA(2)PbI(4) but also emphasize the unique lattice dynamics arising from the orientational dynamics of EA molecules and their coupling with the PbI6 octahedra.

Mixed-anion compounds, which incorporate multiple types of anions into materials, displays tailored crystal structures and physical/chemical properties, garnering immense interests in various applications such as batteries, catalysis, photovoltaics, and thermoelectrics. However, detailed studies regarding correlations between crystal structure, chemical bonding, and thermal/vibrational properties are rare for these compounds, which limits the exploration of mixed-anion compounds for associated thermal applications. In this work, we investigate the lattice dynamics and thermal transport properties of the metal chalcohalides, CuBiSCl2. A high-purity polycrystalline CuBiSCl2 sample, successfully synthesized via modified solid-state synthetic method, exhibits a low lattice thermal conductivity of 0.9-0.6 W m-1 K-1 from 300 to 573 K. By combining various experimental techniques including 3D electron diffraction with theoretical calculations, we elucidate the origin of low lattice thermal conductivity in CuBiSCl2. The stereo-chemical activity of the 6s2 lone pair of Bi3+ favors an asymmetric environment with neighboring anions involving both short and long bond lengths. This particularity often implies weak bonding, low structure dimensionality, and strong anharmonicity, leading to low lattice thermal conductivity. In addition, the strong two-fold linear S-Cu-S coordination with weak Cu – Cl interactions induces large anisotropic vibration of Cu or structural disorder, which enables strong phonon-phonon scattering and decreases lattice thermal conductivity. The investigations into lattice dynamics and thermal transport properties of CuBiSCl2 broadens the scope of the existing mixed-anion compounds suitable for the associated thermal applications, offering a new avenue for the search of low thermal conductivity materials in low-cost mixed-anion compounds.

Argyrodite-type compounds are renowned for their exceptional thermoelectric performance and ultralow thermal conductivity. While the latter is commonly attributed to the superionic behavior of cations, there has been limited research into how cations' static or dynamic behavior affects the thermal transport properties of argyrodites. To address and bridge this research gap, we employ a wide range of measurements and develop ab-initio based machine-learning interatomic potentials to perform large-scale molecular dynamics simulations on Ag8SiTe6 under different temperatures. We highlight the symmetry breaking and lattice-distortion scattering caused by chilled ions at low temperatures and the enhanced ionic diffusion behavior at elevated temperatures endowing argyrodites with superior superionicity and liquid-like thermal conductivity. Our findings also provide valuable insights into the ionic diffusion kinetics and the exotic lattice dynamics of liquid-like thermoelectrics.

Mixed-anion compounds, which incorporate multiple types of anions into materials, display tailored crystal structures and physical/chemical properties, garnering immense interest in various applications such as batteries, catalysis, photovoltaics, and thermoelectrics. However, detailed studies regarding correlations among crystal structure, chemical bonding, and thermal/vibrational properties are rare for these compounds, which limits the exploration of mixed-anion compounds for associated thermal applications. In this work, we investigate the lattice dynamics and thermal transport properties of the metal chalcohalide, CuBiSCl2. A high-purity polycrystalline CuBiSCl2 sample exhibits a low lattice thermal conductivity (κL) of 0.9-0.6 W/(m·K) from 300 to 573 K. By combining various experimental techniques, including three-dimensional (3D) electron diffraction, with theoretical calculations, we elucidate the origin of low κL in CuBiSCl2. The stereochemical activity of the 6s2 lone pair of Bi3+ favors an asymmetric environment with neighboring anions involving both short and long bond lengths. This particularity often implies weak bonding, low structure dimensionality, and strong anharmonicity, leading to a low κL. In addition, the strong 2-fold linear S-Cu-S coordination with weak Cu···Cl interactions induces a large anisotropic vibration of Cu, which enables strong phonon-phonon scattering and decreases κL. The investigations into lattice dynamics and thermal transport properties of CuBiSCl2 broaden the scope of the existing mixed-anion compounds suitable for the associated thermal applications, offering a new avenue for the search for low thermal conductivity materials in low-cost mixed-anion compounds.

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An exfoliated monolayer CrI3 possessing the ferromagnetic (FM) nature of out-of-plane Ising spin-up (or spin-do Psi n) electrons can be considered as a qubit Psi ith a quantum state of |Psi>=|up arrow>=|0> (or |Psi>=|down arrow>=|1>) due to the theory of the Bloch sphere. Therefore, here a bipartite quantum system of the antiferromagnetic (AFM) and FM bilayer CrI3 is proposed for four fundamental t Psi o-qubit (2Q) quantum states (-|Psi Psi>) of |up arrow down arrow>=|01>, |down arrow up arrow>=|10>, |up arrow up arrow>=|00> and |down arrow down arrow>=|11>, respectively. Energy-resolved magnetic circular dichroism (MCD) spectropolarimetry was used to detect d-d transitions of the FM and AFM bilayer CrI3 for the four fundamental quantum states. The obtained MCD spectra of the d-d transitions with spin-frustration and spin-parallelism possess quantum signals of the four fundamental 2Q quantum states at BB = 0, Psi here BB is the angle between the magnetic field and the surface normal. Hence, the bilayer CrI3 is a potential candidate for use in quatum computer.

Taking advantage of fact that the surface electrons of metallic nanoparticles (NPs) can be effectively released even at a low voltage bias, we demonstrate an improvement in the electrochemical performance of nanosized Prussian Blue (PB)-based secondary batteries through the incorporation of bare Ag or Ni NPs in the vicinity of the working PB NPs. It is found that the capacity for electrochemical energy storage of the 17 nm PB-based battery is significantly higher than the capacity of 10 nm PB-based, 35 nm PB-based or 46 nm PB-based batteries. There is a critical PB size for the highest electrochemical energy storage efficiency. The full specific capacity CF of the 17 nm PB-based battery stabilized to 62 mAh/g after 130 charge–discharge cycles at a working current of IW = 0.03 mA. The addition of 14 mass percent of Ag NPs in the vicinity of the PB NPs gave rise to a 32% increase in the stabilized CF. A 42% increase in the stabilized CF could be obtained with the addition of 14 mass percent of Ag NPs on the working electrode of the 35 nm PB-based battery. An enhancement in CF was also found for electrodes incorporating bare Ni NPs but the effect was smaller.

Lithium-ion batteries with Li3V2(PO4)3/C as the cathode have been a popular research topic in recent years; however, studies of the effects of external magnetic fields on them are less common. This study investigates the effects of an external magnetic field applied parallel to the direction of the anode and cathode on the ion transport through iron-doped Li3(V1-x Fe x )2(PO4)3, the outer carbon coating, the film/electrolyte/separator, and up to the lithium metal electrode on a microscopic level. The results reveal that for the x = 0.05 sample with lower doping, the magnetostriction expansion of Li3(V1-x Fe x )2(PO4)3 and the magnetostrictive contraction effect of the outer ordered carbon layer cancel each other out, resulting in no significant enhancement of the battery's energy and power density due to the external magnetic field. In contrast, the x = 0.1 sample, lacking magnetostrictive contraction in the outer ordered carbon layer, shows that its energy and power density can be influenced by the magnetic field. Under zero magnetic field, the cyclic performance exhibits superior average capacity performance in the x = 0.05 sample, while the x = 0.1 sample shows a lower decay rate. Both samples are affected by the magnetic field; however, the x = 0.1 sample performs better under magnetic conditions. In particular, in the C-rate tests under a magnetic field, the sample with x = 0.1 showed a significant relative reduction in capacity decay rate by 20.18% compared to the sample with x = 0.05.