Controlling nanoscale interactions to suppress aggregation from short-range attractive forces is a key problem in nanoengineering. Here, we demonstrate a route to modulate Casmir–Lifshitz interactions between anisotropic nanoparticles and magnetic fluids. By semiclassical quantum electrodynamics, we study ground state dispersion forces for cylindrical dielectric nanorods made of polystyrene (PS) and zinc oxide (ZnO) embedded in toluene-based host media with gold-coated magnetite nanoparticles and also predict magnetic contributions to the fully retarded excited state interaction. The variation in magnetic permeability enables tuning between repulsive and attractive interactions, and measurable magnetic Casimir traps are predicted between a pair of ZnO–PS nanoparticles whose equilibrium position can be modulated over an order of magnitude with a small variation in the size of the magnetite nanoparticle. This provides an alternative magnetic Casimir-effect pathway to reversibly tune quantum electromagnetic forces at the nanoscale for the assembly and enhancement of colloidal stability.

Macroscopic interactions of liquid iron and solid oxides, such as alumina, calcia, magnesia, silica, and zirconia, manifest the behavior and efficiency of high-temperature metallurgical processes. The oxides serve dual roles, both as components of refractory materials in submerged entry nozzles and also as significant constituents of nonmetallic inclusions in the melt. It is therefore crucial to understand the physicochemical interplay between the liquid and the oxides in order to address the nozzle clogging challenges and thereby optimize cast iron and steel production. This paper presents a methodology for describing these interactions by combining the materials' dielectric responses, computed within the density functional theory, with the Casimir-Lifshitz dispersion forces to generate Hamaker constants. The approach provides a comprehensive understanding of the wettability of iron against these refractory oxides, revealing the complex relation between the molecular and macroscopic properties. Our theoretically determined crystalline structures are confirmed by room-temperature X-ray diffraction, and the contact angles of liquid iron on the oxides are validated with a sessile drop system at a temperature of 1823 K. For comparison, we also present the wettability of the oxides by a liquid tin-bismuth alloy. The findings are essential in advancing the fundamental understanding of interfacial interactions in metallurgical science and pivotal in driving the development of more efficient and reliable steelmaking processes.

There is hardly a more bewildering aspect of the chalcopyrite material Cu(In,Ga)Se2 (CIGSe), used as an absorber in thin-film solar cells, than its relation with off-stoichiometry, which is often manifested in the formation of ordered defect compounds (ODCs). Despite huge efforts devoted to determining the structure and properties of the ODCs, no comprehensive model has been provided. The convention is that the off-stoichiometry is mediated by the charge-neutral [2VCu + IIICu] complexes forming in high concentrations. In this work, we refute this simplistic picture by treating the off-stoichiometry as an integral part of the crystal structure. In part I, herein, we report a discovery of the topotactic transformation series of stable ODC-like structures with different compositions that enable large Cu deficiency in the material. Crucially, the underlying structures are shown practically invisible to X-ray and neutron diffraction, as the parent lattice is preserved and barely deformed within the relevant compositional range. The model we deduce reconciles several lasting conflicts between experimental findings and first-principles calculations. In part II, this model is further validated by computing the electronic properties for the structures in the series and comparing the results with prior experimental findings. The developed structural series is uniquely self-consistent and is thus well-positioned to bolster computational analysis of chalcopyrite compounds and alloys.

In this paper, we investigate the Casimir-Lifshitz free energy mechanism that governs both ice growth and melting near metal surfaces, with a particular focus on the role of oxidation. Our study reveals that metals such as gold, iron, and aluminum induce incomplete premelting, resulting in micron-sized liquid water layers when in contact with ice. These layers could have significant implications for the defrosting of metallic surfaces. When exposed to water vapor at the triple point, aluminum and other metals can induce the formation of notably thick layers of either liquid water or ice, which can theoretically become infinitely thick if other interactions are disregarded. However, when aluminum undergoes oxidation to form alumina, its behavior changes dramatically. Alumina surfaces cause complete melting when in direct contact with bulk ice and result in only micron-sized layers of water or ice in vapor conditions. In contrast, magnetite, the oxidized form of iron, retains metalliclike behavior due to its high dielectric constant, similar to other metals, and continues to support thick layers of water or ice. This distinction highlights the significant influence of oxidation on the dynamics of ice growth and melting near different metal surfaces.

High efficiency, stability, and environmental sustainability are key objectives in the application of solar cells. Cu3SbS4 has received widespread attention due to its low manufacturing costs, environmental friendliness, and excellent optoelectronic properties. However, the small bandgap width, poor crystal quality, and improper band alignment have so far resulted in a power conversion efficiency (PCE) of only 0.46% for laboratory Au/Cu3SbS4/CdS/ZnO solar cells. In the present study, combining first-principles calculations and device simulations, three strategies to improve the performance of Cu3SbS4-based solar cells are proposed: (1) alloying with V, Nb, and Ta elements to increase the bandgap width of the absorber; (2) replacing buffer and window layers to optimize the band alignment of the device; (3) optimizing material synthesis and device fabrication processes to reduce series resistance and enhance shunt resistance. First-principles calculations demonstrate that Cu3Sb1–xAxS4 alloys (A = V, Nb, and Ta) are easy to prepare, and their bandgap widths can be widened while maintaining the original famatinite structure. Device simulations further reveal that the PCEs of the solar cells based on Cu3Sb1–xAxS4 alloys are significantly improved by optimizing the band alignment, reducing the series resistance, and enhancing shunt resistance. Finally, the device configurations Au/Cu3Sb0.75A0.25S4/SnS2/ZnO:Al are demonstrated to achieve PCEs of 19.55%, 19.67%, and 19.99% for A = V, Nb, and Ta, respectively. This study provides a theoretical foundation for optimizing Cu3SbS4-based solar cells and highlights the importance of combining theoretical calculations with device simulations to enhance the performance of solar cell devices.

The formation and growth of ice particles, particularly on the surfaces of spherical water droplets, bear profound implications for localized weather systems and global climate. Herein, we develop a theoretical framework for ice nucleation on minuscule water droplets, establishing that 10-5000nm droplets can considerably increase in volume, making a substantial contribution to ice formation within mist, fog, or even cloud systems. We reveal that the Casimir-Lifshitz (van der Waals) interaction within these systems is robust enough to stimulate both water and ice growth on the surfaces of ice-cold spherical water droplets. The significant impacts and possible detectable phenomena from the curvature are demonstrated.

The operational efficiency of continuous casting in steel production is often hindered by the clogging of submerged entry nozzles (SEN), caused due to the agglomeration of nonmetallic inclusions (NMIs). SEN clogging is challenging to monitor and requires probabilistic models for accurate real-time prediction. In this context, data-driven models emerged as a promising tool to be used in the existing industrial settings. Despite frequent occurrence of SEN clogging, collecting large datasets under varied operational conditions remains challenging. The scarcity of data hampers the ability to develop and train traditional data-driven models effectively. To overcome these challenges, physics-informed data-driven models are proposed in this work. The integration of outputs generated from theoretical calculations is sufficient to compensate for the lack of available datasets. To further enhance accuracy, an advanced methodology involving use of ab initio repository is developed. This repository contains material-specific data including high-temperature nonretarded Hamaker constants of NMIs in specific particle size range of 1–10 μm. A novel parameter, “Clogging Factor” is proposed to monitor and integrated into the modeling architecture to track the reduction in the available volume inside SEN due to the accumulation of NMIs. The proposed model has yet to be validated online but has shown potential in reducing SEN clogging.

Compared to heterojunction solar cells, homojunction solar cells have better lattice and band edge matching, which can effectively reduce the loss of open-circuit voltage and enhance the fill factor. AgInSe<inf>2</inf> is a stable chalcopyrite semiconductor with a direct-type band structure, and its band edge positions are in the range of the empirical limits for allowing both n-type and p-type doping, making it an ideal absorber for homojunction solar cells. Here, the possibility of a AgInSe<inf>2</inf> p-n junction as an absorber for homojunction solar cells is explored by using first-principles calculations and device simulations. Firstly, the electronic structure, defect properties, and corresponding material property parameters of AgInSe<inf>2</inf> are determined by calculations. The results show that p-type and n-type AgInSe<inf>2</inf> semiconductors can be prepared under Ag-poor, In-poor and Se-rich, and non-Ag-poor environments, respectively, and that their corresponding defect and carrier concentrations can be selected and optimized to the requirements for use as photovoltaic absorbers. Subsequently, the material's property parameters from first-principles calculations were used as input data for SCAPS-1D device simulations. The results demonstrate that homojunction solar cells exhibit an open circuit voltage of 0.74 V, a short circuit current of 36.34 mA cm⁻², and a power conversion efficiency (PCE) of 22.48%. Finally, the PCE is still 21.62% after optimizing the thickness of the p-n junction to reduce the cost, which is higher than the experimentally reported PCE of AgInSe<inf>2</inf> heterojunction solar cells and close to the PCE record of chalcopyrite-based heterojunction solar cells. Our theoretical work provides a concrete research scheme for further experimental study of AgInSe<inf>2</inf> homojunction solar cells.

Many diamond-like semiconductors with tetrahedral bonds, such as Si, CdTe and Cu(In,Ga)Se2, have been utilized as absorbers in photovoltaics (PV). In this work, a novel group of diamond-like compounds, namely Cu4-IIGe2-VI7 with II = Zn/Cd and VI = S/Se, have been explored by first-principles means. From the calculations of the electronic structures and related optical properties, we have demonstrated that all these quaternaries have direct-type band structures, while their band gap energies are not suitable for PV applications. By anionic alloying, however, the width of the band gaps can be tuned to the desired energy. For example, the Cu4ZnGe2S4Se3 alloy has a suitable band gap of 1.34 eV. Our work provides the support and perspective for further experimental research on this group of semiconductors and their alloys as potential candidates in PV technologies.

The present study investigates the structure stability, electronic structures, and optical properties of Zintl compounds CsZn4P3 and CsZn4As3 by first-principles calculations. An assessment of the phonon dispersion curves and elastic constants indicate both dynamic and mechanical stability for the both compounds. By employing the HSE06 hybrid functional, both compounds display direct bandgap with widths of 0.93 eV for CsZn4P3 and 0.66 eV for CsZn4As3. Furthermore, an analysis of the dielectric constant, refractive index, extinction coefficient, and energy loss as functions of photon energy is conducted to study the optical properties. Based on the semi-classical Boltzmann transport theory and the Slack's equation, a large Seebeck coefficient and minimum lattice thermal conductivity are obtained for CsZn4As3, which result in a figure of merit value of 0.79 at 700 K. These findings underscore the potential of CsZn4As3 as a promising candidate for future research and development in the realm of thermoelectric materials.