We investigate proton soliton transport in one‐dimensional hydrogen‐bonded chains using a quasi‐spin framework and sophisticated analytical methods. An effective Hamiltonian incorporating coherent proton tunneling, nearest‐neighbor proton–proton interactions, and external electric field effects is used to develop a nonlinear evolution equation for collective proton soliton excitations. A nonlinear Schrödinger equation with higher‐order dispersive terms is obtained by transforming the system through the Holstein–Primakoff transformation and using the continuum approximation. According to Hirota's bilinearization method, kink–antikink soliton solutions can be accurately obtained for both single and interacting soliton dynamics analysis. The Bäcklund transformation of Riccati equation (BTRE) method produces more precise analytical results for the investigation of shape‐modifying features. Depending on the coupling strengths, solitons in BTRE solutions can transform from topological to nontopological states and back again. Soliton localization and amplitude are controlled by nearest‐neighbor coupling, while coherence and spatial confinement are affected by interactions.
Zinc oxide (ZnO) thin films are promising immobilized photocatalysts,but their performance is strongly influenced by native point defects introduced during deposition and post‐annealing. In this work, Zn thin films were deposited on glass substrates by thermal evaporation and converted to ZnO by annealing at 600 °C for 2 h in either air or an oxygen‐poor argon atmosphere. The films were characterized by X‐ray diffraction, scanning electron microscopy, optical transmittance, photoluminescence (PL), electron paramagnetic resonance (EPR) spectroscopy, and methylene blue (MB) photodegradation under UV–visible irradiation. The apparent optical bandgap increased from 2.96 eV for the as‐deposited film to 3.16 and 3.32 eV for the air‐ and argon‐annealed films, respectively, mainly due to improved crystallinity and reduced disorder‐related sub‐bandgap absorption. PL deconvolution and EPR analysis revealed enhanced defect‐related signatures after argon annealing, including visible deep‐level emission and an EPR signal near g ≈ 1.96. The argon‐annealed film exhibited the highest MB degradation efficiency, reaching 93% after 180 min, with an apparent first‐order rate constant of 0.01604 min −1 . These results support a strong structure–defect–function correlation in defect‐mediated ZnO photocatalysis.
Rare‐earth titanates RTiO 3 exhibit a magnetic crossover from G‐type antiferromagnetism (G‐AFM) to ferromagnetism (FM) governed by the A‐site ionic radius. We investigate the phase‐boundary solid solution Gd 0.5 Sm 0.5 TiO 3 using density functional theory (DFT) + U calculations to analyze competing magnetic orders. Our results identify the G‐AFM configuration as the zero‐temperature DFT ground state, separated from the metastable FM state by only 13.54 meV/Ti, indicating that 50% Sm substitution drives the system into the AFM regime. Conversely, A‐type AFM and C‐type AFM configurations are dynamically unstable. Analysis of local magnetic moments reveals robust rare‐earth ferrimagnetism but highly sensitive Ti moments (0.15–0.64 ) arising from exchange frustration. The energetic proximity of the G‐AFM and FM phases suggests that field‐induced metamagnetic transitions are achievable at accessible magnetic fields (5–10 T). Thus, the Gd 1 − x Sm x TiO 3 series offers a tunable platform for optimizing magnetocaloric effects for cryogenic cooling applications.
A series of Pr 3+ ions activated K 5 La(MoO 4 ) 4 trigonal structured molybdate phosphors were prepared using a solid‐state reaction method. Structural, morphological, and optical properties of as‐synthesized material are reported. X‐ray diffraction (XRD) pattern confirmed the trigonal crystal system with a R‐3m (#166) space group. Surface morphology with irregularly shaped particles with a size in micrometers and elemental composition was confirmed using the scanning elelctron microscopy (SEM) and energy dispersive spectra (EDS). Under 450 nm excitation, photoluminescence spectra exhibit a strong orange emission with a dominant peak at 606 nm for Pr 3+ ions. The Obtained results indicate that single‐phase K 5 La(MoO 4 ) 4 : Pr 3+ phosphors could be a potential material for orange‐emitting light emitting diodes and other optoelectronic applications.
The high‐pressure structural, mechanical, electronic, and thermal transport properties of the layered MAB‐phase ternary boride Hf 2 SeB are systematically investigated via first‐principles across a pressure range of 0–50 GPa. Hf 2 SeB crystallizes in a hexagonal P6 3 /mmc structure and retains thermodynamic, mechanical, and dynamical stability throughout the investigated pressure regime. Hydrostatic compression induces pronounced anisotropic lattice contraction, with enhanced stiffness along the basal plane relative to the c‐axis, accompanied by a pressure‐amplified elastic anisotropy. Electronic structure analyses reveal robust metallic conductivity dominated by Hf‐d states near the Fermi level, with a substantial pressure‐induced increase in the electronic density of states. Notably, compression markedly strengthens the mechanical response, with the theoretical Vickers hardness increasing from 12.02 GPa at ambient conditions to 17.52 GPa at high pressure. In parallel, Hf 2 SeB exhibits an ultralow minimum thermal conductivity (0.68–0.90 W m −1 K −1 ) and a continuously rising melting temperature, suggesting its potential for applications in high‐pressure, high‐temperature, and thermomechanically demanding environments, though its oxidation resistance at elevated temperatures remains a critical consideration for practical use.
Negative Poisson's ratio (NPR) structures, as representatives of advanced lightweight honeycomb materials, have demonstrated broad application prospects in aerospace, civil engineering, and biomedical fields due to their unique deformation mechanisms and energy absorption potential. This article proposes a novel t2D, centrally symmetric, concave‐chiral hybrid honeycomb (CSCHH) exhibiting an NPR effect. This structure is constructed by adding vertical ribs at the nodes of the traditional re‐entrant hexagonal (TRH) to form a “hollow bamboo” honeycomb, which is then combined with chiral units. The compressive performance of the structure was systematically evaluated through axial compression experiments and finite element simulations, with experimental results validating the accuracy and applicability of the finite element model. Compared to the TRH, the CSCHH structure improves the platform stress and energy absorption capacity by 203% and 146.4%, respectively, while demonstrating a stable NPR effect. Based on orthogonal simulation experiments, the influence of geometric parameters such as the height and width of the concave inclined rods and the radius of the rings on the quasi‐static compressive performance of the CSCHH unit was analyzed. This study provides a theoretical basis for design and energy absorption of NPR materials, and indicates that CSCHH possesses excellent mechanical properties and broad engineering prospects.
Two‐dimensional (2D) materials have emerged as a frontier for high‐efficiency thermoelectric energy conversion due to their unique quantum confinement and suppressed thermal conductivity. In this work, we employ comprehensive first‐principles calculations to investigate the structural, mechanical, and thermoelectric properties of the SnAs monolayer. Phonon dispersion calculations, evaluation of the Born mechanical stability criteria, and ab‐initio molecular dynamic (AIMD) simulations confirm the dynamical, mechanical, and thermal stability of the SnAs monolayer. Furthermore, stress–strain analysis shows that the monolayer can withstand biaxial strains of up to 0.20, while the AIMD results demonstrate its thermal stability up to 900 K. Transport properties reveal a high Seebeck coefficient (~1800 µV/K) and a significant power factor. Notably, the dimensionless figure of merit ( ZT ) reaches a maximum of approximately 0.85 at 900 K, approximately twice the value at 300 K. These findings highlight the SnAs monolayer as a mechanically robust and high‐performance candidate for next‐generation, high‐temperature thermoelectric applications.
Nonclassical states of quantized light are essential resources for quantum information science and emerging quantum technologies. In this work, we investigate the generation of such states in a dissipative hybrid system, namely a microcavity consisting of a ferromagnetic yttrium iron garnet (YIG) sphere coupled to a quantized microwave cavity mode, and particularly incorporating several nonlinear quantum optical elements including various Kerr media, optical parametric amplifier (OPA), and a magnonic parametric amplifier (MPA) which is introduced as the magnonic analog of the OPA. Decoherence effects arise from thermal photonic and magnonic reservoirs. Using the Heisenberg–Langevin formalism, we analyze the influence of Kerr nonlinearities, OPA, and MPA on several nonclassical signatures, including antibunching, entanglement, quadrature squeezing, and violation of the Cauchy–Schwarz inequality. Numerical results show that photon and magnon antibunching, as well as violation of the Cauchy–Schwarz inequality, can persist even in the presence of considerable dissipation, although these effects weaken as the thermal photon and magnon populations increase. In contrast, entanglement and quadrature squeezing remain remarkably robust against thermal noise. Furthermore, we demonstrate that the inclusion of OPA and MPA generally enhances all investigated nonclassical effects, whereas Kerr nonlinearities have negligible influence within the considered parameter regimes.
Using spin‐polarized density functional theory within the full‐potential linearized augmented plane wave framework, we investigated the structural and electronic properties of La‐substituted SrNbO 3 (Sr 0 . 875 La 0 . 125 NbO 3 ). We used volume optimization and equation‐of‐state fitting to check further structural stability. This showed that cubic symmetry was preserved after La atom was added by replacing Sr atom. The computed spin‐resolved electronic band structure shows that multiple bands cross the Fermi level, showing metallic behavior of material under doped condition. There is a distinct spin asymmetry observed at the Fermi energy. This is because 12.5% La doping at the Sr site causes finite spin polarization. The total density of states study shows that most of the electronic states at the Fermi level have contribution from Nb‐4d orbitals while the valence‐band region has substantial Nb 4d–O 2p hybridization. The contribution of Sr and La states near the Fermi level is relatively small, indicating that their primary role is to act as electron donors to the system. These results provide insight into the modification of electronic structure and spin characteristics of SrNbO 3 upon La substitution and may serve as a basis for further theoretical and experimental investigations of doped perovskite oxides.
Density functional theory (DFT) calculations were employed to investigate the CO adsorption mechanism on Cu‐doped C 21 (C 21 Cu). The adsorption configurations, adsorption energies, adsorption heights, electronic structures, and charge transfer characteristics were systematically analyzed to reveal the interaction between CO molecules and the C 21 Cu substrate. The results show that C 21 Cu exhibits strong adsorption toward CO molecules. Among the investigated configurations, C‐end adsorption is more favorable than O‐end adsorption, with adsorption energies of −3.36 and −1.62 eV, respectively. The corresponding adsorption heights are 0.73 and 3.36 Å, and the most stable adsorption sites are identified as H2 and T sites. The stronger interaction and shorter adsorption distance of the C‐end configuration indicate enhanced adsorption activity. Although the O‐end configuration exhibits relatively weaker adsorption, it still belongs to the chemisorption regime. This study provides theoretical insights into the CO adsorption mechanism on Cu‐doped C 21 and suggests its potential application as a CO gas adsorption and sensing material.
In this study, the structural and electronic properties of hexagonal Li 3 P (space group P6 3 /mmc, No. 194) and sulfur‐doped Li 3 P 1‐ x S x were investigated by the density functional theory (DFT) within the generalized gradient approximation (GGA‐PBE), as implemented in the Quantum ESPRESSO package. After full geometric optimization of the host material, sulfur incorporation was modeled by substituting P atoms within a supercell, corresponding to a 3.125% doping concentration. Cohesive energy analyses confirm the thermodynamic stability of both pristine and doped configurations, as indicated by their negative values. Electronic structure calculations reveal an indirect bandgap of 0.703 eV for pristine Li 3 P, obtained consistently with both ultrasoft pseudopotential (USPP) and projector augmented‐wave (PAW) PBE functionals. Remarkably, sulfur substitution at P sites induces pronounced reconstruction of the electronic band structure, giving rise to new energy states that cross the Fermi level ( E F ), which are attributed to the dopant‐induced electronic states. Through systematic structural relaxations and analysis of total (TDOS) and partial (PDOS) densities of states, the underlying modulation mechanism is elucidated. A detailed bonding‐character analysis further identifies the hybridization states of both doped and undoped systems.
Zintl compounds have many technological applications, although they are formed by electropositive and electronegative elements via a simple chemical bonding rule. Only a few of them crystallize in the ZrNiAl‐type structure. In this work, we selected P‐62m Na X P ( X = Sr, Ba) as representative compounds to study their electronic, photovoltaic, elastic, and infrared properties using the density functional method. Calculated phonon spectra confirm their dynamical stability. Band structures and electron localization functions reveal both crystals to be narrow direct‐gap semiconductors with ionic bonding. The origins of the band structures are revealed by calculated partial densities of states and their respective spectroscopic limited maximum efficiencies are calculated. Obtained elastic constants uncover that these two crystals are mechanically stable but anisotropic. Investigations into the elastic‐related properties of P‐62m Na X P ( X = Sr, Ba) unveil that both crystals are brittle, more resistant to volume change, and characterized by low hardness and low Debye temperature. Infrared spectra are simulated, and the vibrational modes at the Brillouin zone center are assigned by factor group analysis. In addition, their dielectric constants and piezoelectric coefficients are also computed and discussed.
Lead‐free (1‐ x )(0.65Bi 0.5 Na 0.5 TiO 3 ‐0.35SrTiO 3 )‐ x Fe 2 O 3 (BNST‐ x F) ceramics ( x = 0–0.08) were successfully synthesized via solid‐state reaction, aiming to develop environmentally friendly high‐performance energy storage materials. The study systematically reveals how Fe 2 O 3 doping optimizes the functional properties of BNST‐based ceramics. All samples retained a pure perovskite structure with dense microstructures and clear grain boundaries. Notably, Fe 2 O 3 doping significantly enhanced the energy storage density, relaxation behavior, and breakdown strength compared with pure BNST. At higher doping levels ( x ≥ 0.06), an electric‐field‐induced phase transition occurred, accompanied by antiferroelectric‐like P – E hysteresis within 15–70 kV/cm, attributed to electric‐field‐regulated dipole ordering. Dielectric analysis identified two distinct relaxation mechanisms below and above x = 0.06, originating from polar nanoregions (PNRs) and oxygen vacancies (VOs), respectively. This study reveals the microscopic mechanism of doping‐induced phase transition and relaxation dynamics, providing a feasible strategy for designing high‐performance lead‐free energy storage ceramics.
In the present work, nanoparticles of CdS and ZnO were synthesized using the coprecipitation method, and their respective composites were formed using an ultrasonic technique with varying ZnO concentrations. The effect of ZnO concentration enhancement on the structural, electrical, and optical properties of CdS/ZnO composites has been studied. The X‐ray spectroscopy and Raman spectroscopy confirm the formation of CdS and ZnO nanoparticles and their composites. X‐ray diffraction spectroscopy (XRD) has been used to study the structural properties of CdS, ZnO nanoparticles, and their composites. The coexistence of the planes corresponds to both CdS and ZnO nanoparticles in the XRD diffractogram of nanocomposites, confirming the formation of the composites. Linear absorption properties of the material are studied with the help of UV–Visible (UV–Vis) spectroscopy and photoluminescence spectroscopy (PL). The bandgap of nanoparticles and their respective composites has been studied using Tauc's Plots. The bandgap calculated from the UV–Vis spectra first increases and then decreases with a rise in ZnO concentration in the composites discussed in UV–Vis section. The KEITHLEY 6517A electrometer is used to study the electrical properties of these materials, which show a rise in current with an enhancement in ZnO concentration at a fixed voltage. The results obtained from the current–voltage characteristics are in good agreement with the UV–Vis spectroscopy analysis. In this work, we tuned the optical properties of CdS/ZnO nanocomposites can be tuned by varying the ZnO composition in the nanocomposites. Moreover, the composites have enhanced visible light adsorption capacity, which extends their use in photocatalytic applications. Findings from various characterizations are consistent with each other.
The electronic and optical properties of CuGa x In 1−x Se 2 are explored in the full component range through first‐principles calculations. Our findings demonstrate that the lattice parameters decrease as the Ga component increases. CuGa x In 1−x Se 2 is an alloy with a direct bandgap. Its bandgap enlargement is due to the rise of the conduction band minimum (CBM) and the fall of the valence band maximum (VBM). Our findings also show that Cu plays a secondary role in determining the dependence of the VBM on Ga component because the Cu‐3d and Cu‐4p states are nearly independent of the Ga component. The rise of the CBM is caused by the enhanced total coupling, while the fall of the VBM is mainly due to the enhanced total coupling. Analysis of the imaginary part of the dielectric function reveals that the transition energies of the critical points E 0 , E 1 (A), E 1 (B), E 2 (A), E 2 (B), and E 3 move toward the higher‐energy direction approximately linearly in the whole component range. Similar results are also found by analyzing the absorption spectra, refractive index spectra, and reflectivity spectra.
Semiconductor heterostructures capable of separating photogenerated electrons and holes have a wide range of optoelectronic applications, including photodetectors, solar cells, and photocatalysts. β‐Ga 2 O 3 and rutile GeO 2 are both ultrawide‐bandgap semiconductors, with bandgaps of 4.85 eV and 4.68 eV, respectively, which have attracted increasing interest due to promising applications in next‐generation high‐power electronics and deep ultraviolet optoelectronics. Here, using first‐principles calculations, we investigate the interfacial property and band alignment of the β‐Ga 2 O 3 /rutile GeO 2 heterojunction and explore the effect of interfacial oxygen vacancy. Calculations using the PBE0 hybrid functional based on an interface model show that a type‐II band alignment emerges at the β‐Ga 2 O 3 /rutile GeO 2 interface, which facilitates the separation of photogenerated carriers. The valence band maximum of β‐Ga 2 O 3 lies 0.38 eV below that of rutile GeO 2 , and its conduction band minimum lies 0.36 eV below. The presence of an interfacial oxygen vacancy in the stable configuration leads to a reduction in the band offset. Our results suggest that the β‐Ga 2 O 3 /rutile GeO 2 heterojunction holds significant promise for application in strictly solar‐blind photodetectors.
The time‐reversal symmetry broken antiferromagnetic Weyl metallic phase is rare, and it is a typical example of composite quantum materials. Double‐perovskite Sr 2 TaMnO 6 has been investigated using the first‐principles electronic structure method to explore the frustrated antiferromagnetic (AFM)‐metallic electronic state. It has been found that pairs of Weyl points (WP) in the Brillouin zone (BZ). The calculated Wannier charge center and normalized Berry curvatures reveal that the pair of WP are of opposite chirality and connected via Fermi arcs. The calculated anomalous Hall conductivity reached a moderate value just below the Fermi energy (E), coinciding with the WP crossing in the bulk bands due to the non‐cancelation of the Berry curvature in AFM state. The present investigations will lead to a new direction of further exploration of the existence of Weyl metal in the compensated AFM state for prospective future spintronics and quantum computing purposes.
This work investigates the synthesis and characterization of LuAG:Ce ceramics produced by conventional and laser sintering, focusing on crystal structure, densification, and photoluminescent properties. X-ray diffraction confirmed the formation of a single-phase cubic LuAG structure after calcination at 900 degrees C, with no secondary phases or Ce3+ segregation. Laser sintering was optimized by varying beam diameter, heating rate, and dwell time, resulting in ceramics with high relative density and homogeneous microstructure in significantly reduced processing times. Photoluminescence analysis revealed excitation bands at 350 nm and 445 nm, and an emission band centered at 510 nm. Increasing Ce3+ concentration caused a red shift in the emission peak, more pronounced in laser-sintered samples. This effect, along with reduced emission intensity and changes in excitation band ratios, was associated with a higher concentration of oxygen vacancies. These results demonstrate the potential of laser sintering for efficient production of dense and luminescent ceramics, with important implications for defect control and optical performance.
The polycrystalline samples of La 1.98‐ x Y x Sr 0.02 CuO 4 , where 0 ≤ x ≤ 0.06, have been synthesized by solid‐state reaction method, and the impact of Y cosubstitution on the thermoelectric properties of the material has been studied. Rietveld analysis of X‐ray diffraction data confirms orthorhombic structure with systematic decrease of the “c” axis on Y doping, indicating lattice strain due to the Y 3+ doping. The field‐emission scanning electron microscope analysis reveals an anisotropic grain structure with diminishing grain volume and increased grain boundaries density on yttrium doping. Electrical resistivity measurement shows weak metallic behavior with a resistivity minimum at lower temperatures. The low‐level substitution of yttrium (≈2 wt%) significantly reduces electrical resistivity, possibly due to enhanced carrier concentration. The thermopower measurement indicates hole‐type conduction across all compositions in the investigated temperature range. However, codoping of Y suppresses the thermopower at low doping concentration owing to the increased carrier concentration. A quantitative interpretation of the temperature‐dependent thermopower reveals that the two‐band model provides the closest description up to ≈220 K, corroborating the coexistence of delocalized carriers with weakly localized states. Again, the optimized composition, La 1.96 Y 0.02 Sr 0.02 CuO 4 , exhibited a peak power factor of 7.9 µW/cm·K 2 at 130 K, highlighting its potential for low‐temperature thermoelectric applications.
We study auxetic lattice structures with curved bi‐material ligaments using the finite element method. The overall Poisson's ratio and coefficient of thermal expansion of the lattices can be simultaneously tuned to be negative by adjusting their microstructural geometries and constituent material parameters. The Young's modulus of ligaments plays an important role in controlling the effective Poisson's ratio and coefficient of thermal expansion. The size and Young's modulus of the joints that connect ligaments strongly affect the effective mechanical properties. When Young's modulus of the joint is given, a larger joint size gives rise to stronger auxeticity, but less negative thermal expansion. By tuning the coefficient of thermal expansion of each constituent, the overall coefficient of thermal expansion may be negative, zero, or positive. The bicamaterial auxetic structures studied here may be designed to possess desired properties for real‐world applications when their microstructural properties are appropriately tuned.
