This study presents a systematic investigation of nanostructured Bi10Sb30Se60 chalcogenide thin films and their heterojunctions with n-type silicon for advanced optoelectronic and photovoltaic applications. Structural analysis confirmed a stable polycrystalline morphology with grain sizes of 88.54 nm and a surface roughness of approximately 36 nm, promoting enhanced light scattering and carrier interaction. Optical measurements revealed a direct band gap of 2.38 eV, a high carrier concentration to effective mass ratio, and significant thirdorder nonlinear optical susceptibility, indicating strong photonic response. The fabricated Bi10Sb30Se60/n-Si heterojunction devices exhibited pronounced rectifying behavior, efficient charge transport, and low leakage current, demonstrating their suitability for photodetection and solar energy conversion. To further optimize material performance, an Adaptive Neuro Fuzzy Inference System was implemented to model the optical and electrical characteristics. The optimized networks showed excellent agreement with experimental data, achieving minimal prediction errors and reliable extrapolation capability. The integration of experimental validation with intelligent predictive modeling provides a robust framework for accelerating material design and improving the efficiency of next-generation solar cell technologies.
Metal-organic frameworks (MOFs) containing alkali metal ions are emerging as attractive materials due to their low toxicity, flexible coordination chemistry and compatibility with functional materials. In this work, a Cesium-based metal-organic framework (Cs-MOF) was synthesized using benzene-1,2,4,5-tetracarboxylic acid (BTCA) as the organic linker forming (Cs-BTCA) which subsequently combined with polyaniline and nanoporous graphene to form a composite material. Structural and morphological characterizations confirm MOF formation and effective integration of the conductive components. The resulting Cs-MOF/PANI/NPG composite demonstrates synergistic response arising from the porous framework, redox-active polymer, and high-surface-area containing carbon network. The specific capacity confers by the Cs-BTCA and Cs-BTCA/PANI/NPG were 387C/g and 570C/ g at 1.5 A/g respectively via three-electrode configuration. The Cs-BTCA/PANI/NPG//AC based hybrid super-capacitor exhibited maximum specific capacity was 364C/g obtained at 0.5 A/g current density. The obtained energy density of 80.8 Wh/kg. The capacitive and diffusive controlled contributions were evaluated by applying both linear and quadratic models. The quadratic model provides better fitting as compared to linear model. This study highlights a viable strategy for designing MOF-based composites for advanced energy storage applications and electrochemical devices.
We uncover a non-monotonic charge-transfer mechanism in the Ba-I system driven by pressure-induced sequential orbital activation. First-principles calculations combined with CALYPSO structure searches reveal structural and electronic evolution from 0 to 800 GPa, predicting three previously unknown stable compounds: BaI3, BaI, and Ba2I, with dynamical stability confirmed by ab initio molecular dynamics. Notably, charge transfer in Ba-I displays a non-monotonic evolution: Ba -> I transfer decreases from similar to+1.5 e at ambient pressure to +0.1 e around 500 GPa, then increases again to similar to+0.3 e at higher pressures. At intermediate pressures, broadening and partial occupation of Ba d states draw electron density from I p orbitals, suppressing net charge transfer. At higher pressures, activation of I d states and redistribution of Ba p electrons drive a re-entrant increase in charge transfer. This reveals an orbital-competition mechanism governing non-monotonic charge transfer in ionic compounds under high pressure.
We analyse the thermodynamic results for the diatomic molecule BN obtained in a recent paper. The authors failed to obtain the model parameters from experimental data and chose some of them arbitrarily. An unlucky guess led to a potential that does not support bound states. They omitted the contributions of the rotational and translational degrees of freedom in the calculation of the canonical partition function. They chose a reduced mass for the nuclei of the order of the electron mass and a dissociation energy several orders of magnitude smaller that the accepted value. In spite of all these mistakes the authors managed to obtain theoretical results in fairly good agreement with experimental data.
In this work, PVA/PVP/Ag/ZnS nanocomposite were successfully synthesized by blending polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) with silver (Ag) and zinc sulfide (ZnS) nanoparticles. This study addresses the influence of electron irradiation on the surface wettability and optical properties of PVA/PVP/Ag/ZnS nanocomposite. The prepared samples were exposed to doses of 20, 30, and 40 kGy to investigate the influence of irradiation on their optical properties. The successful fabrication and morphology of the nanocomposite films were confirmed using energy dispersive X-ray (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. The wettability measurements revealed a significant decrease in the water contact angle from 40.5 degrees to 23.5 degrees with increasing irradiation dose from 20 to 40 kGy, indicating enhanced hydrophilicity. Correspondingly, the work of adhesion increased from 127.32 to 138.06 mJ/m2. The optical properties such as the optical band gap and Urbach energy were analyzed using UV/Vis spectrophotometer with wavelength 200 to 1800 nm. The Urbach energy modified from 0.50 eV for the PVA/PVP/Ag/ZnS to 0.54, 0.58, and 0.56 eV after irradiation at 20, 30, and 40 kGy, respectively. Also, the absorption edge reduced from 0.86 eV for PVA/PVP/Ag/ZnS to 0.81, 0.75, and 0.74 eV. In addition, the optical band gap decreased from 3.34 eV for PVA/PVP/Ag/ZnS to 3.21, 3.12, and 3.01 eV after irradiation. These findings demonstrate that electron beam is tailoring the surface wettability and optical characteristics of PVA/PVP/Ag/ZnS nanocomposite films, making these PVA/PVP/Ag/ZnS nanocomposite as promising materials applied for optoelectronic applications.
Layered van der Waals (vdW) materials offer promising routes to explore distinct phases of quantum matter. Using density functional theory plus coherent potential approximation (DFT+CPA) we reveal the anisotropic electronic reconstruction induced by electron/hole doping in the disordered regime of CrSBr vdW bulk crystal, quantifying the role played by collective dynamical fluctuations in a ferromagnetic semiconductor. The Anderson disordered electronic structure we derive is promising in the sense that it leads to results that show why moderate perturbations can generate an anisotropic incoherent metal in a vdW system with strongly ferromagnetic spin-polarized t(2g) orbitals.
Orthorhombic cubanite CuFe2S3 is a structurally unique copper-iron ternary sulfide due to the presence of Fe-Fe pairs called dimers, which contribute to its strong antiferromagnetic properties accompanied by weak ferromagnetic properties, which attributes cubanite to the class of canted antiferromagnetics. While historically CuFe2S3 is categorized as a minor ore of copper, its technical significance has expanded into the fields of materials science and solid-state physics. The structural, electronic, magnetic and spectroscopy properties of bulk cubanite are studied via comprehensive experimental and theoretical investigations. The ab initio calculations of dynamical properties based on density functional theory (DFT) using DFT+U and hybrid functional approach are performed. The analysis of phonon states revealed the noncentrosymmetric space group Pna21 as the most preferred one. The results of calculations are confirmed by the experimental data obtained from Raman spectroscopy at ambient conditions. In addition, the irreversible phase transition to cubic phase (isocubanite) at pressure P similar to 3.7 GPa is detected from the baric evolution of the spectra, which is compared to the reference Raman spectrum of the synthesized isocubanite. The low frequency bands in Raman spectra of cubanite is observed for the first time and are attributed to the magnon quasiparticles.The magnetic space group Pn ' a2 ' 1 is established by spin-unrestricted noncollinear ab initio calculations. The calculations reproduce quite well the weak ferromagnetic order predicted experimentally. Finally, the thermodynamic properties are calculated, and the volume expansion, Gibbs energy, and specific heat as a function of temperature are evaluated and compared with experimental data. Orthorhombic CuFe2S3 was found to exhibit negative thermal expansion behavior at the small low-temperature range, as a sequence of strong anharmonicity in cubanite, which was analyzed by the self-consistent phonon approach. The lattice thermal conductivity is studied by solving the Boltzmann transport equation within the relaxation time approximation. The strong anisotropy of thermal transport properties is established, and the obtained mean value x = 0.4 W/m & sdot;K allows one to assign the cubanite to the class of the semiconductors with a record low thermal conductivity.
In this study, we investigate the effect of triaxial strain ranging from-8% to +8% on the properties of the VH2 compound using Density Functional Theory (DFT). For the unstrained structure, geometric optimization gave a lattice parameter of 4.209 angstrom. This compound is mechanically, dynamically, and thermodynamically stable, as indicated by the Born stability criteria, the absence of imaginary phonon modes, and the negative formation energy, respectively. The hydrogen storage capacities, in terms of gravimetric and volumetric values, are 3.8 wt% and 179.81 kgH2/m3, respectively. The application of a compressive strain of epsilon = -8% increases the volumetric capacity to 230.92 kgH2/m3, and the desorption temperature is reduced to 213.40 K, which is close to ambient conditions, thus making the compound ductile, while maintaining its metallic nature, as confirmed by the band structure and density of states (DOS) analysis. These results highlight the potential of VH2 as a promising material for hydrogen storage applications.
The growing demand for efficient spintronic materials with high spin polarization and magnetic stability motivates the exploration of novel half-Heusler alloys. In this work, density functional theory inside the FP-LAPW approach implemented in WIEN2k is used to do a comprehensive first-principles investigation of NaKX (X = C, Si, P, As, Sb) half-Heusler compounds in the cubic F43m structure. Structural optimization confirms ferromagnetic ground-state stability for all alloys. The phonon dispersion analysis confirms the dynamical stability of all investigated compounds, except NaKC, which exhibits imaginary frequencies near the Brillouin zone center, indicating structural instability. The calculated integer magnetic moments are governed by the Slater-Pauling rule, yielding 2 mu B for NaKC and NaKSi and 1 mu B for NaKP, NaKAs, and NaKSb. Nearly 100% spin polarization at the Fermi level results from strong half-metallicity with a semiconducting spin-up channel and metallic spindown channel, as revealed by electronic band-structure and density-of-states investigations. The Tran-Blaha modified Becke-Johnson potential offers an improved description of the band gap compared with GGA. The evaluated elastic constants are consistent with the Born stability requirements, ensuring mechanical stability. The combined ferromagnetic stability, half-metallic electronic structure, and elastic stability identify NaKX alloys as efficient candidate for spin-based device applications.
Spinel chalcogenides with rare-earth elements are gaining attention for their intriguing magnetic and thermoelectric properties, potentially paving the way for advanced energy-harvesting technologies. In the current report, the structural, electronic, magnetic, and transport characteristics of BaCe2(S/Se/Te)4 are investigated comprehensively utilizing the WIEN2k program based on density functional theory. The structural optimization shows that the materials are most stable in the ferromagnetic phase, and the negative formation enthalpies (-2.28 eV, -2.26 eV, -2.21 eV) confirm their thermodynamic stability. The electronic band structure and densities of states computed by mBJ and mBJ + SOC potentials highlight the role of Ce-4f and X-p orbital interactions and reveal a tunable indirect band gap of 0.9, 0.8, and 0.6 eV. The 100% spin polarization is confirmed through the integer value of the total magnetic moment and magnetic spin polarization. Additionally, positive No alpha and negative No beta values provide clear evidence of a half-metallic ferromagnetic nature, and exchange energies (Delta x(f) and Delta x(pf) indicate significant f-p interactions. Thermoelectric parameters, including the electrical and thermal conductivities, Seebeck coefficient, power factor, and figure of merit, are computed by using the Boltztrap code, showing promising values, particularly for BaCe2Se4 and BaCe2Te4. The calculated values of the figure of merit for BaCe2(S/Se/Te)4 are 0.65, 0.81, and 1.04, respectively. The results suggest that BaCe2(S/Se/ Te)4 compounds are promising candidates for next-generation fast data processing devices and thermoelectric devices.
One of the main challenges of four-quadrant photodiodes is ensuring interquadrant resistance and minimizing the photoelectric coupling coefficient between the elements. Errors in these parameters can lead to false alarms and incorrect determination of object coordinates, since a multi-element photodetector can then behave as a single element. In this paper, we propose to increase the insulation resistance between the active elements of four-quadrant p-type silicon p-i-n photodiodes by forming p + - regions between the responsive quadrants by boron diffusion. It was found that the best option is to simultaneously front alloy with the diffusion of boron to the back side of the substrate, since this does not introduce additional thermal operations into the technological route. The proposed method enables the fabrication of photodiodes with an interquadrant resistance of the order of 140-550 M Omega and a photoelectric coupling coefficient of less than 2 %.
High-resolution near-infrared (NIR) photodetectors (PD) find wide applications in medical imaging, diagnostics, autonomous driving, telecommunications and optical sensing. Electrical crosstalk in PD systems has become increasingly significant with continued reduction in pixel size, which leads to problems of sensitivity degradation and deterioration of image quality. Addressing this issue demands structural optimization to enhance optical confinement. In this study, scallop-shaped silicon nanowire (SS-SiNW) structures with improved optical absorption compared to planar designs are studied to enhance NIR sensitivity and suppress crosstalk simultaneously. The influence of substrate thickness, guard-ring doping and deep trench isolation (DTI) structures on lateral carrier diffusion is systematically investigated using TCAD simulations to assess the severity of crosstalk. The model is first validated against published data for silicon planar PDs. The results show that deep and highly doped guard-rings of the same type as the substrate effectively block lateral electron flow without compromising the external quantum efficiency in the case of thin substrates (10-25 & micro;m). In contrast, for thick substrates (150300 & micro;m), guard-rings of the opposite doping type to the substrate exhibit superior crosstalk suppression by electrically collecting laterally diffusing carriers. DTI structures with comparable depths effectively suppress crosstalk only in thin substrates, while their effectiveness becomes limited for thick substrates due to the insufficient blockage of deep diffusion paths. These findings provide quantitative guidelines for designing NIR photodiodes with appropriate substrate thickness and electrical isolation structures and offer practical design criteria for the development of high-sensitivity, high-resolution image sensors.
Radiation shielding materials for aerospace systems must balance attenuation efficiency, low mass, and longterm environmental durability. However, existing studies remain fragmented across material classes and radiation environments, limiting the development of generalizable design strategies. Here, machine learning was applied as an interpretable framework to integrate literature data on radiation-resistant aerospace materials. Principal component analysis, feature-importance analysis, and unsupervised clustering were performed using normalized shielding-efficiency and durability indices. The results revealed distinct performance regimes for bulk composites, coatings, and multilayer architectures. The first principal component (similar to 55-60% variance) described the trade-off between attenuation capability and mass efficiency, while the second (similar to 20-25%) reflected environmental durability. Multilayer architectures exhibited approximately 15-25% higher mass-normalized shielding efficiency together with improved durability compared with conventional systems. Feature-importance analysis identified areal density and architectural configuration as the dominant design variables. These findings demonstrate that aerospace radiation protection is fundamentally governed by architecture-enabled multifunctionality.
Rhenium diselenide (ReSe2), a layered transition metal dichalcogenide, has attracted considerable interest for photodetection applications due to its strong light absorption and favourable carrier transport properties. In this work, a comprehensive comparative study of bulk ReSe2 single-crystal and nanosheet-based thin-film photodetectors under self-biased condition is presented. High-quality bulk crystals were synthesized using the Direct Vapor Transport (DVT) technique, while few-layer nanosheets were obtained via Liquid-Phase Exfoliation (LPE) and were subsequently assembled into uniform thin film. Comprehensive structural and morphological characterization using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), X-ray Photoelectron spectroscopy (XPS) and energy dispersive x-ray analysis EDAX confirms phase purity and structural integrity. Optical properties reveal enhanced and broadened optical absorption in the nanosheet thin film, accompanied by slight increase in band gap, attributed to quantum confinement effect. Photodetector measurement demonstrates stable, repeatable, and self-bias photo-response under visible illumination. The nanosheet-derived thin-film device exhibits superior performance, achieving 24.4 mu A/W at an incident power density of 20 mW/cm(2), significantly higher than that of the crystal device 7.96 mu A/W. Moreover, the thin-film device shows enhanced detectivity of 6.47 & times; 10(7) Jones. At 638 +/- 40 nm, the crystal device exhibits a maximum detectivity of 6.09 & times; 10(8) Jones, while the thin-film device maintains competitive detectivity 3.64 & times; 10(8) Jones and enhanced visible-light sensitivity. The improved performance of the nanosheet-based photodetector is attributed to increased bandgap, enhanced light absorption, reduced recombination. Thus, this study demonstrates the clear advantage of solution-processed ReSe2 nanosheet thin films for self-powered photodetector applications, offering a viable pathway toward low-power and scalable optoelectronic devices.
In the present study, Multiphase-engineered CoCdS2 (CCD) nanocomposites were successfully synthesized via controlled solvothermal approach and investigated through structural, morphological, linear, and NLO analyses. Raman spectroscopy confirmed coexistence of cubic-Co3S4, cubic-CdS, and hexagonal-CdS phases. While FESEM micrographs revealed well-defined nanostructures and elemental mapping verified the homogeneous distribution of Co, Cd, and S elements. UV-Vis-NIR absorption spectrum exhibited strong optical absorption extending from ultraviolet to near-infrared region, with estimated optical bandgap of 1.54 eV and Urbach energy of 55.9 meV. The photoluminescence spectrum displayed dominant near-band-edge emission at 390 nm with defect-mediated visible emissions. Furthermore, NLO behaviour was investigated using open-aperture Z-scan technique which revealed pronounced reverse saturable absorption (RSA) with strong two-photon absorption (TPA) coefficient. Additionally, CCD nanocomposites demonstrated an effective optical limiting threshold of 1.02 & times; 1012 W/m2, highlighting their capability to attenuate high-intensity laser irradiation. These findings establish CCD nano-composites as attractive candidates for next-generation photonic-limiters and laser-protection application.
In this work, we prob the impact of various synthesis routes [sol-gel (SG) and hydrothermal (HT)] on structural, optical, magnetic, and electrical properties of Nd2CoFeO6 (NCFO) double perovskite nanoparticles. Rietveld refinement of XRD patterns confirmed a monoclinic structure (space group P21/n) for both samples, but the NCFO-HT sample exhibited higher crystallinity and a larger crystallite size due to the distinctive synthesis conditions. XPS analysis revealed mixed Fe2+/Fe3+/Fe4+ and Co2+/Co3+ valence states, with significantly more oxygen vacancies in the HT sample. A reduced optical band gap was observed for NCFO-HT (1.35 eV) compared to NCFO SG (1.52 eV). Quantitative comparison of the magnetic parameters in studied samples indicates better magnetic performance for the NCFO-HT sample due to forming double exchange interaction between Fe3+-Fe4+ valence states. Moreover, lattice distortion caused by more oxygen vacancies can lead to enhancement of the Dzyaloshinskii-Moriya (DM) interaction in this sample. Furthermore, the HT sample showed a higher dielectric constant and lower loss over broad temperature and frequency ranges. Impedance spectroscopy indicated correlated barrier hopping, with grain boundaries dominating the relaxation process in NCFO-SG and bulk relaxation dominating in NCFO-HT. Overall, the above results signify enhancement of physical properties owing to synthesis conditions. This manner depicts further tunability in double perovskite compounds as a promising candidate for applications in electronic devices and energy storage systems.
A dual-band mid-infrared smart thermal management emitter based on a vanadium dioxide (VO2) metasurface is proposed, achieving within a single compact device the functional decoupling of a persistent radiative thermal safety channel and ultrabroadband adaptive emissivity modulation. In the mid-wave infrared (MWIR, 3-5 & micro;m) band, a stable emissivity is maintained in both the low-temperature (313 K) and high-temperature (353 K) states. Such stability is insensitive to the VO2 phase transition and thereby establishes a persistent radiative thermal safety channel. Meanwhile, ultrabroadband emissivity modulation is realized in the 7.50-17.36 & micro;m range by exploiting the insulator-to-metal phase transition of VO2, which covers and extends beyond the long-wave infrared (LWIR, 8-14 & micro;m) atmospheric window. The high-temperature emissivity reaches as high as 0.97, yielding a modulation depth of 0.76. The physical mechanisms of the dual-band emission performance are further explained through the analysis of the electromagnetic field distributions and power loss density. Specifically, the thermal safety channel is jointly governed by the Fabry-P & eacute;rot (FP) cavity resonance and the localized surface plasmon resonance (LSPR) of the Ti patch, whereas the ultrabroadband high emission originates from the localized magnetic dipole (MP) resonance excited by antiparallel current loops. Furthermore, the independent regulation roles of each structural component on the dual-band emission performance are clarified through a component-wise contribution analysis. In addition, parametric sweeps of the structural geometry systematically illustrate the tuning rules of each geometric parameter on the emission characteristics of both bands. Moreover, the proposed device exhibits polarization-independent behavior and robustness against wide-angle incidence. The designed emitter holds promising potential in spacecraft thermal management, high-power electronics, and adaptive thermal management.
We developed a photo-magnetically actuated soft propeller robot with variable-pitch capabilities specifically for microfluidic manipulation. The device is constructed from a PNIPAM/MWCNT composite hydrogel integrated with magnetic components. Its ternary structure successfully decouples magnetic rotational drive from photo-thermal pitch adjustments. Material optimization using 20% to 30% ethanol volume, 0.3 mm thickness, and a balanced crosslinker ratio ensured robust mechanical strength and thermo-responsive swelling. Leveraging rapid photothermal conversion, the hydrogel achieved a 90 degrees bend in 1.35 s, and up to 140 degrees of directional deformation when constrained by a pre-dehydrated rigid layer. Hydrodynamic evaluations showed that a three-bladed design surpassed a two-bladed alternative in both ascending efficiency and fluid flow stability. The robot achieved complete microfluidic mixing in just 23 s, outperforming conventional single-mode hydrogel propellers by 1.2 to 2.0 times. Ultimately, this comprehensive study provides a robust theoretical and experimental framework for successfully deploying photo-magnetically coupled soft robots in complex microenvironments.
This study presents a simple and energy efficient approach for varying Co3O4 incorporated PVA porous magnetic nanofibers for targeted drug delivery. Low temperature calcination in air environment was performed to obtain cobalt oxide. X-ray photoelectron studies (XPS) confirm the presence of mixed valence state (Co2+ and Co3+). XRay diffraction studies (XRD) reveal the crystalline nature of Co3O4 in PVA. Fourier transform infra-red (FTIR) Spectroscopy also confirm the mixed valence state of cobalt oxide. A red shift was observed in UV-visible and the band gap varies from 1.80 eV to 1.40 eV. Smooth, uniform and interconnected fibers are revealed in Scanning electron microscope (SEM) images. The Vibrating sample magnetometer (VSM) studies confirm the ferromagnetic nature after post calcination treatment. Differential scanning calorimetric studies (DSC) confirm the thermal stability. Electrical studies confirm the reduction in resistive nature with higher loading and contact angle proves the hydrophilicity of Co3O4 in prepared composite fibers.
Amorphous SnOx ultrathin films exhibit absorption edges governed by distributed transitions involving localized tail states and near-mobility-edge extended states, so a single band-gap value cannot adequately describe their near-edge optical behavior. Here, we present a unified transmission-based, curvature-linked framework that directly compares Tauc, absorption spectrum fitting (ASF), derivative ASF (DASF), and Urbach analyses for as-deposited and annealed films in the high-transmittance regime. Treating each formalism as a probe of a distinct near-edge sector yields internally consistent multi-threshold markers of the amorphous density of states. Upon annealing, Tauc-and ASF-derived thresholds shift to lower energies, whereas the DASF curvature-defined threshold remains essentially unchanged, indicating band-edge sharpening without displacement of the intrinsic edge. Because conventional Urbach extraction becomes unreliable as transmittance approaches unity, four transmittance-based reconstructions were tested. A pre-edge-normalized exponential reconstruction yielded stable Urbach energies of 0.294 and 0.151 eV, while BTSC and BECI confirmed tail compaction and sharpening.
