Materials Today Physics最新文献

Designing new, technologically relevant superconductors has long been at the forefront of solid-state physics and chemistry research. However, developing efficient approaches for modeling the thermodynamics of superconducting alloys while accurately evaluating their physical properties has proven to be a very challenging task. To fill this gap, we propose an ab initio thermodynamic statistical method, the Extended Generalized Quasichemical Approximation (EGQCA), to describe off-stoichiometric superconductors. Within EGQCA, one can predict any computationally accessible property of the alloy, such as the critical temperature in superconductors and the electron-phonon coupling parameter, as a function of composition and crystal growth conditions using a few small supercells. Importantly, EGQCA incorporates directly chemical ordering, lattice distortions, and vibrational contributions. As a proof of concept, we applied EGQCA to the well-known Al-doped MgBb₂ and to niobium alloyed with titanium and vanadium, showing a remarkable agreement with the experimental data. Additionally, we modeled the near-room temperature sodalite-like Y_1−xCa_xH₆ superconducting solid solution, demonstrating that EGQCA particularly possesses a promising potential for designing in silico high-T_c superhydride alloys. Our approach enables the high-throughput screening of complex superconducting solid solutions, providing valuable insights into these systems' synthesis, thermodynamics, and physical properties.

Ferromagnetic side layers sandwiching a nonmagnetic spacer as a metallic trilayer has become a pivotal platform for achieving spintronic devices. Recent experiments demonstrate that manipulating the width or the nature of conducting spacer induces noncollinear magnetic alignment between the side layers. Our theoretical analysis reveals that altering the width of spacer significantly affects the interlayer exchange coupling (IEC), resulting in noncollinear alignment. Through analytic and first-principles methods, our study on the Fe/Ag/Fe trilayer shows that at a specific width of the Ag spacer, the magnetic moments of side layers tend to be perpendicular. This alignment is mediated by Ag quantum well states, exhibiting spin spirals across the trilayer. Our results reveal that the noncollinear IEC offers a degree of freedom to control magnetic devices and boot spintronic technology with improved transport capabilities.

With the increasing development of advanced technologies and new materials, recent trends in laser processing-assisted two-dimensional (2D) functional materials have gained significant interest. The ability to precisely control the features of these 2D materials through laser processing has expanded their potential applications in various fields. This review presents a comprehensive summary of recent trends in and potential applications of laser-assisted processing of 2D functional materials. General concepts of working principles, key parameters (i.e., laser wavelength, pulse duration, and repetition rate), and technical approaches (i.e., direct laser writing, doping, thinning, and creating defects) of laser processing are first introduced and discussed carefully. Laser processing-assisted 2D functional materials are then extensively discussed and listed. Finally, some specific applications (i.e., sensing devices, semiconductors, supercapacitors, and batteries, etc.) of laser processing-assisted 2D functional materials are presented. This review provides insights into laser processing-assisted 2D functional materials, offering guidance to researchers and industries on selecting the most suitable advanced technologies and potential 2D materials. This review also offers viewpoints and outlooks for future research directions and potential innovations that will markedly contribute to advances in laser processing-assisted 2D functional materials.

In the pursuit of developing fast and reliable gas sensors, a new ternary oxide semiconductor, a bismuth oxyiodide (BiOI)-based sensing material, has been reported with desirable adsorption energy, short recovery time, and high sensitivity and selectivity for detecting nitrogen oxide mixtures (NO_x, typically NO and NO₂). The structural, electronic, and transport properties of both (001) and (012) planes of BiOI surfaces upon the adsorption of six environmentally relevant gases (NO, NO₂, SO₂, SO₃, O₂, and H₂O) are systematically explored using a combination of density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods. The results indicate that BiOI (001) exhibits weak interaction with these gases, with the highest adsorption energy observed for NO. In contrast, the BiOI (012) surface shows enhanced adsorption stability for these gases, particularly acceptable strong adsorption to NO₂, indicating its promising capability for detecting these gases with high specificity. Moreover, it demonstrates the most intense chemisorption for SO₃, suggesting it to be a reliable SO₃ adsorbent/cleaner. The obtained transport characteristics, including current-voltage (I-V) and resistance-voltage (R-V) curves, further highlight the higher selectivity of the BiOI (001) device towards NO and the BiOI (012) device towards NO₂ against the other gases. Furthermore, the transmission spectra analyses reveal that the BiOI-based sensor can electrically discriminate the target gas molecules from other considered gas molecules. Besides, the practical application possibilities of both orientations are explored by estimating their recovery time, and the results show that the BiOI sensor has excellent recovery times at room temperature (NO/BiOI (001) = 0.158 ns, and NO₂/BiOI (012) = 3.89 s), highlighting its potential as an ideal reversible gas-sensing material for detecting NO_x gases.

In this study, we employ density functional theory (DFT) and subgroup discovery (SGD) to explore the structural and magnetic properties of full cubic Heusler compounds, with a particular emphasis on their Curie temperatures (T_c) and magnetic stability. Our comprehensive examination of 2903 structures across both L2₁ and Xa phases identifies configurations that exhibit both structural stability and superior magnetic properties. Notable among these, compounds such as Co₂MnSi, Co₂CrGe, and Cr₂VGe exhibit remarkable magnetic stability, maintaining their ferromagnetic properties well above room temperature. Co₂MnSi displays a substantial magnetic moment of 5.00 μB and maintains its ferromagnetic properties up to a Curie temperature of 937 K, underscoring its suitability for high-temperature applications. Similarly, Co₂CrGe, with a magnetic moment of 4.00 μB, transitions to a paramagnetic state at a higher temperature of 952 K, demonstrating enhanced thermal durability. Moreover, Cr₂VGe, notable for its robust magnetic moment of 2.81 μB, retains its ferromagnetic characteristics until an exceptional 2412 K, making it extremely valuable for thermally intensive environments. These findings underscore the potential of these materials in developing durable and efficient spintronic devices that operate under extreme thermal conditions. By mapping the interplay between electronic structure and magnetic properties, our study provides a predictive framework for optimizing the performance of spintronic materials.

Studies on altermagnetic materials are attracting extensive research efforts owing to their directional dependent spin split band structure. However, it is rare to find reports on the possibility of multifunctionality in altermagnetic systems. Here, we explore the spin dependent transport properties and piezoelectricity of two-dimensional V₂SeTeO altermagnet. The V₂SeTeO system has a direct band gap of 0.32 eV with a Neel temperature of 510 K. We find a giant effective Seebeck coefficient of 0.64 mV/K at 300 K. This is several times larger than that found in bulk and other two-dimensional materials. Moreover, the effective Seebeck effect is entirely determined by either only spin-up or spin-down component. This feature implies that we can generate highly spin polarized current by temperature gradient at room temperature. We attribute this pure spin current generation to the directional dependent spin split band structure. Along with the spin dependent transport properties, we also find that the Janus V₂SeTeO altermagnet shows outstanding flexibility and piezoelectric response with out-of-plane piezoelectric coefficient of $d_{31}=0.245\text{pm}/V\text{.}$ Overall, we propose that the V₂SeTeO altermagnet system exhibits multifunctional physical properties at room temperature, and this can be utilized for potential spintronics and flexible piezoelectric applications simultaneously.

Near-infrared (NIR) phosphor-converted light emitting diodes (NIR pc-LEDs) hold great promise for applications in night vision imaging, nondestructive analysis, and plant growth. Although some NIR phosphors have been developed in recent years, there are fewer studies on Cr³⁺-doped multisite luminescent phosphors. Here, we report a novel LiGaAl₄O₈:xCr³⁺ (LGAO:Cr³⁺) phosphors with double Cr³⁺ luminescence centers. At low doping concentration, LGAO:Cr³⁺ is dominated by the emission of Cr1. With the increase of doping concentration x, the Cr2 portion of emission intensity increases due to the increased probability of the energy transfer from Cr1 to Cr2. Finally, using the LGAO:0.02Cr³⁺ NIR phosphor and a commercial 410 nm chip, a NIR pc-LED prototype with a NIR output power of 43.7 mW at 100 mA drive current and a photovoltaic conversion efficiency of 19.2 % at 10 mA was fabricated and its application in visual inspection of precise devices and angiography was demonstrated. This work provides an in-depth and careful study of the luminescent mechanism of the dual-centerd NIR phosphor and serves as a good paradigm for the development of NIR pc-LEDs.

The intact heart undergoes complex and multiscale mechanical remodeling processes. Measuring rhythmic spatial contraction of the myocardium is crucial for assessing mechanical durability and the ability to mount coordinated responses to pressure, electrical, and hemodynamic signals. However, current cardiomyocyte measurement platforms typically focus on action potentials and XY-plane contractions. Therefore, effective evaluation methods for studying the influence of mechanical cues on the spatial dynamic contraction of cardiomyocytes are still lacking. In this study, we developed a topographic guiding combined with an optical spatial motion tracking method to provide controllable mechanical stimulation for inducing directed contraction of cardiomyocytes and obtaining spatial motion information in vitro. We first performed a detailed investigation of cell connections and cytoskeleton orientations by combining the proposed method with immunofluorescence. Next, spatial constrictive modes, features, and key parameters of microgroove-guided cardiomyocytes were studied. Finally, the three-dimensional (3D) motions of the cardiomyocytes at different positions on the structure were compared. We found that the XY-plane contraction of cardiomyocytes typically has only one direction and shows a significant phase delay compared to the axial motion. In addition, cardiomyocytes located near the edges of the microgrooves were restricted by stronger mechanical forces, resulting in a significant height change reduction. These results provide new perspectives for structural and functional research on cardiomyocytes under long-term mechanical regulation. Overall, this study provides a highly precise and convenient method for evaluating the 3D cardiomyocyte motion under mechanical induction. This method is expected to enhance understanding of cardiomyocyte development and be useful for research on cardiac mechanics and functions.

Dielectric capacitors with high recoverable energy storage density (W_rec) are in urgent demand for clean energy technologies. However, their lower breakdown strength (E_b) strongly limits their energy storage performance. We, herein, propose a facile method to enhance E_b by enhancing mechanical strength via second phase modulation. The efficiency of this method is validated in the (1-x)(0.94Na_0.5Bi_0.5TiO₃-0.06BaTiO₃)-xSr(Ta_0.5Sb_0.5)O₃ ((BNT-BT)-xSTS, x = 0.1, 0.15, 0.2, 0.25, and 0.3) ceramics. The introduction of Sr(Ta_0.5Sb_0.5)O₃ (STS) increases the relaxor degree, refines grain size, and most importantly, creates a second phase of BiSb₂O₇, which hinders dislocation movement and improves mechanical strength. Our results show that the breakdown strength strongly depends on the mechanical strength. The highest hardness of 7.42 GPa accompanied by the largest E_b of 620 kV/cm was obtained in (BNT-BT)-0.25STS sample. The sample exhibits the best energy storage properties of a large W_rec = 8.3 J/cm³, a high efficiency of 82.3 %, and excellent temperature/frequency stability. Furthermore, the sample also exhibits good charge/discharge stability and ultra-fast transient discharge time (62.26 ns). This work provides a theoretical guidance for developing lead-free dielectrics with superior energy-storage performance.

Flexible Organic solar cells (OSCs) have garnered widespread attention due to the increased popularity of wearable electronic devices. To enhance the efficiency and stability of the device we have prepared (2E,2′E)-3,3'-(4,4,9,9-tetrahexadecyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b'] dithiophene-2,7-diyl)bis(2-cyanoacrylic acid) (IDT) based dopant by reacting the aldehyde precursor with cyanoacetic acid in the presence of piperdine. Here, we investigate the effect of IDT on the performance of OSCs by adding IDT to star active layers PM6:Y6 and PM6:BTP-eC9 to improve OSCs' performance through morphology optimization. The addition of 5 wt% IDT significantly improved the device performance, achieving a remarkable PCE of 16.08 % for PM6:Y6 devices. The charge transport and recombination dynamics analysis showed that the appropriate concentration of IDT can provide better channels for carrier transport, promoting effective charge generation and extraction in OSCs. It is observed that the addition of IDT promotes effective generation and dissociation of excitons, thus improving OSC performance. The flexible ITO-free OSC was fabricated using PM6:Y6:IDT as the active layer film, achieving a high PCE of 12.59 % with V_OC, J_SC, and FF of 0.83 V, 23.21 mA/cm² and 68.63 %, respectively. Hence, the findings indicate a reliable approach which could potentially deliver rigid and flexible OSCs with excellent performance and commercial viability.