Science and Technology of Advanced Materials最新文献

For developing high-performance composite-type thermal diodes, this study focuses on silver chalcogenides, which undergo structural phase transitions in the temperature range of 350 K to 473 K, accompanied by a significant stepwise change in thermal conductivity. Ag_2 + x Te_0.9S_0.1 (x = 0, 0.01, 0.02, 0.025, 0.03, 0.035, 0.04, and 0.05) and Ag₂S_{1 - y} Se _y (y = 0.35, 0.375, 0.4, 0.425, and 0.45) samples were synthesized with precisely controlled compositions, and their temperature-dependent thermal conductivity across the phase transition was studied with the composition dependence. Ag₂Te_0.9S_0.1 exhibits a stepwise decrease in thermal conductivity with transitioning from the low-temperature phase (LTP) to the high-temperature phase (HTP), and this behavior was further enhanced by adding excess Ag. The added silver precipitated in the LTP and dissolved into the HTP of Ag₂Te_0.9S_0.1, resulting in a maximum thermal conductivity change (κ _LTP / κ _HTP) of 2.7-fold with the phase transition at x = 0.025. On the other hand, the Ag₂S_{1 - y} Se _y samples exhibited a stepwise increase in thermal conductivity with transitioning from the LTP to the HTP, and the maximum thermal conductivity change of κ _HTP / κ _LTP = 5 was observed at y = 0.4. A composite thermal diode was fabricated using Ag_2.025Te_0.9S_0.1 and Ag₂S_0.6Se_0.4 with the length ratio of Ag_2.025Te_0.9S_0.1: Ag₂S_0.6Se_0.4 = 47:53 and, consequently, exhibited TRR = 3.3 when it was placed between heat reservoirs maintained at T _H = 412 K and T _L = 300 K. This TRR value is the largest ever reported for all-solid-state composite thermal diodes.

The pursuit of sustainable thermoelectric materials requires the development of cost-effective and efficient compounds derived from earth-abundant elements. Here, we investigate the effects of samarium (Sm) substitution on the thermoelectric performance of SrSi₂ with compositions Sr_1-x Sm _x Si₂ (x = 0, 0.05, 0.1, 0.15, and 0.2). Substituting Sm for Sr in SrSi₂ enhances the power factor at low substitution levels, while further substitution leads to a decrease, due to increased carrier scattering and reduced Seebeck coefficient. Introducing Sm substitution enhances phonon scattering through point defects, reducing lattice thermal conductivity. A peak figure of merit (ZT) of ~0.23 at room temperature is achieved for Sr₀.₉₅Sm₀.₀₅Si₂, demonstrating a 35% improvement over undoped SrSi₂. The weighted mobility of ~285 cm²/V·s and the tailored thermal transport emphasize the role of Sm substitution in modulating both electronic and thermal properties. These findings establish Sr_1-x Sm _x Si₂ as a promising candidate for next-generation thermoelectric devices.

Checkpoint blockade immunotherapy emerges as a potential cure of cancer, but the monotherapy suffers from a low response rate in clinic. Photothermal therapy (PTT) that harvests light energy to ablate tumor is reported to activate tumor-specific immune response, meanwhile nitric oxide (NO) is considered to involve in immune regulation. Herein, we designed a multifunctional nanoplatform that enables photothermal-gas combination therapy by conjugating indocyanine green-thiol (ICG-SH) and s-nitrosoglutathione (GSNO) onto polyvinyl pyrrolidone (PVP)-coated gold nanoparticles (AIG). Upon near-infrared light (NIR) irradiation, AIG heats up the cancer cells and triggers NO release from GSNO, thus inducing apoptosis in the tumor. We found the combination of NO with photothermal treatment causes immunogenic cell death, which should synergize with checkpoint blockade immunotherapy. In the mouse colon cancer bilateral model, we observed complete eradication of light-irradiated tumors and suppression of distant untreated tumors in the AIG with anti-PD-1 (αPD-1) group. We detected significant increase of pro-inflammatory factors in serum, such as interferon- (IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) after PTT-gas-immunotherapy treatment, indicating the successful activation of the immune response. The improved immunogenicity caused by AIG with αPD-1 group allows for efficient antigen presentation, as evidenced by the increased infiltration of dendritic cells (DCs) into the tumor-draining lymph nodes (LNs). We also found promoted infiltration of CD8⁺ T cells in the untreated tumors in the AIG with αPD-1 group comparing to αPD-1 alone. Therefore, phototermal-gas-immune checkpoint blockade combination therapy represents a new promising treatment of metastatic cancer.

In this study, we propose an accurate, simple, and versatile measurement method for power generation efficiency and device figure of merit ZT of thermoelectric devices. Toward the energy harvesting applications of thermoelectric generators, the performance characterization under low heat inflow and temperature difference is crucial. However, when the conventional solid-state heat flow meter is used, the uncertainty of power generation performance increases as heat input decreases. We have solved these problems by using a laser for heat input, improving the simplicity and accuracy of power generation efficiency measurements, especially at low heat flow. The direct and non-contact measurement of the temperature difference by using a thermography allowed us to determine ZT as well as power generation efficiency. The obtained mean power generation efficiency and ZT values are consistent with the values obtained by the conventional method within the error range, thereby validating the reliability of the proposed method. The relative uncertainties of the efficiency and ZT were estimated to be less than 3% and 12% for our method, respectively, whereas those were 19% and 24% in situations where the temperature difference was less than 6 K for the conventional method.

Emergent ferromagnetism on the surface of two-dimensional (2D) MXene is investigated by X-ray magnetic circular dichroism (XMCD) and angle-dependent hard X-ray photoemission spectroscopy (HAXPES). Focusing on Cr₂N as one of the 2D-MXenes, high quality bilayers of Cr₂N/Co and Cr₂N/Pt are prepared by a magnetron sputtering technique. XMCD reveals the induced magnetic moment of Cr in the Cr₂N/Co interface, while it is not observed in the Cr₂N/Pt interface at room temperature. In order to distinguish the possible origins of either the interlayer magnetic exchange coupling or the charge transfer model as the source of ferromagnetism at the interface, the additional controlled Cr₂N/Cu bilayer, whose work function of Cu is consistent with Co, is prepared. HAXPES spectra for the Cr 2p core level near the interface of Cr₂N/Cu are consistent with that of Cr₂N/Co, indicating that the induced magnetic moment of Cr observed by XMCD for Cr₂N/Co can be attributed to the model of interlayer magnetic exchange coupling, rather than the charge transfer model, leading to emergent ferromagnetism at the interface with 2D-MXene.

The spontaneous Hall effect (SHE), a finite voltage occurring transversal to the electrical current in zero-magnetic field, has been observed in both conventional and unconventional superconductors, appearing as a peak near the superconducting transition temperature. The origin of SHE is strongly debated, with proposed explanations ranging from intrinsic and extrinsic mechanisms such as spontaneous symmetry breaking and time-reversal symmetry breaking (BTRS), Abrikosov vortex motion, or extrinsic factors like material inhomogeneities, such as non-uniform critical temperature (T_c) distributions or structural asymmetries. This work is an experimental study of the SHE in various superconducting materials. We focused on conventional, low-T_c, sharp transition Nb and unconventional, intermediate-Tc, smeared transition Fe(Se,Te). Our findings show distinct SHE peaks around the superconducting transition, with variations in height, sign and shape, indicating a possible common mechanism independent of the specific material. We propose that spatial inhomogeneities in the critical temperature, caused by local chemical composition variations, disorder, or other forms of electronic spatial inhomogeneities could explain the appearance of the SHE. This hypothesis is supported by comprehensive finite elements simulations of randomly distributed Tc's by varying T_c-distribution, spatial scale of disorder and amplitude of the superconducting transition. The comparison between experimental results and simulations suggests a unified origin for the SHE in different superconductors, whereas different phenomenology can be explained in terms of amplitude of the transition temperature with respect to Tc-distribution.

Capacitive Deionization (CDI) has emerged as an energy-efficient and environmentally friendly technology for water desalination. This review provides a comprehensive analysis of CDI, covering both experimental and simulation approaches. It introduces the background, definition, and diverse applications of CDI, from water desalination to environmental monitoring and resource recovery. The review highlights CDI's advantages, such as low energy consumption and operational simplicity, as well as its limitations, particularly its design-specific operating window favoring low-to-moderate salinity waters and sensitivity to organic-rich conditions. Strategies such as hybrid CDI systems and electrode surface functionalization are discussed to mitigate these challenges. Key working principles and advancements, including innovations in electrode materials, synthesis methods, and reactor design, are examined to improve ion removal efficiency, selectivity, energy use, and system durability. Material modification strategies are presented in the context of structure - performance relationships, emphasizing rational design principles. The review also explores simulation methods, including reactor modeling, computational fluid dynamics, molecular dynamics, and numerical approaches, and machine learning highlighting their synergy with experiments in optimizing CDI performance and guiding scale-up. Coupling CDI with other systems and its applications in water purification, particularly for ion and organic compound removal are also discussed. Finally, challenges in both experimental and simulation efforts, such as material cost, model complexity, computational demands, and scalability, are discussed. While CDI shows promise for sustainable water desalination and resource recovery, further research on hybrid configurations, predictive modeling, and pilot-scale validation is needed to address its limitations and enable large-scale adoption.

We measured the residual stress tensor in a nitrogen-doped chemical vapor deposition (001) diamond film. The stress tensor was evaluated from the amount of the shift in optically detected magnetic resonance (ODMR) spectra of NV center in the diamond. A confocal microscopy setup was used to observe the spatial variation of the stress tensor in the diamond film. We found that the components of the stress tensor, σ_xy, σ_yz, σ_zx and σ_xx+ σ_yy+ σ_zz, of the residual stress were approximately 0.077, -0.39, -0.67 and 1.52 GPa, respectively, in the x = [100], y = [010], z = [001] coordinate system. Regarding the components of the shear stress, σ_xy, σ_yz and σ_zx, the nitrogen-doped CVD diamond film grown in this study had mainly sheared stress in the z-direction, which was the growth direction of the CVD diamond film. In addition, regarding axial stress σ_xx+ σ_yy+ σ_zz, the CVD diamond film was subjected to compressive stress. Due to this compressive stress, the volume of the CVD diamond film decreased by approximately 0.073%. We considered that nitrogen doping contributed to the decrease in volume of the CVD diamond film.

The magnetocaloric effect (MCE) provides a promising foundation for the development of solid-state refrigeration technologies that could replace conventional gas compression-based cooling systems. Current research efforts primarily focus on identifying cost-effective magnetic materials that exhibit large MCEs under low magnetic fields across broad temperature ranges, thereby enhancing cooling efficiency. However, practical implementation of magnetic refrigeration requires more than bulk materials; real-world devices demand efficient thermal management and compact, scalable architectures, often achieved through laminate designs or miniaturized geometries. Magnetocaloric materials with reduced dimensionality, such as ribbons, thin films, microwires, and nanostructures, offer distinct advantages, including improved heat exchange, mechanical flexibility, and integration potential. Despite these benefits, a comprehensive understanding of how size, geometry, interfacial effects, strain, and surface phenomena influence the MCE remains limited. This review aims to address these knowledge gaps and provide guidance for the rational design and engineering of magnetocaloric materials tailored for high-performance, energy-efficient magnetic refrigeration systems.

Heat flux sensors based on the anomalous Nernst effect (ANE) have emerged as a promising solution for achieving thin and flexible designs. ANE-based heat flux sensors typically employ thermopile structures composed of two ANE materials with opposite signs, connected in series to enhance sensing performance. However, a mismatch in the Seebeck coefficient between the two ANE materials causes a considerable offset voltage due to the Seebeck effect (SE) under oblique heat flux. This parasitic sensing voltage hinders direct sensing of heat flux in the intended direction. In this study, a sign-reversed ANE with matched Seebeck coefficient is examined in Fe₃Ln (Ln = Gd, Tb, Dy, Ho, and Er), enabling a thermopile structure free from the SE-induced offset voltage. Based on density functional theory calculations, Fe₃Ln is selected as a suitable candidate for exhibiting sign reversal of ANE while maintaining the Seebeck coefficient. At 300 K, Fe₃Ln (Ln = Gd, Tb, Dy, and Ho) exhibits a positive ANE sign, whereas Fe₃Er exhibits a negative ANE sign, facilitating the combination of two sign-reversed ANE materials. Among these, Fe₃Ho and Fe₃Er demonstrate the lowest Seebeck coefficient difference of 0.45 μV K^-1, minimizing the offset voltage-induced relative uncertainty, as confirmed by COMSOL simulations - comparable to that of other SE-based heat flux sensors. This study paves the way for the development of ANE-based heat flux sensors by introducing a novel approach to pairing opposite-ANE-sign materials with matched Seebeck coefficient, enabling direct and accurate heat flux sensing via thermopile structures.