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A series of Ce4+-doped Pr 2 Zr 2 O 7 ceramics were produced using a solid reaction method to utilize novel ceramic materials as potential candidates for thermally protective coatings. The effects of Ce4+ doping on the phase composition and mechanical, infrared radiative, and thermophysical properties were studied in detail. The results indicated the good phase stability and sintering resistance of the Pr 2 (Zr 1−x Ce x) 2 O 7 ceramics. Moreover, Ce4+-doped Pr 2 Zr 2 O 7 bulk materials exhibited higher infrared emissivity (0.904) at wavelengths of 3–5 μm and 1000 °C for Pr 2 (Zr 0.5 Ce 0.5) 2 O 7) owing to the introduction of impurity energy levels. Pr 2 (Zr 0.7 Ce 0.3) 2 O 7 exhibited an appropriate average coefficient of thermal expansion of 12.4 × 10−6 K−1 and a low thermal conductivity of 1.14 W m−1 K−1 at 1000 °C, owing to the reduction of lattice energy and the presence of more oxygen vacancies and substitution atoms. [ABSTRACT FROM AUTHOR]

High temperature material with low infrared emissivity in 3–5 μm waveband plays a crucial role in the infrared stealth capability of hot-end aircraft components. In this study, 3 mol% Ce doped ZnO ceramic powders were annealed at various temperatures to reduce their infrared emissivity. The effects of the annealing temperature on the lattice structure, microscopic morphology, and elemental valence variation in the ZnO ceramic powders were systematically investigated. Additionally, a conductivity–dielectric–lattice vibration synergy theory was proposed to provide insights about the changes in the infrared emissivity of the ZnO ceramic powders. The infrared emissivity of the sample powder gradually decreased to its lowest value (0.092 at 500 °C) as the annealing temperature increased to 1100 °C, exhibiting a U-shaped curve from room temperature to 800 °C. Furthermore, the obtained powder was used as a filler to prepare a low infrared emissivity coating, which exhibited an infrared emissivity of 0.213 in 3–5 μm waveband at 500 °C. An infrared thermographic analysis of the coating indicated that it significantly suppressed infrared radiation at 500 °C, demonstrating an excellent high temperature infrared stealth performance. [ABSTRACT FROM AUTHOR]

High infrared radiation materials have crucial applications in energy saving, heat conversion, and heat dissipation. SrZrO 3 (SZO) is a potential material for high infrared radiation, however, its infrared emissivity still needs to be improved. To address this, in this study, Sr(Zr 0.9375 Cu 0.0625)O 3-δ (SZCO) perovskite ceramic with high infrared emissivity was prepared, and the impact of Cu ion doping on the electronic structure, infrared radiation characteristics, and thermal conductivity of SrZrO 3 were explored. The findings reveal that SZO doped with Cu ions markedly decreases its band gap width from 5.658 eV to 1.467 eV. The infrared emissivity of the SZCO ceramic, sintered at 1200 °C, increases by 28 % in the 3–5 μm band compared to SZO at room temperature. This emissivity positively correlates with temperature, reaching up to 0.95 at 600 °C. The emissivities of SZCO are greater than that of SZO in the 8–14 μm and 1–22 μm band ranges over the test temperature range from room temperature to 600 °C, and both increase with increasing temperature, reaching 0.978 and 0.946 at 600 °C, respectively. Furthermore, the SZCO ceramic demonstrates thermal conductivities ranging from 1.90 to 3.2 W m−1 K−1 below 1400 °C. These results highlight the potential of Sr(Zr 0.9375 Cu 0.0625)O 3-δ ceramic as a high infrared radiation material. [ABSTRACT FROM AUTHOR]

The Co-doped α-MoO 3 with thermochromism and variable infrared emissivity were prepared. The defects in the crystal structures and the regulatory mechanism of local defects on band gap width and conductivity were further investigated. The Co-doped α-MoO 3 samples from different heating atmosphere were designed to study the influences of oxygen vacancy on thermochromism and infrared emissivity. Concentration of oxygen vacancy determines optical absorption/reflectivity and conductivity. Results show that the Co-doped α-MoO 3 sample prepared by thermal treatment at 500 °C in argon atmosphere owns appropriate oxygen vacancy, reflectivity and conductivity, rich colorful change and strong infrared radiation regulation. Color can reversibly change from purple to yellow-green, and the effective infrared emissivity is regulated to 0.242 at 3–5 μm. It indicates a new strategy to enhance high temperature thermochromism and variable infrared emissivity by ion doping. • The thermochromic and infrared emissivity of Co-doped α-MoO 3 were changed by the atmosphere and temperature control structure and the band gap. • The changed oxygen vacancy in the interlayer octahedron is the main reason for the varied band gap and conductivity at different temperature. • Co-doped α-MoO 3 thermal treated in argon atmosphere has reversible thermochromic infrared emissivity with Δ ε of 0.242 and color ranging from purple to yellow-green. [ABSTRACT FROM AUTHOR]

How to maximize the extraction of heat by infrared radiation while reducing the thermal conductivity to prevent heat transfer is the main challenge of radiative thermal management for emerging industrial and aerospace applications. Herein, we reported a high-temperature broadband high emissivity (Y 0.5 Lu 0.5) 2 SiO 5 ceramic with emissivity above 0.9 at room temperature and above 0.61 at elevated temperature of 1200℃ across the entire range of wavelength (1–14μm). Lu-doped rare earth monosilicate with high lattice entropy has a more complex electronic structure, boosting the emissivity of near-infrared wavelength (1–3 μm), as well as enhanced emissivity in the MIR range (3–14 μm) is derived from the lattice distortion and extra multi-mode vibrations induced by the substitutional doping of Lu3+ into the host lattice. Moreover, based on Stephen-Boltzmann law and energy conservation law found that the emissivity of rare earth monosilicate-based ceramics is negatively correlated with temperature, which may be due to the fact that rising temperature increases damping of phonon vibration of the ceramic lattice, reducing the ability of infrared absorption. This doped rare earth monosilicate ceramic has a high emissivity at high temperatures above 1200 °C, revealing immense potential in the radiation thermal protection field. [ABSTRACT FROM AUTHOR]

In this paper, cordierite ceramics with high far-infrared emission properties are synthesized by a high-temperature solid-phase method using molybdenum tailings and vanadium-titanium magnetite tailings. The microstructure, physical properties and far-infrared emission mechanism of ceramics are investigated. The results show that the ceramics synthesized with 10 wt% molybdenum tailings and 30 wt% vanadium-titanium magnetite tailings have a flexural strength of 67 MPa, a bulk density of 2.531 g/cm3 and a maximum far-infrared emissivity of 0.958 when the sintering temperature is 1200 °C. The crystal phase of the ceramic are 21.4 % cordierite and 58.7 % magnesia-alumina spinel. In the sintering process, the Fe3+ in vanadium-titanium magnetite tailings doped into the cordierite to substitute the Mg2+, which has the similar ionic radius with Fe3+, to form a substitutional solute. Ionic substitution causes the lattice parameters of cordierite larger, reducing the symmetry of the lattice vibrations and leading to lattice distortion. In addition, the composition of a large amount of magnesia-aluminum spinel is attributed to the far-infrared emission properties of ceramics. [ABSTRACT FROM AUTHOR]

Metal fiber surface combustion, with potential advantages of low NOx emission and flashback prevention, is a promising technology to burn hydrogen-enriched methane that is regarded as a low-carbon fuel when seeking the carbon-peaking and carbon neutrality target. In this piece of work, we studied two combustion modes, namely the infrared radiation mode (flame submerging in the metal fibers and the radiation of hot metal fiber dominating the heat transfer) and the blue flame mode (flame roots attached to the metal fibers forming visible blueish flame), of premixed hydrogen-enriched methane/air mixtures on two different metal fiber surface burners in terms of their blowout limit, high-temperature corrosion of the metal fibers, and pollutant emissions. The morphology of the premixed flames on the metal fiber surface burners was found to be essentially a group of tiny premixed jet flames. Higher excess air ratio under the fuel-lean condition, lower hydrogen volumetric fraction in the fuel, and lower porosity of the metal fiber favored the blue flame mode, accompanied by the decreased NOx and increased CO. The detailed characterization of the metal fibers confirmed that the infrared radiation mode may be accompanied by the high-temperature corrosion of the metal fibers. To obtain the optimized operation conditions for hydrogen-enriched methane flames on metal fiber surface burners, we proposed and experimentally verified a dimensionless semi-empirical criterion K * for high-temperature corrosion and flame blowout by considering the ratio of overall flow velocity to laminar flame speed, the ratio of characteristic jet diameter to laminar flame thickness, the porosity of the metal fiber, as well as the preferential diffusion effect induced by hydrogen. The results showed that there existed a high-temperature corrosion risk when K * <1.4, and a flame blowout risk when K * >4. Combining the criterion and NOx emission characteristics, combustion mode phase diagrams were also demonstrated as well as the optimized operation conditions. • The metal fiber burner with two different fiber porosities was adopted. • Two combustion modes on metal fibers were experimentally analyzed. • The morphological and elemental analyses were conducted to confirm the corrosion. • The stability and emissions of hydrogen-enriched methane/air flames were studied. • A criterion was proposed to quantitatively evaluate the risks of instability and corrosion. [ABSTRACT FROM AUTHOR]

Broadband absorber materials with high solar absorptivity and infrared emissivity are conducive to high-efficient and cost-effective heating technology in the civil and industrial field. The BaTi 1- x Co x O 3 ceramics are prepared by sol-gel method, showing mixed tetragonal/hexagonal phases. Co doping slightly reduces the phase transition temperature of BaTiO 3. Meanwhile, BaTi 1- x Co x O 3 ceramics present a composite Mott/charge transform band nature and the Co-3d impurity level and oxygen vacancies level lead to a narrowed bandgap. The enhancement of the absorption induced by free carriers, impurity level and lattice vibration promote the UV-Vis-NIR absorption and mid-infrared radiation of BaTi 1- x Co x O 3 ceramics. In conclusion, the optimized BaTi 0.95 Co 0.05 O 3 ceramic achieves a high solar absorptivity (0.88) in 0.25–2.5 µm and a high infrared emissivity (0.83) in 8–14 µm. The radiative performance presents good temperature stability, unaffected by phase structure and lattice thermal expansion, which provides prospective applications in solar energy conversion and infrared radiation heating. [ABSTRACT FROM AUTHOR]

Developing high-performance infrared radiation ceramic materials with desired broadband emissivity while reducing thermal conductivity to prevent heat transfer is highly desirable for emerging industrial and aerospace applications. Nevertheless, it remains a grand challenge to simultaneously meet these requirements in existing infrared radiation ceramic materials. Herein, a high-entropy strategy is employed to enhance the high-temperature infrared radiation property with a high emissivity above 0.9 at room temperature and 0.68 at 1200 °C across the entire range of wavelength (1–14 μm), and integrate a low thermal conductivity (<0.88 W m−1 K−1 at 1000 °C) and remarkable mechanical properties. High-entropy rare earth (RE) disilicates ((Y 0.4 Yb 0.4 Tm 0.1 Lu 0.05 Ho 0.05) 2 Si 2 O 7) ceramic coating with high lattice entropy has a more complex electronic structure, inducing lattice distortion and extra multi-mode vibrations, which boosts the emissivity in mid-infrared range (3–14 μm). Meanwhile, the high-entropy strategy prompts the formation of impurity energy levels as gap states, achieving optical absorption at low photon energies, and thus enhancing the emissivity in near-infrared range (1–3 μm). Simultaneously, (Y 0.4 Yb 0.4 Tm 0.1 Lu 0.05 Ho 0.05) 2 Si 2 O 7) ceramic coating owns diffusion-mediated thermal transport properties with strong phonon scattering, assisted further by the lamellar porous structure, thereby enabling a low thermal conductivity. The excellent mechanical properties ensure the reliability of the coating in extreme environments. All these merits render the high-entropy ceramic coating competitive for the development of high-temperature broadband high-emissivity thermal radiation materials. [ABSTRACT FROM AUTHOR]

Aerogel composites reinforced by fibers have found extensive applications in the field of thermal insulation and energy conservation. However, the composites are hindered by their high infrared radiation transmittance and weak interface adhesion in practical applications. Herein, we designed and prepared a novel thin composite called 'fiber/whisker/aerogel paper' (SWAP) with a thickness of less than 1 mm. The SWAP integrated SiC nanowhiskers (SiC nw) as opacifiers and ultrafine SiO 2 fibers as reinforcement, fabricated through wet manufacturing and sol-gel process. The 'fiber/aerogel paper' (SAP) and SWAP exhibited low thermal conductivity at room temperature, measuring 0.025 W/(m·K) and 0.033 W/(m·K), respectively. Additionally, they exhibited low densities of 0.195 g/cm3 and 0.225 g/cm3, respectively. Notably, SWAP exhibited excellent high-temperature insulation performance, primarily due to its low infrared transmittance (50% at 3 μm). The incorporation of SiC nw and ultrafine SiO 2 fibers collectively enhanced the interfacial adhesion with the aerogel matrix even amidst rigorous testing (weight loss less than 3%). SWAP also demonstrated flexibility, high thermal stability, hydrophobicity, and flame resistance. Furthermore, a comprehensive investigation into the performance variations and influencing g factors of the material was conducted under different heat treatment conditions. This research provides guidance for the application of such materials under high temperatures. [ABSTRACT FROM AUTHOR]

Developing highly reliable infrared radiation materials with broadband high emissivity at high temperatures, low thermal conductivity, and excellent thermal stability is highly desirable for aerospace thermal protection applications. However, it remains a huge challenge to take into account infrared radiation heat dissipation and blocking heat transfer through low thermal conduction simultaneously. In this work, we reported a broadband high emissivity Ca2+-doped YbCrO 3 ceramic with emissivity above 0.89 at room temperature across the entire range of wavelength (1–14 μm). This doping strategy leads to the introduction of impurity energy levels into the band gap of YbCrO 3 , which increases the possibility of light absorption to promote electron transition, improving the emissivity of the near-infrared band (1–3 μm). Simultaneously, un-equivalent doping induces electron exchange between chromate ceramic ions, which complicates the electronic structure (producing lattice distortion and extra multi-mode vibrations) and reduces the band gap width, thus boosting the emissivity in the mid-infrared band (3–14 μm). More importantly, (Yb 0.8 Ca 0.2)CrO 3 presents a high emissivity (0.76) at an elevated temperature of 1200 °C, together with low thermal conductivity (2.5 W m−1 K−1 at 1000 °C) due to strong phonon scattering. Moreover, the doping-dominating phase stabilization effect contributes to impressive thermal stability (stable at 1300 °C for 50 h) and a high coefficient of thermal expansion (9.0–9.5 × 10−6 K−1), which makes it suitable for long-term high-temperature thermal protection application. All these merits render the development of thermally stable high-temperature infrared radiation ceramic materials core competitive. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBCs) utilized for thermal insulation in gas turbines are typically semitransparent to infrared thermal radiations, resulting in a limited thermal insulation performance. In this study, plasma spraying TBCs with intra-splat spherical pores (SPs) are designed and prepared by the oxidation of micro carbon spheres particles. SPs with diameter of 0.5–1.5 µm remarkably improve the scattering coefficients (1.9 times vs conventional coating) and reduce the thermal conductivity of TBCs, leading to a temperature drop of 79.8 K at coating/substrate interface. The coatings with SPs in micrometers also exhibit excellent anti-sintering behavior. The average reflectance in 1.0–1.8 µm of coatings with SPs keep almost unchanged after heated at 1300 °C for 80 h. As SPs are wrapped by YSZ laminar splats, the embedded SPs shows neglectable decrease (<10%) in Young's modulus and hardness to the coating. [Display omitted] [ABSTRACT FROM AUTHOR]

SiC reticulated porous ceramics (SRPC) was the critical part of porous media burners. During the ignition and shutdown process of porous burner, SRPC have to subject the large thermal stress caused by sharp temperature gradients. Meanwhile, most of the heat exchange in the burner is achieved through the high-temperature radiation heat transfer of the medium material. The strength and infrared emissivity of SRPC directly determined their service life and heating efficiency. In this work, a multi-layer strut in SRPC was constructed to improve the strength and infrared radiation properties via vacuum infiltration and spraying, including SiC skeleton, dense alumina transition layer and Ca/Cr co-doped LaAlO 3 coating. The results indicated that the multi-layer strut significantly increased the strength of SRPC, and the Ca/Cr co-doped LaAlO 3 coating increased the boiling rate of porous burner from 25.5 °C/min to 31.2 °C/min. Furthermore, the Ca/Cr co-doped LaAlO 3 coating with its high infrared emissivity (0.80) increased the surface temperature of porous burner, also reduce the pollutant emission (CO and NO x) of SRPC. In addition, Ca/Cr co-doped LaAlO 3 promoted the combustion of low concentration methane, the lean-burn limit of methane stable combustion for porous burner had been enlarged, even the mixed gas containing 4 vol% methane could achieve stable combustion. [ABSTRACT FROM AUTHOR]

Novel (La 0.2 Eu 0.2 Nd 0.2 Sm 0.2 Pr 0.2)(Al 0.6 Co 0.4)O 3-δ (HE-1) and (La 0.2 Eu 0.2 Nd 0.2 Sm 0.2 Ca 0.2)(Al 0.6 Co 0.4)O 3-δ (HE-2) high-entropy ceramics were synthesized via solid-phase reaction technology. These two ceramics simultaneously own excellent infrared radiation performance and low degradation. The mechanism of emissivity enhancement was investigated, and emissivity decay of ceramics heated at 1500 °C for various holding time was studied. The results verify that the synthesized ceramics have perovskite crystal structure. The emissivity values of HE-1 and HE-2 are 0.78/0.66 and 0.82/0.83 in the near/mid-infrared band, respectively. These IR emissivity values are much higher than that of pure LaAlO 3 , which is attributed to enhanced impurity absorption, free carrier absorption and lattice vibration absorption. Moreover, after heating at 1500 °C for 10 h, HE-1 and HE-2 ceramics appear extremely slower emissivity decay rate (1.2–4.5 %), in comparison with fast decay rate (25.5–36.8 %) of pure LaAlO 3. This phenomenon can be attributed to the hysteresis diffusion effect of high-entropy ceramics, which can inhibit grain growth and emissivity decay. The novel ceramics have important application prospect in long-term energy-saving for high-temperature industry. [ABSTRACT FROM AUTHOR]

Ca2+/Cr3+ co-doped LaAlO 3 has been considered as important ceramic to achieve energy-savings in thermal equipment due to excellent infrared radiation (IR) performance. However, following problems restricted its industrial applications: one is the correlation between emissivity and the valence state of Cr which is not clear, then there is no quantitative evaluation of Cr6+ content in ceramics. In this work, Ca2+/Cr3+ co-doping LaAlO 3 ceramics have been fabricated. By adjusting Ca2+/Cr3+ doped ratio (0 ≤ n (Ca2+)/ n (Cr3+) ≤ 0.75), the "Cr3+→(Cr4+/Cr6+)" transformation ratio has been controlled. The results show that a higher concentration of Cr4+ in the material can significantly enhance the emissivity, while Cr6+ has no such effect. In addition, the Cr6+ content was measured by leaching method and high-temperature volatilization methods, respectively. This work can be used to guide the fabrication of environment-friendly Ca2+/Cr3+ co-doped LaAlO 3 -based ceramics with high emissivity in the field of energy-saving for thermal equipment. [ABSTRACT FROM AUTHOR]

Most high melting temperature oxides are translucent in the visible-infrared region characteristic of the blackbody thermal radiation at high temperatures. Consequently, over this broad-band spectral region, the "thermal radiation window", they do not absorb thermal radiation. Translucent oxides, such as the zirconates, can be extensively doped with rare-earth (RE) ions (Nd, Sm, Er, Dy, Yb) to achieve selective spectral absorption, and the doped oxides exhibit low thermal conductivity. The optical absorption bands are due to electronic transitions between electronic states associated with the rare-earth ions and are relatively insensitive to other rare-earth ions within the same compound. Therefore, mixed rare-earth compounds exhibit optical absorption characteristic of the sum of the individual ions' absorptions. By contrast, the thermal conductivity of the RE zirconates is shown to be relatively independent of composition suggesting that their optical properties in the thermal radiation window regions can be modified without affecting their thermal conduction properties. • Most low thermal conductivity oxides are transparent to infrared thermal radiation. • Substitutional rare-earth ions absorb infrared and visible thermal radiation. • Absorption of multiple rare-earth ions in solid solution is spectrally additive. • Multiple rare-earth doping doesn't affect zirconate high temperature conductivity. • Design basis for high-emittance oxides in visible and infrared. [ABSTRACT FROM AUTHOR]

Highly stabled antireflection layers play a crucial role in enhancing the optical and thermal performance of cermet-based solar selective absorbing coatings. Few state-of-the-art antireflection layers are qualified for high-temperature (>873 K) utilizations due to the insufficient thermal stability and increased infrared emissivity. Herein, a highly stable multilayer cermet-based absorber with an AlCrO antireflection layer is developed using cathode arc ion plating. The deposited coating exhibits a solar absorptivity of 0.908 ± 0.005 and a thermal emissivity of 0.144 ± 0.004 even after annealing at 923 K for 2000 h in air, compared to the pristine coating with a spectral selectivity of 0.898 ± 0.002/0.186 ± 0.003. After undergoing the extensive annealing treatments, abundant particles with an average size of approximately 8 μm have been detected on the coating surface. However, the AlCrO layer exhibits a remarkably flawless and dense surface topography devoid of any cracks or voids. Based on the GI-XRD and TEM evaluations, the particles have been identified as Mn 2 O 3 nanocrystals. The formation of Mn 2 O 3 particles originates from the diffusion of Mn atoms from the stainless-steel substrate to the surface of the AlCrO layer, where they undergo oxidation. The presence of Mn 2 O 3 can enhance the solar absorptivity by increasing transmittance in the visible light spectrum and reduce the emittance by enhancing reflection of infrared radiation. Then, the impact of Mn 2 O 3 on spectra selectivity and thermal stability is discussed. These results indicate that the AlCrO layer exhibits remarkable durability when subjected to high-temperature annealing in an air environment, thereby significantly enhancing the thermal stability and optical performance of cermet-based solar selective absorbing coatings. These findings suggest that the AlCrO layer exhibits exceptional durability under high-temperature annealing in an air environment, thereby significantly enhancing the thermal stability and optical performance of cermet-based solar selective absorbing coatings. [ABSTRACT FROM AUTHOR]

Nanofibrous aerogel composites have emerged as most promising materials for their high-temperature insulation in complex environments due to their ultra lightweight, high elasticity, and superior thermal performance. However, the release of particles caused by weak bond strength between nanofibers and aerogel, lead to insulation failure which presents serious challenge. This research presents, a novel approach to mitigate the particle release and significantly improve the overall performance of nanofibrous aerogel composites. The proposed method involves the preparation of particle-free nanofibrous aerogel composites through unique combination of sol-aerogel blending, electrospinning, and freeze-casting processes. The effect of particle release has been successfully eliminated by embedding TiO 2 aerogel within SiO 2 nanofibers even under rigorous conditions (weight loss rate less than 0.57%). Furthermore, the resulting nanofibrous aerogel composite exhibits exceptional thermal insulation properties, with a low thermal conductivity of 0.0251 W/mK at room temperature. Additionally, the proposed composite material configuration demonstrates superior infrared radiation suppression performance resulting in an infrared transmittance of 39.52%. The lamellar structure of the nanofibers aerogel is tailored to provide high compressive strength (2.2 kPa at 40% strain), exceptional cyclic fatigue resistance after 50 cycles, and temperature (−196 to 500 °C) conditions. The outstanding combination of thermal and mechanical properties exhibited by these nanofibrous aerogel composites makes them highly promising for stable thermal protection in extreme environmental conditions. These novel materials promise great potential for application in various engineering industries where reliable thermal insulation is critical. [ABSTRACT FROM AUTHOR]

Infrared radiation (IR) ceramics are generally recognized as energy-saving materials for thermal equipment. In this work, as novel infrared radiation ceramics, Co2+-doped LaAlO 3 ceramics were synthesized via a solid-phase reaction method, and the influence of the Co2+ doping concentration on the infrared emissivity of ceramics was systematically investigated. The original Al element position was replaced by Co in Co2+-doped LaAlO 3 , leading to lattice distortion, oxygen vacancy generation and the "Co2+→Co3+" transformation. The increase in doped Co content leads to enhanced impurity absorption, free carrier absorption and lattice vibration absorption, which significantly improve infrared emissivity. The average emissivity values in the 0.76–2.5 μm and 2.5–14 μm bands of the LaAl 0.6 Co 0.4 O 3-δ specimen (40 mol% Co) are 0.89 and 0.86 respectively, which are 324% and 28% higher than those of pure LaAlO 3. This novel Co2+-doped LaAlO 3 ceramic with high infrared emissivity has significant application prospects for energy-saving applications of thermal equipment. [ABSTRACT FROM AUTHOR]

Using a simple and scalable solid-state synthesis process, a series of spinel-structured high-entropy oxides were systematically designed and synthesized in a Co–Mn–Fe–Cr–Ni–Zn–O system. These included (Co,Mn,Fe,Cr) 3 O 4 , (Co,Mn,Fe,Ni) 3 O 4 , (Co,Mn,Fe,Cr,Ni) 3 O 4 , (Co,Mn,Fe,Zn) 3 O 4 , (Co,Mn,Fe,Cr,Zn) 3 O 4 , (Co,Mn,Fe,Ni,Zn) 3 O 4 and (Co,Mn,Fe,Cr,Ni,Zn) 3 O 4. The phase, microstructure and color evolution of 1/3Co 3 O 4 –1MnO-1/2Fe 2 O 3 -1/2Cr 2 O 3 –1NiO powders were studied without ZnO addition. These underwent four phase evolution processes and three color evolution processes before forming the final phase of black, octahedral (Co,Mn,Fe,Cr,Ni) 3 O 4 powders. The formation of an intermediate phase of (Co,Mn,Fe) 3 O 4 medium-entropy oxide powders served as the foundation for the creation of other high-entropy oxide powders. The infrared radiation properties of these synthesized medium and high-entropy oxides powders were evaluated in the near-infrared region at room temperature. Among these synthesized powders, the infrared emissivity values of (Co,Mn,Fe) 3 O 4 , (Co,Mn,Fe,Ni) 3 O 4 and (Co,Mn,Fe,Cr,Ni) 3 O 4 powders exceeded 0.8. All the synthesized powders exhibited excellent thermal stability after being annealed at high temperatures. Notably, after being annealed at high temperatures, the infrared emissivity values of these synthesized powders increased markedly without degradation, surpassing a value of 0.8, and displayed potential for applications in the field of high-temperature infrared energy savings. [ABSTRACT FROM AUTHOR]

Spinel materials are gradually becoming high infrared radiation materials with the most potential because of their special crystal structure. However, it is still difficult to design the microstructure reasonably and synthesize it at low temperature. In this paper, the honeycomb-like CuMn 2 O 4 spinels were prepared via a facile sol-gel method with a subsequent low-temperature sintering treatment. Therefore, the CMO samples with numerous pores are conducive to improving absorptivity and emissivity. Moreover, the optimum experimental conditions for high infrared emissivity were acquired by detailed investigation of the synthesis parameters including the molar ratio of trimonium citrate to metal ions, the molar ratio of urea to metal ions and the sintering temperature. Under the synergistic effect of internal factors such as, a suitable amount of impurities, abundant oxygen vacancy, small band gap, and good crystallinity, the obtained sample CMO-800 achieved excellent infrared radiation performance. Its infrared emissivity values at the test temperature of 30 °C and 600 °C separately reached 0.801 and 0.965 in the wavelength range of 3–5 μm. More significantly, this work provides significant guidance for the design and preparation of spinel materials with excellent infrared emissivity. [ABSTRACT FROM AUTHOR]

Cordierite bonded silicon carbide ceramics with different cordierite content were prepared by hot pressing sintering at 1650 °C. The samples with more than 30 wt% cordierite were nearly dense with relative densities greater than 99%. Cordierite existed in amorphous form, and was closely bound to SiC grains without transition layer, which resulted in the excellent mechanical properties of the composites. The sample with 30 wt% cordierite showed the best mechanical properties, with flexural strength of 411.44 ± 27.63 MPa, fracture toughness of 5.01 ± 0.54 MPa m1/2 and Vickers hardness of 12.02 ± 0.25 GPa, respectively. In addition, cordierite could effectively improve the infrared radiation performance of SiC ceramics, that the total emissivity of the sample with 40 wt% cordierite was 0.726, which was 16.5% higher than pure SiC ceramics. [ABSTRACT FROM AUTHOR]

The design and preparation of infrared stealth materials that meet the application in complex environments is urgently demanded in military fields. In this paper, composites with low emissivity and thermal insulation are designed to be used for indoor and outdoor infrared stealth. Thereinto, nanoPE-MXene, yttrium oxide coated hollow glass microspheres (HGMs@Y 2 O 3) and polypropylene nonwoven (PPF) were used as low emission, insulation, and antifouling layers, respectively. The sandwich-structured composite reduce the infrared radiation temperature of the 80 °C heat source object to 33.9 °C , and the average infrared emissivity of 3-15 μm is only 0.17. In addition, the infrared stealth performance of the composite is not affected by environmental changes. More importantly, the composite exhibits excellent anti-fouling and ageing resistance performance, which lays the foundation for the practical application of efficient stealth infrared materials. [ABSTRACT FROM AUTHOR]

SiC ceramic is an excellent infrared source material that can be used in a wide range of fields, like infrared heating, night vision and communication, but its poor electrical properties limit it. In this work, carbon nanotubes (CNTs) were selected as conductive phase filler, and SiC-CNT composite ceramics were prepared by SPS method. The effects of CNT content on the microstructures, electrical properties and infrared radiation performance of the composites were studied. The introduction of CNT effectively reduced the height of Schottky barrier at grain boundary, thus weakening the grain boundary effect, reducing the grain boundary resistance, further weakening the nonlinear characteristics and bulk resistivity of the composite ceramics. When the content of CNT was 1 wt%, electrical percolation was achieved, and the bulk resistivity of SiC ceramics dropped by nearly 3 orders of magnitude. The preferred orientation distribution of CNT made the bulk resistivity perpendicular to the pressure direction R ⊥ always lower than that parallel to the pressure direction R //. The sample with 5 wt% CNT assumed linear conductivity characteristics, with bulk resistivity in different direction of 16.5 Ω cm (R //) and 11.8 Ω cm (R ⊥), respectively. CNT addition slightly increased the infrared radiation performance of SiC ceramics, and the sample with 5 wt% CNT possessed the highest total emissivity of 0.675. The excellent electrical conductivity and infrared radiation performance of SiC-CNT composite ceramic confirmed this class as a promising infrared source material. [ABSTRACT FROM AUTHOR]

Materials with excellent infrared radiation properties are important for preparing infrared radiation coatings that are applied in industrial furnaces, to improve the efficiency of heating equipment. To find a new material with better infrared radiation performance, La 3 Ni 2 O 7 , a layered perovskite structural material, was prepared by the sintering method, and its infrared radiation performance was studied in detail. It was found that La 3 Ni 2 O 7 has excellent infrared radiation properties, and the measured emissivity values at the 3–5 μm waveband were above 0.970, which was determined by its narrower forbidden bandwidth. Furthermore, La 3 Ni 2 O 7 -based coatings on clay brick substrates were prepared. The thermal behavior of the coatings, from room temperature to 1400 °C, was studied using thermogravimetry and differential scanning calorimetry (TG-DSC). The results indicated that a series of reactions occurred for the coatings at temperatures higher than 1000 °C. Furthermore, the coatings were heated in a muffle furnace at 1000 °C, 1100 °C, and 1200 °C, for 60 min to study the effect of thermal reactivity on the infrared radiation performance of the coatings. The results showed that at high temperatures, although the thermal reactivity led to a phase change for the coatings, the change had little effect on the emissivity. Above 1100 °C, La 3 Ni 2 O 7 starts to decompose into La 2 NiO 4 and NiO, and above 1200 °C, the La 2 NiO 4 content is above 50%, implying that the decomposition product La 2 NiO 4 plays a key role in maintaining the high emissivity of the coatings. The emissivity of La 2 NiO 4 specifically fabricated was tested and it was found that its emissivity was above 0.970. Furthermore, thermal shock resistance tests of the coatings were conducted. The results showed that the transition layer was formed by the chemical reactions between La 3 Ni 2 O 7 and the oxides in the substrate, which plays a positive role in prolonging the service life of the coating. • The infrared emissivity in 3–5 μm waveband of La 3 Ni 2 O 7 is higher than 0.970. • Reactions occur in La 3 Ni 2 O 7 -based coatings at temperatures higher than 1000 °C. • La 2 NiO 4 generated by thermal reactivity maintains the high emissivity of the coatings. • The transition layer formed by thermal reactivity improves the thermal shock resistance. [ABSTRACT FROM AUTHOR]

The yellow fever mosquito Aedes aegypti uses multiple sensory systems to identify a blood-meal victim. Recent work by Chandel et al. identifies infrared radiation as a medium-distance cue acting through TrpA1 and two opsins to help target hosts, furthering our understanding of the multisensory hunting strategy used by mosquitoes on the prowl. [ABSTRACT FROM AUTHOR]

• Aerogel-based cool roof compared with ceramic paint and bituminous membrane. • Summer and autumn campaign in a full-scale test-room in a Mediterranean climate. • Aerogel paint determines a surface temperature reduction of 9.7 °C during the day. • During extremely hot day the maximum surface temperature decreases of −36%. • After one year of aging Aerogel shows a solar reflectance 47% greater than traditional cool roof. Passive radiative cooling material for building application show consolidated energy environmental and economic benefit, both to the users than community. Technological progress allows to develop new types of cool materials able, for instance, to emit infrared radiation into the space or to have a dynamic behaviour. There are also some paints based on Aerogel, marketed as insulating paints, which however, achieve a limited insulation, due to the extremely reduced thickness. The study of their spectral characteristics and behavior is limited in scientific literature and, their commercialization lacks independent scientific evidence and relies on non-standard detection methods. This paper aims to investigate, under real climatic conditions, the thermal performance of Aerogel-based cool roof, with a solar reflectance of 84% and a thermal emissivity of 90%. It is compared with a ceramic-based paint and a common finishing roof material of bituminous membrane. Since in literature there are mainly numerical/simulative studies or in-lab based, the analysis covers a whole summer and autumn season of continuous experimental campaign in a full-scale test-room, placed in Mediterranean climate. The application of ceramic paint determines an average surface temperature reduction of 9.0 °C during the day and 2.1 °C at night; while the Aerogel one 9.7 °C and 2.2 °C respectively. During the sunniest day the maximum surface temperature decreases of 25% and 28% for the ceramic and Aerogel coating respectively. This percentage increases on extremely hot day (-36% for both coatings) and decreases on windiest day (-20% for Ceramic coating and −24% for Aerogel coating). [ABSTRACT FROM AUTHOR]

Ceramic nanofibrous aerogels have attracted great interest because of their extraordinary multifunctional properties. Herein, a facile strategy was proposed to create SiO 2 nanofibers-BN nanoribbons assembled binary aerogel with excellent temperature-invariant super-flexibility, as well as low thermal conductivity, low infrared radiation and excellent sound absorption properties. In addition, the unique structure of the nanofibers-nanoribbon aerogel acts as the thermal insulation layer, combined with Al foil acting as an infrared reflection layer, forming a component that can effectively hide high infrared targets. The nanofibrous-nanoribbons binary aerogel possess low thermal conductivity (0.0288 W/(m⋅K)) and outstanding sound-absorption ability (NRC value of 0.43), as well as excellent infrared stealth ability, which makes it an ideal candidate for thermal insulation and sound absorption in multi fields. [ABSTRACT FROM AUTHOR]

MgCr 2 O 4 is one of promising candidate to develop high near- and mid-infrared emissivity materials for industrial furnaces energy-saving, and its infrared emissivity property will be improved by doping Cu ions. The results show that Cu ions can be doped into the spinel lattice by solid-state sintering, and the single phase Mg 1-x Cu x Cr 2 O 4 (0.1 ≦ x ≦ 0.4) radiation materials were prepared at 1200 °C. With the increase of the molar ratio of Cu ions from 0.1 to 0.4, their near- and mid-infrared emissivity all increase. The average infrared absorptivity of Mg 0·6 Cu 0·4 Cr 2 O 4 is 0.81 in the wavelength range of 0.8–2.5 μm, and the average infrared emissivity of Mg 0·6 Cu 0·4 Cr 2 O 4 is 0.94 in the wavelength range of 2.5–13 μm. Compared with MgCr 2 O 4 , the average infrared absorptivity in 0.8–2.5 μm waveband and emissivity in 2.5–13 μm waveband of Mg 0·6 Cu 0·4 Cr 2 O 4 increased by 224% and 35% respectively. Cu ions in Mg 1-x Cu x Cr 2 O 4 had a mixed valence with Cu2+ and Cu+ valence state, and the forbidden bandwidth of MgCr 2 O 4 decreased with doping Cu ions, which were responsible for the increase of near- and mid-infrared radiation of MgCr 2 O 4 with doping Cu ions. [ABSTRACT FROM AUTHOR]

Object detection is one of the crucial tasks that has made deep learning of fundamental importance in last years, also thanks to the use of drones and unmanned aerial vehicles able to obtain images and videos in real-time from any location. In the absence of daylight or artificial light for object detection, it is necessary to resort to thermal images, obtained by converting infrared radiation (i.e., heat) into visible images that depict the spatial distribution of temperature differences in a scene viewed by a thermal camera. However, object detection in this type of image and video stream is still challenging due to the complicated scene information and coarse resolution compared to a visible image or video. In this paper, we propose a method aimed to detect objects in thermal images, in particular, the proposed method is aimed to identify persons and dogs acquired from a thermal camera installed, for instance, on drones or unmanned aerial vehicles. We employ an object detection model, i.e., the "You only look once" one, for the automatic localization of objects in thermal images. In the evaluation of a dataset composed of 203 images with 257 annotations, the proposed method obtains a precision of 0.897, a recall equal to 0.904, and a mean Average Precision value (with an Intersection over Union greater than 0.5) equal to 0.924, showing the effectiveness of the proposed method for the identification and location of persons and dogs from images directly acquired with thermal cameras. [ABSTRACT FROM AUTHOR]

Aging is accompanied by loss of foot skin sensitivity and reduced postural control. Increasing foot temperature can improve both skin sensitivity and postural control in adults. However, it remains unclear whether similar effects can be observed in older adults. Can foot warming improve postural control in older adults, similar to observations in younger adults? Two foot warming protocols were conducted in 18 older adults (14 women, 4 men) to increase foot temperature by using infrared radiation to (1) warm the plantar aspect and (2) the skin of the entire foot and ankle area. We assessed the foot skin sensitivity before and after warming, considering tactile stimulation and center of pressure (CoP) displacement during 30-s standing with eyes open and closed. Both foot warming protocols led to similar increases in skin temperature (∼6 °C) compared to the basal condition, but only warming the entire foot and ankle area increased foot sensitivity for the different regions assessed. No main effects or interactions were found for CoP variables in response to the two warming protocols. The short-term effects identified after warming the entire foot and ankle region suggest that this might be a strategy to improve skin sensitivity in older adults as observed in younger adults, but this was not the case for CoP. Future research should clarify whether the magnitude and long-lasting effects of warming could be determinant of CoP results. • Foot sensitivity is enhanced by warming the whole foot and the ankle. • Warming only the plantar aspect of the foot did not improve foot sensitivity. • Warming the foot ∼6ºC did not improve balance in older adults during quiet standing. [ABSTRACT FROM AUTHOR]

Infrared thermography is commonly used in a variety of applications. It is a fast, passive, non-contact, non-invasive alternative to conventional techniques. Nevertheless, its use has several associated errors that must be minimized or eliminated. One source of error is the radiation reflected on the surface of the studied object, coming from the surroundings, and captured by the thermographic camera lens. A measurement of the reflected apparent temperature may compensate for this error. In fact, during the thermographic inspections, the operator generally assumes that the reflected apparent temperature is equal to the ambient temperature, resulting in a less accurate thermal image pattern. This study aims to verify the impact of suppressing reflected radiation on improving the thermal image details of the thermograms obtained during thermographic inspections. For this purpose, a wood sample was observed in the presence and absence of heat and light sources. The results suggest that the suppression of reflected radiation leads to better-quality thermograms and enhances the accuracy of defect detection and identification. [ABSTRACT FROM AUTHOR]

[Display omitted] Selective and ultrathin films and coatings capable of controlling infrared (IR) emission are crucial for highly integrated thermal management systems, but are challenging produce using conventional materials. Here, we report that the MXene family of two-dimensional carbides and carbonitrides offers a broad range of IR emissivity values (∼0.06–0.59) with diverse colors, varying with MXene composition and structure. Specifically, 200 nm thick purple Ti 3 C 2 T x coating has an average IR emissivity of 0.06, while gold Nb 2 CT x coating is 0.59 at wavelengths from 3-25 μm. We demonstrate that the IR emissivity can be finely tuned by combining different metals in solid-solution MXenes. Furthermore, the IR identification capability at varying temperatures was validated using different MXene coatings and patterned MXene fabrics. The versatility of MXenes at optical and infrared wavelengths provides a platform for developing MXene-based smart, flexible devices and wearables capable of selective and localized thermal management, aiming at radiative heating/cooling, IR identification, photothermal conversion, and thermal imaging. [ABSTRACT FROM AUTHOR]

Traditional chemotherapies target rapidly developing cells in the human body resulting in harsh side effects including fatigue, immune system suppression, and nausea, among others. Delivery systems to focus the active pharmaceutical ingredients (APIs) to the diseased tissue can diminish the negative side effects while improving treatment outcomes. Gold nanoparticles (AuNP) offer many unique advantages as drug delivery vehicles, including being biologically inert, easily adaptable to various shapes and sizes, able to create a strong Au-thiol bond, and able to generate heat upon the absorption of near-infrared light. To this end, a AuNP delivery vehicle was engineered to load and release two DNA binding anti-cancer drugs, mithramycin and doxorubicin, in a controlled fashion. The drugs were loaded onto the surface of the AuNP with temperature sensitive linkages. The amount of heat generated, and subsequent release of the drugs was controlled by the irradiation time with a near-infrared laser. By modulating the linkage used to load the drugs three different release profiles were able to be achieved, indicating the feasibility of such a system for combinational therapy requiring sequential release of APIs. [ABSTRACT FROM AUTHOR]

SiC–TiB 2 composite ceramics were fabricated by pressureless sintering at 2200 °C using B 4 C and C as sintering additives. The effects of TiB 2 content on the microstructure, electrical properties, infrared radiation properties and mechanical properties of the composites have been systematically studied. The prepared composites have high relative density (>98%) and good mechanical properties. The existence of Schottky barrier at the SiC–SiC grain boundary makes SiC-based ceramics showing high resistivity and nonlinear electrical feature. The introduction of TiB 2 forms the SiC–TiB 2 grain boundary with lower barrier height, which allows electrons to pass through more easily. Therefore, the nonlinear coefficient and the resistivity of SiC–TiB 2 composite ceramics both gradually decrease with the increase of TiB 2 content. When the TiB 2 content reaches 15 vol%, the electrical percolation property is obtained, and the bulk resistivity drops to 0.87 Ω cm. The infrared emissivity of the composites shows a decreasing tendency, which is not conducive to practical application. According to the results of electrical and infrared radiation properties, the addition amount of 15 vol%TiB 2 is a better formula. [ABSTRACT FROM AUTHOR]

Traditional macro data distort information on oil and gas exploitation and processing capacities and cannot track the movement of gas combustion. This study proposes a new way to retrieve those capacities and to explore changes in the trajectory of China's oil and gas exploitation and processing centres via gas flaring based on a combination of kernel clustering-kernel principal component analysis (KPCA) and spatial methods. We use data from the Visible Infrared Imaging Radiometer Suite (VIIRS) between 2012 and 2016. Results show that the upstream centre of gravity of oil and gas exploitation and processing in China moved to the southwest and the downstream centre of gravity moved to the southeast. Results of Kernel clustering-KPCA show that production, processing and transportation of oil and gas production moved from inland areas to coastal ports. Results from spatial analysis show existence of the influence of inter-regional externalities on the development of oil and gas exploitation and processing. The new economic geography theory provides a theoretical framework to explain the spatial evolution of oil and gas exploration and processing. Empirical findings of the changing path of the oil and gas exploitation and processing centres of gravity and the kernel clustering-KPCA analysis provide a scientific basis for tracking the effectiveness of government environmental policy and for policymaking on mitigation of combustion gases. This novel application extends the utilisation of the VIIRS and can be applied globally for tracking dynamic changes in the centre of gravity of oil and gas exploration and processing. [Display omitted] • Oil and gas exploitation and processing capacities and gravity movement were retrieved. • Kernel clustering analysis was applied to oil and gas exploitation and processing. • The evidence provides insights for policies that reduce gas flaring emissions. [ABSTRACT FROM AUTHOR]

SiC reticulated porous ceramic (SRPC) as the key component determined the service life and combustion characteristics of porous burner. The novel multi-layer struts were constructed to synergistically improve the oxidation resistance and infrared radiation of SRPC, including microporous cordierite coating, dense mullite transition layer, SiC skeleton and filling layer. The continuous mullite transition layer significantly improved the resistance to water vapor oxidation of SRPC, also their strength and thermal shock resistance were enhanced because the elimination of strut defects in multi-layer struts. In addition, the microporous cordierite coating generated from the burnt out of pitch increased the burner surface temperature from 764.4 °C to 1061.7 °C, and obviously reduced the CO/NOx emission due to its improved infrared radiation property. Furthermore, the porous cordierite coating enhanced the heat radiation of SRPC, thus increasing the heating rate of the burner from 29.4 °C/min to 33.1 °C/min in the process of water heating. [ABSTRACT FROM AUTHOR]

[Display omitted] • The spectral reshaping intermediate structure on silicon substrate with simple fabrication process. • The hierarchical Si NW absorber exhibits an excellent optical absorption performance from 220 nm to 1100 nm and a lower emittance above 1100 nm. • The Si-W-SiN/SiNO multilayer emitter shows a selective narrowband absorption (i.e., emission) peak in the target wavelength and low thermal radiation loss in long wave range. • The overall efficiency of the whole STPV system is precisely optimized by varying emitter parameters and system parameters. • At achievable light concentration intensity of 1000, the STPV system efficiency can exceed 29% using this integrated silicon-based intermediate structure. Solar thermophotovoltaics (STPV) system is a technique that uses absorber and emitter to remold wide-band solar radiation into narrowband infrared emission and then convert it into electric energy in order to get high energy conversion efficiency. In this study, we fabricated an integrated silicon-based intermediate structure to enable the spectral reshaping. The absorber is a hierarchical Si NW structure, which exhibits excellent absorption performance of over 95 % in the spectral range of 220–1100 nm and a low heat loss in the long-wavelength band. The emitter is planar Si-W-SiN/SiNO structure, exhibiting a selective narrowband absorption (i.e., emission) peak in the target wavelength. When the emission peak of emitter is at 1800 nm, the overall efficiency of the STPV system based on this silicon-based intermediate structure can theoretically exceed 29 % with an achievable solar concentration of 1000 and an emitter-to-absorber area ratio of 4. We also test the prepared spectral reshaping intermediate structures on real systems and discuss further optimizations. [ABSTRACT FROM AUTHOR]

• The ΔAIRT shows a double exponential decline with the increase of desorption time. • The DICI of coal exhibits multifractal characteristics. • The parameters of IR can reflect the trend in the amount of coal gas desorbed. Studying the infrared radiation (IR) variation during the coal gas desorption (CGD) process is a critical aspect in understanding and controlling abnormal coal gas emissions, and preventing coal gas disasters and accidents, such coal and gas outburst. We conducted IR experiments on CGD to analyze the mechanisms and factors influencing changes in infrared radiation temperature (IRT), as well as to assess the multifractal characteristics. The results indicate that as gas desorption time increases, the average infrared radiation temperature difference (ΔAIRT) of coal under varying adsorption equilibrium pressure (AEP) follows a double exponential downward trend. Concurrently, the differential infrared cloud image (DICI) transitions from a high temperature to a low temperature distribution state. The counts of infrared radiation temperature difference (ΔIRT) in the DICI during CGD are normally distributed, with the classification count of ΔIRT in the interval showing an upward trend. The multifractal spectra of the DICI gradually change from a left hook to a right hook as gas desorption time increases, and its degree of opening increases when the CGD time and AEP are increased. Both multifractal spectral parameters Δ α and Δ f (α) increase with the rise in CGD time. The changes in IRT and its derivative parameters can effectively reflect the trend and distribution characteristics of the amount of CGD. These results provide a theoretical foundation for understanding the characteristics of CGD, real-time monitoring of abnormal changes in coal gas emission, and the prevention of coal and gas outbursts. [ABSTRACT FROM AUTHOR]

Recently, infrared and visible image fusion has attracted considerable attention from researchers. Under extreme or low resolution conditions, the existing image fusion algorithms are easily misled by redundant information in visible images. It is difficult to maintain thermal radiation targets in infrared images clearly. To address this issue, we introduce an AutoEncoder framework for image fusion named HFHFusion(heterogeneous feature highlighted Fusion Network), which integrates a heterogeneous feature extraction network and an RCF edge detection network.The HFHFusion framework introduces a heterogeneous two-branch feature extraction structure, leveraging distinct feature extraction methods tailored to diverse sensor inputs. Firstly, we design an edge extraction network specialized for visible images, aimed at capturing detailed texture information effectively. Secondly, we devise an infrared image contrast enhancement network leveraging a channel attention mechanism, directly linked to an encoder. Our experiments demonstrate that this network facilitates better integration of infrared thermal radiation information into the fusion results. To effectively integrate image features from multimodal scenes into a unified network, we propose a heterogeneous feature extraction network, combining an AutoEncoder structure with a CNN structure. It underscores the significance of the feature extraction process in image fusion tasks. Extensive experiments conducted on public datasets highlight the advantages of our HFHFusion over state-of-the-art image fusion algorithms and task-specific image fusion methods. HFHFusion was subjected to corresponding fusion test experiments on the TNO, RoadScene and M3FD data sets respectively and compared with 8 excellent fusion algorithms. The experiments have demonstrated that our method is more suitable for extreme conditions with complex environments and low resolutions. [Display omitted] • A novel heterogeneous feature highlighted image fusion network is proposed. • A multi-layer receptive field contrast enhancement network is designed. • An edge enhancement network to retain the pertinent texture is proposed. • Experiments on public datasets demonstrate the effectiveness of our results. [ABSTRACT FROM AUTHOR]

Broadband photodetection finds indispensable utility across a spectrum of applications, spanning optical communication, spectrum switching, and memory storage. In this work, we demonstrate the fabrication of a heterojunction-based broadband photodetector using visible-infrared activated molybdenum disulfide (MoS 2) and ultraviolet-responsive molybdenum trioxide (MoO 3). The MoO3-x thin films were grown at room temperature using DC sputtering techniques, and subsequent annealing at varied temperatures mitigated defects, increased crystallinity, and produced stoichiometric MoO 3 thin films. Through the sulphurisation of MoO 3 via the chemical vapour deposition (CVD) technique, a heterojunction of transition metal oxide/transition metal dichalcogenide between MoO 3 and MoS 2 is developed. The heterostructure device exhibits broad spectral responsivity, ranging from ultraviolet A to short-wave infrared regions. In particular, ultraviolet ray incidence yields a maximum responsivity of 0.34 A W−1, a minimum noise equivalent power of 1.36 × 10−11 W Hz−1/2, and a maximum quantum efficiency of 119 %. Conversely, under infrared ray illumination, the device achieves a peak responsivity of 13.85 A W−1, a minimum noise equivalent power of 2.89 × 10−13 W Hz−1/2, and the highest quantum efficiency of 1618 %. The ensuing investigations hold promise for advancing heterojunction-based broadband photodetection applications. [Display omitted] • Broad Spectrum: The study addresses the need for broadband photodetectors, covering UVA to SWNIR for diverse applications. • High Responsivity: WO 3 -based photodetector achieves 13.85 A/W at 5V under 1064 nm light with 10 μW power. • MoS 2 /MoO 3 Heterojunction: Introduces a novel MoS 2 /MoO 3 junction, expanding photodetection range. • Sensitive Detector: Reveals a highly sensitive broadband photodetector, ideal for optoelectronics. [ABSTRACT FROM AUTHOR]

• Gradient stress loading simulations of structure rockburst are conducted. • The macroscopic damage characteristics and ejection process of structure rockburst are studied. • The dip angle of the structural surface on the structure rockburst mechanism is investigated. • The evolution of high-temperature points under gradient loading is analyzed. • Two infrared thermal imaging indicators are proposed for predicting structure rockburst. To investigate the macroscopic failure characteristics and infrared thermal imaging evolution of structure rockburst under gradient stress, gradient stress loading simulation tests were conducted using a true triaxial rockburst testing apparatus with combined gradient and hydraulic-pneumatic loading. Tests included three stress gradient coefficients and four structural surface angles. Macroscopic failure observations and infrared thermal imaging of the unloading surfaces were analyzed to understand the characteristics of structure rockburst and the influence of structural surfaces. Two infrared thermal imaging evolution parameters, the relative temperature mean (HRT) and the coefficient of variation (COV), were introduced to explore precursor indicators of structure rockburst. The results indicated that: (1) The dip angle of the structural surface (θ) and the stress gradient coefficient (k) both affect the peak stress during rockburst. (2) The structural surface angle significantly influences rockburst characteristics: θ = 30° or 60° results in shear slip-type rockbursts along or exposed on the structural surface, while θ = 0° or 90° manifests as buckling and tensile cracking-type rockbursts. (3) Infrared thermal imaging reveals that from initial loading to rockburst, temperature distribution transitions from uniform to normal, and then to non-normal. Accumulation of high-temperature points near rockburst indicates failure locations, with increased k intensifying non-normal distribution. (4) Peak values of HRT and COV positively correlate with k. (5) Fluctuations or sharp increases in HRT and COV values serve as precursors for predicting debris spalling and rockburst events. [ABSTRACT FROM AUTHOR]

• The evolution characteristics of rock IRT were obtained. • The correlation between stress and IRT was quantitatively characterized. • The skewed distribution pattern of rock IRT was identified. Abnormalities in infrared radiation temperature (IRT) often accompany the loading In this investigation, stress experiments and splitting tests were conducted on sandstone to investigate the IRT characteristics of sandstone under various loading conditions. The results shows that the Maximum Infrared Radiation Temperature (MAXIRT) increases by up to 5 °C, while in splitting tests, the minimum infrared radiation temperature (MINIRT) decreases by approximately 1.5 °C. Compared to the average infrared radiation temperature (AIRT), MAXIRT is more sensitive to compressive stress, whereas (MINIRT) is more responsive to tensile stress. The correlation between IRT indicators and stress were further analyzed. The findings reveal a positive correlation between IRT and compressive stress. At low stress levels, the correlation coefficient fluctuates between −0.4 and 0.6, generally showing low correlation. As stress increases, the correlation coefficient rises, reaching above 0.8, indicating a high correlation. Tensile stress exhibits a negative correlation, with a consistent trend. Additionally, a statistical analysis of the frequency distribution of IRT under different stress conditions was conducted, followed by hypothesis testing. The results demonstrate that the probability distribution of IRT during loading follows a skewed normal distribution. The changes in skewness can be divided into three stages: initial fluctuation, stable variation, and abrupt failure. Under compressive stress, a right-skewed distribution is observed, with skewness exceeding 3.5 before fracture and reaching above 10 near fracture. Under tensile stress, a left-skewed distribution is noted, with skewness reaching −4.5 near fracture. These findings contribute to the assessment of rock stress states and provide early warning information for predicting rock failure. [ABSTRACT FROM AUTHOR]

• Infrared thermal imaging technology was used to predict the development of coal cracking under cyclic loading of dry and wet coal. • Data fitting analysis show that there was a single exponential attenuation function relationship between average infrared radiation temperature (AIRT) and dissipated strain energy of samples. • Utilizing the Particle Flow Code (PFC) software simulation the fracture development of samples. The continuous mining activities at the working face cause periodic disturbances to the surrounding coal rock mass. Investigating the response characteristics of surface infrared radiation temperature, energy evolution features, and fracture development patterns in coal rock under cyclic loading and unloading is crucial for enhancing our understanding of the mechanisms of damage, degradation, and instability in rocks associated with mining operations. In this research work, we conducted infrared radiation observation experiments on both dry and wet coal samples subjected to uniaxial cyclic loading and unloading. Furthermore, we carried out a thorough analysis of the resulting temperature variations, energy changes, and fracture evolution patterns. It was found that the average infrared radiation temperature (AIRT) generally increases during the loading phase and decreases during the unloading phase, with the variance of successive minus infrared image temperature (VSMIT) exhibiting a sharp change just prior to failure. Energy analysis indicates that dissipated energy during the pore compaction and elastic deformation stages is minimal, while in the plastic deformation stage, the proportion of dissipated energy to total energy increases, displaying a "concave" upward trend. Additionally, fitting results show that the AIRT follows a single exponential decay relationship with dissipated energy, with wet coal exhibiting a greater decay coefficient, highlighting that moisture accelerates the rate of temperature decline. The Particle Flow Code (PFC) simulation results further demonstrate that the number of cracks in dry coal samples significantly exceeds that in wet coal samples, showing a single exponential relationship between the number of fractures and dissipated energy, which indicates that the development of fractures in dry coal rock occurs at a faster rate with increasing dissipated energy compared to wet coal rock. [ABSTRACT FROM AUTHOR]

[Display omitted] • The importance of astronomical existence of Ethanol has been outlined. • Synchrotron radiation high resolution far infrared (FIR) spectrum has been analysed in the gauche states of the ground vibrational state of Ethanol. • The intricate phenomenon of avoided crossing, causing a mixing of the trans and gauche states, has been meticulously identified. Intensity borrowing transitions have been found for trans ↔ gauche states and other ΔK = ±2 and ±3. • The lowest-lying vibrational band at 420 cm−1 corresponding to the CCO-bending band transitions shows parallel character. • Assignment work has been initiated for the CCO-bending band transitions. In this communication, the analyses of synchrotron radiation far infrared (FIR) spectrum corresponding to the gauche- (e 1 a n d o 1) states of Ethyl Alcohol are reported. Detailed assignments have been performed for b-type transitions for K values ranging from 5 to 32 and up to a maximum J value of 50. The assignments confirmed the earlier microwave (MW) and millimeter wave (MMW) spectroscopic results. The transition wavenumbers have been used to determine the term values for the gauche-states involved for all the K and J values for which observation has been made. About 2000 spectral lines have been assigned, including some accurately calculated lines that fall in the MW and MMW regions. Although transitions between the trans-species and gauche species are not allowed in Ethanol, many resonances and level crossings of energy levels cause forbidden transitions. One such system of level crossings between K = 10 o 1 and 12 e e 0 0 has been analyzed in detail, and the interaction coefficient determined. The state mixing seems quite strong and causes forbidden transitions (Δ K = 0 , 2 , 3) , including transitions for trans ↔ g a u c h e , have been found. In addition, many new strong transitions have been assigned, which belong to the trans-species. To extend our work to higher wave numbers to facilitate observations made by the infrared detector on board the James Webb Space Telescope (JWST), the analysis of the torsional fundamental band transitions (around 220 cm - 1 ) for o 2 ← e 0 and o 2 ← e 1 has been taken up. Some of the assignments are discussed here. Lastly, the lower-lying vibrational bands centered around 425 cm - 1 (CCO– bending mode) and the band at around 800 cm - 1 ( CH 3 - rocking mode) have been recorded. The CCO bending band shows an unmistakable parallel character for the trans -species. The assignment work on the CCO-bending band is in progress, and the assignments for K = 0 a n d K = 1 (+ a n d -) are included in this report. Accurate term values for the CCO-bending mode could be obtained. The results allowed the determination of the leading rotational constants for the trans -species in the excited vibrational state of the CCO-bending state. The complete known assigned lines of about 16,000 lines for the parent isotopomer and about 650 lines for 13 - C 1 and 13− C 2 (see graphical abstract) substituted Ethanol isotopomers are gathered in Appendix I and II, respectively. These atlases should be a valuable tool for further energy level analysis and astronomical detection of Ethanol in interstellar space. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal mid-IR emissions resonating with LO or LO-like phonons. • This emission is from the surface metal–semiconductor grating structures. • Spectrum peak energy depends on the LO-phonon and Reststrahlen band width. • Material-dependent emission efficiency is elucidated. • Balance of radiative and nonradiative LO-phonon annihilation dominates the efficiency. Infrared thermal radiation emission in the 8.5 – 28 THz frequency region is obtained using surface metal–semiconductor grating structures on undoped (u-) GaAs, u-GaP, u-ZnO, u-GaN, and n-type SiC in a temperature range of 430 – 630 K. These emissions resonate with longitudinal optical (LO) phonon or LO-like lattice vibration energies determined by the zero points of the real parts of the dielectric functions in the surface structures. The emissions of materials with Reststrahlen bandwidths of a few tens of cm−1 show the emissions resonating with their LO phonon modes, while materials with bandwidth of more than 170 cm−1 show peak energies significantly lower than the LO phonon: LO-like phonon resonance. The emission intensity is found to be dominated by the balance of radiative and nonradiative LO or LO-like phonon annihilation rates. The radiative rate is dominated by the LO-phonon–radiation interaction Hamiltonian and the Bose-Einstein factor. High emission intensity is obtained for the structure on u-ZnO with intense LO-like phonon–radiation interaction. The dependence of the emission intensity on temperature and emission window width for various materials shows the effect of material-dependent metal/semiconductor interface conditions on the emission efficiency. [ABSTRACT FROM AUTHOR]

• The innovative gas–solid coupling infrared observation system is used to conduct the experiment. • The variance of the differential infrared temperature of coal and the whole sample mutates before peak stress. • AE events with larger energy are mainly concentrated at the coal–rock interface and inside the coal. • The density and area of the RA–AF high-density core zone tend to move toward the shear crack area. Exploring the characteristics of the instability and failure processes of gas-bearing coal and rock is crucial for monitoring and predicting mine gas accidents. Thus, a real gas environment was simulated based on a self-developed gas–solid coupling infrared observation system. The acoustic–thermal response characteristics and failure mode of the gas-bearing coal–rock composite structure were studied. The results showed the following: (1) From the plastic stage, the average infrared radiation temperature of the coal increased significantly. The variances of differential infrared temperature (VDIRT) of the combination and coal started to mutate approximately 30 s before the peak, and the b value of the combination began to fluctuate frequently, while the VDIRT of rock remained approximately 2.128 × 10−4 throughout the process. (2) When stress was about to peak, a clear temperature boundary formed between coal and rock. Acoustic emissions with high energy were mainly concentrated at the interface and inside the coal. (3) The early plastic stage was dominated by high-frequency, low-amplitude events. In the post-peak stage and late plastic stage, the proportion of events with 80–90 dB amplitude rose, and there was a significant increase in low-frequency, high-amplitude events. (4) As the loading proceeded, the density and area gradually increased and tended to move toward the shear crack region. The distribution range of the rise time/amplitude expanded from 0–12 ms/V at the beginning of the loading to the range of 0–60 ms/V in the post-peak stage. [ABSTRACT FROM AUTHOR]