Search

Doped GeSbTe (GST)-based phase change materials are of growing interest due to their ability to enable high-temperature data retention for embedded memory applications. This functionality is achieved through Ge enrichment and addition of dopants such as N and C in stoichiometries such as GST-225, which improve the crystallization temperature and thermal phase stability. In this study, we examine the effect of these dopants on thermal conductivity using Raman thermometry. We report the temperature-dependent thermal conductivity of the amorphous and crystalline phases of Ge-rich GeSbTe (GGST) and Ge-rich GeSbTe N-doped (GGSTN) thin films. The results reveal a surprising temperature dependence of the thermal conductivity of the crystalline phase of GGST and GGSTN, a phenomenon not typically observed for GST-based materials. Additionally, enrichment of Ge and subsequent N-doping result in reduced thermal conductivity, which can benefit the power consumption of phase change memories. From a characterization perspective, Raman thermometry has been developed as a technique for simultaneous structural and thermal characterization of GST-based materials. [ABSTRACT FROM AUTHOR]

BiFeO3–BaTiO3 (BF–BT) is one of the lead-free piezoceramic materials with high Curie temperature (TC) and high polarization. Herein, the (Bi0.5Li0.5Ti)6+ group elements are introduced into the 0.75BiFeO3−0.25BaTiO3 (0.75BF–0.25BT) system to optimize comprehensive performances via optimizing the intrinsic piezoelectric contribution and the extrinsic piezoelectric contribution. For intrinsic piezoelectric contribution, the tetragonal phase ratio of the ceramics is increased. For extrinsic piezoelectric contribution, the grain structures and the domain structures of the ceramics are improved with a relaxor state in which small-sized domains and large-sized domains coexist. The best overall performances are obtained at x = 0.010 with piezoelectric constant d33 ∼ 130 pC/N at room temperature, d33 ∼ 231 pC/N at 313 °C, resistance ρ ∼ 1.49 × 106 Ω cm at 300 °C, and Curie temperature TC ∼ 632 °C that improved significantly. Moreover, when x = 0.010, the piezoelectric thermal stability is also significantly improved, with Δd33 being less than 15% before 200 °C and maintaining 60% of d33 at 400 °C. The present experiments provide a new strategy to investigate the origin of the enhanced piezoelectric response of BF–BT ceramics as well as their applications in the field of high-temperature lead-free piezoelectricity. [ABSTRACT FROM AUTHOR]

Low-temperature PL analysis reveals an intriguing temperature-dependent emission pattern in WSe2: excitonic dominance above the 150 K Debye temperature, a balance between excitonic and trionic emissions at 150 K, and trionic dominance below this threshold. At lower temperatures, both excitons and trions display linearly polarized emissions, with polarization increasing from 0% at 300 K to 23% (excitons) and 7% (trions) at 150 K, and 12% for trions at 90 K. Moreover, the synthesized monolayer of WSe2 exhibits high thermal conductivity (246 W m−1 K−1 for A 1 g and 185 W m−1 K−1 for E 2 g 1 modes). This property is attributed to Se vacancies and defects at triangle edges, which redirect phonons, reducing scattering and enabling efficient heat transport along boundaries. The unveiling of these novel insights within the synthesized 2D WSe2 material holds significant promise for its potential applications in nano-optoelectronics. Its demonstrated efficiency in dissipating heat, coupled with improved thermal stability, suggests the possibility of employing it in future devices. This could facilitate compact designs and the miniaturization of advanced technological tools, showcasing the material's potential for practical implementation. [ABSTRACT FROM AUTHOR]

Nitrogen-rich ultra-thin (1–2 nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800 eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C–N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500–600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800 eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented. [ABSTRACT FROM AUTHOR]

Geometry plays an important role in the nucleation, stabilization, and manipulation of magnetization patterns within magnetic nanoelements. This work analyzes the impact of curvature on the thermal stability of skyrmions hosted on Gaussian-shaped nanoshells. Based on annihilation processes observed in flat nanoparticles, three distinct annihilation processes—skyrmion contraction, expansion, and displacement toward the nanodot border—are analyzed. We show that curvature-induced effective interactions significantly alter the energy barriers associated with these annihilation processes. The changes in energy are related to the relative alignment between the skyrmion core and the direction normal to the surface, highlighting the presence of favorable and unfavorable chiralities for skyrmion stabilization in curved nanodots. We also show that, unlike the one obtained for flat nanodots, where the skyrmion lifetimes typically span seconds, the lowest energy barrier values in curved nanodots reach values that ensure skyrmion lifetimes at room temperature to months before thermal fluctuations annihilate them. Curvature parameters can control the annihilation mechanism. This enhancement in skyrmion stability holds even without external additional stimuli. This underscores the profound impact of curvature on the dynamic behavior and thermal stability of skyrmions within magnetic nanoelements. [ABSTRACT FROM AUTHOR]

Temperature is an important parameter to be monitored in new wearable electronic devices. Layered black phosphorus (BP) has inherent good thermal stability and semiconductor properties and has a promising application as a temperature sensing layer. Here, we investigate the temperature sensing properties of BP, using in situ Raman spectroscopy and x-ray diffraction techniques. Flexible sensors are constructed, and temperature response is investigated in the range of 6–38 °C. The prospect application for monitoring the temperature of human body parts is demonstrated. The results show that the BP-based temperature sensors demonstrate good negative temperature coefficient characteristics and display high sensitivity and reproducible sensing performance. The temperature-dependent performance suggests the feasibility of BP as a sensitive layer in a wide temperature range. This work paves the way for exploring new applications of amazing layered materials, such as BP, in wearable electronic devices. [ABSTRACT FROM AUTHOR]

Point defect color centers acting as single-photon emitters are promising for quantum technology applications and have been extensively studied, e.g., in the 4H polytype of silicon carbide (SiC). However, the physics of such color centers in other SiC polytypes is much less explored. Herein, we study the formation and thermal stability of such color centers in 6H-SiC using photoluminescence spectroscopy. The emissions from typical single-photon emitters, such as silicon vacancies, divacancies, and carbon antisite-vacancy pairs in 6H-SiC, were monitored as a function of the proton irradiation fluence and post-irradiation annealing, and compared to that in 4H-SiC. Overall, at the background of similarities between the emission behavior in 4H- and 6H-SiC polytypes, we observed prominent differences; e.g., for the thermal stability of the carbon antisite-vacancy pair, which exhibited maximized emissions upon 300 and 900 ° C anneals in 4H- and 6H-SiC, respectively. Moreover, we observed a range of defect emission signatures not previously reported for 6H-SiC in the literature and discussed their potential origin in the context of the thermal stability. For example, among the PL-lines in 6H-SiC, we detected periodically repeatable emission signatures, resembling the so-called L-lines recently reported in 4H-SiC, even though their exact origin has not yet been settled in the literature. Thus, we use color centers comparison in different polytypes to better understand the nature of the single-photon emitters in SiC. [ABSTRACT FROM AUTHOR]

The Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) ferroelectric single crystals have been commercially available as important components in medical ultrasound transducers due to their excellent piezoelectric and electromechanical coupling performance. The variation in piezoelectric and dielectric properties of PMN-PT single crystals with ambient temperature is an important application indicator. In this work, the PMN-PT single crystals after direct current poling (DCP) and alternating current poling (ACP) were subjected to the cyclic thermal treatment process. The thermal cycling stability and microstructural changes in PMN-PT single crystals were investigated. The ACP single crystals exhibit a higher dielectric constant ε 33 T / ε 0 (6500–7600) and piezoelectric coefficient d33 (2100–2500 pC N−1) compared to the DCP single crystals (ε 33 T / ε 0 of 4100–5000, d33 of 1200–1300 pC N−1). Under thermal cycling at 60 °C, the DCP and ACP single crystals exhibit good thermal cycling stability after 150 cycles. Microstructural observations show that the domain structure of the DCP single crystals exhibits "staggered domain walls, inhomogeneous domain size, variety of domain structure," while the relatively homogeneous stripe-like domains were observed in the ACP single crystals. After thermal cycling, new fine striped domains appear in both the DCP and ACP single crystals due to the instability of rotated polarization, but the piezoelectric and dielectric properties are not greatly affected. This work provides an intensive understanding of the effects of thermal cycling on the domain structure, which is useful for applications. [ABSTRACT FROM AUTHOR]

We report an investigation into the substantially large and customizable exchange anisotropy (HEA) and coercivity (HC) in a set of bottom-pinned Ir7Mn93/Co2FeAl bilayer heterostructures fabricated using ion-beam sputtering at room temperature (RT) in the presence of an in-situ in-plane static magnetic field of 1 kOe. This modulation is achieved by controlling the microstructural parameter (i.e., grain diameter) of the antiferromagnetic (AF) Ir7Mn93 (IrMn) layer. These bilayers revealed strong positive exchange anisotropy (PEA) at RT, while negative exchange anisotropy (NEA) became evident when field-cooled to 15 K in the presence of 3 kOe. By systematically controlling the AF grain diameter from ∼5.39 to ∼6.94 nm, the PEA and NEA were found to increase by a factor of ∼2.1 and ∼1.8, respectively. However, once the AF grain diameter exceeded the necessary threshold for thermal stability, further enhancement in grain diameter above ∼6.94 nm led to a reduction in both HEA and HC. This decrease was attributed to a reduction in pinning centers at the AF/FM (ferromagnet) interface. The training data are fitted by utilizing various theoretical models, such as thermal relaxation, Binek's model, and spin relaxation model. The spin relaxation model was found to be applicable to fit the complete range of training data, encompassing both thermal and athermal decay, within the context of frozen and rotatable spins. [ABSTRACT FROM AUTHOR]

C4F7N/CO2 gas mixtures have attracted extensive attention because of their excellent insulating properties and environmental friendliness. High electrical and thermal stability is an important indicator for evaluating their performance, but there have been few molecular dynamics studies of their decomposition mechanisms. In this study, using ReaxFF molecular dynamics simulations and quantum chemistry theory, the decomposition mechanism of a C4F7N/CO2 gas mixture and the effect of the O2 content on the decomposition of the mixture were simulated on the microscopic level. It was found that there are three main decomposition pathways of C4F7N molecules, of which the generation of C3F4N⋅ and CF3⋅ free radicals is the most likely to occur. COF2 is the main oxygen-containing product of the C4F7N/CO2 gas mixture, and its generation is significantly affected by the simulation time and temperature. COF2 can be regarded as the characteristic decomposition product of the C4F7N/CO2 gas mixture. The addition of O2 slightly promotes the decomposition of C4F7N, whereas the maximum decomposition rate of CO2 decreases by 0.3% and 1% after the addition of 2% and 8% O2, respectively. Relevant results of this research can provide a theoretical basis and guidance for research into the performance of C4F7N/CO2 gas mixtures and practical engineering applications of these mixtures in the future. [ABSTRACT FROM AUTHOR]

In this work, the applicability of pulsed laser deposition (PLD) of transparent conductive oxides (TCOs) on high-quality ultra-thin poly-Si based passivating contacts is explored. Parasitic absorption caused by poly-Si layers can be minimized by reducing the poly-Si layer thickness. However, TCO deposition on poly-Si contacts, commonly by sputtering, results in severe deposition-induced damage and further aggravates the surface passivation for thinner poly-Si layers (<20 nm). Although a thermal treatment at elevated temperature (∼350 °C) can be used to partially repair the surface passivation quality, the contact resistivity severely increases due to the formation of a parasitic oxide layer at the poly-Si/ITO interface. Alternatively, we show that PLD TCOs can be used to mitigate the damage on ultra-thin (∼10 nm) poly-Si layers. Further improvement in poly-Si contact passivation can be achieved by increasing the deposition pressure while low contact resistivities (∼45 mΩ cm2) and good thermal stability (up to 350 °C) are achieved with a PLD indium-doped tin oxide (ITO) layer on high-quality ultra-thin poly-Si(n+) contacts. This allows for the application of a highly transparent front side contact by combining the excellent opto-electrical properties of a PLD ITO film with a 10 nm thin poly-Si contact. [ABSTRACT FROM AUTHOR]

We investigated the thermal stability and performance of AlGaN/AlN/GaN Hall-effect sensors under industry-relevant atmospheric conditions. The thermal stability and performance of Hall sensors are evaluated by monitoring Hall sensitivity, two-dimensional electron gas density, and Ohmic contact resistance during aging at 200 °C for up to 2800 h under atmospheric conditions. This was accomplished by characterizing AlGaN/AlN/GaN micro-Hall sensors, with and without contacts, and before and after being placed under different thermal aging times. Observed electrical performance was correlated with the micro-structural evolution of AlGaN/AlN/GaN Hall sensor heterostructures. Results indicate that the AlGaN/AlN/GaN Hall sensor provides stable performance for as long as 2800 h aging at 200 °C without any significant degradation of (i) Hall sensitivity, (ii) two-dimensional electron gas, and (iii) Ohmic contacts. However, there was a small change in sheet density and mobility, which is due to a decrease in polarization, resulting from local inhomogeneous strain relief at the barrier layer. During the early stage of thermal aging, a decrease in contact resistance was also observed and attributed to (i) out-diffusion of "Ga" at the vicinity of the contact interface, and (ii) a reduction in oxygen concentration and formation of Al–Ti intermediate alloy at the GaN/Ti interface, resulting in a reduced barrier and enhanced electron transport at the contacts. However, despite these small changes, results indicate that the AlGaN/AlN/GaN Hall sensor provides stable performance for as long as 2800 h thermal aging at 200 °C. [ABSTRACT FROM AUTHOR]

Piezoceramics with the formula Pb0.93Sr0.06Ba0.01(Mg1/3Nb2/3)0.035(Ni1/3Nb2/3)0.2 (Sb1/2Nb1/2)0.015(ZrxTi1−x)0.75O3 + 0.5 wt. % Li2CO3, where x = 0.51, 0.50, 0.49, 0.48, 0.47, and 0.46, have been made using the one-step solid-state method. The phase structure and electrical properties were systematically investigated in the quinary system. Here, the crystalline structure transformed gradually from the rhombohedral to tetragonal phase with decreasing Zr content. More importantly, the effective piezoelectric coefficient d33* of the ceramics demonstrates an excellent thermal stability below the Curie temperature. Meanwhile, piezoelectric ceramics with x = 0.49 exhibited the extraordinary electrical properties near the morphotropic phase boundary. A huge piezoelectric coefficient d33 = 853 pC/N, high Curie temperature TC = 152 °C, and the electromechanical coupling coefficients kp = 67.4%, kt = 63.5%, and k33 = 67.4% were obtained at the composition of x = 0.49, which may lead a promising future for the transducer applications. [ABSTRACT FROM AUTHOR]

During the crystallization process of aluminum hydride (AlH 3), disordered growth often leads to the formation of α′- and γ-AlH 3 , making it difficult to obtain pure α-AlH 3 , which reduces its thermal stability. Herein, the liquid phase crystal seed template method is adopted to prepare high-quality α-AlH 3. Due to epitaxial growth, the D 50 (the particle size corresponding to the sample when the cumulative particle size distribution percentage reaches 50%) of α-AlH 3 increases from 12.84 μm to 29.81 μm with a 132.2% increase. Excellent thermal stability of α-AlH 3 is achieved at the optimal crystal seed (7.5%). Combined Kinetic results indicate the decomposition model of the crystal products is altered, thereby the thermal decomposition activation energy is increased by 34.16%–104.2 kJ/mol. Specifically, the addition of 7.5% seed changes the decomposition model from the L2 model (random chain break model) to the A3 model (random instantaneous nucleation and three-dimensional nuclear growth), influenced by the fragmentation of the molecular skeleton and the diffusion of gaseous products. The crystal seed template method could prepare high purity and thermal stability α-AlH 3 due to the template effect, expanding the application of AlH 3 in the field of solid propellants. High-quality α-AlH 3 crystals are meticulously crafted using a crystal seed strategy, enabling precise manipulation of the crystalline product's attributes by adjusting the ratio of crystal seeds utilized in the synthesis process. [Display omitted] • Crystal seed template method was employed to prepare high-quality α-AlH 3. •Combustion heat of α-AlH 3 reaches 39.75 kJ/mol at 3.75% crystal seed addition. •The high crystal seed addition gains an optimized decomposition model and high E a. [ABSTRACT FROM AUTHOR]

A series of epoxy modified polymethylpenylsiloxane (EPMPS) emulsions for oil agent in carbon fibers production were synthesized with EPMPS resins and non-ionic emulsifier by phase inversion emulsification. The EPMPS resins with different epoxy content were prepared by non-hydrolytic sol–gel method. The influence of epoxy content on the chemical structure, molecular weight, surface tension and thermal stability of EPMPS resins were investigated by Fourier transform infrared (FTIR), gel permeation chromatography (GPC), contact angle meter and thermogravimetric analysis (TGA), respectively. The properties of EPMPS emulsions and their effects on polyacrylonitrile (PAN) precursor were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). It was found that the increase of epoxy content not only obviously decreased the molecular weight and surface tension of EPMPS, but also conduced to the processing of PAN precursor. With the decreasing of surface tension, the oil agent was easier to spread and film on the surface of PAN precursors. In addition, the TGA curves showed that the EPMPS resins had good thermal stability at low temperature and can be completed volatilized under high temperature conditions. Hence, the EPMPS emulsions could be used as oil agent for PAN precursors. [ABSTRACT FROM AUTHOR]

The commercialization of perovskite solar cells (PSCs), as an emerging industry, still faces competition from other renewable energy technologies in the market. It is essential to ensure that PSCs are durable and stable in high‐temperature environments in order to meet the varied market demands of hot regions or seasons. The influence of high temperatures on the PSCs is complex, encompassing factors such as lattice strain, crystal phase changes, the creation of defects, and ion movement. Furthermore, it intensifies lattice vibrations and phonon scattering, which in turn impacts the migration rate of charge carriers. This review focuses on the durability of organic–inorganic hybrid PSCs under high temperatures. It begins by analyzing the impact of external temperature variations on the internal energy dynamics of PSCs. Subsequently, it outlines the various mechanisms provided by different functional molecules, applied to interface stabilization, grain boundary passivation, crystal growth control, electrode protection, and the development of new hole transport layers, to enhance the thermal stability of PSCs. Additionally, machine learning (ML) is discussed for predicting crystal structure stability, PSCs operational stability, and material screening, with a focus on the potential of deep learning and explainable artifical intelligence (AI) techniques in the commercialization of PSCs. [ABSTRACT FROM AUTHOR]

The structural, optical and temperature-dependent luminescence properties of Y2Mg2Al2Si2O12:Cr3+ phosphors were investigated for their multifunctional applications. The as-prepared phosphors exhibited an intense far-red emission band around 600-850 nm with a peak at 687 nm, which matches well with the absorption band of plant phytochromes. Importantly, the optimized sample showed excellent thermal stability and its emission intensity at 423 K maintained about 77% of that at 298 K. The potential application of the phosphors in plant-growth LED devices was also demonstrated. Furthermore, owing to the unique thermal quenching behavior of Cr3+, a three-mode luminescent thermometry system was designed based on fluorescent intensity (FL), fluorescent intensity ratio (FIR), and full width at half maximum (FWHM). The maximum temperature relative sensitivity (Sr) of each mode could reach 2.74% K-1, 1.09% K-1, and 1.47% K-1, respectively. These results indicate that the Y2Mg2Al2Si2O12:Cr3+ phosphors have potential applications for plant growth and optical thermometry. [ABSTRACT FROM AUTHOR]

The near-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) is heavily reliant upon the performance of NIR phosphors. However, the current NIR pc-LEDs suffer from low photoelectric efficiency and insufficient near-infrared output power. In this study, Cr3+-doped Ca3MgZrGe3O12 phosphors leading to high-performance NIR pc-LEDs were developed for the first time. They feature robust and wide NIR emission that extends over the spectrum from 650 to 1100 nm with a full width at half maximum of 120 nm, a high quantum yield of 82% and excellent thermal stability of T50% = 250 °C and I150°C = 80% when excited at 460 nm. The NIR pc-LED was constructed by combining the Ca3MgZrGe3O12:0.04Cr3+ phosphor with a blue LED chip, resulting in a device that exhibits a photoelectric conversion efficiency of 20% and a near-infrared output power of 54.19 mW when operated at a current of 100 mA. The obtained luminous efficacy is superior to that of the vast majority of current broadband near-infrared pc-LEDs. In addition, this NIR pc-LED exhibits strong penetration and its applications in bio-imaging are demonstrated. The results indicate that Ca3MgZrGe3O12:Cr3+ NIR broadband phosphors are efficient for NIR pc-LEDs. [ABSTRACT FROM AUTHOR]

Glass-ceramic coatings with different Al 2 O 3 content were prepared for oxidation protection of 06Ni9DR alloy steel. The microstructure and oxidation protection rate of coatings with different content of Al 2 O 3 at 1200 °C were investigated. The results showed that the average internal pore size decreased with Al 2 O 3 content and the protection of the coating increased after oxidation test for 3 h. The oxidation protection rate of coating with 20 wt% Al 2 O 3 was the worst due to many large-size pores in the coating and bad thermal stability, and the melting of FeO into the liquid phase accelerated the formation of cracks inside the steel and further deteriorate the oxidation protection. As the alumina content increased, the liquid phase in the coating significantly decreased, and correspondingly the thermal stability increased; At the same time, a large number of 0.5–3 μm pores were formed in the coating, which effectively prolonged the oxygen diffusion path, further enhanced the oxidation resistance of the coating. The glass-ceramic coating with 80 wt% Al 2 O 3 exhibited good oxidation protection, reaching 73.6 ± 1.6 % at 1200 °C for 3 h. [ABSTRACT FROM AUTHOR]

In this investigation, we successfully synthesized a series of Swedenborgite-type Y 1-x Pr x BaCo 3 ZnO 7+δ (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5, abbreviated as YP x BCZ) oxides by a solid-state reaction method. The results show that YP x BCZ (x = 0.0, 0.1, 0.2, and 0.3) are single-phase structures, but YP 0.4 BCZ and YP 0.5 BCZ show interesting self-assembled composite phases. After long-term phase stability testing, YP 0.3 BCZ showed the best thermal stability. All samples show good chemical and thermal compatibility with La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ electrolyte. The thermal expansion coefficients in the temperature range from 30 °C to 1000 °C are equal to 9.8-13.1 × 10−6 K−1, close to that of the LSGM electrolyte. It is also found that Pr doping improves high temperature conductivity of YP x BCZ. The conductivity of YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ reach 15.1, 18.5, and 22.5 S cm−1 at 800 °C. In addition, the area specific resistance (ASR) value decreases as the Pr content increases (0.038, 0.033, and 0.027 Ω cm2 at 800 °C for YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ), improving the catalytic activity of the material. Another interesting finding was that the ASR of samples subjected to high temperature thermal decomposition was not adversely affected by the presence of decomposition products. The maximum power densities of YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ in the single cells at 800 °C were 845, 930, and 1044 mW cm2, respectively. These results indicate that YP 0.3 BCZ, YP 0.4 BCZ, and YP 0.5 BCZ are promising cathode materials for intermediate-temperature solid oxide fuel cell. [Display omitted] [ABSTRACT FROM AUTHOR]

BaLa 1-x-y MgNbO 6 : xSm3+, yY3+ phosphors were successfully synthesized via high-temperature solid-state reaction method. The crystal structure of representative samples was determined using X-ray diffraction and Rietveld refinement, confirming high phase purity of the prepared phosphors. In the singly doped BaLa 1-x MgNbO 6 : 0.05 S m3+ sample, red emission was observed under 406 nm excitation with an internal quantum efficiency of 27.8 %. The thermal stability at 599 nm (483 K) retained 72.39 % of the emission intensity. To further enhance the luminescent properties, co-doping strategy was employed by substituting Y3+ for La3+ ions. This adjustment significantly improved the brightness of the phosphors. For instance, in BaLa 0.93 MgNbO 6 : 0.05 S m3+, 0.02Y3+, the emission intensity at 599 nm was enhanced by 3.27 times compared to BaLa 0.95 MgNbO 6 : 0.05 S m3+, with an internal quantum efficiency increased from 27.8 % to 60.2 %. Moreover, the color purity of BaLa 1-x-y MgNbO 6 : xSm3+, yY3+ phosphors reached 99 %. Warm white LED devices fabricated using BaLa 0.93 MgNbO 6 : 0.05 S m3+, 0.02Y3+ exhibited a color rendering index (Ra) of 95.7 and a color temperature of 4938K, indicating broad application potential. Experimental results demonstrate that BaLa 0.93 MgNbO 6 : 0.05 S m3+, 0.02Y3+ phosphors with double perovskite structure are a novel and high-performance material for warm white LED phosphors. [ABSTRACT FROM AUTHOR]

In this study, the sol-gel stage co-precursor method was used to hydrophobically modify the gel and increase the content of alkali catalyst in the gel, thereby reducing the capillary force generated during ambient pressure drying and enhancing the strength of the gel skeleton. This improvement makes the gel skeleton structure not easy to destroy during the rapid drying process, thus greatly reducing the preparation time of atmospheric pressure drying, which could be as short as 10 h. It is worth mentioning that this method does not require extensive use of modifiers and organic solvents, so it has low cost, high efficiency, and broad industrial production application prospects. The experimental results show that the DDS/ZSA aerogel exhibits the lowest thermal conductivity (0.035 W m−1 K−1) when the dilute ammonia content is 5 ml. However, it should be noted that too low or too high an amount of dilute ammonia will lead to a decrease in aerogel performance, so it needs to be controlled within the appropriate range. In addition, the prepared aerogel has excellent hydrophobic properties with a contact angle greater than 140° and excellent thermal stability at 1000 °C, which can be used in harsh, humid, and high-temperature environments. [ABSTRACT FROM AUTHOR]

To reduce the dielectric loss of MXene/PVDF composites near the percolation threshold, a MnO 2 /MXene hybrid structure was successfully synthesized via an ultrasonic-assisted solution process, and MnO 2 /MXene/PVDF composite films were prepared by a solution casting method. The effects of different amounts of MnO 2 nanorods on the microstructure, thermal stability, dielectric properties and mechanical properties of the composite films were investigated. At 1 kHz, the dielectric constant of 7 wt% MnO 2 /MXene/PVDF is 37.3, and the dielectric loss is as low as 0.05. The electric modulus curve, Nyquist curve and equivalent analog circuit of the composites revealed strong interface polarization and microcapacitance effects in the composites. In addition, the composite films exhibit excellent mechanical properties, and the storage modulus of the composite film loaded with 10 wt% MnO 2 is 1990.5 MPa, which is 3.44 times that of pure PVDF. This study confirms that incorporating MnO 2 nanorods into MXene/PVDF composites is an effective approach for fabricating high-performance dielectric composites. [ABSTRACT FROM AUTHOR]

This study meticulously examines how oxygen incorporation alters the microstructure, mechanical, and high-temperature properties of AlN coating prepared via cathodic arc deposition. Substitution of nitrogen by oxygen in the AlN lattice leads to the formation of Al(O x N 1-x) y metastable solid solutions from wurtzite Al(O)N structure to cubic AlO(N) structure, culminating in a full conversion to γ-Al 2 O 3 with increased oxygen content. This substitutive solid solution induces solid solution strengthening and grain refinement effect, thereby escalating hardness from ∼18.5 GPa for AlN to ∼23.9 GPa for Al(O 0.18 N 0.82) 1.09. Despite an observed tendency towards enhanced thermal decomposition of oxynitride coatings upon annealing, the occurrence of α-Al 2 O 3 oxide phase significantly preserves the mechanical integrity at elevated temperatures, outperforming pure AlN coating. Notably, the strategic alteration by minimal oxygen incorporation facilitates the formation of an Al-rich oxide layer, which exhibits superior anti-oxidative characteristics. After oxidation at 1100 °C for 10 h, the Al(O 0.10 N 0.90) 1.03 with an oxide layer of ∼1.2 μm exhibits remarkable oxidation resistance. [ABSTRACT FROM AUTHOR]

A nanocrystalline textured stainless steel (SS) surface passivated with an AlCr oxide layer is proposed for use as a high temperature solar selective absorbers (SSAs). The textured SS surface was prepared by oxidizing in air at 800 °C for 30 min. The heating resulted in outward diffusion of the SS substrate Mn atoms, their oxidation on the surface, and formation of octahedral Mn 3 O 4 nanocrystals, which play a role of textured surface. The passivation AlCr oxide single layer was deposited on the textured surface using reactive RF magnetron sputtering to protect the SS from further oxidation. The solar absorptivity α s and thermal emissivity ε 298K of the as-deposited SSAs were 0.84 and 0.165, respectively. In order to study high temperature stability, SSAs were heat treated under air conditions at 600–900 °C for 0.1–300 h. SSAs demonstrated thermal stability at 600 °C for at least 300 h and degradation of optical properties with performance criterion PC < 0.05 at 700, 800, and 900 °C for 300 h, 30 h, and 1 h, respectively. The increase in thickness of the surface Cr 2 O 3 layer on SS substrate was identified as the main degradation mechanism of SSA optical performance. SSAs demonstrated a high activation energy of 330 ± 30 kJ/mol. The obtained data can be used to design high temperature SSAs for concentrating solar energy systems operating under vacuum or air conditions at 500 °C. [ABSTRACT FROM AUTHOR]

The key challenge of producing titanium-aluminum alloy by vacuum induction melting technology is to develop crucible materials with excellent thermal stability and thermal shock resistance. In this work, Ba 0.8 Ca 0.2 ZrO 3 ceramic materials were synthesized by pressure-less sintering of BaZrO 3 and CaZrO 3. In order to improve the thermal shock resistance of Ba 0.8 Ca 0.2 ZrO 3 , a pore-forming agent of BaCO 3 was introduced into the material. The thermal shock resistance of the material improved significantly and reached its maximum when 9 wt% BaCO 3 was added (the retained flexural strength increased from 2.61 MPa to 3.52 MPa). At the same time, the addition of BaCO 3 significantly reduced the penetration of the crucible material by the melt and the pollution of the secondary-phase alloy in the material (the penetration depth decreased from ∼200 μm to ∼100 μm). Based on the combination effect of Ba 0.8 Ca 0.2 ZrO 3 solid solution and fine closed pores, a potential titanium-aluminum alloy smelting material with excellent chemical stability and thermal shock resistance was obtained. [ABSTRACT FROM AUTHOR]

To regulate the comprehensive performance of ethylene‐propylene‐diene monomer (EPDM)‐based oil‐absorbing expandable rubber, a series of irradiated α‐olefin‐EPDM7001 rubbers (EOR7001‐X‐Y) are prepared. The influence of the carbon chain length and content of α‐olefins on the structure and properties of the rubber is systematically investigated. Results show that EOR7001‐X‐Y possesses a cross‐linked network structure, and its gel fraction decreases gradually with the increase in carbon chain length and content of α‐olefins. The incorporation of α‐octadecene successfully creates micro‐nanoscale porous structures within the rubber matrix, providing favorable conditions for oil absorption. The introduction of α‐olefins and changes in irradiation dose do not significantly affect the thermal stability of EPDM7001 rubber. The tensile strength slightly reduces, while elongation at break significantly increases, improving the deformation capability. EOR7001‐18‐20 demonstrates exceptional resistance to aging and withstands external forces even after oil absorption. This study supports the development of high‐performance oil‐absorbing expandable rubber. [ABSTRACT FROM AUTHOR]

All‐polymer solar cells (all‐PSCs) present compelling advantages for commercial applications, including mechanical durability and optical and thermal stability. However, progress in developing high‐performance polymer donors has trailed behind the emergence of excellent polymer acceptors. In this study, we report a new electron‐deficient arene, fluorinated bithiophene imide (F‐BTI) and its polymer donor SA1, in which two fluorine atoms are introduced at the outer β‐positions in the thiophene rings of BTI to fine‐tune the energy levels and aggregation of the resulting polymers. SA1 exhibits a deep HOMO level of −5.51 eV, a wide bandgap of 1.81 eV and suitable miscibility with the polymer acceptor. Polymer chains incorporating F‐BTI result in a highly ordered π–π stacking and favorable phase‐separated morphology within the all‐polymer active layer. Thus, SA1 : PY‐IT‐based all‐PSCs exhibit an efficiency of 16.31 % with excellent stability, which is further enhanced to a record value of 19.33 % (certified: 19.17 %) by constructing ternary device. This work demonstrates that F‐BTI offers an effective route for developing new polymer materials with improved optoelectronic properties, and the emergence of F‐BTI will change the scenario in terms of developing polymer donor for high‐performance and stable all‐PSCs. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) has been utilized as a semiconductor material and has been shaped into various structural forms to obtain outstanding electromagnetic wave (EMW) absorption properties, characterized by low weight and excellent absorption capabilities even at high temperatures. A chemical vapor infiltration (CVI) approach was used to synthesis a periodic structured SiC microtube ceramic on a carbon fiber plain preform, taking inspiration from the porous structure found in SiC materials. Afterwards, the carbon fibers were removed by oxidation at a temperature of 900 °C. The periodic structural SiC microtube ceramic exhibited a porosity above 68 %, rendering it a lightweight material possessing a density of 0.8 g/cm3. The SiC microtube ceramic displays a periodic structure and exhibits anisotropy at 0° and 45°, respectively, as a result of the braided structure of the fiber fabric. When evaluated at a 0° angle of incidence, the SiC microtube ceramic, with a thickness ranging from 2.4 to 2.6 mm, showed excellent absorption of EMW energy in the Ku-band frequency range, attenuating more than 90 % of the energy, with a minimum reflection loss of −56.36 dB at 15.65 GHz. SiC microtube ceramics have demonstrated an effective absorption bandwidth exceeding 8.2 GHz throughout a temperature range of ambient temperature to 600 °C, with a thickness of 2.8 mm. Furthermore, the SiC microtube ceramic exhibited stable EMW absorption properties and thermal conductivity even at temperatures as high as 600 °C. [ABSTRACT FROM AUTHOR]

This work prepared [GeSb 9 (x nm)/Ga 3 Sb 7 (16-x nm)] 5 multi-layer phase change thin films and studied their related properties. Compared to traditional GST and GeSb 9 , [GeSb 9 (6 nm)/Ga 3 Sb 7 (10 nm)] 5 multi-layer phase change thin films have a higher crystallization temperature (∼205 °C) and an extremely low resistance drift coefficient (0.0004). The crystalline behavior and bonding of thin films are analyzed to elucidate their intrinsic mechanisms, thermal stability, and interfacial effects. According to crystal mechanism analysis, the Avrami index (n) is 0.904, indicating that the [GeSb 9 (6 nm)/Ga 3 Sb 7 (10 nm)] 5 multi-layer phase change thin films grow in one dimension. The presence of interfaces alters the crystallization behavior of crystals, leading to a growth mode that transitions from diffusion-controlled to interface-controlled and back to diffusion-controlled. This transformation significantly reduces the nucleation index (m ≤ 0.16), minimizing the inherent randomness of the film itself and achieving extremely low resistance drift. Research has demonstrated that [GeSb 9 (6 nm)/Ga 3 Sb 7 (10 nm)] 5 multi-layer phase change materials have promising applications in embedded memory. [ABSTRACT FROM AUTHOR]

Bi 4 Ti 3- x (Mg 1/2 W 1/2) x O 12 (BTMW100 x) ceramics were synthesized using a direct reaction method combined with a two-step sintering technique. The study systematically investigated the effects of B-site equivalent substitution of (Mg 1/2 W 1/2)4+ on BTMW100 x ceramics. The experimental results indicate that an appropriate amount of (Mg 1/2 W 1/2)4+ doping effectively reduces grain thickness, enhances grain distribution uniformity, and decreases the concentration of oxygen vacancies. Consequently, these modifications lead to improved piezoelectric performance while maintaining a high Curie temperature. Notably, Bi 4 Ti 2.95 (Mg 1/2 W 1/2) 0.05 O 12 (BTMW5) ceramics exhibit excellent piezoelectric properties and thermal stability, with a piezoelectric coefficient of 23 pC/N and a Curie temperature of 683 °C. These findings suggest that BTMW5 ceramics are promising candidates for high-temperature piezoelectric applications. [ABSTRACT FROM AUTHOR]

TiO 2 -based colossal dielectric ceramics have emerged as a prominent research focus in recent years. However, their further applications have been constrained by several key limitations, including the requirement of high sintering temperature (>1400 °C), relatively high dielectric loss (>0.05, 1 kHz), and temperature stability (<200 °C). This study reports rutile (In 0.5 Ta 0.5) 0.1 Ti 0.87 O 1.88 F 0.12 ceramics at 1220 °C sintering using 12 % InF 3 as the acceptor In3+ source, which exhibits a colossal dielectric constant (1.1 × 105) and an ultra-low dielectric loss (0.0071) at 1 kHz and room temperature, even loss values below 0.04 (20 Hz - 100 kHz). Notably, the thermal stabilities (10 kHz, 100 kHz) simultaneously satisfy X9E (Δε r /ε 25 °C ≤ ±4.7 %) above 300 °C. F − not only supplies electrons to enhance the semiconductivity of grains, but also decreases the oxygen vacancy and average grain size (270 ± 12.53 nm) to improve grain boundaries resistances, which reduces dielectric loss and enhances frequency and temperature stabilities. As a result, the dielectric mechanism is mainly related to internal barrier layer capacitor (IBLC) and high grain boundary resistance. Therefore, this strategy provides a creative design for developing TiO 2 -based ceramics. [ABSTRACT FROM AUTHOR]

The lead metaniobate (PbNb 2 O 6 , PN) with high Curie temperature is widely used to fabricate transducer for high-temperature application up to 300 °C. However, evident dielectric anomalies and direct-current resistivity degradation were experimentally observed in PN-based ceramics at high temperature, which may significantly restrict the working temperature range for well logging application. When the sample was heat-treated at 260 °C for 3 h in silicon oil, the dc-resistivity of ceramics at 260 °C decreased from 3.8 × 108 to 1.0×107 Ω⋅cm, accompanied by 43 times increase in tan δ at 1 kHz. To investigate the cause of these phenomena, the in-situ piezoelectric, dielectric properties and dc-resistivity were systematically investigated in the samples subjected to heat-treatment at 260 °C in silicon oil. It is revealed that the porous structure of PN-based ceramics allows for the infiltration of silicon oil as a minor phase, and the accumulation of its decomposers within the pores would exert significant influence on the dielectric property and dc-resistivity of ceramics at elevated temperatures. However, the samples still demonstrate excellent thermal stability in piezoelectric property, with value of k t maintaining 0.39 at 260 °C in oil. In addition, the low Q m is not the intrinsic property of PN ceramics, but rather related to the phase transition of silicon oil within pores of ceramics, as indicated by the increase in Q m from 47 to 80 after heat-treatment in air. [ABSTRACT FROM AUTHOR]

This study investigated the preparation of SiC porous ceramics using an organic foam impregnation-high temperature sintering process. To address the poor wettability of SiC ceramics when used as the reinforcement phase, the surface of SiC porous ceramics was modified with Al 2 O 3. SiC-Al 2 O 3 /2A50 co-continuous composites were then fabricated by infiltrating 2A50 aluminum alloy into the SiC-Al 2 O 3 porous ceramics under pressure. Microstructural observations, along with friction, wear performance, and thermal stability test, demonstrated that Al 2 O 3 surface modification significantly enhances the friction and wear performance as well as the thermal stability of the co-continuous composites. The prepared SiC-Al 2 O 3 /2A50 co-continuous composite exhibited excellent wear resistance, good thermal stability and stable bonding at heterogeneous interfaces. Compared to 38CrSi steel, the SiC-Al 2 O 3 /2A50 co-continuous composite not only offers the advantage of reduced weight but also shows a significantly lower wear rate of 9.3 × 10−5 mm3/N·min under a 50 N load. These findings suggest that the SiC-Al 2 O 3 /2A50 co-continuous composite has the potential to replace 38CrSi steel as a wear-resistant material. [ABSTRACT FROM AUTHOR]

In this paper, Eu3+ doped multi-component transparent aluminosilicate and oxyfluoride aluminosilicate glasses were fabricated by the melt-quenching procedure, and the glass-ceramics containing LiAlSi 2 O 6 microcrystals (LAS glass-ceramics) were produced by a two-step heat treatment process. The XRD, SEM, and EDS data demonstrate that spherical single-phase LiAlSi 2 O 6 microcrystals have precipitated from the glass matrices. The microhardness and flexural strength of the glass-ceramics vary in 6.27–6.66 GPa and 89.18–155.75 MPa, respectively. Phonon sideband analysis reveals that the phonon energies for both fluorine-containing and fluorine-free LAS glass-ceramics are approximately 971 cm−1, and the multiphonon relaxation rates (W mp / W 0) of the former are lower than those of the latter. Given its lower W mp / W 0 values, the fluorine-containing LAS glass-ceramic exhibits a higher emission intensity and a longer lifetime. Under 394 nm excitation, the fluorine-containing LAS glass-ceramic presents a warm and nearly pure red emission, characterized by a correlated color temperature of less than 3300 K and a color purity approaching 100 %. Time-resolved emission spectra support the photoluminescent stability of the Eu3+ ions. According to the Judd-Ofelt theory and spectral results, the fluorine-containing LAS glass-ceramic possesses lower Ω 2 / Ω 4 and asymmetry ratios, leading to a more symmetrical local environment for the Eu3+ ions. Benefiting from its enhanced red emission, the 5D 0 →7F 2 transition in the fluorine-containing LAS glass-ceramic exhibits a higher branching ratio (69.28 % > 50 %), emission cross-section (8.94 × 10−22 cm2), and gain bandwidth (12.12 × 10−28 cm3). Additionally, temperature-dependent photoluminescence spectra substantiate the excellent thermal stability of the Eu3+ doped fluorine-containing LAS glass-ceramic. Specifically, the intensity of the 5D 0 →7F 2 transition at 150 °C remains 80 % of the initial intensity. Therefore, the Eu3+ doped multi-component transparent oxyfluoride aluminosilicate glass-ceramic has a significant competitive advantage in the field of red lasers and trichromatic WLEDs. [ABSTRACT FROM AUTHOR]

[Display omitted] Alloying-type anode materials are considered promising candidates for next-generation alkali-ion batteries. However, they face significant challenges owing to severe volume variations and sluggish kinetics, which hinder their practical applications. To address these issues, we propose a universal synthetic strategy, which can realize the facile synthesis of various alloying-type anode materials composed of a porous carbon matrix with uniformly embedded nanoparticles (Sb, Bi, or Sn). Besides, we construct the interactions among active materials, electrolyte compositions, and the resulting interface chemistries. This understanding assists in establishing balanced kinetics and stability. As a result, the fabricated battery cells based on the above strategy demonstrate high reversible capacity (515.6 mAh g−1), long cycle life (200 cycles), and excellent high-rate capability (at 5.0 C). Additionally, it shows improved thermal stability at 45 and 60 °C. Moreover, our alloying-type anodes exhibit significant potential for constructing a 450 Wh kg−1 battery system. This proposed strategy could boost the development of alloying-type anode materials, aligning with the future demands for low-cost, high stability, high safety, wide-temperature, and fast-charging battery systems. [ABSTRACT FROM AUTHOR]

This work delineates the thermal safety of full-scale sodium-ion batteries (SIBs) by interrogating the material-level electrochemical and thermal responses of micro and nano-structured tin (Sn) based anodes and sodium vanadium phosphate (NVP) cathodes in suitable electrolyte systems. Informed by these material-level signatures, we delineate cell-level thermal safety maps cognizant of underlying electrode–electrolyte interactions in SIBs. [ABSTRACT FROM AUTHOR]

Photoluminescence energy transfer is a good strategy to enhance the efficiency or tuning of emission colors. A phosphor host containing Gd3+ may facilitate the host-sensitization effect and transfer the so-absorbed photon energy to other activators. Zn1−xMnxGdB5O10 (0.005 ≤ x ≤ 0.07), ZnGd1−yDyyB5O10 (0.01 ≤ y ≤ 0.09), and ZnGd1−zSmzB5O10 (0.01 ≤ z ≤ 0.09) were synthesized via the traditional high-temperature solid-state method. A powder X-ray diffraction technique was employed to confirm the phase purity and successful doping. In all phosphors, by monitoring the characteristic emission of Mn2+, Dy3+ and Sm3+, the excitation spectra of all were found to contain the typical absorption belonging to Gd3+; in addition, the largely shortened fluorescence lifetimes of Gd3+ after Mn2+, Dy3+ or Sm3+ doping strongly proved the existence of the host-sensitization effect. Along with Gd3+-sensitization, Mn2+ doped at the Zn2+ site emits a close-to-ideal red light. Dy3+ and Sm3+ doped at the Gd3+ site emit close to white and orange light, respectively. The calculated internal quantum efficiency is 25.5% for Zn0.995Mn0.005GdB5O10, 17.0% for ZnGd0.97Dy0.03B5O10 and 17.4% for ZnGd0.97Sm0.03B5O10. The high thermal stability of the photoluminescent emission for Mn2+, Dy3+, and Sm3+ can be demonstrated through in situ high-temperature experiments, which suggest possible enhanced energy transfer efficiency at high temperatures. [ABSTRACT FROM AUTHOR]

Development of energetic materials with enhanced thermostability and diminished sensitivity is one of the main objectives of current research. In this work, an N,N-alkylidene bridge was used to synthesize a series of tricyclic heat-resistant fused ring compounds. The physical and chemical properties of newly synthesized compounds are verified and quantified through experimental and theoretical methods. The structures of all fused compounds were determined through single-crystal X-ray diffraction, elemental analysis, NMR spectroscopy, and IR spectroscopy. Among these compounds, 9-nitro-5,6-dihydrotetrazolo[1,5-a][1,2,4]triazolo[5,1-c]pyrazine (3) and 10-nitro-6,7-dihydro-5H-tetrazolo[1,5-a][1,2,4]triazolo[5,1-c][1,4]diazepine (4) exhibit excellent thermal stability with the decomposition temperatures higher than 300 °C (3: 301 °C and 4: 311 °C). Furthermore, compounds 3 and 4 are more insensitive in comparison with the applied heat-resistant material HNS (3: IS = 33 J, FS > 360 N; 4: IS > 40 J, FS > 360 N; HNS: IS = 5 J, FS = 240 N). Additionally, compound 3 displays significantly superior detonation properties compared to HNS (3: VD = 8021 m s−1, P = 25.8 GPa; HNS: VD = 7612 m s−1, P = 24.3 GPa). The potential of compound 3 as a heat-resistant material is demonstrated by these experimental and theoretical data. [ABSTRACT FROM AUTHOR]

Zn2P2O7−y (referred to as ZPO) is expected to be an ideal anode material for lithium-ion batteries (LIBs) owing to its low cost, good chemical and thermal stability, and environmental friendliness. The effects of oxygen vacancies on the structure, morphology, and electrochemical performance of ZPO were systematically investigated. The sample obtained in an argon–hydrogen atmosphere (referred to as ZPO-1) exhibited an initial discharge capacity of 1178.4 mA h g−1 at 0.2 A g−1, which was superior to that of the samples obtained via calcination in argon (referred to as ZPO-2, 749.1 mA h g−1), vacuum (referred to as ZPO-3, 901.3 mA h g−1), and the air (referred to as ZPO-4, 911.2 mA h g −1). The excellent electrochemical performance of ZPO-1 could be attributed to the introduction of more defects under reducing atmospheres, which accelerated the transmission rate of lithium ions and improved discharge capacity. Appropriate amounts of oxygen vacancies not only enhance electrical conductivity, but also act as active sites for electrochemical reactions. Additionally, synthesizing ZPO with oxygen vacancies provides a reference for exploring anode materials with exceptional performances for LIBs. [ABSTRACT FROM AUTHOR]

Phase‐change random access memory is anticipated to break the bottleneck of the “storage wall” due to its advantages in simultaneous data storage and in‐memory computing. However, operation speed constrains its application scenarios. Antimony (Sb) thin film has ultrafast phase change speeds, low power consumption, and a straightforward chemical composition. In this study, silicon (Si) doping is employed to enhance the stability of pure Sb while achieving both ultrafast operational speeds and superior thermal stability concurrently. By utilizing optoelectronic hybrid phase change memory, the SET and RESET operation speeds can reach as fast as 26 and 13 ps, respectively, when using Si‐doped Sb films. The absence of the Si─Sb bond results in simple cubic nuclei within the amorphous film, which is posited as the structural basis for the high operational speed. These novel insights into ultrafast speed and phase mechanisms are poised to have valuable evidence for future high‐speed memory designs. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskite solar cells (HPSCs) are gaining attention as a promising technology for next‐generation photovoltaic devices owing to their impressive power conversion efficiency (PCE) and cost‐effective fabrication methods. Although, solution‐processed passivation using 2D perovskites can improve the interface recombination, this approach hampers its effective charge transportation. In this study, the study investigates the properties and performance of the bilayer 3D/3D methylammonium lead iodide (MAPbI3)/formamidinium lead iodide (FAPbI3)‐based perovskite heterojunction (BPHJ) to address these concerns. The bilayer structure consists of two distinct perovskite absorbers having independent structure that are sandwiched between two charge transporting layer (CTLs) to make functional device. First, the fabrication process is optimized to achieve high‐quality MAPbI3 perovskite films with controlled morphology and crystallinity followed by the formation of BPHJ using FAPbI3 deposition by thermal evaporation technique. The BPHJ‐160 nm‐based PSCs with optimized parameters exhibit an enhanced PCE of 23.08% compared to single‐layer reference (20.15%) device. The improved performance can be attributed to the effective charge extraction at the heterojunction interface and reduced charge recombination losses due to favorable energy levels. Furthermore, the long‐term stability of the BPHJ‐based perovskite device is assessed under continuous illumination along with its ambient and thermal stability across different environmental conditions. [ABSTRACT FROM AUTHOR]

One of the key challenges for high‐performance proton‐conducting solid oxide fuel cells (H‐SOFCs) is the mismatch in thermal expansion coefficients (TEC) between the cathode and electrolyte. While incorporating negative thermal expansion (NTE) materials can mitigate this issue, mechanical mixing often weakens cathode strength. To address this, a TEC gradient cathode is proposed and successfully implemented by co‐sintering PrBa(Co0.7Fe0.3)2O5‐δ(PBCF) with Y2W3O12 (YWO) in this work. In this work, Ba atoms at the A‐site of PBCF migrated from the lattice, generating A‐site defects. The resulting BaWO4 and Y10W8O21 phases, which have low TEC, are uniformly distributed between PBCF and YWO, forming a TEC gradient composite cathode. In addition, the transition phase captures the A‐site element Ba in the electrolyte layer, optimizing the electrolyte‐cathode interface. The composite cathode exhibits a reduced TEC, closely matching that of the electrolyte, significantly enhancing interface bonding, thereby providing a lower ohmic resistance of 0.051 Ω cm2 and a higher power density of 1.88 W cm−2 at 700 °C. Remarkably, thermal cycling tests conducted under temperature switching conditions demonstrate the composite cathode's long‐term thermal and chemical stability. [ABSTRACT FROM AUTHOR]

Industrial fermentation applications typically require enzymes that exhibit high stability and activity at high temperatures. However, efforts to simultaneously improve these properties are usually limited by a trade‐off between stability and activity. This report describes a computational strategy to enhance both activity and thermal stability of the mesophilic organophosphate‐degrading enzyme, methyl parathion hydrolase (MPH). To predict hotspot mutation sites, we assembled a library of features associated with the target properties for each residue and then prioritized candidate sites by hierarchical clustering. Subsequent in silico screening with multiple algorithms to simulate selective pressures yielded a subset of 23 candidate mutations. Iterative parallel screening of mutations that improved thermal stability and activity yielded, MPHase‐m5b, which exhibited 13.3 °C higher Tm and 4.2 times higher catalytic activity than wild‐type (WT) MPH over a wide temperature range. Systematic analysis of crystal structures, molecular dynamics (MD) simulations, and quantum mechanics/molecular mechanics (QM/MM) calculations revealed a wider entrance to the active site that increased substrate access with an extensive network of interactions outside the active site that reinforced αβ/βα sandwich architecture to improve thermal stability. This study thus provides an advanced, rational design framework to improve efficiency in engineering highly active, thermostable biocatalysts for industrial applications. [ABSTRACT FROM AUTHOR]

Photoluminescence energy transfer is a good strategy to enhance the efficiency or tuning of emission colors. A phosphor host containing Gd3+ may facilitate the host-sensitization effect and transfer the so-absorbed photon energy to other activators. Zn1−xMnxGdB5O10 (0.005 ≤ x ≤ 0.07), ZnGd1−yDyyB5O10 (0.01 ≤ y ≤ 0.09), and ZnGd1−zSmzB5O10 (0.01 ≤ z ≤ 0.09) were synthesized via the traditional high-temperature solid-state method. A powder X-ray diffraction technique was employed to confirm the phase purity and successful doping. In all phosphors, by monitoring the characteristic emission of Mn2+, Dy3+ and Sm3+, the excitation spectra of all were found to contain the typical absorption belonging to Gd3+; in addition, the largely shortened fluorescence lifetimes of Gd3+ after Mn2+, Dy3+ or Sm3+ doping strongly proved the existence of the host-sensitization effect. Along with Gd3+-sensitization, Mn2+ doped at the Zn2+ site emits a close-to-ideal red light. Dy3+ and Sm3+ doped at the Gd3+ site emit close to white and orange light, respectively. The calculated internal quantum efficiency is 25.5% for Zn0.995Mn0.005GdB5O10, 17.0% for ZnGd0.97Dy0.03B5O10 and 17.4% for ZnGd0.97Sm0.03B5O10. The high thermal stability of the photoluminescent emission for Mn2+, Dy3+, and Sm3+ can be demonstrated through in situ high-temperature experiments, which suggest possible enhanced energy transfer efficiency at high temperatures. [ABSTRACT FROM AUTHOR]

Nitrocellulose (NC) finds widespread use in propellants and launchers. Nanoscale modification can effectively enhance its combustion performance by shortening the mass and heat transfer distance. However, it also presents greater safety challenges for storage and application. To further investigate the thermal safety characteristics of nanoscale NC, this study explores the impact of additives on nanoscale NC. Nanoscale NC was prepared via electrospinning, and the samples were characterized using focused ion beam scanning electron microscopy to examine the influence of precursor concentration and stabilizer on sample morphology, leading to the formulation determination. Samples incorporating triphenylamine and lithium carbonate (Li2CO3) were fabricated using both electrospinning and traditional mechanical mixing techniques. Following preparation, fourier transform infrared spectroscopy, the methyl violet test, and thermogravimetry–differential scanning calorimetry were performed on six samples, each prepared using different methods and additives. These analyses aimed to investigate the thermal decomposition characteristics of the samples under varying heating rates. The study also compared the impact of nanoscale modification on the thermal performance of composite nitrocellulose. Various model-free methods were employed to calculate the relationship between activation energy and conversion rate and to analyze alterations in activation energy. Considering the thermal decomposition characteristic parameters, the study delved into the stabilizing effect of typical stabilizers in nanocomposite fibers. This research is instrumental in guiding preparation process optimization, promoting the application of NC-stabilizer mixtures, and providing valuable references for the preparation and thermal stability investigations of similar nanomaterials. [ABSTRACT FROM AUTHOR]

Deep Eutectic Solvents (DESs) have emerged as promising eco-friendly pre-treatment agents for lignocellulosic biomass, offering considerable advantages for the nanofibrillation process. This study investigates the impact of DESs on cellulose fibers morphology, focusing on solubilization phenomena in the amorphous regions that may facilitate cellulose nanofiber production. The pre-treatment process combining a DES (triethylmethylammonium chloride and imidazole, TEMA:IMD) with microwave (MW) energy was optimized to enhance the solubility of cellulosic fibers. A response surface methodology (RSM) was employed to optimize the DES-MW-assisted pre-treatment. Results show that the reaction time and the temperature significantly influence the solubility of cellulosic fibers. The optimized conditions resulted in cellulose fibers with low content of hemicellulose and lignin, high crystallinity index, and improved thermal stability. The effectiveness of DES-MW pre-treatment in producing cellulose nanofibers (CNFs) from native and pre-treated fibers was investigated. Cellulose fibers pre-treated with a DES yielded CNFs with a narrower diameter distribution. Overall, optimized DES-MW pre-treatment offers a promising strategy for the efficient and sustainable extraction of CNFs. [ABSTRACT FROM AUTHOR]

Ammonium‐calcium mixed‐cation pentaborate NH4Ca[B5O7(OH)4]·H2O has been synthesized for the first time. Single‐crystal X‐ray diffraction analysis reveals that it crystallizes in the triclinic space group P‐1 with lattice parameters a = 6.7042(3) Å, b = 7.1859(3) Å, c = 10.7447(4) Å, α = 100.304(3), β = 97.774(3), γ = 96.972(3). The structure is characterized by 1D boron–oxygen chains composed of [B5O7(OH)4]3− polyanions that are further interspaced by Ca2+, NH4+ cations, along with lattice water molecules. The phase purity and thermal stability of the as‐synthesized sample were confirmed by XPRD and TG‐DSC analyses. Experimental UV–vis diffuse reflectance spectroscopy coupled with Urbach fitting indicates a direct bandgap of 4.50 eV, contrasting with theoretical calculations that suggest an indirect bandgap of 5.53 eV. Additionally, both theoretical computation and polarized light experimental test indicate that NH4Ca[B5O7(OH)4]·H2O exhibits moderate birefringence. [ABSTRACT FROM AUTHOR]

Lightweight, flexible, and thermostable thermally conductive materials are essential for enhancing heat dissipation efficiency in advanced electronics. The development of intrinsic thermally conductive polymers is the key to expanding the space for improving the thermal conductivity of polymer‐based thermal management materials. In order to balance the thermal conductivity and mechanical performance of bulk polymers, thermally conductive aramid nanofiber (ANF) films are assembled by manipulating the proton‐donating ability of solvents. Compared to water as a conventional proton donor, ethanol‐induced multi‐scale structures composed of dense hydrogen bonding interaction, large grain size, and uniform fiber topology endow the resulting ANF films with enhanced intrinsic thermal conductivity up to 5.05 W m−1 K−1 with a 34% increase, salient mechanical performance with the tensile strength of 181.4 MPa, and exceptional thermal stability higher than 500 °C. These outstanding properties of ANF films provide many possibilities for the preparation of polymer‐based thermally conductive materials. [ABSTRACT FROM AUTHOR]

The high electrostatic discharge (ESD) sensitivity and mechanical sensitivity of silver acetylide-silver nitrate (SASN) seriously affects its application. For solving this problem, novel SASN@GO nanocomposites were successfully prepared by a self-assembly method. Thin sheet graphene oxide (GO) was coated on the surface of SASN, and prevented the agglomeration of SASN nanoparticles effectively. GO content in SASN@GO nanocomposites was controlled (0.5 ~ 1.5 wt%) to balance explosive performance and safety. Results reveal that SASN@(1%)GO exhibits the best thermal safety and desensitization, with thermal decomposition temperature, impact sensitivity (Is), friction sensitivity (Fs) and electrostatic energy at 50% ignition probability (E50) of 208.2°C, 1.96 J, 128 N and 0.64 mJ respectively, which are much better than that of SASN, indicating safety performances of SASN are improved through the introducetion of a small amount of GO. This work provides a strategy for reducing the explosion risk of SASN. [ABSTRACT FROM AUTHOR]