Low-temperature Annealing Process Research Articles

Modificated microstructure and enhanced mechanical properties of Cu-Sn-P alloy with rare earth La addition

Rare earths are often added to copper alloys as trace alloying elements to modify the structure and improve related properties. In this study, the Cu-7.8Sn-0.16P and Cu-7.8Sn-0.16P-0.15La alloy strips were fabricated through full-chain process of vacuum casting, cold rolling, intermediate annealing, cold rolling and low temperature annealing process. Then, the distinctive microstructure features and mechanical properties of Cu-7.8Sn-0.16P and Cu-7.8Sn-0.16P-0.15La alloys were comprehensively analyzed in special view of rare earth affected phase types and property evolution. The results indicate that the addition 0.15wt.% La has effectively refined the dendrite segregation and dispersed the microporosity. Specifically, La combines with P and form a stable and dispersed micron sized LaP2 intermetallic compound, which replaces the low melting point (α+δ+Cu3P) ternary phase in the La-free alloy. Furthermore, a new nanoscale La(Cu2P)2 precipitated phase is characterized in the Cu-7.8Sn-0.16P-0.15La alloy during low-temperature annealing process. As well, the tensile strength of Cu-7.8Sn-0.16P-0.15La strips display notable increase to 915MPa from 834MPa of Cu-7.8Sn-0.16P after low-temperature annealing. Such increase in tensile strength is attributed to the formation of La-containing phase of varied sizes in the Cu-7.8Sn-0.16P-0.15La alloy, where the nano scale La(Cu2P)2 precipitated phase makes the most significant contribution.

Spray-Coated MoO3 Hole Transport Layer for Inverted Organic Photovoltaics.

This study focuses on the hole transport layer of molybdenum trioxide (MoO3) for inverted bulk heterojunction (BHJ) organic photovoltaics (OPVs), which were fabricated using a combination of a spray coating and low-temperature annealing process as an alternative to the thermal evaporation process. To achieve a good coating quality of the sprayed film, the solvent used for solution-processed MoO3 (S-MoO3) should be well prepared. Isopropanol (IPA) is added to the as-prepared S-MoO3 solution to control its concentration. MoO3 solutions at concentrations of 5 mg/mL and 1 mg/mL were used for the spray coating process. The power conversion efficiency (PCE) depends on the concentration of the MoO3 solution and the spray coating process parameters of the MoO3 film, such as flow flux, spray cycles, and film thickness. The results of devices fabricated from solution-processed MoO3 with various spray fluxes show a lower PCE than that based on thermally evaporated MoO3 (T-MoO3) due to a limiting FF, which gradually increases with decreasing spray cycles. The highest PCE of 2.8% can be achieved with a 1 mg/mL concentration of MoO3 solution at the sprayed flux of 0.2 mL/min sprayed for one cycle. Additionally, S-MoO3 demonstrates excellent stability. Even without any encapsulation, OPVs can retain 90% of their initial PCE after 1300 h in a nitrogen-filled glove box and under ambient air conditions. The stability of OPVs without any encapsulation still has 90% of its initial PCE after 1300 h in a nitrogen-filled glove box and under air conditions. The results represent an evaluation of the feasibility of solution-processed HTL, which could be employed for a large-area mass production method.

Synthesis of ultra-small Co3O4-C core-shell nanoparticles with improved thermal stability and microwave absorption properties

Ultra-small Co3O4-C nanoparticles were synthesized with an average core size of 8.2 nm by annealing CoC nanoparticles in air at a relative low temperature. The formation mechanism of these nanoparticles can be attributed to the presence of defective C shells, the high chemical activity of ultra-small Co nanoparticles, and the gradual oxidation of the C shell during the low-temperature annealing process. The Co3O4-C nanoparticles demonstrated remarkable thermal stability at temperatures of up to 360 °C in air. Moreover, he Co3O4-C nanoparticles exhibited excellent microwave absorption performances, with an optimal reflection loss of −64.2 dB and an effective bandwidth of 6.08 GHz at a single thickness of 2.2 mm. These impressive microwave absorption properties can be attributed to the small size effects, the core-shell nanostructure, and the presence of defective C shells in the nanoparticles. Overall, the as-synthesized Co3O4-C nanoparticles show great potential for future applications as microwave absorbers, thanks to their large bandwidth, strong microwave absorption, and high thermal stability in air.

Effect of surfactant-assisted low-temperature annealing on the refinement of particle size and enhancement of magnetic properties of SrFe12O19 ferrite

The fabrication of SrFe12O19 ferrite powders with good magnetic properties is a key process in the industrial production of permanent magnets. Remanence and coercivity of the powders was seriously decreased due to the generation of surface lattice defects produced during the crushing of pre-sintered ferrite powders. And the traditionally applied high-temperature annealing above 800 °C can only partially restore the magnetic properties. In this work, the effects of types, adding mode and contents of surfactant (hexadecyl trimethyl ammonium bromide, triethanolamine) on the magnetic properties of crushed powders of the pre-sintered SrFe12O19 ferrite under a low-temperature annealing of 400 °C process were systematically explored. The results showed that surfactants are beneficial to restore or even enhance the magnetic properties of the crushed powders compared with the pre-sintered ferrite due to the refinement of the particles and repairing the surface defects. The surfactant-assisted low-temperature annealing process proposed in this work will promote the commercial production of high performance ferrite powders and ferrite magnets, which can also effectively reduce the production energy consumption.

Oxygen-deficient tungsten oxide inducing electron and proton transfer: Activating ruthenium sites for hydrogen evolution in wide pH and alkaline seawater

The design of electrocatalysts for the hydrogen evolution reaction (HER) that perform effectively across a broad pH spectrum is paramount. The efficiency of hydrogen evolution at ruthenium (Ru) active sites, often hindered by the kinetics of water dissociation in alkaline or neutral conditions, requires further enhancement. Metal oxides, due to superior electron dynamics facilitated by oxygen vacancies (OVS) and shifts in the Fermi level, surpass carbon-based materials. In particular, tungsten oxide (WO3) promotes the directed migration of electrons and protons which significantly activates the Ru sites. Ru/WO3-OV is prepared through a simple hydrothermal and low-temperature annealing process. The prepared catalyst achieves 10 mA cm−2 at overpotentials of 23 mV (1 M KOH), 36 mV (0.5 M H2SO4), 62 mV (1 M PBS), and 38 mV (1 M KOH + seawater). At an overpotential corresponding to 10 mA cm−2 in 1 M KOH and 1 M KOH + seawater, the mass activity of Ru/WO3-OV is about 7.7 and 7.86 times that of 20 wt% Pt/C. The improvement in activity and stability arises from electronic modifications attributed to metal-support interaction. This work offers novel insights for modulating the HER activity of Ru sites across a wide pH range.

Reduction of internal stress in InGaZnO (IGZO) thin film transistors by ultra-thin metal oxide layer

In this study, the modification of indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) with an ultrathin metal oxide layer successfully reduces internal film stress. The introduction of an Al2O3 metal oxide layer effectively diminishes defects within the film and minimizes distortion in the film densification process. A low-temperature annealing process at 200 °C was employed to mitigate thermal expansion differences between the film and the substrate, thus reducing internal stress within the device. Furthermore, we have discovered that this structural modification holds the potential to enhance mechanical stress resistance. This paper offers a novel perspective and an experimental foundation for the stress analysis of flexible TFTs.

Low-temperature fusion bonding of aluminosilicate glass via intermediate water

Aluminosilicate glass holds significant importance across various applications including display screens, medical devices, and the aerospace industry, owing to its excellent optical properties, superior strength, and chemical resistance. Compared with frequently used high-temperature fusion bonding, low-temperature direct glass bonding, with its potential for reliable, non-damaging fabrication of glass-based devices, is highly promising. However, achieving aluminosilicate glass bonding at a low temperature has remained a challenge due to its inherent chemical stability. This paper proposes a novel low-temperature fusion bonding method using a standard cleaning recipe assistant with intermediate water, resulting in bonding strength exceeding 10 MPa and optical transmittance surpassing 90 % at a moderate annealing temperature of 200 °C. Through surface and interface characterization, the role of water intermedia and bonding mechanism is analyzed and declared. The water trapped in the bonding interface reacts with the glass and lowers the glass transition temperature (Tg), softening the glass and filling the nanoscale gaps to further increase the bonding area in the low-temperature annealing process. Consequently, a continuous bonding interface is established, contributing to robust bonding strength and avoiding optical loss. Finally, this method is further demonstrated through the successful bonding of the glass with grating structures showing great optical properties. Notably, in contrast to traditional fusion bonding, this low-temperature fusion bonding method will not destroy the microstructures in the devices. This bonding strategy paves the way for the applications of aluminosilicate glass.

Obtaining synergy of strength and ductility in low-density steel via two-step annealing treatment

Adding light elements such as Mn and Al to steels can significantly reduce the density and obtain good strength-ductility of steels, making it a suitable choice for the development of lightweight materials. In this study, the microstructure and mechanical properties of Fe-30Mn-10Al-1C low density steel after cold rolling and annealing heat treatment were investigated. The results demonstrated that nano-sized κ-carbides are unevenly precipitated during the low temperature (500 °C) annealing process, which pin austenite grain boundaries and restrain the growth of austenite grains during the subsequent high temperature (900 °C) annealing process. As a consequence, the two-step annealed sample exhibits a fine and heterogeneous grain structure, leading to improvements of approximately 30 MPa in the yield strength to 752 MPa while keeping almost the same uniform elongation. Compared to the one step annealed sample (900 °C annealed for 3 minutes), the two-step annealed sample can achieve a high strength-ductility product (58 GPa·%) and an excellent impact toughness (128 J/cm2 at -40 °C).

Effects of deformation and applied temperature on the microstructure and performance of industrial ultra-thin rolled Cu foil

Five-generation communication, foldable cell phone, and wearable devices promote the development of Cu foils by applying multi-layer printed circuit board (MLPCB) and flexible printed circuit board (FPCB). However, few research focused on the combined influence of processing, defects (dislocation, stacking faults, and grain boundaries), and textures modification and its effects on applied performance evolution in the electronic circuit board of ultra-thin Cu foil. In this paper, 12 μm Cu foils were fabricated by the rolling process at reduction deformations of 93.3% and 95.2%. The low-temperature annealing process was utilized to simulate the application of printed circuit boards. The results show that the dislocation density is significantly decreased after annealing, but the influence of reduction deformation has no changes and the dislocation density of the samples with large deformation increased by 40%. In addition to defects, grain orientation has a significant influence on copper foil properties. With the increase of brass and S textures, the tensile strength increased 28.5%. Moreover, the high index of grain plane of S, R, and {025}<001> improves the corrosion resistance by about 130.7%. This work has great significance for preparing high-performance Cu foil applied in PCB.

High L21-atomic ordering and spin-polarization in Co2MnZ (Z = Ge, Sn) Heusler thin films with low-temperature annealing process

Although an enhanced magnetoresistance (MR) has been observed in many Co2-based Heusler alloys by promoting their structural ordering from B2 to L21 by post-annealing at higher temperatures (Tann &amp;gt; 500 °C), it is desirable to search for other Heusler alloys that crystallize in L21-order below 300 °C, as the maximum Tann is restricted for processing devices. For Co2MnZ (Z = Ge, Sn) Heusler alloys, an L21-order is expected to appear even in the as-deposited state or by a low-temperature annealing process due to their very high L21 to B2-order transition temperature (&amp;gt;1500 K). Here, epitaxial Co2MnZ films were grown on MgO (001) substrate at room temperature (RT) and post-annealed at Tann = 200–500 °C. Interestingly, as-sputtered films exhibit L21-ordering, which improves systematically upon increasing Tann. The spin-polarization of electric current (β) was estimated at RT using nonlocal spin-valve (NLSV) devices by measuring the spin-accumulation signal in a copper (Cu) channel. It was found that at Tann = 300 °C, the β value of Co2MnGe films is higher (∼0.65) than that of Co2FeGe0.5Ga0.5 films due to a higher degree of L21-order, which makes the Co2MnGe alloy a promising ferromagnetic electrode for spintronic device applications.

Achieving high tensile ductility in a fully nanostructured Al–Mg alloy by low-temperature annealing

Low ductility has always been a drawback for nanostructured materials. In this study, we applied a low-temperature annealing process on a cold rolled Al-8.1Mg-0.15Zr alloy with supersaturated state. It is found that the uniform elongation of the rolled specimen was improved by 124% after a low-temperature annealing treatment at 333 K, while an enhanced tensile strength was obtained in the annealed specimen. The good combination of tensile strength and ductility was mainly attributed to the fully nanostructured microstructure and the formation of nanoscale precipitates and segregation of Mg element after annealing treatment.

Reconfigurable fiber-to-waveguide coupling module enabled by phase-change material incorporated switchable directional couplers

In silicon photonics, grating-assisted fiber-to-waveguide couplers provide out-of-plane coupling to facilitate wafer-level testing; however, their limited bandwidth and efficiency restrict their use in broadband applications. Alternatively, end-fire couplers overcome these constraints but require a dicing process prior usage, which makes them unsuitable for wafer-level testing. To address this trade-off, a reconfigurable fiber-to-waveguide coupling module is proposed and designed to allow for both grating-assisted and end-fire coupling in the same photonic circuit. The proposed module deploys a switchable directional coupler incorporating a thin layer of phase-change material, whose state is initially amorphous to render the coupler activated and hence facilitate grating-assisted coupling for wafer-level testing. The state can be altered into crystalline through a low-temperature annealing process to deactivate the directional coupler, thus facilitating broadband chip-level coupling through end-fire couplers. All the components encompassing conjoined switchable directional couplers as well as the grating and end-fire couplers were individually designed through rigorous simulations. They were subsequently assembled to establish the proposed reconfigurable coupling module, which was simulated and analyzed to validate the selective coupling operation. The proposed module gives rise to a low excess loss below 1.2 dB and a high extinction ratio over 13 dB throughout the C-band, when operating either under grating-assisted or end-fire input. The proposed reconfigurable coupling module is anticipated to be a practical solution for flexibly expediting the inspection of integrated photonic circuits on a wafer scale.

Mechanically Robust and Elastic Graphene/Aramid Nanofiber/Polyaniline Nanotube Aerogels for Pressure Sensors.

The preparation of graphene-based aerogels with excellent mechanical strength, elasticity, and compressibility is still a challenge. Herein, we demonstrate a robust, elastic, and lightweight graphene/aramid nanofiber/polyaniline nanotube (rGO/ANF/PANIT) aerogel that is prepared by mixing graphene oxide (GO), ANF, and PANIT dispersions, followed by thermal treatment at 90 °C, freeze-drying, and a low-temperature annealing process. The PANIT bonds the graphene sheets tightly, benefitting the formation of composite gels. The ANF tightly interconnects the graphene sheets and further reinforces the composite network framework significantly, hence endowing rGO/ANF/PANIT composite aerogels with robust mechanical property. The prepared aerogels present a low density of ∼12 mg cm-3, high conductivity, good resilience, and high compressibility. The rGO/ANF/PANIT aerogels as pressure sensors exhibit a high sensitivity of 1.73 kPa-1, low detection limit (40 Pa), wide detection range, and excellent compressive cycle stability, highlighting the promising applications in pressure-sensitive electrical devices, including medical health detection, wearable electronics, and intelligent packaging fields.

Electrical Characteristics of Diamond MOSFET with 2DHG on a Heteroepitaxial Diamond Substrate

In this work, hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field-effect-transistors (MOSFETs) on a heteroepitaxial diamond substrate with an Al2O3 dielectric and a passivation layer were characterized. The full-width at half maximum value of the diamond (004) X-ray rocking curve was 205.9 arcsec. The maximum output current density and transconductance of the MOSFET were 172 mA/mm and 10.4 mS/mm, respectively. The effect of a low-temperature annealing process on electrical properties was also investigated. After the annealing process in N2 atmosphere, the threshold voltage (Vth) and flat-band voltage (VFB) shifts to negative direction due to loss of negative charges. After annealing at 423 K for 3 min, the maximum value of hole field effective mobility (μeff) increases by 27% at Vth − VGS = 2 V. The results, which are not inferior to those based on homoepitaxial diamond, promote the application of heteroepitaxial diamond in the field of electronic devices.

Electrospun 1D TiO2 nanofibers for dye-sensitized solar cell application

In this work, we have synthesized 1-dimensional (1D) TiO2 nanofibers (NFs) by using the electrospinning technique for dye-sensitized solar cells (DSSCs) application. The synthesized 1D-TiO2 NFs were characterized by using UV–Visible spectroscopy, Fourier-transform infraredspectroscopy, X-ray diffraction, field emission scanning electron microscope and energy dispersive spectroscopy techniques. The optimized1D-TiO2 NFs were used to develop DSSCs using solution-processable techniques. In this work, we have explored the effect of annealing temperature (450 °C and 500 °C) and dyes (N719 and N350) on the solar cell properties. Our results asserted that the low-temperature annealing process provides good efficiency and N719 dye performs better than N350 dye. In addition to this, the diameter of the TiO2 NFs was varied to investigates its effect on different solar cell properties. The present investigation is helpful to optimize the NFs based DSSCs.

Metallic Tin Nanoparticle-Reinforced Tin-Doped Porous Silicon Microspheres with Superior Electrochemical Lithium Storage Properties

Improving the electronic conductivity and drastic volume expansion is attractive and challenging for constructing high-performance Si-based anode materials for lithium-ion batteries. Herein, tin-doped porous silicon microspheres embedded with tin nanoparticles (Sn–PSi@Sn) are fabricated from easily available low-cost silicon–aluminum alloy precursors through a simple and scalable strategy with a chemical replacement/etching and a low-temperature annealing process. The 3D porous framework structure of Sn–PSi@Sn microspheres may buffer severe volume expansion during the electrochemical cycling and shorten the transport paths of Li+ ions. The doping of Sn atoms in the Si crystal lattice can lead to a lattice expansion in silicon, reinforce the electronic and ionic conductivities, and minimize the effect of Li trapping, which is advantageous for enhancing the rate performance and improving the initial Coulombic efficiency. The Sn nanoparticles anchoring in porous silicon microspheres may further improve the conductivity and structure stability of Sn–PSi@Sn composites. Based on the density functional theory calculation results, the effects of partial substitution of Sn into the Si lattice mentioned above have been successfully confirmed. As a consequence, the as-prepared tin-doped porous silicon microspheres embedded with tin nanoparticles show a high reversible capacity (1165.6 mA h g–1 at the 400th cycle at 1 A g–1), excellent rate properties (1433.4 mA h g–1 at a high rate of 2.5 A g–1), and superior cycling performance at an ultrahigh rate (910.9 mA h g–1 at the 500th cycle even at a high current density of 4 A g–1). This work provides a promising strategy to design high-performance anode composites.

Synergistic engineering of morphology and electronic structure in constructing metal-organic framework-derived Ru doped cobalt-nickel oxide heterostructure towards efficient alkaline hydrogen evolution reaction

Hydrogen generation by alkaline electrochemical water splitting urgently requires new techniques capable of fabricating efficient and robust electrocatalysts for hydrogen evolution reaction (HER). However, it remains a major challenge to achieve this aim through a conjoint modulation in morphology and electronic structure. Herein, a metal–organic framework-derived (MOF-derived) Ru doped cobalt–nickel oxide heterostructure grown on Ni foam (Ru-Co3O4-NiO-NF) is fabricated by a simple and scalable preparation method. Systematic experimental characterizations verify that through a tailored low-temperature annealing process, the resulted Ru-Co3O4-NiO-NF can effectively inherit the advantageous two-dimensional (2D) nanosheet morphology of Co-MOF precursor and simultaneously maintain the mechanical robustness of three-dimensional (3D) Ni foam, which are beneficial for active site exposure and charge or mass transport. Furthermore, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculation are hired to reveal that Ru-doping and Co3O4-NiO heterointerface can collectively regulate the electronic state of Ni and Co sites, thus optimizing the H2O adsorption/desorption and proton adsorption in alkaline HER process. As expected, the optimized Ru-Co3O4-NiO-NF is much more active than the commercial Pt-C (20 wt%) for electrocatalytic HER in 1 M KOH, exhibiting the low overpotential of 44 mV and 115 mV at the current density of 10 mA cm−2 and 100 mA cm−2. Moreover, the obtained self-supported electrode material can maintain catalytic activity over 60 h at 100 mA cm−2 without significant decay. This study provides a new perspective for constructing the advanced MOF-derived alkaline HER self-supported electrocatalysts by synergistic engineering of morphology and electronic structure for future energy application.

Improved High-Performance Solution Processed In₂O₃ Thin Film Transistor Fabricated by Femtosecond Laser Pre-Annealing Process

The low-temperature annealing process has a critical impact on the electrical performance of thin-film transistors (TFTs). This paper reports significant performance enhancements of TFTs using a femtosecond laser pre-annealing (FLA)-based preparation method. The solution-processed In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> films were fabricated by FLA at various laser irradiation times and then annealed on a hot-plate at 230 °C. When the FLA time was set to 30 s, the device exhibited high saturation mobility of 10.03 ± 0.64 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> of 3.4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> , low V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> of 0.14 ± 0.64 V, and small SS of 1.44 ± 0.37 V/dec. The FLA process improved the formation of M-O lattices effectively, which led to an improvement in mobility. Furthermore, the gate-bias-stress stability and time-dependent environmental stability were improved considerably by the FLA process. These results show that high-performance In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> TFTs can be prepared at low temperatures using FLA-centered annealing technology. This work suggests that the FLA preparation method has tremendous potential for the fabrication of low-cost, high performance, and flexible TFT devices.

High-throughput large-area vacuum deposition for high-performance formamidine-based perovskite solar cells

An in-vacuum low-temperature annealing process is developed to make high-density formamidine-based perovskite films. When the temperature is optimized, the efficiency increases to 21.32%, the highest value for a PSC fabricated with vacuum deposition.

Microstructure of 1469 aluminum alloy after severe plastic deformation and ion irradiation

The effect of accelerated Ar+ ion beams with an energy of 10 keV on the microstructure and phase composition in 1469 alloy (Al-Cu-Li-Ag-Mg-Zr-Sc) initially subjected to severe plastic deformation (SPD) has been investigated by transmission electron microscopy. Irradiation has been found to result in the formation of a predominantly recrystallized nanocrystalline or fully recrystallized submicrocrystalline structure in the alloy, depending on the ion fluence. The irradiation liquidates the banded structure found in the alloy after SPD. Therefore, the structural elements (nanofragments, nanograins, submicrocrystals) are distributed uniformly in the volume of the irradiated sample. In addition, irradiation increases the volume fraction and the size bimodality of heterogeneously-generated T2-phase particles. The mechanism of nucleation and growth of excess phases has been proposed. The structure changes at a higher rate than it does during a long low-temperature annealing process, and structural changes are observed at a distance of ∼200 μm from the surface, which considerably exceeds the projected ion range (∼ 10 nm).