Effect Of Thermal Annealing Research Articles

Enhanced Platinum-Based Thin-Film Catalysts for Electro-Oxidation of Methanol

Surface morphology is one of the critical factors affecting the performance of electrocatalysts. Thus, with careful manipulation of the surface structures at the atomic level, the effectiveness of the catalyst can be significantly improved. Heat treatment is an effective method for inducing surface atom rearrangement, hence modifying the catalyst’s characteristics. This study investigated the substrate’s influence and the effect of thermal annealing on the morphology and surface reconstruction of platinum (Pt) thin-film catalysts. Our findings indicate that heat treatment in a reductive atmosphere (95% Ar + 5% H2) at 300 °C can significantly impact the degree of rearrangement of surface atoms. This process induces long-range ordering, resulting in domains with a high proportion of (111) and (100) sites without an epitaxial template. Considering that the reactivity of low-index platinum single crystals for the methanol oxidation reaction follows the following sequence Pt(111) < Pt(110) < Pt(100), increasing the proportion of (100) planes leads to a notable enhancement (up to three times) in performance, compared to untreated catalysts. Furthermore, considering the amount of precious metal consumed, a mass-specific current density obtained on annealed Pt@Ni is larger by one order of magnitude and ~2 times that obtained on Pt@Cr and Pt@GCox catalysts, respectively. Our results demonstrate that an easy-to-implement way of controlling atomic orientations improves catalyst performance. With this contribution, we propose a method for designing improved electrocatalysts, as catalytic reactions occur only at the surface.

Fabrication of graphene oxide-reinforced polyvinyl alcohol and study effect of thermal annealing of GO/PVA nanocomposites on their properties

In the presented work, graphene oxide (GO) was obtained as a plate using the Hummer technique. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) show the formation of pristine GO. Composite materials were prepared by adding different percentages of GO to polyvinyl alcohol (PVA) (2%GO/PVA, 3% GO/PVA, and 20% GO/PVA). To determine the effect of thermal annealing on the structure, physical properties, and morphology of the samples, thermal annealing of the samples was performed for 1 hour at temperatures (40°C, 70°C, and 110°C). Following that, to explore how the characteristics of GO/PVA composites vary with concentration and thermal annealing temperature, the structural, optical, and morphological features of the samples were determined using XRD, Fourier-transform infrared (FTIR), and Raman spectroscopy, as well as SEM used to investigate the properties of all samples. From the XRD results, by the increasing thermal annealing temperature, the space between the sheets is decreased. From Raman measurements, the ID/IG ratio for 2% and 3% GO/PVA composite materials increased with increasing temperature compared to the pristine GO. It indicates that the defect in the structure increases due to the effect of temperature.

Effect of thermal annealing on the luminescent and structural properties of the SiOxCy thin films by organic catalytic chemical vapor deposition

Photoluminescent silicon oxycarbide (SiOxCy) thin films were deposited on n-type (100) silicon substrates using the organic catalytic chemical vapor deposition (O-Cat-CVD) technique employing tetra-ethyl orthosilicate (TEOS) as an organic-based precursor. These films were annealed at a temperature of 500, 800 and 1000°C for 30 minutes in a nitrogen (N2) environment. The as-deposited and annealed SiOxCy films were analyzed using optical and structural characterizations, such as photoluminescence (PL), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Secondary ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). The PL spectrum of the as-deposited film showed emission in the blue-green region, while the annealed SiOxCy films showed strong emission from blue to near-infrared. The PL in all the films was attributed to different structural defects related to oxygen and carbon that act as radiative centers in the SiOxCy network. The annealed films showed an increase in the emission intensity, where the annealed film at 800°C displayed the highest emission intensity. This is related to an increase in the amount of radiative defects in the films due to structural and compositional changes after the thermal annealing (TA). XPS and SIMS measurements showed an oxygen incorporation with the TA, increasing from 54.59 at. % to 63.5 at. % for the as-deposited and annealed at 1000°C films, respectively. FTIR spectra showed an increase in the Si-O-C and Si-O-Si bonds and the hydrogen and other radicals desorption. These results support the creation of radiative centers due to structural changes in the films after the thermal annealing.

Effects of Thermal Annealing and Chemical Abrasion on In-situ U-Pb Dating of Complex Ancient Zircons by Laser Ablation ICP-MS

Effects of Thermal Annealing and Chemical Abrasion on In-situ U-Pb Dating of Complex Ancient Zircons by Laser Ablation ICP-MS

The effect of thermal annealing of GO/PVA on their physical, structural, and morphological properties

ABSTRACT In this research the synthesis of graphene oxide (GO) through the Hummers method, to obtain various percentage nanocomposite materials incorporating GO into polyvinyl alcohol (PVA) (2%GO/PVA, 3%GO/PVA, and 20%GO/PVA), and the detailed investigation of these composites’ morphological, structural, and optical characteristics using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Raman spectroscopy, and Scanning electron microscopy (SEM). The main goal of the presented work is to investigate how the physical properties change in the wide-range concentrations of the GO/PVA composite materials, as well as at different thermal annealing temperatures. From the XRD results, the space between the sheets is decreased by increasing the thermal annealing temperature. By the Halder-Wagner method, crystallite size and microstrain of the various percentages of GO/PVA were determined. The high microstrain and crystallite size belong to thermal annealed at 70°C of 3% GO/PVA (D = 8.50 nm/ε = 11%) and thermal annealed at 40°C of 20% GO/PVA (D = 13.70 nm/ε = 16 %). At room temperature and the highest annealing temperature, the microstrain value is minimal or equal to 0, because, its crystal structure is stable at low temperatures and it occurs as a result of relaxation due to rearrangement of the polymer chain at high temperatures. From Raman measurements, the ID/IG ratio for 2% and 3% GO/PVA composite materials increased with increasing temperature compared to the pristine GO. This indicates that the defect in the structure increases due to temperature.

Study of structural, dielectric properties of ZnFe2O4: effect of thermal annealing

Abstract We report structural, dielectric properties of sol-gel auto-combustion-synthesized ZnFe2O4 nano-ferrites (grain-size: 53.43 - 64.81 nm), and study the effect of thermal annealing on structural dielectric properties by X-ray diffraction (XRD), dielectric measurements. Results show that thermal-annealing shows: i) an increase of lattice parameter (aexp.), and on B-site: there is an increase of Zn2+ population with concurrent decrease of Fe3+ ions, ii) alterations of inversion-degree from 0.18 to 0.32, strengthening of A-O-B, A-O-A interactions, accompanied by a weakening of B-O-B super-exchange-interaction, iii) decrease of theoretical magnetization at 0 K (Ms(th)), iv) with increasing frequency, real-imaginary components (ε', ε'') of dielectric constant, and loss-tangent decreases, v) that at higher frequencies, ac conductivity (σac) shows a significant increase and exhibited a power law dependence, suggesting a typical of charge transport assisted by a hopping or tunneling processes. Results also reveal that polarizability strength decrease with annealing temperature, and correlated-barrier-hopping remains the dominant mechanism for conduction. Cole-Cole plots (ε', ε''), corresponding complex impedance (Z', Z'') data are indicative of the growing influence of grain boundaries on the dielectric properties for the studied samples. Observed improved-response of σac, recommends the potential-applications of the studied samples in high-frequency device applications.

Effect of thermal annealing on the average and local structure of superconducting polycrystalline NbRe films

Abstract NbxRe1−x is a non-centrosymmetric superconductor recently realized in thin film form. The access to the basic physics that governs this material is hindered by the polycrystalline structure of the films which consist of grains of small dimensions. In these conditions, films are not decisive in revealing the nature of the superconducting order parameter, and, in particular, the possible presence of a spin-triplet component. In this work, post-deposition annealing procedures were performed to improve the crystalline quality of the as-grown films. As determined by X-ray diffraction measurements, by tuning the annealing process, it was possible to increase the crystalline size from 1-2 nm up to several nanometers, beyond the values of the superconducting coherence length. Pair distribution function analyses revealed the non-centrosymmetric crystal structure of the treated NbRe films. Finally, electrical transport measurements, performed to study the relationship between structural and transport properties of the samples, showed an improved metallicity and a reduction of the superconducting critical temperature after the thermal treatment. This last result can be reasonably ascribed, for instance, to oxygen contamination, modification of the electronic density of states at the Fermi level, or change in the electron-phonon coupling. The results of this work are useful to realize films for future experiments meant to access nature of the superconducting order parameter.

Thermal Annealing Effect on Elastoplastic Behaviour of Al/Cu Bimetal during Three-Point Bending.

This paper presents the results of experimental studies on the effects of temperature and time of annealing on the elastoplastic properties of bimetallic aluminium-copper sheets. Mechanical tests were carried out on flat samples previously heated to temperatures of 250, 350, 450, and 500 °C for 40, 90, and 150 min. At the beginning of the tests, the elastic constants and internal friction energy were determined after thermal exposure using the impulse vibration exposure method. Further tests were carried out on the same samples using the three-point bending test. Based on the tests, the following quantities were determined and analysed: elasticity angles, translocations of the neutral axes of the cross-sections of samples, and changes in the values of bending moments plasticizing the extreme layers of bimetallic Al/Cu samples resulting from thermal interactions. The final part of this paper presents the results of measurements of the thickness of diffusion zones at the interface and their effect on the stability of the joint after annealing. The studies that were conducted indicate the dominant influence of the thermal factor on the properties of the Al/Cu bimetal above the temperature of 350 °C, which leads to the weakening of its strength and the degradation of the structure at the metallic phase boundary.

Effects of thermal and laser annealing on the structure of Ge2Sb2Te5 thin films

In this study, we used Raman spectroscopy to compare the local structure of Ge2Sb2Te5 (GST) thin films with thicknesses of 90 nm and 271 nm that were crystallized through thermal annealing and laser radiation (laser annealing) during the recording of Raman spectra in situ. We found that for all crystallized films, the position of the main peaks in the Raman spectra was almost the same, and their structure corresponded to a hexagonal close packed state. It is noteworthy that the full width at half maximum (FWHM) of the main peaks varies considerably depending on the crystallization method used.

Thermal Annealing Effects on Long-Lived Fluorenol Room Temperature Phosphorescence for Styrene Detection.

Fluorene derivatives have been widely developed in OLEDs because of its efficient fluorescence quantum efficiency, but for which unique rigid biphenyl planar structure and large conjugated system, we hypothesize that they have a great potential for room temperature phosphorescence (RTP) applications, and confirmed this conjecture by subjecting polyvinyl alcohol (PVA) and phosphors to thermal annealing. The cross-linked structure formed during thermal annealing judiciously modulates the phosphorescence emission characteristics of the fluorenol with the synergistic interaction between PVA and fluorenol. Specifically, the lifetime exhibited a substantial increase from 1352.2 ms to 2874.1 ms, accompanied by a quantum yield augmentation from 4.8 % to 11.3 %, which substantiate that cross-linked induced by thermal annealing effectively amplifies the phosphorescent intensity and stability of the phosphors, facilitating ultralong phosphorescent emission at ambient conditions. Furthermore, an effective probe based on this film is developed for its highly sensitive, quantitative and immediate detection of volatile organic compounds. This investigation not only proffers a novel paradigm for the development of advanced RTP materials but also imparts insightful considerations for optimizing the performance of polymers in conjunction with functional materials, encompassing bioimaging, sensing, and optoelectronic devices.

Nanoscopic analysis of rapid thermal annealing effects on InGaN grown over Si(111)

This study explores the impact of rapid thermal annealing (RTA) on InxGa1-xN grown over Si(111) by molecular beam epitaxy (MBE). Through X-ray diffraction (XRD) and reciprocal space map (RSM) characterization, notable shifts in diffraction peaks were observed post-annealing, suggesting alterations of the Indium content in the nanostructures. Morphological assessments using scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicated that RTA could smooth the surface of the samples, though some instances of degradation were also noted. Energy-dispersive X-ray spectroscopy (EDS) showed further stoichiometric modification following annealing. Photoluminescence spectroscopy (PL) revealed notable shifts and increases in the intensity of the InxGa1-xN peaks, indicating the formation of regions with high Indium or Gallium concentration. The presence of these enriched regions was particularly evident from the peaks at around 540 nm and 433 nm, suggesting significant changes in the material's composition. Transmission electron microscopy combined with electron energy loss spectroscopy (TEM-EELS) corroborated the presence of In-rich and Ga-rich areas, affirming the phenomenon of Indium surface segregation. So, this study contributes to understanding the behavior of InxGa1-xN nanostructures under rapid thermal annealing, providing insights for advanced optoelectronic applications.

Dark-field microscopy studies of single silicon nanoparticles fabricated by e-beam evaporation technique: effect of thermal annealing, polarization of light and deposition parameters.

Herein, we report the dark-field microscopic studies on single silicon nanoparticles (SiNPs) fabricated using different deposition parameters in the electron beam (e-beam) evaporation technique. The morphology of the fabricated SiNPs is studied using the Atomic Force Microscope. Later, for the first time, the effect of thermal annealing and deposition parameters (i.e., beam current and deposition time) on the far-field scattering images and spectra of single SiNPs is studied using a transmission-mode dark-field optical microscope to estimate the wavelength locations and full-width at half maxima of the optical resonances of single SiNPs. Finally, the role of polarization of incident light on the optical resonances of single SiNPs is also studied by recording their scattering images and spectra.&#xD.

Effects of Rapid Heat Treatments on the Properties of Cu2O Thin Films Deposited at Room Temperature Using an Ammonia-Free SILAR Technique

We report herein the analysis of the properties of copper(I) oxide thin films deposited by an optimized ammonium-free successive ion layer adsorption and reaction (SILAR) technique. The Cu2O thin film deposition process was carried out at room temperature using copper acetate monohydrate, sodium citrate as complexing agent, and hydrogen peroxide as precursors of copper and oxygen ions, respectively. The harmless and easy-to-handle sodium citrate replaces the volatile NH4OH commonly employed as complexing agent in the SILAR technique for the deposition of metal oxide thin films. The optical, structural, morphological, and electrical properties of the as-deposited Cu2O thin films were studied as a function of the number of cycles during deposition, as well as their modifications produced by the effect of rapid thermal annealing (RTA) in vacuum in a temperature range of 200–250°C for 1 min, 3 min, and 5 min. The as-deposited thin films had cubic crystalline structure corresponding to the Cu2O phase as determined by x-ray diffraction (XRD), with a direct energy bandgap of 2.43–2.51 eV depending on the number of cycles, and electrical resistivity of the order of 103 Ω cm. The XRD and x-ray photoelectron spectroscopy (XPS) analysis of the Cu2O thin films treated by RTA demonstrated an increase of the crystal size with time and temperature of the RTA and reduction effects from Cu2+ to Cu1+ oxidation states. On the other hand, the RTA treatments also decreased their energy bandgap to 2.38 eV and electrical resistivity to 102 Ω cm. The high energy bandgap values of the Cu2O thin films were attributed to quantum confinement effects produced by their small crystal size in the range of 3.6–8.6 nm.Graphical

Effect of thermal annealing on the maximal apparent etched track lengths of alpha particles in a CR-39 nuclear track detector

Effect of thermal annealing on the maximal apparent etched track lengths of alpha particles in a CR-39 nuclear track detector

Effect of rapid thermal annealing on DC performance of Mg0.30Zn0.70O/Cd0.15Zn0.85O MOSHFET

This study focuses on a cost-effective method for fabrication of a metal oxide semiconductor-heterostructure field effect transistor (MOSHFET) based on MgZnO/CdZnO (MCO) using dual ion beam sputtering (DIBS), in contrast to the more expensive epitaxial growth system. The MOSHFETs developed in this research exhibit notable characteristics, such as a substantial two-dimensional electron gas (2DEG) transconductance (∼2.6 mS), a high ION/IOFF response ratio in the order of 108, and minimal gate leakage current. Furthermore, we explore the impact of rapid thermal annealing (RTA) on the drain current at various temperatures (600 °C and 800 °C). The results indicate a fourfold improvement in drain current compared to unannealed conditions, primarily attributed to reduced contact resistance and no degradation in term of MgZnO/CdZnO structure. Additionally, an analysis of post-RTA treatment under a nitrogen (N2) atmosphere on gate leakage current is presented. The investigation spans temperatures ranging from 400 °C to 800 °C, revealing that above 600 °C (gate leakage at 400 °C–600 °C is around ∼10−9 A), gate leakage in HFET is augmented by one order of magnitude (∼10−8 A) due to a phase change in the dielectric. These findings underscore the feasibility of DIBS-grown MCO MOSHFETs as an economical solution for the mass production of switching devices and sensors.

Carbon molecular sieve electrodes with intrinsic microporosity for efficient capacitive deionization

Capacitive deionization (CDI), apromisingprocessfor desalinatinglow-salinity water, is currently characterized by the prevalent use of activated carbon (AC) electrodes that exhibit somewhat suboptimal performance. One potential method for increasing the electrosorption capacity of an electrode involves boosting its porosity and conductivity by using conductive polymers or applying heat treatment to porous polymers. This study examines the performance of the capacitive deionization (CDI) process using a range of highly porous carbon molecular sieve (CMS) electrodes. These electrodes are derived from intrinsically microporous polyimide 4,4′-(hexa-fluoroisopropylidene) diphthalic-anhydride (6FDA)-3,3′ dimethyl-naphthidine (DMN) (6FDA-DMN) and prepared at temperatures of 600, 800, and 1000 °C. The electrodes that were produced exhibited a high Brunauer-Emmett-Teller (BET) surface area ranging from 574 to 729 m2g−1. Additionally, they displayed a symmetric cyclic voltammetry (CV) plot with a specific capacitance ranging from 17.75 to 67.91 Fg−1 at a scan rate of 5 mVs−1. The charge transfer resistance (Rct) values for the 6FDA-DMN-based CMS P1, P2, and P3 electrodes were measured to be 9.7 Ω, 1.2 Ω, and 0.9 Ω, respectively, in a 1 M NaCl solution. The CMS electrode, synthesized at a temperature of 800 °C (P2), exhibits exceptional electrosorption capabilities in a saline solution with a concentration of 600 mgL−1. It displays a remarkable capacity of 36.9 mgg−1 and a rate of 2 mgg−1min−1, surpassing the performance of activated carbons (ACs). This research establishes a pathway for optimizing the characteristics and performance of electrodes by thermal treatment. This research demonstrates for the first time the effect of thermal annealing on the CDI performance of CMS materials, which will aid in developing electrode materials for large-scale water desalination.

Effects of Thermal Annealing on V‐Based Ohmic Contacts on n‐Type AlGaN with High Al Content

The effects of thermal annealing on V‐based electrodes (V/Al/X/Au) with different diffusion barrier metal X are investigated for n‐type Al0.7Ga0.3N. At an annealing temperature of 800 °C, linear current (I)–voltage (V) characteristics are obtained, and the specific contact resistivities of the electrodes for X = Pt, Ni and V are 9.7 × 10−5, 2.3 × 10−4, and 1.8 × 10−4 Ω cm2, respectively. When the annealing temperature is increased to 850 °C, the I–V characteristics become nonlinear. Especially in the case of the V diffusion barrier, significant degradation of the ohmic contact is observed. The coverage of the electrode on the n‐type Al0.7Ga0.3N surface is significantly reduced after thermal annealing at 850 °C, resulting in a decrease in the current value. Furthermore, the formation of V–Al–Au and Al–Au alloys and diffusion of Au to the interface between the n‐type Al0.7Ga0.3N and electrode are found. The Au diffusion preferentially occurs through the domain boundaries of the alloys and causes the deterioration of the ohmic contact properties. In contrast, from the viewpoint of miscibility, Pt and Ni diffusion barriers are more effective than V in suppressing the formation of alloys with Au and then the diffusion of Au.

Metal-organic decomposed lanthanum cerium oxide thin films: A study of chemical and surface properties

Lanthanum cerium oxide thin films have been deposited on n-type (100) silicon wafers using the spin coating technique. The post-deposition annealing was performed over spin-coated films. The compositional studies were conducted by performing Fourier transform infrared spectroscopy, Energy dispersive X-ray spectroscopy, and X-ray diffraction. Ellipsometry was used to determine the thickness and atomic force microscopy was performed to understand the surface morphology of the deposited thin films. The effect of rapid thermal annealing at different temperatures over the structural and chemical properties of the LaCeO2 thin films was observed. The FTIR spectra show the formation of silicates at the interface of the oxide and semiconductor, while XRD results show that the films become crystalline with increased annealing temperature. The refractive index was observed to be reduced with an increase in the annealing temperature and a minor reduction in the physical thickness as per the sample standard deviation of 0.2981[Formula: see text]nm.

Investigation on thermal annealing effect on the physical properties of CuO-SnO2:F sprayed thin films for NO2 gas sensor and solar cell simulation

Thin films, owing to their versatility, are extensively employed in various applications, including solar cells and gas detection. In this study, CuO-SnO2:F thin films were fabricated using spray method. The influence of annealing temperature on their properties was examined. X-ray diffraction analysis of post-annealing at 300 °C revealed the emergence of the Cu2O phase, which disappeared at higher annealing temperatures of 500 °C. Substantial improvements in structural, optical, and electrical characteristics were observed, with the optimized films exhibiting heightened responsiveness at low NO2 gas concentration (4 ppm). The optimum operating temperature was determined at 150 °C, demonstrating small response and recovery times, and good reproducibility. Furthermore, Silvaco TCAD simulation was employed to model CIGS (Copper Indium Gallium Selenide) solar cells incorporating CuO-SnO2:F thin films as a buffer layer, yielding an impressive efficiency of 15.31 %.

Enhancement of hole mobility in high-rate reactively sputtered Cu2O thin films induced by laser thermal annealing

In presented work, a reactive high-power impulse magnetron sputtering (r-HiPIMS) was used for high-rate deposition (≈ 170 nm/min) of Cu2O films. Films were deposited on a standard soda-lime glass (SLG) substrate at a temperature of 190 °C. As-deposited films exhibit poor hole mobility in the orders of ≈ 1 cm2/Vs. We have systematically studied the effect of laser thermal annealing (LTA) procedure performed using high-power infrared laser under different laser parameters (number of pulses, length of the pulse). We have found, LTA procedure could significantly enhance the hole mobility (up to 24 cm2/Vs in our case). We have also fitted the results of a temperature-dependent Hall measurement to clarify the mechanism of the reported increase in hole mobility. Moreover, we have discussed the effect of the LTA procedure on microstructure (crystallinity, surface morphology) and on the value of optical band gap.