Effect Of Annealing Conditions Research Articles

Synthesis of hierarchical hollow nest-like WO3 micro/nanostructures with enhanced visible light-driven photocatalytic activity

Novel hierarchical hollow nest-like WO3 micro/nanostructures (HNWMs) were prepared via a facile hydrothermal method. These nanostructures were successfully synthesized without using any templates or surfactants. The photocatalysts were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersion spectroscopy (EDX), X-ray and photoelectron spectroscopy (XPS), thermogravimetric analysis/differential scanning calorimetry (TG/DSC), and Brunauer–Emmett–Teller (BET) measurements. We found that the HNWMs are assembled of a number of regular-shaped nanosheets with an average thickness of approximately 30–40 nm. Based on detailed time-dependent experiments, a possible formation mechanism is proposed. The effects of annealing conditions on the structure and photodegradation properties of the HNWMs are investigated. Furthermore, the effect of hexamethylenetetramine (HMTA) on the structure of HNWMs is studied under the same conditions. In addition, the as-prepared HNWMs are found to exhibit excellent photocatalytic activity towards an aqueous solution of tetracycline (TC) and possess good stability and reusability under visible light. This study provides a reliable strategy for the simple and controllable preparation of hollow photocatalysts for use in wastewater treatment.

Investigation on limiting factors affecting Cu2ZnGeSe4 efficiency: Effect of annealing conditions and surface treatment

This work aims to unveil the optimal annealing conditions and surface treatments of CZGeSe absorbers, synthesized using vacuum-based deposition technique, with an eye to optimizing the main parameters allowing better control of secondary phases formation and improving crystalline quality of this absorber. Firstly, a comparative study is given of one and two-step annealing profiles, where, for each thermal treatment, the optimal temperature is probed. The second section of this study underlines the evaluation of the surface treatment effect on the as-annealed absorber using different etching agents. Finally, the effect of different post-annealing treatment temperatures on the overall performance of the fabricated devices is evaluated. For the studied optimizations, a deep understanding of the cell behavior is provided through structural, morphological and electrical characterizations. Preliminary results have given an efficiency up to 5.6% with higher Voc = 572 mV and FF = 65% compared to the reported record cell using similar absorber (Voc = 558 mV, FF = 59%). This performance is linked to the implementation of a two-step annealing process with lower temperatures (330 °C/480 °C) as it showed the best crystallinity-efficiency trade-off along with the smallest amount of ZnSe secondary phase among all the thermal routines studied. In addition, after the evaluation of several etching agents, the implementation of a KCN etching has shown to be the most effective leading to a remarkable improvement of the PN junction through a surface passivation.

Effect of annealing conditions on the superconducting properties of nano-sized metallic Au-added Bi1.8Sr2Au0.2Ca1.1Cu2.1Oy (Bi-2212) ceramics

In this study, the effects of annealing process on the phase formation and electrical and magnetic properties of nano-sized metallic Au-added Bi-2212 ceramics have been investigated. The Bi1.8Sr2Au0.2Ca1.1Cu2.1Oy including x = 0.2 Au content as starting composition was chosen due to the improved transport properties in the Bi-2212 system, as known in the literature. The samples for the post-annealing technique were exposed at different dwell times (10 m, 30 m, 1 h, and 2.5 h) at a fixed temperature of 870 °C after the application of normal heat treatment of 850 °C for 120 h. The XRD diagrams clearly indicate that a significant part of the phases in all the samples belongs to Bi-2212 phase. SEM results show that all the samples have randomly oriented grain forms as the main characteristic of applied solid-state method. In all cases, the post-annealed samples showed better superconducting properties of Bi-2212 phase, indicating that the increases in the dwell time positively affect its granular polycrystalline character such as inter-connectivity of the grains, the nucleation, and growth of the Bi-2212 phase. Moreover, the sample with dwell time of 2.5 h at 870 °C reveals significant enhancement in the M–H loops compared to the sample with less dwell time, despite the fact that the Bi-2212 phase can easily decompose into secondary phases such as Cu-free and Bi-free due to thermodynamic instabilities of Bi-2212 at temperatures above 860 °C. Finally, the intragranular critical current density values (Jc) have been obtained by using the data from M-H measurements according to the critical Bean model. It has been found that the Jc value (16.5 × 104 A/cm2 in 0.15 T at 15 K) of the sample in the dwell time of 2.5 h at 870 °C is higher than that of the sample (13.4 × 104 A/cm2 in 0.15 T at 10 K) with the same starting composition reported in the literature.

Candle soot carbon nanoparticles as high-performance universal anode for M-ion (M = Li+, Na+ and K+) batteries

Candle soot carbon nanoparticles (CSC-np) collected from candle burning can be converted into an effective universal anode for metal-ion (M-ion; M = Li, Na and K) batteries. As-collected CSC-np particles exhibiting fractal-like interconnected porous carbon nanostructure chains are annealed in air (at 350 °C) and Ar (at 750 °C). The effect of annealing conditions on the structural and electrochemical performance of CSC-np are evaluated. Electrochemical studies show that a two-step annealing process yield most efficient anode and possess superior electrochemical performance for all three Li-, Na- and K-ion batteries compared to CSC-np either annealed only in air or in Ar. As-collected CSC-np, though electrochemically active, exhibit poor characteristics emphasizing the importance of annealing conditions required to activate it to be used as an appropriate anode for M-ion battery application. Detailed structural, microstructural and chemical analyses were made on CSC-np. These studies suggest that crystallinity, surface area and chemical composition of two-step annealing of CSC-np are found to be most favourable for high capacity M-ion storage. At low charging rate, capacity (current-rate) of 1247 mAh g−1 (0.15 A g−1), 461 mAh g−1 (0.02 A g−1) and 406 mAh g−1 (0.02 A g−1) and at high charging rate, capacity of 237 mAh g−1 (25 A g−1), 124 mAh g−1 (25 A g−1) and 22 mAh g−1 (15 A g−1) are realized in Li-, Na- and K-ion batteries, respectively.

Effect of Annealing Process on Mechanical and Microstructural Properties of Al6061/Cu and Al/6063/Cu Cladding Materials Fabricated by the Caliber-Rolling Process.

Al6061/Cu and Al6063/Cu cladding materials have been produced by the caliber-rolling process at 298 K. The prepared specimen was post-annealed at a temperature of 773 K for various time durations, and the effects of annealing conditions have been investigated. Vickers hardness of Al6061, Al6063 and Cu decreases as annealing time decreases; however, that of the interface between Al alloys and Cu increases with an annealing time of 1 h, and then decreases as annealing time increases further. The growth of a diffusion layer in Al6063/Cu is larger than that in Al6061/Cu, because the activation energy in the Al6063/Cu is lower than that in Al6061/Cu during the annealing process. Cracking of the diffusion layer occurs by annealing for extended periods of time in both materials, which contributes to the decrease in hardness.

Fe2+ Diffusion in CVD ZnSe during Annealing in Different (Ar, Zn, and Se) Atmospheres

We have studied Fe2+ diffusion in polycrystalline CVD ZnSe during high-temperature (900–1100°C) annealing in different atmospheres, determined effective Fe2+ diffusion coefficients in CVD ZnSe, and evaluated the activation energy for the diffusion process. Distinctive features of the doping process in Zn vapor have been identified that are responsible for the observed order-of-magnitude increase in Fe diffusion rate in comparison with annealing in Ar and Se. The effect of annealing conditions on Fe diffusion mechanisms is discussed.

Effects of annealing conditions on the properties of SnO films deposited by e-beam evaporation process

Abstract The SnO thin films have been deposited on quartz glass substrates using an e-beam evaporation system at room temperature and different post-deposition thermal treatments have been carried out. In case of annealing in air, n-type polycrystalline SnO films are obtained after annealing at 300 °C and 400 °C, respectively. For the 500 °C annealed film, SnO2 phase is generated due to the strong oxidation. However, when annealed in vacuum, pure p-type polycrystalline SnO films are produced. The feasible and controllable methods of p- and n-type SnO films contributes to the development of high performance devices.

Large-scale chemical vapor deposition of graphene on polycrystalline nickel films: Effect of annealing conditions

In the present study, 8-in. silicon substrates, covered with thin (200 nm) polycrystalline nickel films have been employed for the growth of graphene by chemical vapor deposition. In order to control the uniformity and coverage of the graphene, thin nickel layers were used due to their less deep grain boundary grooves and ability to store less carbon in comparison with thick nickel films (>500 nm). The preferential sites for the growth of multilayer graphene were influenced by the surface pretreatment of the polycrystalline nickel films at 1025 °C under different ambient conditions (hydrogen and vacuum). Significant differences in the surface morphologies were observed for the annealed nickel films. The growth of larger grains up to ~6 μm for the films annealed in hydrogen could be attributed to hydrogen interstitials. On the other hand, grains up to ~3 μm were extracted for the films annealed in vacuum. Graphene was grown after exposing the annealed Ni films to ethylene at 925 °C. The lower range (42–106 cm−1) of full width at half maxima of the 2D band as determined by Raman spectroscopy was obtained for the films annealed in hydrogen as compared to the ones annealed in vacuum (51–128 cm−1), indicating that the thickness uniformity of graphene was strongly influenced by the surface modifications of nickel films.

Effect of heat treatment in vacuum on photoluminescence of anodic alumina.

The results are presented of a study of the photoluminescent (PL) properties of an undoped porous anodic alumina (PAA) and PAA doped with manganese ions. The PAA samples were prepared by anodization of aluminum. The effect of annealing conditions in vacuum on the PL spectra was studied for the first time and a comparative analysis was made with the spectra of the PAA annealed in air. Vacuum annealing was used to obtain oxygen-deficient alumina. A strong dependence of the PAA PL intensity on the annealing temperature in vacuum has been found: for the samples annealed at 600°С, the PL intensity is 15 times higher than that measured on the initial samples, whereas for the samples annealed in air it increases only 4.5-fold with excitation at the wavelengths of 275nm. This is the result of the formation of a high concentration of oxygen vacancies during annealing in vacuum under conditions of oxygen deficiency as compared with the samples annealed in air, where diffusion of oxygen from air leads to a decrease in vacancies. A significant increase in the PL intensity permits consideration of the vacuum-annealed PAA as a promising material for dosimetry.

Improving CIGS thin film by evaporation of CIGS nanoparticles without phase change

CIGS nanoparticles (NPs) were synthesized using solvothermal method and evaporated to deposit the CIGS layer. The effects of annealing conditions and selenization process on the CIGS phase, optical properties and morphology of the resulting layers were investigated. It was found that heating process did not change the phase of CIGS layer and the phase was similar to that of NPs, while the phase of CIGS layer was changed in the selenized layer. The crystallinity was improved for the selenized and heated layers and the grain size and energy gap of the layers were affected by these processes. The AFM images showed that the heated layer had smoother surface compared to the selenized layer. The results revealed that the layers fabricated by evaporation method are very compact and the uniform surface can be achieved only by heating the layer.

Formation of SnSSe thin films by heat treatment of SnS thin films in S/Se atmosphere

In the present work we have deposited ternary SnS-Se thin films by thermal treatment of SnS in S/Se atmosphere. The effect of annealing conditions on the formation of ternary phase was studied and the optimum condition was identified. The structural, morphological and optoelectronic studies were analyzed by techniques such as X-ray diffraction (XRD), Raman spectroscopy, AFM and photo-response. The best results were found for samples treated under S/Se atmosphere at a temperature of 500 °C during 15 min. The XRD results showed good crystallinity. The formation of SnS-Se compound is confirmed by Raman measurements which illustrated the contribution of three peaks reported at 137, 200 and 299.5 cm−1. The morphology of the film was analyzed by the AFM technique and the results were compared with SnS thin films obtaining a slight increase in the roughness of the ternary films and a similar grain size. XPS analyses confirmed the presence of Sn, S and Se elements on the surface of the film. The bandgap of the films was calculated from the optical transmittance in the visible spectrum, showing direct transitions for SnS and SnSSe at 1.3 eV and 1.12 eV respectively. As a fundamental part of this work, SnSSe thin films showed response to light with higher photosensitivity values, in comparison to SnS films without treatment.

The effects of annealing conditions on the wear of PDA/PTFE coatings

The effects of annealing conditions on the micro-wear properties of polydopamine (PDA)/polytetrafluoroethylene (PTFE) coatings were studied using atomic force microscopy (AFM) and molecular dynamics (MD) and coarse-grained simulations. It was found that annealing at 372 °C for 4 min and 8 min caused columnar PTFE particles to elongate into spindle shapes and bind together more tightly than the 0 min annealing sample, which increases the adhesion between PTFE particles and thus the wear resistance of the PDA/PTFE coatings. However, larger islands formed on the 8 min annealing sample make them easily be scraped off, resulting in more wear at the initial scratch stage than the 4 min annealing sample. Longer annealing duration also caused the degradation of PTFE chain structure, which weakens the strength of the PTFE molecular chain and makes the folded structure in the spindle-shaped PTFE particles more readily pulled out to form fibers. Moreover, more weakly bond paralleled spindle-shaped PTFE particles were formed in the sample with longer annealing duration making the coatings less wear resistant. These results show that controlling the final annealing duration of PDA/PTFE coatings is an effective approach for the fabrication of highly durable PTFE coatings.

Effect of annealing conditions on dopants activation and stress conservation in silicon-germanium

As the miniaturization of the size of semiconductor components, the silicon-based transistor has reached its material limitations, so that researching the new materials (silicon-germanium compound) to replace silicon is more important. The ion implantation technology is conducted to discuss the activation issue of p-type dopants, due to silicon-germanium epitaxial layer has the stress effect to enhance the carrier mobility, it is in a conflict of high-temperature annealing. In order to maintain the stress of the epitaxial silicon germanium layer and achieve the activation level of the carrier at the same time, this paper explores a new annealing method - microwave annealing (MWA) with the low thermal budget. In this study, we have investigated that using one-step microwave annealing energy in 3P (1P = 600W), which can make boron implanted into 30% Ge content of silicon germanium layer has the lowest sheet resistance (170 ohm/sq), the best epitaxial layer quality and the better residual stress index (1.48%). However, using two-step microwave annealing energy in 3P+1P over 100s, it can further achieve higher activation level for Si0.7Ge0.3: B sample without stress relaxation. (Sheet resistance as low as 134.6 ohm/sq, Hall measurement mobility of 302.7 cm2/Vs.).

The effect of annealing conditions: temperature, time, ramping rate and atmosphere on nanocrystal Cu2ZnSnS4 (CZTS) thin film solar cell properties

Abstract Cu2ZnSnS4 (CZTS) nanoparticles were fabricated successfully using the hot injection method; CZTS films were deposited by spin coating of nanocrystal ink. The aim of this work is to study the effect of annealing parameters: temperature, time, ramping rate and atmosphere on CZTS thin film structure and optical properties. XRD, Raman Spectroscopy, SEM, EDX mapping are used to analyse the films and they demonstrate the increase in quality and improvement in the crystallinity of CZTS and the homogeneity of elements which is one of the important factors for CZTS thin film solar cells. The crystallinity, structure and chemical composition of CZTS thin films increased and improved under annealing in H2S+N2 atmosphere which demonstrated that annealing at 500 oC for 1 h with a ramping rate of 10 oC/min under H2S+N2 atmosphere is a suitable condition for the fabrication of CZTS thin films used in solar cell devices.

Topochemical polymerization of hierarchically ordered diacetylene monomers within the block copolymer domains

Effect of annealing conditions on the hierarchical ordering of PCDA monomers within the block copolymer supramolecules and their subsequent topochemical polymerization.

Effects of annealing conditions on the oxygen evolution activity of a BaTaO2N photocatalyst loaded with cobalt species

Precise engineering of the cocatalyst-photocatalyst interface and optimization of the cocatalyst dispersion are essential for improving the activity of particulate semiconductor photocatalysts. Herein, we report the effects of varying the conditions used to load cobalt oxide (CoOx) as a cocatalyst on the O2 evolution activity of a particulate BaTaO2N photocatalyst, based on trials in an aqueous silver nitrate solution under visible light irradiation. Annealing under an N2 flow after loading the Co species increased the O2 evolution rate threefold compared to that obtained following conventional annealing under an NH3 flow. Subsequent annealing under an H2 atmosphere exposed the BaTaO2N surface as a result of the aggregation of CoOx particles, and further enhanced the photocatalytic O2 evolution by a factor of two, yielding an apparent quantum efficiency of 0.55% at 420 nm. These results indicate the importance of intimate contact between cocatalyst particles and the photocatalyst, as well as the necessity of exposing the photocatalyst surface to make it available for reduction reactions during photocatalytic water oxidation.

The effect of severe plastic deformation and annealing conditions on mechanical properties and restoration phenomena in an ultrafine-grains Fe-28.5%Ni steel

ABSTRACTThe effect of annealing condition on the microstructure evolution, together with mechanical properties of Fe-28.5Ni steel processed by one and six cycles of accumulative roll bonding (ARB), was explored. The evolution of microstructure was studied by means of Electron Backscattered Diffraction method. The ARB-processed specimens were annealed for 30 minutes between 500°C and 600°C, and the effect of these annealing processes was elaborated. Results showed a significantly reduced martensite phase during ARB process cycles. Moreover, a refined and stabilised ultrafine structure was obtained in 6-cycle ARB-processed specimen. Results also show that by annealing the 1-cycle specimen at 550°C, no significant microstructural change and mechanical properties variation are identified. As such, no significant microstructural change and mechanical properties variation were notified for annealing of 6-cycle ARB-processed specimen at 500°C. However, annealing at 600°C in both conditions led to a complete recrystallisation of the deformed structure. Annealing at 550°C in 6-cycle ARB-processed specimen showed partial recrystallisation as well as an abnormal grain growth characteristic. The abnormal grain growth was seen by annealing of 1-cycle ARB-processed specimen at 600°C. The changing features of dislocations were discussed in these specimens in terms of changing the dynamics of low- and high-angle grain boundaries. Tensile test results also showed a significant increase in the yield/ultimate tensile strengths with the application of ARB cycles. Although ARB process led to a rapid reduction of total elongation, full restoration during high-temperature annealing returned this value back to the initial, non-deformed, condition.

Effect of annealing conditions and temperatures on phase formation and magnetic behaviour of CrFeMnNiTi high entropy alloy

An equiatomic CrFeMnNiTi high entropy alloy (HEA) was synthesized through mechanical alloying (MA) technique. The synthesized HEA consists of FCC, BCC and a minor σ-phase. In order to investigate the phase evolution and magnetic characteristics, the synthesized HEA was annealed under different conditions (vacuum and open air) at two different temperatures (500 and 700 °C). After vacuum annealing at 500 and 700 °C the volume fraction of FCC and BCC phases are changed. However, after open air annealing, the volume fraction of synthesized phases (FCC and BCC) is altered effectively along with the formation of an oxide (Mn2O3) and a spinel type (Fe,Ti)3O4 phase. The synthesized sample exhibits ferromagnetic characteristic and the value of saturation magnetization (Ms) and coercivity (Hc) are found to be 13.39 emu/g (A-m2/kg) and 162.2Oe (12.9 × 103 A/m) respectively. After annealing in vacuum and open air at 700 °C the value of Ms. is found to be 2.95 and 11.63 emu/g (A-m2/kg) respectively. Open air annealed sample at 500 °C shows better magnetic characteristics with Ms = 32.85 emu/g (A-m2/kg) and Hc = 159.34Oe (12.67 × 103 A/m) as compared to the synthesized and annealed samples. The enhanced value of Ms for open air annealed HEA at 500 °C corresponds to increase in the volume fraction of BCC phase and the formation of Mn2O3 and (Fe,Ti)3O4 spinel phase. The effect of annealing conditions on the phase formation and their correlation with magnetic characteristic are discussed and described in detail.

Influence of annealing treatment on the structure and properties of poly(4‐methyl‐1‐pentene)‐based films and membranes

ABSTRACTThe poly(4‐methyl‐1‐pentene) casting films were prepared by melt extrusion and annealed below the melting temperature. The effect of annealing conditions on the structure and properties of casting films and stretched membranes was discussed. In this work, a new peak around annealing temperature, as shown in melting curves, revealed the increase in thickness of lamellar structure. Annealing treatment led to improvements of amorphous thickness and crystal orientation. And the thickness of crystal phase correlated with the logarithm of annealing time. The increase in annealing temperature or time led to the improvements of the hard elasticity of samples. Additionally, the larger porosity of stretched membranes was observed as the annealing time and temperature increased. An optimum annealing condition to prepare microporous membranes was 30 min, 200 °C. This work also discussed the importance of annealing treatment in the preparation of microporous membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46491.

Solution-Processed Efficient Nanocrystal Solar Cells Based on CdTe and CdS Nanocrystals

Solution-processed CdTe nanocrystals solar cells have attracted much attention due to their low cost, low material consumption, and potential for roll-to-roll production. Among all kinds of semiconductor materials, CdS exhibits the lowest lattice mismatch with CdTe, which permits high junction quality and high device performance. In this study, high quality CdS nanocrystals were prepared by a non-injection technique with tetraethylthiuram disufide and 2,2′-dithiobisbenzothiazole as the stabilizers. Based on the CdTe and CdS nanocrystals, devices with the architecture of ITO/ZnO/CdS/CdTe/MoOx/Au were fabricated successfully by a solution process under ambient condition. The effects of annealing conditions, film thickness, and detailed device structure on the CdTe/CdS nanocrystal solar cells were investigated and discussed in detail. We demonstrate that high junction quality can be obtained by using CdS nanocrystal thin film compared to traditional CdS film via chemical bath deposition (CBD). The best device had short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) of 17.26 mA/cm2, 0.56 V, and 52.84%, respectively, resulting in a power conversion efficiency (PCE) of 5.14%, which is significantly higher than that reported using CBD CdS as the window layer. This work provides important suggestions for the further improvement of efficiency in CdTe nanocrystal solar cells.