Papers by Keyword: Surface Morphology

Abstract: In this study, zinc telluride (ZnTe) thin films were deposited using radio frequency (RF) sputtering at various powers ranging from 100 to 250 W for 60 minutes. Structural and optical properties were investigated as a function of RF power. X-ray diffraction (XRD) analysis revealed that increasing the RF power led to a growth in the crystallite size from 3 to 9.4 nm, while dislocation density and microstrain decreased. The ZnTe films exhibited a cubic crystal structure with a lattice parameter of 6.08 Å. Scanning Electron Microscopy (SEM) showed that the film surfaces are uniform and free of cracks. Optical measurements using UV-Vis-NIR spectrophotometry indicated that both transmittance and optical band gap increased from 1.82 to 1.94 eV with increasing RF power. The modulation of the optical and structural properties of ZnTe thin films by RF power, as demonstrated in this study, opens perspectives for optimizing these materials in real device architectures, particularly for more efficient solar cells or high-performance sensors.

Abstract: Modern engineering components require composites that are robust, lightweight, and inexpensive as integrated particulate for solid strengthening and corrosion resistance alloy. This study envisions a snail shell particulate (SSP) as a potential biofillers on aluminium alloy due to its inherent characteristics. The fabrication of the developed alloy was done through liquid stir casting method with determination to examine the correspondent physical, optoelectrical, electrochemical, and microstructural behaviour for chemical application. Composite infringement varies from 10% - 25% SSP after optimization using design of experiment. The result of electrochemical analysis showed a notable decrease in corrosion rate with increased SSP content from 12.06 mm/yr, of control sample to (75Al-25SSP) which had a corrosion rate of 7.59 mm/yr, resulting in a 40.1% drop-in degradation rate. Notably, microhardness properties increase from 28.1 to 45.5 HRB as a result of solid strengthening characteristics of doped fillers. Opto-electrical assessment demonstrated decreasing resistivity with higher SSP content, indicating improved current flow resistance. The microstructural properties showcased SSP's distinctive dispersion with few micro pores. The intermetallic phases confirmed their integration into the metal matrix by providing an enhancing adhesion and solid crystalline structure.

Abstract: This research focuses on reusing waste materials to reduce the demand for fresh raw materials, thereby preserving natural resources. This approach also minimizes the energy and greenhouse gas emissions of extracting and manufacturing raw materials. We are developing eco-friendly, versatile polymer composites, aligning with the circular economy movement's goals of promoting sustainable resource utilization and waste minimization through closed-loop product life cycles. This research uses a hybrid polymer reinforced with lignocellulose agro-fibers (LCAF) from vegetable waste residues. Three different agro-wastes, such as orange peels, jute, and palmyra fruit peduncle, have been used. It investigates two phases, initially different fiber ratios from 3 to 12% and varying fiber lengths from 5 to 20 mm in the secondary phase, respectively. The LCAF is obtained through mechanical and chemical pre-treatment to enhance its properties for use in food packaging. The fiber containing 9% LCAF demonstrated a superior hardness and tensile strength of 118 BHN and 63 MPa compared to the polyester matrix. The water absorption improved from 2.03% to 4.76%, depending on the type of raw material and pre-treatment used to produce the LCAFs.

Abstract: This paper presents an investigation into the surface morphology control of 4H-SiC (0001) wafers cut to 4º off during thermal processing, aiming to suppress the propagation of basal plane dislocations (BPD) into the epitaxial growth layer. Developing methods for debunching rough surfaces with macro step bunching (MSB) using thermal processes removes many of the limitations of the conventional epitaxial growth process. This study presents a surface morphology control method that includes debunching of steps by thermal sublimation etching/growth using the Dynamic AGE-ing^® (DA) method. By controlling the surface morphology before and after growth using this method, the dependence of the BPD-threading edge dislocation (TED) conversion ratio on surface morphology was systematically revealed. By selecting the optimal pre- and post-growth surface morphology, a 100 % BPD-TED conversion ratio was obtained for the 10 mm × 25 mm area. It was indicated that an innovative and stable surface morphology control technique using the DA sublimation process could solve numerous technological challenges in various fields.

Abstract: The synthesis of ceramic composites consisting of cerium and titanium-doped zirconium (ZCT) oxide was achieved by the solid-state reaction technique. The ZCT composite ceramic powder undergoes sintering at various temperatures, including room temperature (RT), 1000°C, 1100°C, 1200°C, and 1300°C. Extensive study has been conducted on ceria-based materials in the field of catalysis, owing to their vast array of uses. Nevertheless, there was a limited amount of research conducted on the impact of ceria in the solid-state reaction approach. The current study employed a solid-state reaction method to fabricate ceramic composites comprising ZrO₂, CeO₂, and TiO₂. Various sintering temperatures were employed in the process. This study aimed to evaluate the impact of the sintering effect of ZCT ceramic oxides on several aspects, including crystal structure, surface morphology, optical properties, and electrical properties. The ZCT ceramic oxide underwent sintering at room temperature (RT), 1000°C, and 1100°C, resulting in the formation of a monoclinic crystal structure. However, sintering at 1200°C and 1300°C led to the presence of mixed phases, characterized by both monoclinic and tetragonal crystal structures, as observed through X-ray diffraction (XRD) analysis. When the sintering temperature is increased from 1000 to 1300°C, there is a modest drop in the band gap of a ZCT material from 3.43eV to 3.25eV. frequency(1mHZ-200kHz) dependence of dielectric constant, dielectric loss and ac electrical conductivity of the synthesized composites were carried out. The results indicate that dielectric constant and loss decreases with frequency rises and reaches a constant value at higher frequencies. The electrical conductivity of all ZCT samples exhibits an increase as the frequency is raised, whereas it reaches a minimum at lower frequencies.

Abstract: Laser shock peening has been widely studied and pioneeringly applied in aerospace industry as a life-extension technology for structured mechanical components. However, in other promising fields such as nuclear power industry, little has been studied concerning such critical issues as long-distance transmission of the laser beam by optical fiber and optimized parameters of typically low pulse energy with micrometer-sized beam spots. In such scenario, the overlapping rate between adjacent small spots plays a critical role in obtaining homogenous residual stress and surface morphology. In this study, a three-dimensional finite element model in AISI 420 martensitic stainless steel has been developed to correlate the residual stress as well as surface morphology with varying overlapping rates. Multiple laser spots are loaded with VDLOAD user subroutine in Abaqus. The residual stress distribution is analyzed with respects of laser shocking and in-depth planes. And the surface morphology is evaluated in terms of depression depth as well as surface roughness. Combined results suggest that the overlapping rate of 61% as an optimized value, which can be used as a basis for future experimental studies and industrial applications.

Abstract: The present study deals with the effect of the Diatomite (D) microcomposite with and without chemical modification in a polypropylene (iPP) blend. The objective is to achieve a material with a better performance at a lower cost and more accessible and more suitable processing. The chemical surface modification of Diatomite (MD) was achieved using a crosslinking system based on a mixture of sulfur, accelerator, and peroxide. The iPP/Diatomite composite was prepared by batch melt mixing in a Brabender Plasti-Corde under intense shearing at high temperatures and varying the Diatomite content from 0 to 15 wt%. The rheological behavior was examined by monitoring the Brabender Plasti-Corde torque/time rheographs. Different techniques were used to characterize the sample: Fourier transform infrared spectroscopy (FTIR), WAXS, SEM, and DSC. In addition, tensile strength tests and impact strength mechanical tests were conducted to study the performance. It was found that chemical modification strongly affected rheological behavior and generated a new rheological characteristic compared to the composites without modification. This has induced a new structure form that has improved mechanical properties. Moreover, the chemical modification used and due to its simplicity, can be successfully used on an industrial scale with the appropriate process.

Abstract: High quality semipolar (1122) AlN films have been grown on (1010) m-plane sapphire substrates with the help of dual moderate-temperature-grown (MTG) AlN interlayers by using metal-organic chemical vapor deposition technology. The layer thickness of the semipolar (1122) AlN film was determined by employing relative optical transmittance spectrum measured with ultraviolet-visible spectrophotometer. The effect of the insertion of 80 nm-thick MTG AlN interlayer on structural and optical properties was investigated in detail based on the characterization results of the atomic force microscopy, high-resolution X-ray diffraction, and Raman spectroscopy. Comparing with the semipolar (1122) AlN film grown without the MTG AlN interlayer, both the surface morphology and crystalline quality of the semipolar (1122) AlN film grown with the insertion of dual 80 nm-thick MTG AlN interlayers have been improved significantly. In fact, the root mean square value of the surface roughness decreased from 3.5 to 1.4 nm, and the full width at half maximum value of X-ray rocking curve decreased from 1667 to 1174 arcsec, respectively. These facts reveal that the insertion of the dual MTG AlN interlayers is a powerful method to improve the surface morphology and crystalline quality of the semipolar (1122) AlN films owing to the formation of nanoscale patterned substrate-like structure and its blocking effect on the propagation of the dislocations.

Abstract: We study the crystal structure of carbon-doped Al-rich MnAl thin films deposited on Si substrates. The effects of carbon content and vacuum heat treatment parameters are studied. It is shown that the carbon content, in combination to heat treatment, allows to tailor structural phase transitions in the films. The main phases detected are Al₂Mn₃, pure Mn, and pure C. As carbon content increases, the amount of Al₂Mn₃ phase decreases and the content of pure crystallized Mn phase increases. In addition, it is shown that as the heat treatment temperature increases – up to 500 °C – the Al₂Mn₃ phase content increases, whereas a pure C phase appears at lower temperatures.

Abstract: Nowadays, nanomaterials have become the research hot topic by the virtue of their fascinating attributions in human civilization. Zinc phosphate nanoparticles (ZnPNPs), an inorganic material, possess some unique features, such as high thermal stability, low solubility in corrosive media, biocompatibility, non-toxicity and luminescence property. As a result, ZnPNPs have enormously been explored by researchers in many important applications, such as anticorrosion pigment, drug delivery, antibacterial as well as anticancer agents, biocatalyst, lubricant additives, regeneration of bone tissues and removal of toxic metal from the environmental samples, and so on. Considering diversified applications potential, morphologically different ZnPNPs have mainly been fabricated by precipitation, sonochemical and biological methods. The surface property of ZnPNPs differs with pH, temperature, reaction time, and substrate concentrations. One-step in situ and facile synthetic procedures, as well as greener synthesis protocols of ZnPNPs can be advantageous over conventional methods to eliminate toxic chemicals and by-products. In addition, both artificial and natural polymer-modified ZnPNPs would offer improved properties, such as better colloidal stability, option for further functionalization, and render desired biocompatibility of prepared hybrid nanocomposite particles in applying for targeted applications. Furthermore, both in vitro and in vivo studies of polymer functionalized ZnPNPs can be an attractive research topic in biotechnological and electrochemical fields. Therefore, the current review provides a summary of the recent progress on the fabrication methods, an opportunity for the future directions to the researchers in the improvement of shape-selective synthesis and application potentials of ZnPNPs.