Papers by Keyword: TEM

Abstract: Synthesis of silver nanoparticles (AgNP) by pulsed liquid laser ablation (PLAL) produces AgNPs that are better suited for biological applications compared to those prepared by standard wet-chemical methods. These were mainly achieved by water ablation with pulse widths in the nanosecond range. In the case of surface NP activation, we previously detected a strong surface-enhanced Raman scattering (SERS) signal from such AgNPs. To do this, we dilute Colloid slightly with LiCl. These surface alterations may have an effect on the NPs' capability to combat bacteria. every time, AgNPs with a median diameter of under ten nm were created., that has been incontestible in alternative studies to be the optimum size for germicidal activity.. Furthermore, minimum restrictive concentration (MIC) values for LiCl-modified AgNPs fell inside a slender vary of 1.1-3.8 g/mL, creating them the foremost efficient. This result's believed to be explained by the metal surface's enhanced surface reactivity, which is brought on by the existence of charged active sites.

Abstract: Phase constitution and phase transition temperature are important factors to influence deformation parameters, recrystallization behavior and density of precipitates of wrought Mg-Zn-Ce alloys. In this work the microstructures and phase constitution of as-cast Mg-6Zn-xCe (x = 0.6, 1, 2) alloys were characterized by XRD, SEM, TEM and DTA. The results show that the major compounds in Mg-6Zn-0.6Ce are blocky Mg₄Zn₇ phase, laminar Mg₇Zn₃ phase and cellular T phase. All compounds are almost blocky and cellular T phase in Mg-6Zn-1Ce alloy, and all T phase transformed to block in Mg-6Zn-2Ce alloy. The onset temperatures of phase transformation of T phase are increased with increasing Ce contents due to the decrease of solid solubility of Zn in T phase. The corresponding endothermic peaks of T phase in Mg-6Zn-0.6Ce, Mg-6Zn-1Ce and Mg-6Zn-2Ce are 358 °C, 494 °C and 514 °C, respectively. The increase of content of Ce result in the decrease of the concentrations of Zn in matrix, which leads to the decrease of β₁′ precipitate density and the increase of onset temperatures of melting of matrix.

Abstract: Cerium oxide has been widely used in many application. One of the most important applications is for chemical mechanical application/planarization (CMP). In the current work, ceria nanoparticles have been prepared via precipitation method using ethanol/water mixture as the solvent, while cerium nitrate hexahydrate as cerium source and ammonium solution as precipitant. The effects of two different temperatures (i.e. 30 and 50°C) and two different apparatus setup (i.e. Setup A and Setup B) on the morphology and crystallite size of the ceria nanoparticles were studied. The morphology and crystallite size of the ceria were analyzed using X-Ray Diffractometer (XRD) and Tranmission Electron Microscopy (TEM). The XRD analysis results showed that the peak intensity of the ceria nanoparticles prepared by using setup B was much higher than the ones prepared by using Setup A. The XRD results revealed that the crystallinity growth and mean crystallite size of the ceria was better or higher when using Setup B. The crystallite size of the calcined ceria nanoparticles were found to be 9.8; 10.5; 14.5 nm for Ceria-1, Ceria-2, and Ceria-3 samples, respectively. In addition, the TEM images showed that Ceria-3 sample exhibited better morphology and less agglomerated compared to that of Ceria-1 and Ceria-2 samples. Futhermore, Ceria-3 sample also had better dispersion stability compared to that of Ceria-1 and Ceria-2 samples due to its better morphology.

Abstract: Silver nano-colloids have been generated via Laser Ablation Synthesis in Solution (LASiS) system. Nanoparticle formation with particle size below 50 nm in DI water was confirmed using UV-VIS spectroscopy, Dynamic Light Scattering (DLS) technique, and transmission electron microscopy (TEM). Supercapacitor structure, having dimension 11 mm x 10 mm, was successfully Aerosol Jet printed on an untreated polymer substrate using as produced LASiS silver nano-colloid.

Abstract: This paper discusses a novel annealing technique for 4H-SiC implants which involves the use of pulsed XeCl laser (l=308 nm). In particular, an absorbing graphitic coating is used to protect the sample from surface atoms desorption or phase separation. Both conventional furnace annealing and laser annealing on P and Al implants, commonly employed for source and body in metal-oxide-semiconductor field-effect transistors (MOSFETs), were examined through Transmission Electron Microscopy (TEM), u-Raman spectroscopy and Scanning Electron Microscopy (SEM). It is shown that the implant activated through traditional thermal annealing at 1650 °C for 30 min has a large network of dislocation loops, while they do not appear to be present in the laser annealed implant. Through Raman spectroscopy and SEM investigations both the crystalline quality of the laser annealed sample and the integrity of the surface were attested.

Abstract: In this study, the synthesis and analysis of the crystal structure of silver nanowires (AgNWs) have been performed using the polyol method. In this research, materials used as the main raw material were silver nitrate (AgNO₃). Polyvinyl pyrrolidone (PVP) was used as a capping agent and stabilizer, and Iron (III) Chloride (FeCl₃) for controlling the shape and size of AgNWs. AgNWs were synthesized using two different solvents i.e., ethylene glycol (EG) and propylene glycol (PG). The crystal structure of AgNWs was analyzed using X-ray diffraction (XRD) with a scanning 2θ in the range of 20° to 90°. Furthermore, the structure and electron diffraction patterns were analyzed using transmission electron microscopy (TEM). The XRD pattern of the AgNW sample also has five diffraction peaks, these five diffraction peaks were identified at 38.24°, 44.42°, 64.54°, 77.52°, and 81.68° representing lattice constants (111), (200), (220), (311), and (222), respectively. Based on the results of the calculation of lattice constant values of AgNWs-EG and AgNWs-PG were 4.084 Å. The TEM images of AgNWs-EG have a diameter of 84 to 133 nm, corresponding to the SEM calculation data having a diameter of 109 ± 22 nm. AgNWs-PG has a diameter of 84 to 264 nm. The study results revealed that the results of the characterization performed are interconnected. The XRD characterization results revealed that both samples were crystal-indexed. AgNWs-PG has a larger crystal size than AgNWs-EG.

Abstract: The commercial Al–Zn–Mg–Cu-based alloys (7xxx series) are widely used in metalworking, automotive and aircraft industries as well as in aeronautical applications. The positive effect of the Sc,Zr-addition on mechanical properties of laboratory Al-based alloys is generally known. The microstructure, mechanical and thermal properties of the conventionally cast, heat-treated and cold-rolled Al–Zn–Mg–Cu (–Sc–Zr) alloys during isochronal annealing and natural ageing were studied. Microstructure observation by scanning electron microscopy and transmission electron microscopy proved the Zn,Mg,Cu-containing eutectic phase at grain boundaries. The distinct changes in microhardness curves as well as in a heat flow of the alloys studied are mainly caused by dissolution of the clusters/Guinier-Preston (GP) zones and precipitation of particles from the Al–Zn–Mg–Cu system. An easier diffusion of Zn, Mg and Cu atoms along dislocations in the cold-rolled alloys is responsible for the precipitation of the Zn,Mg,Cu-containing particles at lower temperatures compared to the cast alloys. Microhardness values of the heat-treated alloys increase immediately from the beginning of natural ageing due to the formation of the clusters/GP zones. Addition of Sc and Zr elements results in a higher hardness above ~ 270 °C due to a strengthening by coherent secondary Al₃(Sc,Zr) particles with a good thermal stability. Sc,Zr-addition has probably no influence on the evolution of the solute clusters/GP zones.

Abstract: This study was conducted to study the effect ultrasonic vibrations on the evolution of the microstructure and hardness of the AlMg3 aluminum alloy in a solution treated condition. To understand the process physics in this article, after the deformation the microstructures of the samples before and after deformation were analyzed by the light and electron microscopy, including the electron backscatter diffraction (EBSD) analysis. The result evidently shows that the ultrasonic-assisted deformation has a meaningful influence on the grain refinement – the application of the USV enhances the formation of deformation bands and new sub-grains. This resulted in a certain hardness enhancement.

Abstract: In this study, commercial Al-3%Mg aluminium alloy was subjected to ECAP processing using two different ECAP die configurations. The first one – conventional and the second one modified in which a part of the exit channel in the ECAP die, causes twist deformation, to impose extra shear strains to the sample. The local changes in microstructure were characterized by Light Microscopy, SEM equipped with an EBSD facility and TEM. Mechanical properties of the ECAP processed samples were compared based on hardness measurement. The results showed that when ECAP with modified die, the greater grain and crystalline refinement is possible. The microstructures exhibit high dislocation density within subgrains with non-equilibrium and Moiré boundaries. Moreover, the mechanical examinations display a significant improvement in hardness and calculated yield strength when the ECAP process is conducted using a modified die.

Abstract: In this work, zinc oxide were synthesized by biological method using Aloe vera plant and the water solution of zinc . The detail characterization of the nanoparticles was carried out on different PH value . The samples were examined with an X-ray diffraction device and the results were almost identical to the JCPDS standard. It was also observed that the size of the particles was affected by the basic and acidic medium in a large way, as the results obtained from the Transmission Electron Microscopy The particle sizes ranged from 5nm to 100nm depending on the change of the PH value.