Papers by Keyword: SEM

Abstract: This study reports the impact of two distinct capping agents on the structural and optical properties of CdZnS nanoparticles (NPs) using an aqueous colloidal synthesis technique. The samples were characterized using SEM, UV-Visible, Photoluminescence (PL) spectroscopy and X-ray diffraction (XRD). In all of the synthesized samples, SEM exhibits a granular texture with uniform distribution of particles. The capping agent helps in crystallite size reduction and hexagonal structure. The variation in the band gap is caused by quantum confinement depicted in PL spectra. The PL analysis also reveals the excitation-dependent blue emission for all the synthesized samples, with the capping agent-processed samples exhibiting a less pronounced blue shift in the emission peak. The IV characteristics measured via four probe shows the semiconducting nature of the synthesized nanoparticles.

Abstract: The synthesis of Cd_0.5Zn_0.5S/PVP and Cr_x: Cd_0.5-xZn_0.5S/PVP(x = 0.02, 0.04, 0.06, 0.08) nanoparticles were carried out using a chemical co-precipitation reaction using homogeneous solutions of cadmium, zinc and chromium salts. The impact of Cr doping on the morphological, structural, and optical characteristics of nanoparticles was investigated in this study. Energy dispersive analysis of X-rays (EDAX), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Diffuse Reflectance spectroscopy (DRS) have been utilized to examine the structural, optical, and morphological properties of elements. EDAX analysis verified the existence of chromium (Cr) within the cadmium zinc sulphide (CdZnS) crystal structure. The XRD analysis revealed that the Cr doped CdZnS nanoparticles exhibited crystallization in the zincblende structure, with a predominant orientation along the (1 1 1) plane. The nanoparticles have an average size ranging from 3 to 6 nm. The particle size determined from the SEM images corresponded with the findings from the XRD analysis. The DRS revealed that the increase in Cr concentration caused a shift of the absorption edge towards lower wavelengths. The bandgap energy estimates ranged from 3.85 to 4.05 eV. The blueshift is caused by the quantum confinement phenomenon.

Abstract: Strontium Calcium Titanate (Sr_0.9Ca_0.1TiO₃) ceramic powders were synthesised using a solid sintering technique and were uniaxially pressed and sintered at different temperatures of 1100 °C, 1150 °C, 1200 °C, 1250 °C, and 1300 °C for three hours. Physical, phase, microstructure and dielectric properties were studied. Perovskite Cubic Strontium Calcium Titanate phase was crystallized. With an increase in sintering temperature, the density and grain size of Sr_0.9Ca_0.1TiO₃ ceramics increased. Grain boundaries were observed in the microstructure of Sr_0.9Ca_0.1TiO₃ sintered at higher temperatures. At room temperature, the dielectric constant and dielectric loss are observed to increase with the increase in sintering temperature. AC conductivity enhanced with sintering temperature.

Abstract: This study investigates the influence of Cu and La additions on the solidification structure and phase formation behavior of Fe-6.5wt%Si high silicon steel. The alloy's phase composition and structure were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic performance was measured using a high and low-temperature vibration magnetometer. The results revealed that the microstructure of the Fe-6.5wt.%Si alloy ingot, treated with Cu and La inhibitors, is segmented into three layers. From the bottom to the top, the phase morphology is fine crystals, columnar crystals, and isoaxial crystals. Adding Cu and La inhibitors significantly refined the Fe-6.5wt.%Si alloy; adding 0.05% Cu transformed thick columnar crystals into slender branches, while 0.03% La led to a uniform refinement of grains. Cu addition maintained the alloy saturation magnetization strength but increased coercivity. La addition decreased the alloy's saturation magnetization and increased coercivity.

Abstract: Fe-6.5wt%Si high silicon steel alloy was prepared using the vacuum induction melting method. Ordered phase formation in Fe-6.5wt%Si alloy was inhibited by adding trace Cu and induction cycle heating purification treatment. The microstructure and magnetic properties of high silicon steel were investigated. The results show that with the increase of Cu content, the alloy microstructure first changed from coarse grain to fine isoaxial crystal, followed by strip dendrite, with ordered cracking. The saturated polarization strength of the alloy decreased from 25.1 emu of the sample without adding Cu and heating once to 21.5 emu for seven cycles, the residual magnetic polarization increased from 0.0255 emu to 0.048 emu, the slope of the magnetization curve slowed down, and the coercive force increased from 2.4 Oe to 4.0 Oe. With the increase of cyclic heating times, the microstructure of the alloy without added Cu refined and transitioned from columnar to equiaxial crystals, from isoaxial dendrite to strip with the addition of 0.03 wt%Cu, and from strip to isoaxial structure with the addition of 0.05 wt%Cu. With the increase of cycle heating times, the saturation magnetization strength of the alloy without Cu and with 0.03 wt%Cu alloy increased, while the recalcitrant force reduced. Conversely, the saturation polarization strength decreased for the alloy with 0.05 wt% Cu, and the coercive force was also reduced.

Abstract: Sn-Cu-Ni-Ge (SN100C®) is a high-performance Pb-free solder alloy widely used in the electronics manufacturing industry due to its excellent soldering performance and lower cost. SN100C has a huge potential to replace the commonly used Sn-Ag-Cu solders. This work investigates the effect of different strain rates (10^-3 to 8×10^-1s^-1) on tensile performance for bulk SN100C samples at room temperature. The tensile properties, e.g., elastic modulus (E), yield strength (σ_y) and tensile strength (σ_T) are determined from the stress-stress curves. The value of σ_y and σ_T increases with increasing strain rates and this increase becomes less prominent at higher strain rates. Necking and ductile fracture are observed for all samples with a significant number of dimples, voids and tongues formed. The level of ductility of the samples decreases with increasing strain rates, which is further confirmed by the stress-strain behaviour. The microstructural evolution of the samples is evaluated by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) to reveal the generation of recrystallisation and fracture of the intermetallic compounds (IMCs) at the fracture tips and identify the embedded of IMCs within the sample matrix.

Abstract: Thin films of pure and iron doped MnS, have been deposited on glass substrates using a straightforward and cost-effective technique named Chemical Bath Deposition (CBD). The temperature of the heating water bath was maintained at 90°C for three hours of deposition. Deposition is done by varying the doping concentration of Fe from 0 to 10%. Manganese chloride, iron chloride tetrahydrate, urea, and thioacetamide were the precursors employed in this work. The X-ray diffraction method was used to ascertain the thin film's structural properties. Using the Scherrer formula, the average crystallite size for an undoped MnS thin film was observed to be 30.28 nm and is decreased to 24.02 nm for 4% of Fe doping. For an undoped MnS thin film, the values of dislocation density and material strain were 1.09× 10⁻³(𝑛𝑚)⁻² and 3.418× 10⁻³, respectively. These values were increased to 1.73× 10⁻³(𝑛𝑚)⁻² and 4.65× 10⁻³, respectively due to decrement in the crystallite size. Grain size and morphology were examined using Scanning Electron Microscopy (SEM). Micrographs of samples were obtained at different magnifications and their values were noted as 0.9 μm for pure and 4.69 μm for 4% Fe doped thin films. Optical properties were determined using DRS method. The energy band gap was found as 2.21 eV for pure samples and it was decreased to 2.14, 2.09, 1.98, 1.96 and 1.93 eV for 2, 4, 6, 8 and 10% iron doping, respectively. Solar cells, solar selective coatings, sensors, optical mass memory, and anti-reflection coatings have all made substantial use of MnS thin films.

Abstract: The lightweight composition, non-magnetic nature, and machinability of aluminum alloy A356 make it an important material in many industries due to its significant mechanical properties such as strength, ductility, fatigue resistance, and castability. Aluminium alloy forms an oxide layer when exposed to air. The microstructure of this alloy plays a critical role in determining its mechanical behavior. This study utilized aluminum alloy A356, composed of 92.05% aluminum, 7% silicon, 0.35% magnesium, 0.20% copper, 0.10% manganese, and 0.10% zinc. This alloy exhibits extremely high corrosion resistance, similar to stainless steel, with a melting point of 650°C. The study examines multi- component (mainly Al with Si) A356 containing small amounts of Mg, Cu, Mn, and Zn for their complex microstructural behavior. It includes observations using techniques such as optical microscopy and X-ray diffraction (XRD). This research was carried out to investigate different areas of the same metal’s microstructure and to discover the influence of cooling rates during the solidification process. The findings revealed that there are dissimilarities between the central parts and outer areas, as well as similarities between the two side portions. Also, this study highlights processing conditions’ impact on the material response while looking at heat transfer rate effects during solid-state transformation. The findings of this study highlight the presence of distinct microstructures (dendritic and equiaxed structures) across different sections of the cast Aluminum alloy A356. These findings contribute to a better understanding of the microstructure-property relationship of Aluminum alloy A356, assisting in improvising design and manufacturing processes for enhanced performance.

Abstract: Investigation of the doped areas in 4H-SiC power devices has been done by non-destructive characterization methods. It consists of local surface potential measurements by Kelvin Probe Force Microscopy (KPFM) coupled with scanning electron microscopy (SEM) and µ-Raman spectroscopy. Near-field mappings of the devices’ surface have been realized, allowing us to discern the differently doped areas.

Abstract: In this article, a picosecond laser source was employed to irradiate the nanostructured ZnO thin film prepared by the sol-gel method. The impact of laser irradiation on the characteristics of a nanostructured ZnO thin film was investigated. Analysis using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy confirmed a significant influence on the structure of the ZnO thin film. As the duration of laser irradiation (the number of laser pulses) increased, there was a remarkable decrease in both the electronic and photoluminescence intensities of the nanostructured film. Tauc's plot indicates a noticeable change in the optical band gaps of the thin film with the increase in irradiation time. The morphological image suggests that the laser irradiation energy induces both degradation and modification of the film surface, consequently causing changes in the structural, absorption, and photoluminescence properties of nanostructured ZnO. The observed effects are attributed to alterations in the crystal structure and size of the nanostructured ZnO film, as confirmed by XRD. The reduction in photoluminescence intensity observed over the laser irradiation times may be a result of potential degradation in the crystalline structure of the nanostructured ZnO film.