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Full-Text Articles in Nanoscience and Nanotechnology
Investigation On The Tribological Properties Of Al2o3-Tic Substrates In Fixed Abrasive Lapping For Data Storage Application, Benjie Fernandez
Investigation On The Tribological Properties Of Al2o3-Tic Substrates In Fixed Abrasive Lapping For Data Storage Application, Benjie Fernandez
Chulalongkorn University Theses and Dissertations (Chula ETD)
Alumina titanium-carbide (Al2O3-TiC) or simply AlTiC substrates were widely used in the magnetic recording industry for their superior mechanical and tribological properties. This study investigated the effect of AlTiC substrate properties in slider lapping tribology. Two types of AlTiC substrates, Type-A AlTiC and Type-B AlTiC equipped with an electro lapping guide (ELG), fully functional reader and writer devices were used in the study. Type-A AlTiC was found to have higher hardness and lower coefficient of friction resulting to lower lapping material removal rate and smoother surface finish. The difference in mechanical properties were attributed to the crystal structure and chemical …
Synthesis Of Fes2 And Fes2-Mns2 Composite Nanostructured Photocatalysts For Dye Degradation, Septian Budiman
Synthesis Of Fes2 And Fes2-Mns2 Composite Nanostructured Photocatalysts For Dye Degradation, Septian Budiman
Chulalongkorn University Theses and Dissertations (Chula ETD)
This research addresses the environmental challenge of synthetic dye pollution by developing and evaluating novel photocatalysts. Iron pyrite (FeS2), an abundant and low-cost semiconductor, is a promising candidate for photocatalysis, but its practical application is severely limited by its high instability and susceptibility to photocorrosion under light irradiation. To overcome this limitation, this study investigates the synthesis of bare FeS2 nanoparticles and their modification with MnS2. FeS2 nanoparticles were first synthesized via a hydrothermal method at 180°C, using FeSO4·7H2O and Na2S2O3·5H2O precursors. Subsequently, a FeS2-MnS2 material was synthesized using a facile reflux method, with optimal conditions identified as 3 hours …
Materials Development Towards Enhanced Performance And Stability Of Zinc-Iron Flow Batteries., Parimol Tippayamalee
Materials Development Towards Enhanced Performance And Stability Of Zinc-Iron Flow Batteries., Parimol Tippayamalee
Chulalongkorn University Theses and Dissertations (Chula ETD)
To reduce CO2 production from fossil fuel consumption, which is the main cause of global boiling, renewable energy is necessary to help achieve zero CO2 emissions. However, large-scale renewable energy systems need huge stationary energy storage with high performance, long lifetime, and reasonable prices to serve energy stock during downtime. Redox flow batteries (RFBs) are one of the promising technologies for stationary energy storage applications. Yet, the current vanadium-based RFBs are plagued by high costs, material toxicity, and environmental concerns. Therefore, there is a need to develop lower-cost, safe, and environmentally friendly RFBs for long storage. For this reason, zinc-based …
Electrolyte/Electrode Interfacial Electrochemical Optimization Strategies For Durable Aqueous Zinc-Ion Batteries, Jingjing Niu
Electrolyte/Electrode Interfacial Electrochemical Optimization Strategies For Durable Aqueous Zinc-Ion Batteries, Jingjing Niu
Chulalongkorn University Theses and Dissertations (Chula ETD)
Aqueous zinc ion batteries, as a type of secondary battery using inorganic aqueous solution as the electrolyte, are considered to be a strong contender in the field of future energy storage technologies due to their high theoretical electric capacity, high safety, low cost and environmental friendliness. However, aqueous zinc ion batteries also face some challenges. The first is the relatively low energy density, which requires further optimisation of electrode materials and battery structure. Secondly, the creation of zinc dendrites can reduce the cycling stability and safety of the battery. In addition, prolonging the cycle life is also a pressing issue. …
Development Of Janus Membrane From Electrospun Nanofiber For Membrane Distillation Processes, Michaela Olisha Lobregas
Development Of Janus Membrane From Electrospun Nanofiber For Membrane Distillation Processes, Michaela Olisha Lobregas
Chulalongkorn University Theses and Dissertations (Chula ETD)
The Janus membrane, characterized by surfaces with opposite wettability, represents an innovative design for membrane distillation (MD). This study introduces new methods for fabricating MD membranes with tailored surfaces to address fouling and wetting challenges in saline systems. A nanofibrous Janus membrane was developed, featuring an omniphobic substrate as the non-wetting layer and a hydrophilic top coating as the wetting layer. Using the dual-spinneret system for simultaneous electrospinning and electrospraying, a composite substrate membrane, comprising a loose network of PVDF nanofibers and PVDF-fluorinated TiO2 microclusters, was produced. This membrane exhibited high resistance to liquids, including water, glycerol, diiodomethane, and saline. …
Air Flow Behavior Assessment In Particulate Filtration Efficiency (Pfe) Tester Via Computational Fluid Dynamics (Cfd), Muhammad Amer
Air Flow Behavior Assessment In Particulate Filtration Efficiency (Pfe) Tester Via Computational Fluid Dynamics (Cfd), Muhammad Amer
Chulalongkorn University Theses and Dissertations (Chula ETD)
Particulate Filtration Efficiency (PFE) assessment is critical for evaluating filter media. There are several PFE testing protocol depending on products and issuing countries, for example ASTM-F2299 standard for disposable medical masks, NIOSH-TEB-APR-STP-0059 for N and R series respirators, and ISO-29463 for HEPA filters. While the PFE testing principles of all standard are the same, their requirement, testing protocol and minute details are different. Air flow characteristic before and after filter media in testing chamber is very important to accuracy of PFE measurement, especially for ASTM F2299 standard. We have developed a custom PFE tester per ASTM F2299 using a simple …
Superconductivity In 2d Janus Monolayers And Bilayers, M Munib Ul Hassan Noor Ul Taqi
Superconductivity In 2d Janus Monolayers And Bilayers, M Munib Ul Hassan Noor Ul Taqi
Chulalongkorn University Theses and Dissertations (Chula ETD)
Janus transition metal dichalcogenides (J-TMDCs) is a new class of materials which shares the same honey-comb structure as graphene and conventional transition metal dichalcogenides (TMDCs) in monolayer. They have versatile physical and chemical properties which mainly feature out from their broken out of plane symmetry. This asymmetry results in an intrinsic electric field orthogonal to their plan. The presence of an intrinsic electric field gives rise to many novel properties like the Rashba effect, increased charge carrier concentration, Schottky barrier, excitons, and superconductivity. Also, they exist in multiple structural phases like, 2H, 1T, 1T' with the electrical properties shifting from …
Value-Added Natural Fiber As A Biocompatible Substrate For Chemical Sensor Applications, Wisarttra Phamonpon
Value-Added Natural Fiber As A Biocompatible Substrate For Chemical Sensor Applications, Wisarttra Phamonpon
Chulalongkorn University Theses and Dissertations (Chula ETD)
This dissertation focuses on the improvement and value added of natural fiber extracted from the UHT milk carton waste, and raw silk cocoon to fabricate the biocompatible substrate for chemical sensors, principally in colorimetric and electrochemical sensors, which is allocated in 3 main parts. Initially, the background studying of the surface modification and the function of natural fiber based chemical sensor for food quality control and clinical diagnosis will be explained in a review article. Subsequently, the development of recycled cellulose from UHT milk carton waste as a novel substrate of dual lactate sensor for milk spoilage indication will be …
Nanoporous Cu-Based Catalytic Electrodes For Electrochemical Conversion Of Carbon Dioxide, Jidsucha Darayen
Nanoporous Cu-Based Catalytic Electrodes For Electrochemical Conversion Of Carbon Dioxide, Jidsucha Darayen
Chulalongkorn University Theses and Dissertations (Chula ETD)
This research investigates the strategies to enhance copper electrodes for carbon dioxides reduction reactions (CO2RR) for generation of valuable chemical products, including methanol and acetaldehyde. Through modifications of physical characteristics of electroplated copper electrodes, particularly introduction of porosity, and chemical composition, namely formation of copper oxides, the key performance parameters for CO2RR including selectivity, Faradaic efficiency, and energy efficiency are examined. Furthermore, the relationships between copper electrodes’ plating variables (current density, deposition time, and bath solution), porosity and compositions, and corresponding CO2RR performances are constructed. The study has demonstrated that the ratio of CuSO4 and H2SO4 of bath solution, current …
A New Spinel High-Entropy Oxides Nanoparticles (Feconimnzn)3o4 As Anode Materials For Lithium-Ion Batteries, Maha Nur Aida
A New Spinel High-Entropy Oxides Nanoparticles (Feconimnzn)3o4 As Anode Materials For Lithium-Ion Batteries, Maha Nur Aida
Chulalongkorn University Theses and Dissertations (Chula ETD)
A novel (FeCoNiMnZn)3O4 HEO as an anode in lithium-ion batteries (LIBs) was developed for the first time. High-entropy oxide (HEO) of (FeCoNiMnZn)3O4 was synthesized using a hydrothermal technique to control size and crystallinity. We also synthesized oxides of each element (Fe, Co, Ni, Mn, Zn) from HEO composition under similar condition for comparison. The samples were then analyzed using XRD, SEM, TEM, EDS elemental mapping, surface area analysis, ICP-OES, and XPS. Cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy, and associated coulombic efficiencies were also used to study the electrochemical performance of (FeCoNiMnZn)3O4. Three samples with different preparation conditions, HEO-3, HEO-6, …
High-Pressure Study Of Hybrid Organic-Inorganic Perovskites And Double Perovskites, Ardimas -
High-Pressure Study Of Hybrid Organic-Inorganic Perovskites And Double Perovskites, Ardimas -
Chulalongkorn University Theses and Dissertations (Chula ETD)
Hybrid and double perovskite have been of great attraction for optoelectronic devices. However, exploring a feasible method to enhance their optical abilities remains a considerable challenge. Here, the researcher reports the pressure-induced phase transition as an effective way to modify optoelectronic properties. The researcher successfully synthesized the hybrid perovskite (MAPbI3) and the double perovskite (Cs2TiBr6) by the inverse temperature crystallization (ITC) and solution method, respectively. the researcher studied the pressure dependence phase transition and photoluminescence (PL) by placing the sample into diamond anvil cells (DACs) through Raman spectroscopy. The first principles method was used to support the idea. The researcher …
Improving Quality Of Cvd Graphene Grown On The Copper Foil By Physical Polishing Electropolishing And Thermal Annealing Pretreatment Processes, Methawut Sirisom
Improving Quality Of Cvd Graphene Grown On The Copper Foil By Physical Polishing Electropolishing And Thermal Annealing Pretreatment Processes, Methawut Sirisom
Chulalongkorn University Theses and Dissertations (Chula ETD)
This study optimized the pretreatment processes (physical polishing (PP), electropolishing (EP), and thermal annealing) for high-quality graphene growth on thin copper (Cu) foils. PP using Brasso solvent was applied to smoothen the substrate surface, followed by EP with H3PO4 to reduce rolling lines and surface contamination. The EP process involved different H3PO4 concentrations (30-60%) and etching times (60-120 seconds). After thermal annealing at 860-940 ºC, graphene growth was performed using direct-liquid-injection chemical-vapor deposition with cyclohexane (C6H12) as the carbon precursor and nitrogen as the carrier gas. The optimized conditions involved PP and EP with 45% H3PO4 concentration and 90 seconds …
Biopolymer Nanocomposites For Food And Healthcare Applications, Tatiya Siripongpreda
Biopolymer Nanocomposites For Food And Healthcare Applications, Tatiya Siripongpreda
Chulalongkorn University Theses and Dissertations (Chula ETD)
This dissertation focuses on development of biopolymers by integrating nanomaterials to improve the properties of pristine polymers for enhancing the performances of chemical sensors and laser desorption/ionization mass spectroscopy (LDI-MS) applied for food quality control health monitoring and biomedical applications. The dissertation is divided into 4 parts: the first part, polylactic acid and cellulose were used for dual detection platform of biogenic amines for food spoilage indication. Highly porous PLA film is fabricated by adding nanosized calcium carbonate resulted in high sensing element entrapment. On another side of platform, pristine cellulose is modified with graphene oxide and exploited a substrate …
Surface Enhanced Raman Spectroscopy Analysis Of Thin-Smear-Contamination On Hdd Read-Write Head, Charin Seesomdee
Surface Enhanced Raman Spectroscopy Analysis Of Thin-Smear-Contamination On Hdd Read-Write Head, Charin Seesomdee
Chulalongkorn University Theses and Dissertations (Chula ETD)
Surface-enhanced Raman spectroscopy (SERS) is one of the most powerful analytical techniques for the identification of molecules in microelectronics industry for failure analysis protocol. In this work, a dry-processed gold nanoclusters were prepared by magnetron sputtering deposition to promote the enhancement of the Raman signal for the best intensity gain from selected common polymers found in hard disk drive as surface contamination. The optimized sputtering conditions was applied for SERS on polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), and high-density polyethylene (HDPE). The Raman spectrum showed the average Raman signal intensity gain at about 114%, 78%, 254%, and 226% respectively. …
Tuning The Wettability Of Metal Surface With Electrodeposited Porous Copper And Graphene Coatings, Husam Eltigani
Tuning The Wettability Of Metal Surface With Electrodeposited Porous Copper And Graphene Coatings, Husam Eltigani
Chulalongkorn University Theses and Dissertations (Chula ETD)
Electrodeposition of porous copper is an interesting type of coating that is emerging for various applications. However, the understanding of the relationships between copper surface wettability control and electrodeposition parameters and post-electrodeposition storage conditions is quite limited. Furthermore, it is worthwhile to explore how nanomaterials such as graphene would interact with porous copper to provide surface wettability modifications. This work therefore aims to develop a framework for the relationship of copper and graphene deposition processes, storage conditions, and the wetting behavior of copper surfaces. The research work performed in this study is divided into 2 parts: (i) effects of plating …
Improvement Of Zno Doping Properties Via Sputtering Process With Gas-Timing Technique, Nattaya Tajina Yossapong
Improvement Of Zno Doping Properties Via Sputtering Process With Gas-Timing Technique, Nattaya Tajina Yossapong
Chulalongkorn University Theses and Dissertations (Chula ETD)
In order to obtain high quality of ZnO thin film on plastic and glass substrate for applying to the production of flexible devices, ZnO thin film was investigated by using LP-ZnO buffer layer and gas-timing technique with RF magnetron sputtering at low or room temperature without heat treatment. Growing ZnO thin film directly on plastic substrate without buffer layer, the result was cracking, cavity and wrinkling film. The first part, the effect of buffer layer was studied by growing homo-buffer layer with low-power on plastic substrate and growing main film with high-power on top of that layer calling 2 step …
Tem Analysis Of Elo Gan Nanostructures On Stripe-Patterned Gaas Substrate By Movpe, Nattamon Suwannaharn
Tem Analysis Of Elo Gan Nanostructures On Stripe-Patterned Gaas Substrate By Movpe, Nattamon Suwannaharn
Chulalongkorn University Theses and Dissertations (Chula ETD)
Epitaxial lateral overgrown (ELO) GaN with AlGaN intermediate layers was grown on stripe-patterned in [110] direction on GaAs (001) substrate by metal-organic vapor phase epitaxy. The purpose of this work is to study the effects of AlGaN intermediate layers and the growth on stripe-patterned in [110] direction on structural phase transformation and defects formation/annihilation in GaN films by high-resolution X-ray diffraction and transmission electron microscopy. The growth rate of AlGaN, and the incorporation of Al into AlGaN was extremely low. According to transmission electron microscopy images, GaN at the window area directly on the substrate nucleates in the mixed phases …
Structural And Optical Analysis Of Cubic Aln Nanostructure On Mgo (001) Substrate Grown By Molecular Beam Epitaxy, Nutthapong Discharoen
Structural And Optical Analysis Of Cubic Aln Nanostructure On Mgo (001) Substrate Grown By Molecular Beam Epitaxy, Nutthapong Discharoen
Chulalongkorn University Theses and Dissertations (Chula ETD)
The effects of an intermediate cubic GaN (c-GaN) buffer layer on structural and optical properties of AlN films grown on MgO (001) substrate by PA-MBE have been investigated. There are 2 types of c-GaN intermediated layer; the one-step buffer layer with a 7nm thick LT c-GaN layer and a two-step buffer layers with a sequence of a 7 nm-thick and 200 nm-thick c-GaN layer. The surface morphology of the AlN film with two-step growth c-GaN buffer layer exhibits the grain boundary facet like a cubic structure. While the other films exhibit the mixing of the grain boundary corresponding with the …
Rice Granules As Natural Carrier To Encapsulate Drug And Aromatic Oils, Xue Liu
Rice Granules As Natural Carrier To Encapsulate Drug And Aromatic Oils, Xue Liu
Chulalongkorn University Theses and Dissertations (Chula ETD)
Rice granules as major energy supply to humanity worldwide are utilized in many fields, such as food, medical, printing and plastic industries. In this thesis work, rice starch/granule is applied as hydrophilic drug (vancomycin) carrier to achieve the release. By confirmation on the stability of rice granules against to various treatments like alkali, acid and heating, as well as a-amylase, trypsin, and lipase, it is possible to use rice granules as 100% natural source to be the capsule and matrix getting the non-core-shell structure of the formation. The success of encapsulation is confirmed by the observations on crystalline, thermal properties …
Thermal Stability Characterization Of Tunneling Magneto Resistive Structure For Data Storage Applications, Pornchai Rakpongsiri
Thermal Stability Characterization Of Tunneling Magneto Resistive Structure For Data Storage Applications, Pornchai Rakpongsiri
Chulalongkorn University Theses and Dissertations (Chula ETD)
The conventional read sensor technology used in hard disk drives is the tunneling magneto resistive (TMR) device. The revolutions of technology have been developed to achieve high performance of reading signal resulting in very thin and complicated device layers which thermal induced degradation and defects would be concerned. In this research, a thermal stress has been applied to TMR devices between 150-250 ℃ for reliability investigation. The resistance, amplitude and asymmetry parameters, before and after the thermal stress, were measured using a quasi-static tester (QST). The results showed the temperature dependence of the percentage change in QST resistance, asymmetry and …
Preparation And Characterization Of Nickel Based Nanocomposite Coatings With Enhanced Mechanical And Surface Properties, Malay Kumar Das
Preparation And Characterization Of Nickel Based Nanocomposite Coatings With Enhanced Mechanical And Surface Properties, Malay Kumar Das
Chulalongkorn University Theses and Dissertations (Chula ETD)
Ni-W alloy and Ni-W/diamond monolayer and multilayer composite coatings were prepared by electrodeposition from a Ni-W plating bath with diamond particles suspended into the bath. Ni-W/diamond composite coatings were also prepared with varying amounts of Cobalt sulphate additives. The morphology and the composition of the deposits was investigated by means of SEM and EDS, respectively. The effect of operating conditions and additives on the Ni-W coatings were analyzed. The effect of the plating parameters, composite particle size, multilayer deposits and cobalt additives on microstructure and mechanical properties of the Ni-W/diamond composite coatings was investigated. The electrodeposited Ni-W/diamond deposits reported a …
Preparation Of Graphene Nanocomposites For Anticorrosion And Sensors, Nadtinan Promphet
Preparation Of Graphene Nanocomposites For Anticorrosion And Sensors, Nadtinan Promphet
Chulalongkorn University Theses and Dissertations (Chula ETD)
This dissertation focused on the development of graphene (GO) nanocomposite coating to improve various substrate properties for the sensor application, which is divided into 2 main parts. The first part is the development of GO incorporated into electroless nickel phosphorus (NiP) coating to improve the properties of metal for electrochemical sensor application. Nickel phosphorus - titanium dioxide sol - reduced graphene oxide (NiP-TiO2 sol -RGO) coated surface was successfully prepared by one-pot electroless deposition on the steel substrate. The results show that the homogeneously formation of water-repellent RGO film covering on the coated surface leading to improve the corrosion resistance …
Structural Characterization Of Ultra-Thin Irmn Films And Their Heterostructures, Kunpot Mopoung
Structural Characterization Of Ultra-Thin Irmn Films And Their Heterostructures, Kunpot Mopoung
Chulalongkorn University Theses and Dissertations (Chula ETD)
We have investigated structural properties of IrMn ultra-thin films with different Mn contents (expected to be at 76 at% and 79 at%) and the substrate temperatures (room temperature and 250 °C). The IrMn films with thickness approximately 50 nm were grown on Ru/SiO2/Si substrates by DC sputtering process. Structural investigation results consist of 3 parts as follows: effects of (i) growth parameters, (ii) water corrosion and (iii) thermal annealing. Effect of growth parameters on growth morphologies and crystal structure of the IrMn alloy was investigated by atomic force microscopy (AFM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and wide-angle X-ray …
Theoretical Studies On Electronic Properties Of Curved Graphene Quantum Dots And Lithium Adsorption On Graphene Quantum Dots, Naruwan Pattarapongdilok
Theoretical Studies On Electronic Properties Of Curved Graphene Quantum Dots And Lithium Adsorption On Graphene Quantum Dots, Naruwan Pattarapongdilok
Chulalongkorn University Theses and Dissertations (Chula ETD)
Graphene quantum dots (GQDs), with their attractive properties, are of interest to apply for electronic devices. Therefore, this dissertation aimed to investigate the electronic of curved graphene quantum dots (CGQDs) and the adsorption of lithium on GQDs. For the first part, two shapes of flat GQDs, rhomboidal (RGQDs) and hexagonal (HGQDs), were modified to make CGQDs with different folding axes and angles. Stabilities and electronic properties of CGQDs were studied using PBE/DNP. The results showed that the deformation energies of GQDs depend on sizes and folding axes but not their shapes. HOMO-LUMO gap variations, both widening and narrowing the gap, …