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Full-Text Articles in Engineering
Electrodeposited Cu-Based Catalysts For Alcohols From Co Hydrogenation And Electrodeposition Of Cuniw/Cuni Multilayered Alloys, Mayank Gupta
Electrodeposited Cu-Based Catalysts For Alcohols From Co Hydrogenation And Electrodeposition Of Cuniw/Cuni Multilayered Alloys, Mayank Gupta
LSU Doctoral Dissertations
Ethanol and higher alcohols can be used as a fuel or fuel additive in gasoline engines as well as a hydrogen carrier. One of the promising methods to synthesize these alcohols is based on thermochemical conversion of CO and H2 (CO hydrogenation). Conventional catalysts used for the conversion CO and H2 (syngas) to ethanol typically give yields less than 20% with the balance resulting mostly in the formation of the thermodynamically favored products CH4 and CO2. New catalysts with compositions designed to kinetically favor the formation of ethanol and higher alcohols are needed. Electrodeposition of nanowires offers a means to …
Electrochemical Fabrication Of Auco Nanostructures, Maoshi Guan
Electrochemical Fabrication Of Auco Nanostructures, Maoshi Guan
LSU Doctoral Dissertations
Electrodeposited Au/CoAu multilayered nanowires are materials with alternating layers of Au and CoAu in a wire where the layer thickness and wire diameter are nanometer size. They can be used for different applications. For example, the wires may exhibit giant magnetoresistance (GMR), a change in the materials resistance with a magnetic field, having applications as a sensor material for microdevices. If Co is etched from CoAu nanowires, rough, porous gold nanostructures will be left behind, which could be used as novel catalysts. In this study, the electrodeposition of Au/CoAu multilayered nanowires and nanotubes in nanoporous templates was explored from a …
Electrodeposition Of Multilayered Nanostructures For Giant Magnetoresistance And Thermoelectric Applications, Despina Davis
Electrodeposition Of Multilayered Nanostructures For Giant Magnetoresistance And Thermoelectric Applications, Despina Davis
LSU Doctoral Dissertations
The electrodeposition of novel materials such as multilayer nanotubes for giant magneto resistance (GMR) applications and bismuth telluride nanotubes for thermoelectric applications are presented in this dissertation. The motivation for the multilayer electrodeposition is the investigation of giant magnetoresistance (GMR), a change in the material resistance in an applied magnetic field as a consequence of antiferromagnetic coupling. The nanowire high aspect ratio geometry allows the measurement of GMR with the current applied perpendicular to the plane (CPP) of the multilayers, which has been theoretically identified as being larger than the GMR in the (CIP) configuration (current in plane of multilayers). …
Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra
Electrodeposition Of Rare Earth-Transition Metal Alloy Thin Films And Nanostructures, Rohit Mishra
LSU Doctoral Dissertations
Rare earth-transition metal alloys are of interest in MEMS and magnetic storage industries because of their unique magnetic properties. However, the applications of these alloys have been limited to bulk and thin film architectures because of the limitations of the contemporary vapor deposition technique to fabricate high aspect ratio nanostructures. The objective of this study is to develop an electrochemical process to deposit rare earth-transition metal alloys thus making it possible to deposit high aspect ratio nanostructures such as nanowires and nanotubes, which helps to tune their properties for specific applications. Electrodeposition of rare earth-transition metal alloys was achieved from …
Electrodeposition Of Cocu Nanostructures, Yutong Li
Electrodeposition Of Cocu Nanostructures, Yutong Li
LSU Doctoral Dissertations
Electrodeposition is a key component in the microelectronic industry because it has the following advantages: low cost, easy operation and the capability to deposit into irregular geometries such as recessed and curved areas. In this dissertation, CoCu alloys were investigated to fabricate multilayers, microdevices and microposts. All of these multilayer structures were composed of nanometric copper and cobalt-rich layers in order to obtain magnetoresistance, a phenomenon where the resistance of multilayer structures decreases with increases of external magnetic field. An investigation was carried out in order to evaluate appropriate plating conditions during multilayered thin film deposition, with the aim to …
Electrodeposited Metal Matrix Nanocomposites As Thin Films And High Aspect Ratio Microstructures For Mems, Alonso Lozano Morales
Electrodeposited Metal Matrix Nanocomposites As Thin Films And High Aspect Ratio Microstructures For Mems, Alonso Lozano Morales
LSU Doctoral Dissertations
The electrodeposition of metal-matrix nanocomposites as thin film and high aspect ratio microstructures (HARM’s) for MicroElectroMechanical Systems (MEMS) components is examined. The effect of -Al2O3 nanopowder on copper reduction from acidic and basic electrolytes is examined with rotating disk electrodes (RDE’s). At pH 0.2, regions of copper inhibition and enhancement are identified in the kinetic regime. Low particle loading (12.5 g/L) results in an inhibited copper rate, while, high particle concentration (60 g/L) does both, inhibits the rate at low overpotentials and accelerates it at higher overpotentials, depending on the electrode rotation rate. At pH 8 the presence of particles …
Electrodeposition Of Auco Alloys And Multilayers, Maoshi Guan
Electrodeposition Of Auco Alloys And Multilayers, Maoshi Guan
LSU Master's Theses
Electrodeposited AuCo and Au/Co multilayers are of interest as potential materials for MEMS components. AuCo alloys have been fabricated by the electrodeposition technique, but from cyanide-containing electrolyte. In this study, we explored the electrodeposition of AuCo and Au/Co multilayer thin films, and nanowires, from a non-cyanide electrolyte. Two variables were considered: the concentration of citric acid and pH. The changes in composition were described by the differences in the partial current densities. The effect of pH and citric acid concentration on the deposit composition and current efficiency was investigated. Results showed that a lower citric acid concentration was favored for …
Electrodeposition Of Magnetic Nanowires And Nanotubes, Despina Mehedintu Davis
Electrodeposition Of Magnetic Nanowires And Nanotubes, Despina Mehedintu Davis
LSU Master's Theses
The current perpendicular to the plane giant magneto-resistance (CPP)-(GMR) effect makes multilayered nanowires of huge interest as magnetic sensor materials. GMR showing multilayer nanostructures are composed of alternating ferromagnetic and nonmagnetic nanometric layers. The giant magnetoresistance (GMR) property is described as a change in electrical resistance when an external magnetic field is introduced. Electrodeposition is the most efficient method for fabricating magnetic nanowires. In addition to the cost-effectiveness, electrodeposition is one of the few methods that can overcome the geometrical restrictions of inserting metals into very deep nanometric recesses, making it the favored method for nanowire and nanotube fabrication. In …
Electrodeposited Nanoscale Multilayers Of Invar With Copper, Diwakar Suryanarayana Iyer
Electrodeposited Nanoscale Multilayers Of Invar With Copper, Diwakar Suryanarayana Iyer
LSU Master's Theses
Materials with low thermal expansion coefficients (CTEs) that will survive temperature cycling are of interest in a variety of applications on the microscale, including actuation, precision assembly, and injection mold fabrication. Invar alloys exhibit a low positive coefficient of thermal expansion ranging between 0.2 – 1.2 µm/m-°C at room temperature. The electrodeposition process for fabricating nanoscale multilayers of Invar and copper in micro-patterns was characterized to assess their value in various MEMS applications. In an ongoing effort to maintain a stable CTE and effectively control the grain growth of Invar, nano-multilayers of near Invar-like FeNiCu and copper were electrodeposited into …
The Electrodeposition And Property Study Of Nickel-Rhenium Alloy, Shirong Wen
The Electrodeposition And Property Study Of Nickel-Rhenium Alloy, Shirong Wen
LSU Master's Theses
The electrodeposition of nickel-rhenium alloys from Ni(II) and Re(VII) solution was studies in an aqueous acidic solution. Different plating current density and pH have been carried out, and the effect of them on the composition of the deposited Ni-Re alloy was studied. Wavelength-dispersive spectrometer (WDS) was used to measure the composition of Ni-Re alloy. The thermal stability of nickel-rhenium alloy system has been investigated. Differential scanning calorimetry (DSC) tests have been conducted for the electroplated Ni-Re samples in order to find the possible heating initiated interactions at elevated temperatures. To investigate the thermal stability of Ni-Re alloys, the samples were …
Electrodeposition Of Feconicu Quaternary System, Qiang Huang
Electrodeposition Of Feconicu Quaternary System, Qiang Huang
LSU Doctoral Dissertations
Electrodeposition is a cost-effective method to produce thin film materials, which have been used widely in the microelectronic industry, and is advantageous to fabricate metal deposits into recessed and curved areas. In this dissertation, FeCoNiCu quaternary alloy system was investigated, both experimentally and theoretically, for fabrication of multilayers, grating structures, and nanowires. Multilayer structures are composed of alternating ferromagnetic and nonmagnetic nanometric layers, and are of interest due to the giant magnetoresistance (GMR) property it possesses, a change in electric resistance in the presence of an external magnetic field. In addition, the compositional modulation, or the composition contrast, in multilayer …
Electrodeposition Of Nickel-Copper Alloys And Nickel-Copper-Alumina Nanocomposites Into Deep Recesses For Mems, Amrit Panda
Electrodeposition Of Nickel-Copper Alloys And Nickel-Copper-Alumina Nanocomposites Into Deep Recesses For Mems, Amrit Panda
LSU Doctoral Dissertations
Electrodeposition is an important component in the fabrication of micro electro mechanical systems (MEMS). Nickel is the most commonly used material to produce three dimensional microstructures and few material alternatives have been demonstrated. In this dissertation, electrodeposited Ni-Cu alloys and nanocomposites are investigated as possible replacements for nickel in microsystems. Ni-Cu alloys are attractive for their corrosion resistance, magnetic and thermophysical properties. Alumina nanoparticulates included into metal matrices improve hardness and tribology of deposits. The Ni-Cu alloys and Ni-Cu-g-Al2O3 nanocomposites were electrodeposited from a citrate electrolyte, both at low and high pH. Electrodeposition experiments were performed in recessed microelectrodes 500 …