This document describes a process for infiltrating carbon nanotube templates with tungsten to create mechanically robust microstructures. Carbon nanotubes are grown vertically in a pattern and then infiltrated with tungsten using chemical vapor deposition of tungsten hexacarbonyl. Parameters like temperature, geometry, and precursor amount influence the infiltration. Near full infiltration and capping of the carbon nanotube structures is achieved at temperatures above 300°C in an inverted sample geometry close to the precursor source. This process allows creation of tungsten-carbon nanotube composites for applications requiring high temperature or corrosion resistance.
Ultra smooth and lattice relaxed zn o thin films [eid]Eid Elsayed
The crystal structure and quality of ZnO thin films were enhanced by high temperature vacuum annealing. 150 nm thick ZnO films were deposited on a-plane sapphire substrates by RF sputtering at 600°C and then annealed in situ at temperatures from 700°C to 900°C. Higher annealing temperatures produced smoother films with root mean square roughness reaching 0.3 nm at 850°C. Raman spectroscopy showed the A1(TO) mode at all annealing temperatures and the A1(LO) mode appeared above 800°C, indicating improved crystal quality. X-ray diffraction revealed narrower diffraction peaks and a relaxed lattice constant matching bulk ZnO at 900°C annealing, demonstrating high quality c-axis oriented epit
A study of Carbon Nanotubes as Smart Reinforcemants for Glass/ Glass ceramic ...Rahul Dubey
This document presents a study on carbon nanotubes (CNTs) as reinforcements for glass and glass ceramic matrix composites. CNTs have excellent mechanical and physical properties due to their nano-scale size. The document discusses methods of CNT production, their properties, and manufacturing of CNT-reinforced glass composites. Incorporating CNTs improves the mechanical, electrical and thermal properties of the brittle glass matrix. Potential applications include structural components, heat sinks, and thermal barrier coatings. However, more research is still needed to fully understand CNT reinforcement effects and address issues like mass production costs and health impacts.
The document summarizes a study on the effect of In, Ce, and Bi dopings on sintering and dielectric properties of Ba(Zn1/3Nb2/3)O3 (BZN) ceramics. In doping between 0.2-4.0% increased density at 1300°C. Ce doping decreased density at 1250°C. Bi doping up to 1.0% negatively affected densification, while higher levels improved it. XRD showed single phase formation for all dopant levels except 0.5% Bi. In and Ce doping increased dielectric constant from 41 to around 66 at 1 MHz. Bi doping initially decreased then increased dielectric constant with higher levels.
Carbon nanotubes with special application to the cnt reoinforced glass and glassRahul Dubey
The document discusses carbon nanotubes (CNTs), their properties, production methods, and applications. Specifically, it focuses on using CNTs to reinforce glass and glass-ceramic matrix composites. The key points are:
1) CNTs have excellent mechanical and thermal properties that make them promising reinforcements. Their production via electric arc discharge, laser ablation, or chemical vapor deposition controls their quality.
2) Manufacturing CNT-reinforced glass/glass-ceramic composites requires well-dispersed CNTs, strong interfaces, and consolidation to high densities using techniques like spark plasma sintering.
3) Preliminary results show the composites have improved hardness, elastic modulus
The preparation of thin zinc air battery. The cell, 1 cm2 area x ca. 460 μm thick, possesses limiting current of 27 mA, maximum power output of 31 mW, and vlumetric energy
density of 924 Wh l-1, rated at 20 mA. A bipolar design
markedly improves the cell performance. The cell, 1 cm2
area x ca. 920 μm thick, possesses limiting current
of 95 mA, maximum power output of 107 mW, and
volumetric energy density of 1189 Wh l-1.
I worked on a research project at Lawrence Berkeley National Lab to develop ceramic scintillators for medical and security applications. I synthesized barium-based ceramic samples doped with elements like europium, measured their performance through techniques like X-ray diffraction and luminescence, and analyzed the results. The most promising sample was lanthanum barium chloride doped with 5% europium, which showed high transparency and light output. Further experiments aim to optimize europium concentration to improve scintillator characteristics.
Ultra smooth and lattice relaxed zn o thin films [eid]Eid Elsayed
The crystal structure and quality of ZnO thin films were enhanced by high temperature vacuum annealing. 150 nm thick ZnO films were deposited on a-plane sapphire substrates by RF sputtering at 600°C and then annealed in situ at temperatures from 700°C to 900°C. Higher annealing temperatures produced smoother films with root mean square roughness reaching 0.3 nm at 850°C. Raman spectroscopy showed the A1(TO) mode at all annealing temperatures and the A1(LO) mode appeared above 800°C, indicating improved crystal quality. X-ray diffraction revealed narrower diffraction peaks and a relaxed lattice constant matching bulk ZnO at 900°C annealing, demonstrating high quality c-axis oriented epit
A study of Carbon Nanotubes as Smart Reinforcemants for Glass/ Glass ceramic ...Rahul Dubey
This document presents a study on carbon nanotubes (CNTs) as reinforcements for glass and glass ceramic matrix composites. CNTs have excellent mechanical and physical properties due to their nano-scale size. The document discusses methods of CNT production, their properties, and manufacturing of CNT-reinforced glass composites. Incorporating CNTs improves the mechanical, electrical and thermal properties of the brittle glass matrix. Potential applications include structural components, heat sinks, and thermal barrier coatings. However, more research is still needed to fully understand CNT reinforcement effects and address issues like mass production costs and health impacts.
The document summarizes a study on the effect of In, Ce, and Bi dopings on sintering and dielectric properties of Ba(Zn1/3Nb2/3)O3 (BZN) ceramics. In doping between 0.2-4.0% increased density at 1300°C. Ce doping decreased density at 1250°C. Bi doping up to 1.0% negatively affected densification, while higher levels improved it. XRD showed single phase formation for all dopant levels except 0.5% Bi. In and Ce doping increased dielectric constant from 41 to around 66 at 1 MHz. Bi doping initially decreased then increased dielectric constant with higher levels.
Carbon nanotubes with special application to the cnt reoinforced glass and glassRahul Dubey
The document discusses carbon nanotubes (CNTs), their properties, production methods, and applications. Specifically, it focuses on using CNTs to reinforce glass and glass-ceramic matrix composites. The key points are:
1) CNTs have excellent mechanical and thermal properties that make them promising reinforcements. Their production via electric arc discharge, laser ablation, or chemical vapor deposition controls their quality.
2) Manufacturing CNT-reinforced glass/glass-ceramic composites requires well-dispersed CNTs, strong interfaces, and consolidation to high densities using techniques like spark plasma sintering.
3) Preliminary results show the composites have improved hardness, elastic modulus
The preparation of thin zinc air battery. The cell, 1 cm2 area x ca. 460 μm thick, possesses limiting current of 27 mA, maximum power output of 31 mW, and vlumetric energy
density of 924 Wh l-1, rated at 20 mA. A bipolar design
markedly improves the cell performance. The cell, 1 cm2
area x ca. 920 μm thick, possesses limiting current
of 95 mA, maximum power output of 107 mW, and
volumetric energy density of 1189 Wh l-1.
I worked on a research project at Lawrence Berkeley National Lab to develop ceramic scintillators for medical and security applications. I synthesized barium-based ceramic samples doped with elements like europium, measured their performance through techniques like X-ray diffraction and luminescence, and analyzed the results. The most promising sample was lanthanum barium chloride doped with 5% europium, which showed high transparency and light output. Further experiments aim to optimize europium concentration to improve scintillator characteristics.
Rosa alejandra lukaszew a review of the thin film techniques potentially ap...thinfilmsworkshop
This document discusses thin film techniques that could be applicable for superconducting radio frequency (SRF) cavities. It reviews various thin film deposition methods like sputtering, evaporation, and ion beam assisted deposition. Challenges in achieving high quality niobium films for SRF cavities are discussed, including issues like adhesion, purity, defects, grain size, stress. The document provides background on thin film nucleation and growth processes. It also summarizes some previous work done on niobium thin films at the College of William and Mary using DC magnetron sputtering and reactive sputtering.
This document provides an overview of carbon nanotubes, including their unique properties, production methods, and applications. Carbon nanotubes are extraordinarily strong and stiff, and can be metallic or semiconducting depending on their structure. There are several methods for producing carbon nanotubes, including arc discharge, laser ablation, and chemical vapor deposition. Carbon nanotubes show promise for applications in energy storage, healthcare, and environmental remediation due to their mechanical, electrical, and thermal properties.
Anne marie valente feliciano - nucleation of nb films on cu substratesthinfilmsworkshop
In the pursuit of niobium (Nb) films with similar performance with the commonly used bulk Nb surfaces for Superconducting RF (SRF) applications, significant progress has been made with the development of energetic condensation deposition techniques. The controlled incoming ion energy enables a number of processes such as desorption of adsorbed species, enhanced mobility of surface atoms and sub-implantation of impinging ions, thus producing improved film structures at lower process temperatures. All these along with the quality of the Cu substrate have an important influence on the nucleation and subsequent growth of the Nb film, creating a favorable template for growing the final surface exposed to SRF fields. This contribution shows how the structure and defect density thus electron mean free path (represented by residual resistance ratio values) of Nb films can be tailored on Cu substrates, by varying the ion energy and thermal energy provided to the substrate, favoring the hetero-epitaxial or the fiber growth mode.
This experiment aims to determine the locations of important molybdenum erosion on Alcator C-Mod that affect the plasma, understand the erosion mechanisms, and improve high-Z plasma facing component operation. Alcator C-Mod uses molybdenum and tungsten plasma facing components and boronization to deposit protective boron layers. Boronization improves plasma performance by reducing radiation and molybdenum levels in the plasma. However, boron layers erode more quickly in regions that receive high particle and heat fluxes, like the outer divertor.
Graphene and hexagonal boron nitride filled epoxy nanocompositesArun Yadav
The document describes a two-stage project to develop polymer nanocomposites with improved thermal conductivity for electronic packaging applications. The first stage involves establishing a high concentration dispersion of hexagonal boron nitride and graphene using a suitable surfactant. The second stage uses this dispersion to prepare epoxy nanocomposites. The nanocomposites will be characterized using techniques like UV-Vis-NIR spectroscopy, FTIR spectroscopy, SEM and TEM to analyze properties. The goal is to create graphene and boron nitride filled polymer composites with higher thermal conductivity.
Carbon nanotubes and their economic feasibilityJeffrey Funk
These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to analyze how the economic feasibility of carbon nanotubes is becoming better through the emergence of new forms of carbon nanotubes, new methods of synthesis, and the increased scale of production equipment. New forms of carbon nanotubes continue to be developed; new ones include carbon nanobuds, doped carbon nanotubes, and graphenated carbon nanotubes, each of which includes many variations. The large number of variations suggests that carbon nanotubes will likely experience improvements in performance and the number of applications will continue to grow.
This document summarizes a study on the effect of crystallite size of zinc oxide (ZnO) filler on the properties of polypropylene (PP)/ZnO nanocomposites. ZnO nanoparticles were prepared using two different methods, resulting in nanoparticles with crystallite sizes of 13.4 nm (NZO) and 29.2 nm (CZO). PP/ZnO composites containing 0-5% ZnO were produced by melt mixing. Composites with NZO exhibited higher mechanical properties, dynamic properties, and thermal stability than those with CZO, due to the smaller crystallite size and more uniform dispersion of NZO in PP. Transparency of the composites improved with decreasing ZnO crystallite
The development of desalination technology become a necessary due to the intense shortage of fresh water, especially in the gulf.
In the last six decades, the number of desalination units have increased dramatically.
Different techniques have been used for water desalination systems such as:
Capacitive deionization (CDI)
Multi-stage flash (MSF) distillation
Reverse osmosis (RO)
Electrodialysis
Nuclear power
This document examines the influence of film thickness on the structural, electrical, and photoluminescence properties of aluminum tris(8-hydroxyquinoline) (Alq3) thin films deposited on silicon substrates via vacuum evaporation. Fourier transform infrared spectroscopy, current-voltage, capacitance-voltage, and photoluminescence spectroscopy measurements were performed on Alq3 films of varying thicknesses. The results showed that molecular structure was unaffected by thickness but photoluminescence intensity and emission energy increased with thickness. Turn-on voltage and transition voltage from current-voltage and capacitance-voltage measurements also increased with thicker films.
1) Copper selenide thin films were prepared by thermal evaporation and annealed at different temperatures to study their structural, optical, and surface properties for thermoelectric applications.
2) XRD analysis showed the films crystallized in the hexagonal phase and crystallite size increased with higher annealing temperatures up to 300°C. Above 300°C, the films became amorphous.
3) Optical analysis found the band gap increased and thickness decreased with increasing annealing temperature, indicating better crystallinity. Surface analysis by FESEM showed denser, more uniform grains with annealing.
Interdiffusion, reactions, and transformations in thin filmMd Ataul Mamun
This document discusses various topics related to interdiffusion, reactions, and transformations in thin films:
1. It explains the concepts of diffusion, nucleation and grain growth that can occur in thin films. Diffusion is impacted by factors like temperature, grain boundaries, and dislocations.
2. Interdiffusion in thin films occurs much faster than in bulk materials due to diffusion along grain boundaries and dislocations. This can impact thin film integrity over time.
3. Reaction and compound formation at interfaces between thin films is discussed, like the growth of SiO2 at the Si/O2 interface or intermetallic compound formation.
4. Phase transformations and the use of diffusion barriers to prevent undesirable
This document summarizes the synthesis, characterization, and properties of nickel ferrite (NiFe3O4) nanoparticles. Nickel ferrite was synthesized using a sol-gel technique and sintered at 600°C. X-ray diffraction analysis confirmed the formation of nickel ferrite and showed structural changes due to ion shifting between lattice sites. Scanning electron microscopy images showed agglomerated, porous nanoparticles with an average size of 0.21μm. AC conductivity measurements showed a conductivity of 1.0 x 10-4 S/cm due to dipole polarization. Dielectric properties were also measured as a function of frequency.
Carbon nanotube fibers (CNTFs) were synthesized using a horizontally spinning chemical vapor deposition (CVD) technique. Scanning electron microscopy (SEM) was used to characterize the microstructure of the CNTFs. The CNTFs were grown using thermal CVD with iron catalyst and methane carbon source. During growth, the CNTs were directly pulled and twisted to form fibers. SEM analysis was conducted to investigate the morphology, shape, and other properties of the CNTFs, including electrical conductivity. This technique aims to develop high performance EM transmitter materials using CNTFs.
Fabrication and characterization of nickelijoejournal
This paper shows that nickel nanowires of length 11μm and diameters 800 and 15nm were grown within
the pores of nuclear track polycarbonate membrane by electrodepositing nickel. Surface morphology and
crystallographic structure of the deposited nanowires was investigated using SEM, TEM and XRD
respectively. It is found that low current density gives good result, while high current density leads to the
formation of curled nanowires. Fabricated nanowires were further investigated for electrical properties
and found that nanowires obey ohm’s law. Through structural characterization it has been observed that
the fabricated nanowires posses FCC lattice structure.
Electrochemical Supercapacitive Performance of Sprayed Co3O4 ElectrodesIJERA Editor
Nanocrystalline cobalt oxide (Co3O4) thin film electrodes were fabricated by spray pyrolysis method on conducting fluorine doped tin oxide (FTO) substrates using ammonia complexed with cobalt chloride (CoCl2. 6H2O) solution. The structural and morphological properties of Co3O4electrodes were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The surface morphology study showed the film formation of porous surface with clusters. The electrochemical supercapacitive properties ofCo3O4 electrodes were evaluated using cyclic voltammetry and galvanostatic charge-discharge method. The Co3O4electrodes showed maximum specific capacitance of 168 F/g in 1 M aqueous KOH electrolyte at the scan rate of 20 mV/s. The maximum specific energy and specific power of the cell are 2.2Wh/kg and 0.23 kW/kg, respectively.
The document discusses the synthesis of single-walled carbon nanotubes using chemical vapor deposition. It then describes the process of acidic oxidation of the nanotubes and their application as ultra-sharp probes for atomic force microscopy through dielectrophoresis. The oxidation process introduces defects in the nanotubes and selectively destroys metallic nanotubes, enriching semiconducting ones, as shown through resonance Raman spectroscopy. Oxidized nanotubes are dispersed and dielectrophoresis is used to attach them to atomic force microscopy probe tips, where their high aspect ratio enables high-resolution imaging.
This document discusses different methods for fabricating carbon nanotube (CNT) interconnects and comparing their performance. It proposes a double layer CNT interconnect structure that includes two CNT networks separated by a 1nm aluminum oxide layer. Testing shows that double layer structures have higher conductivity, less variation in conductance, and higher probabilities of conductive paths compared to single layer structures. The additional aluminum oxide layer is believed to help capture more CNTs during coating, allowing more tunneling pathways between the two CNT networks to improve conductivity. Phase transition phenomena in conductance based on size and structure are also investigated using percolation theory.
Maiyalagan,Template synthesis and characterization of well aligned nitrogen c...kutty79
The synthesis of well-aligned nitrogen containing carbon nanotubes by pyrolysis of polyvinyl pyrrolidone (PVP) on alumina membrane
template is described. The nanotubes were characterized by elemental analysis, electron microscopic analyses, Raman, IR and X-ray photoelectron
(XPS) spectroscopic techniques. SEM, transmission electron microscopy (TEM) and AFM images reveal the hollow structures and
vertically aligned features of the nanotubes. Raman spectrum shows the characteristic bands at 1290 cm−1 (D-band) and 1590 cm−1 (G-band).
IR spectral bands indicated the characteristic C–N bonds in carbon nanotubes. This confirms the presence of nitrogen atoms in the carbon
framework. The XPS and elemental analyses further indicate significant amount of nitrogen in the nanotubes. IR, elemental and XPS analyses
clearly provide evidence for the presence of nitrogen in carbon nanotubes.
Carbon nano tubes for concrete better constructionsriram1052
The document summarizes a presentation on the compressive strength and microstructure of carbon nanotubes-fly ash cement composites. It discusses adding different amounts of carbon nanotubes (CNTs) to fly ash cement mixtures and testing the density, compressive strength, and microstructure of the resulting composites. Testing included SEM, XRD, TGA, DTA, and EDS analyses. The results showed that adding 0.5-1.0% CNTs increased the density and compressive strength of the fly ash cement composites compared to mixtures without CNTs. Microstructural analysis revealed the CNTs were uniformly dispersed in the cement matrix.
Template synthesis and characterization of well aligned nitrogen containing c...madlovescience
This document describes the synthesis and characterization of nitrogen-containing carbon nanotubes produced through the pyrolysis of polyvinyl pyrrolidone on an alumina membrane template. The nanotubes were analyzed using various techniques which showed they had a hollow, vertically aligned structure with a significant amount of nitrogen incorporated into the carbon framework, as evidenced by elemental analysis, Raman spectroscopy, IR spectroscopy, and XPS. The template synthesis method allowed production of well-aligned nitrogen-containing carbon nanotubes with controlled morphology and composition.
Rosa alejandra lukaszew a review of the thin film techniques potentially ap...thinfilmsworkshop
This document discusses thin film techniques that could be applicable for superconducting radio frequency (SRF) cavities. It reviews various thin film deposition methods like sputtering, evaporation, and ion beam assisted deposition. Challenges in achieving high quality niobium films for SRF cavities are discussed, including issues like adhesion, purity, defects, grain size, stress. The document provides background on thin film nucleation and growth processes. It also summarizes some previous work done on niobium thin films at the College of William and Mary using DC magnetron sputtering and reactive sputtering.
This document provides an overview of carbon nanotubes, including their unique properties, production methods, and applications. Carbon nanotubes are extraordinarily strong and stiff, and can be metallic or semiconducting depending on their structure. There are several methods for producing carbon nanotubes, including arc discharge, laser ablation, and chemical vapor deposition. Carbon nanotubes show promise for applications in energy storage, healthcare, and environmental remediation due to their mechanical, electrical, and thermal properties.
Anne marie valente feliciano - nucleation of nb films on cu substratesthinfilmsworkshop
In the pursuit of niobium (Nb) films with similar performance with the commonly used bulk Nb surfaces for Superconducting RF (SRF) applications, significant progress has been made with the development of energetic condensation deposition techniques. The controlled incoming ion energy enables a number of processes such as desorption of adsorbed species, enhanced mobility of surface atoms and sub-implantation of impinging ions, thus producing improved film structures at lower process temperatures. All these along with the quality of the Cu substrate have an important influence on the nucleation and subsequent growth of the Nb film, creating a favorable template for growing the final surface exposed to SRF fields. This contribution shows how the structure and defect density thus electron mean free path (represented by residual resistance ratio values) of Nb films can be tailored on Cu substrates, by varying the ion energy and thermal energy provided to the substrate, favoring the hetero-epitaxial or the fiber growth mode.
This experiment aims to determine the locations of important molybdenum erosion on Alcator C-Mod that affect the plasma, understand the erosion mechanisms, and improve high-Z plasma facing component operation. Alcator C-Mod uses molybdenum and tungsten plasma facing components and boronization to deposit protective boron layers. Boronization improves plasma performance by reducing radiation and molybdenum levels in the plasma. However, boron layers erode more quickly in regions that receive high particle and heat fluxes, like the outer divertor.
Graphene and hexagonal boron nitride filled epoxy nanocompositesArun Yadav
The document describes a two-stage project to develop polymer nanocomposites with improved thermal conductivity for electronic packaging applications. The first stage involves establishing a high concentration dispersion of hexagonal boron nitride and graphene using a suitable surfactant. The second stage uses this dispersion to prepare epoxy nanocomposites. The nanocomposites will be characterized using techniques like UV-Vis-NIR spectroscopy, FTIR spectroscopy, SEM and TEM to analyze properties. The goal is to create graphene and boron nitride filled polymer composites with higher thermal conductivity.
Carbon nanotubes and their economic feasibilityJeffrey Funk
These slides use concepts from my (Jeff Funk) course entitled analyzing hi-tech opportunities to analyze how the economic feasibility of carbon nanotubes is becoming better through the emergence of new forms of carbon nanotubes, new methods of synthesis, and the increased scale of production equipment. New forms of carbon nanotubes continue to be developed; new ones include carbon nanobuds, doped carbon nanotubes, and graphenated carbon nanotubes, each of which includes many variations. The large number of variations suggests that carbon nanotubes will likely experience improvements in performance and the number of applications will continue to grow.
This document summarizes a study on the effect of crystallite size of zinc oxide (ZnO) filler on the properties of polypropylene (PP)/ZnO nanocomposites. ZnO nanoparticles were prepared using two different methods, resulting in nanoparticles with crystallite sizes of 13.4 nm (NZO) and 29.2 nm (CZO). PP/ZnO composites containing 0-5% ZnO were produced by melt mixing. Composites with NZO exhibited higher mechanical properties, dynamic properties, and thermal stability than those with CZO, due to the smaller crystallite size and more uniform dispersion of NZO in PP. Transparency of the composites improved with decreasing ZnO crystallite
The development of desalination technology become a necessary due to the intense shortage of fresh water, especially in the gulf.
In the last six decades, the number of desalination units have increased dramatically.
Different techniques have been used for water desalination systems such as:
Capacitive deionization (CDI)
Multi-stage flash (MSF) distillation
Reverse osmosis (RO)
Electrodialysis
Nuclear power
This document examines the influence of film thickness on the structural, electrical, and photoluminescence properties of aluminum tris(8-hydroxyquinoline) (Alq3) thin films deposited on silicon substrates via vacuum evaporation. Fourier transform infrared spectroscopy, current-voltage, capacitance-voltage, and photoluminescence spectroscopy measurements were performed on Alq3 films of varying thicknesses. The results showed that molecular structure was unaffected by thickness but photoluminescence intensity and emission energy increased with thickness. Turn-on voltage and transition voltage from current-voltage and capacitance-voltage measurements also increased with thicker films.
1) Copper selenide thin films were prepared by thermal evaporation and annealed at different temperatures to study their structural, optical, and surface properties for thermoelectric applications.
2) XRD analysis showed the films crystallized in the hexagonal phase and crystallite size increased with higher annealing temperatures up to 300°C. Above 300°C, the films became amorphous.
3) Optical analysis found the band gap increased and thickness decreased with increasing annealing temperature, indicating better crystallinity. Surface analysis by FESEM showed denser, more uniform grains with annealing.
Interdiffusion, reactions, and transformations in thin filmMd Ataul Mamun
This document discusses various topics related to interdiffusion, reactions, and transformations in thin films:
1. It explains the concepts of diffusion, nucleation and grain growth that can occur in thin films. Diffusion is impacted by factors like temperature, grain boundaries, and dislocations.
2. Interdiffusion in thin films occurs much faster than in bulk materials due to diffusion along grain boundaries and dislocations. This can impact thin film integrity over time.
3. Reaction and compound formation at interfaces between thin films is discussed, like the growth of SiO2 at the Si/O2 interface or intermetallic compound formation.
4. Phase transformations and the use of diffusion barriers to prevent undesirable
This document summarizes the synthesis, characterization, and properties of nickel ferrite (NiFe3O4) nanoparticles. Nickel ferrite was synthesized using a sol-gel technique and sintered at 600°C. X-ray diffraction analysis confirmed the formation of nickel ferrite and showed structural changes due to ion shifting between lattice sites. Scanning electron microscopy images showed agglomerated, porous nanoparticles with an average size of 0.21μm. AC conductivity measurements showed a conductivity of 1.0 x 10-4 S/cm due to dipole polarization. Dielectric properties were also measured as a function of frequency.
Carbon nanotube fibers (CNTFs) were synthesized using a horizontally spinning chemical vapor deposition (CVD) technique. Scanning electron microscopy (SEM) was used to characterize the microstructure of the CNTFs. The CNTFs were grown using thermal CVD with iron catalyst and methane carbon source. During growth, the CNTs were directly pulled and twisted to form fibers. SEM analysis was conducted to investigate the morphology, shape, and other properties of the CNTFs, including electrical conductivity. This technique aims to develop high performance EM transmitter materials using CNTFs.
Fabrication and characterization of nickelijoejournal
This paper shows that nickel nanowires of length 11μm and diameters 800 and 15nm were grown within
the pores of nuclear track polycarbonate membrane by electrodepositing nickel. Surface morphology and
crystallographic structure of the deposited nanowires was investigated using SEM, TEM and XRD
respectively. It is found that low current density gives good result, while high current density leads to the
formation of curled nanowires. Fabricated nanowires were further investigated for electrical properties
and found that nanowires obey ohm’s law. Through structural characterization it has been observed that
the fabricated nanowires posses FCC lattice structure.
Electrochemical Supercapacitive Performance of Sprayed Co3O4 ElectrodesIJERA Editor
Nanocrystalline cobalt oxide (Co3O4) thin film electrodes were fabricated by spray pyrolysis method on conducting fluorine doped tin oxide (FTO) substrates using ammonia complexed with cobalt chloride (CoCl2. 6H2O) solution. The structural and morphological properties of Co3O4electrodes were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The surface morphology study showed the film formation of porous surface with clusters. The electrochemical supercapacitive properties ofCo3O4 electrodes were evaluated using cyclic voltammetry and galvanostatic charge-discharge method. The Co3O4electrodes showed maximum specific capacitance of 168 F/g in 1 M aqueous KOH electrolyte at the scan rate of 20 mV/s. The maximum specific energy and specific power of the cell are 2.2Wh/kg and 0.23 kW/kg, respectively.
The document discusses the synthesis of single-walled carbon nanotubes using chemical vapor deposition. It then describes the process of acidic oxidation of the nanotubes and their application as ultra-sharp probes for atomic force microscopy through dielectrophoresis. The oxidation process introduces defects in the nanotubes and selectively destroys metallic nanotubes, enriching semiconducting ones, as shown through resonance Raman spectroscopy. Oxidized nanotubes are dispersed and dielectrophoresis is used to attach them to atomic force microscopy probe tips, where their high aspect ratio enables high-resolution imaging.
This document discusses different methods for fabricating carbon nanotube (CNT) interconnects and comparing their performance. It proposes a double layer CNT interconnect structure that includes two CNT networks separated by a 1nm aluminum oxide layer. Testing shows that double layer structures have higher conductivity, less variation in conductance, and higher probabilities of conductive paths compared to single layer structures. The additional aluminum oxide layer is believed to help capture more CNTs during coating, allowing more tunneling pathways between the two CNT networks to improve conductivity. Phase transition phenomena in conductance based on size and structure are also investigated using percolation theory.
Maiyalagan,Template synthesis and characterization of well aligned nitrogen c...kutty79
The synthesis of well-aligned nitrogen containing carbon nanotubes by pyrolysis of polyvinyl pyrrolidone (PVP) on alumina membrane
template is described. The nanotubes were characterized by elemental analysis, electron microscopic analyses, Raman, IR and X-ray photoelectron
(XPS) spectroscopic techniques. SEM, transmission electron microscopy (TEM) and AFM images reveal the hollow structures and
vertically aligned features of the nanotubes. Raman spectrum shows the characteristic bands at 1290 cm−1 (D-band) and 1590 cm−1 (G-band).
IR spectral bands indicated the characteristic C–N bonds in carbon nanotubes. This confirms the presence of nitrogen atoms in the carbon
framework. The XPS and elemental analyses further indicate significant amount of nitrogen in the nanotubes. IR, elemental and XPS analyses
clearly provide evidence for the presence of nitrogen in carbon nanotubes.
Carbon nano tubes for concrete better constructionsriram1052
The document summarizes a presentation on the compressive strength and microstructure of carbon nanotubes-fly ash cement composites. It discusses adding different amounts of carbon nanotubes (CNTs) to fly ash cement mixtures and testing the density, compressive strength, and microstructure of the resulting composites. Testing included SEM, XRD, TGA, DTA, and EDS analyses. The results showed that adding 0.5-1.0% CNTs increased the density and compressive strength of the fly ash cement composites compared to mixtures without CNTs. Microstructural analysis revealed the CNTs were uniformly dispersed in the cement matrix.
Template synthesis and characterization of well aligned nitrogen containing c...madlovescience
This document describes the synthesis and characterization of nitrogen-containing carbon nanotubes produced through the pyrolysis of polyvinyl pyrrolidone on an alumina membrane template. The nanotubes were analyzed using various techniques which showed they had a hollow, vertically aligned structure with a significant amount of nitrogen incorporated into the carbon framework, as evidenced by elemental analysis, Raman spectroscopy, IR spectroscopy, and XPS. The template synthesis method allowed production of well-aligned nitrogen-containing carbon nanotubes with controlled morphology and composition.
Template synthesis and characterization of well aligned nitrogen containing c...tshankar20134
This document describes the synthesis and characterization of nitrogen-containing carbon nanotubes produced through the pyrolysis of polyvinyl pyrrolidone on an alumina membrane template. The nanotubes were analyzed using various techniques which showed they had a hollow, vertically aligned structure with a significant amount of nitrogen incorporated into the carbon framework, as evidenced by elemental analysis, Raman spectroscopy, IR spectroscopy, and XPS. The template synthesis method allowed production of well-aligned nitrogen-containing carbon nanotubes with controlled morphology and composition.
The document summarizes research on the chemical solution deposition of CaCu3Ti4O12 (CCTO) thin films. Key findings include:
1) Polycrystalline pure phase CCTO thin films with preferential (220) orientation were obtained after sintering at 750°C. The films exhibited a bimodal grain size distribution.
2) The dielectric constant (k) of a film sintered at 750°C was approximately 2000 and the loss factor (tan δ) was approximately 0.05, as measured at 1 kHz.
3) X-ray diffraction and scanning electron microscopy analysis showed the films had a polycrystalline cubic perovskite structure with exaggerated grain growth
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
This document reviews the use of carbon nanotubes to improve the surface finish of the electrical discharge machining (EDM) process. EDM is commonly used to machine hard materials but often results in poor surface finish with cracks and defects. Researchers have attempted to address this by adding powders like aluminum or silicon carbide to the dielectric fluid. More recently, carbon nanotubes have been explored due to their excellent thermal conductivity and electrical properties. When added to the dielectric fluid, carbon nanotubes are found to disperse the discharge energy more uniformly and reduce cracks and defects on machined surfaces. Surface roughness is improved by 70% or more and machining time is reduced. Carbon nanotubes show better results than other pow
This document provides information on various processes involved in integrated circuit fabrication, including epitaxial growth, oxidation, photolithography, diffusion, ion implantation, isolation techniques, and metallization. Epitaxial growth is used to grow silicon layers on substrates with the same crystal structure. Oxidation grows a silicon dioxide layer for protection and selective doping. Photolithography and etching are used to pattern doped regions. Diffusion and ion implantation introduce impurities. Isolation techniques like PN junctions and dielectric layers separate components. Metallization deposits aluminum for interconnections.
Carbon nanotubes are hollow tubes made of carbon atoms that have a diameter on the nanometer scale. They were discovered in 1991 but research on similar tubular carbon structures dates back to 1952. There are two main types of carbon nanotubes: single-walled nanotubes consisting of a single layer of graphene rolled into a seamless cylinder, and multi-walled nanotubes which contain multiple rolled layers of graphene. Carbon nanotubes exhibit extraordinary strength and electrical conductivity and have many potential applications, such as in materials science, electronics, medicine, and more.
Direct coupling of a carbon nanotube membrane to a mass spectrometer - contra...David Edwards
This document summarizes a study comparing a carbon nanotube membrane to a capillary tube for introducing gas samples to a mass spectrometer. Carbon nanotubes were grown within the pores of an aluminum oxide membrane using chemical vapor deposition. The selectivity and conductance properties of gases passing through the carbon nanotube membrane versus a capillary tube were then evaluated using the mass spectrometer. The study found the carbon nanotube membrane was more transmissive to methane than the capillary tube. Conductance through the two systems also differed in their dependence on total pressure for various gases.
This document provides information about carbon nanotubes. It begins with an acknowledgement and introduction section describing carbon nanotubes. It then discusses the history, chemistry, types (single-walled and multi-walled), methods of preparation (arc evaporation, laser vaporization, chemical vapor deposition), electrical and thermal properties, defects, and applications (water filtration, strengthening materials, capacitors, bone repair, displays, energy storage). It also notes potential health hazards from inhalation of short carbon nanotubes.
Bottom up approaches for nanoparticle synthesiskusumDabodiya
The document discusses bottom-up approaches for synthesizing nanomaterials. Bottom-up approaches involve building nanostructures from individual atoms and molecules, as opposed to top-down approaches which break down bulk materials. Some key bottom-up techniques described are physical vapor deposition methods like inert gas condensation, thermal evaporation, sputtering, and laser ablation which use gas precursors. Liquid phase bottom-up methods including wet chemical synthesis and microemulsion techniques are also covered. The document provides details on the mechanisms and advantages of various bottom-up synthesis methods.
This document describes a new method for producing stable carbon nanotube (CNT) aerogels with high electrical conductivity and porosity. The method involves:
1) Forming a chemically cross-linked gel of CNTs in solution using a chemical cross-linker.
2) Drying the gel using supercritical CO2 to produce an aerogel without shrinkage.
3) Thermally annealing the aerogel in air, which improves electrical conductivity, mechanical stability, surface area, and porosity by reopening pores.
The resulting annealed CNT aerogels are highly porous (>99%), electrically conductive (1-2 S/cm), and have a large specific surface area (590
Enhanced field electron emission of flower like zinc oxide on zinc oxide nano...Suhufa Alfarisa
For the first time, zinc oxide (ZnO) nanoflowers on ZnO nanorods were produced on carbon nanotubes
(CNTs) synthesised from waste cooking palm oil precursor. First, CNTs were grown using thermal chemical vapour deposition method. Next, ZnO nanostructures were deposited using the sonicated sol-gel immersion method
Carbon nanotubes were discovered in 1991 by Sumio Iijima. They can be single-walled or multi-walled cylinders composed of graphene sheets rolled into a tube. Carbon nanotubes have a diameter of 1 nm or less and a length that is millions of times longer. They exhibit extraordinary strength and unique electrical properties and have a wide range of potential applications, including as structural and electronic materials, for energy storage, and in medicine. Carbon nanotubes can be produced through arc discharge, laser ablation, and chemical vapor deposition.
Dielectric Constant of nano- CCTO / Epoxy CompositeIOSR Journals
Nanocrystalline multiphase CaCu3Ti4O12 (CCTO) was prepared using Ca(NO3)2.4H2O, Cu(NO3)2.3H2O, TiO2 and C2H2O4.2H2O. The X-Ray differection and SEM analysed of the prepared CCTO powder sintered at 900oC and 950oC. A homogeneous ceramics-polymer nanocomposites consisting of CCTO particles as fillers and epoxy polymer as matrix have been prepared using a casting process. The nanocomposites exhibit enhanced dielectric constant and dielectric loss. Dielectric properties of CCTO ceramics were characterized in a broad frequency range (100 Hz-1 MHz) and at a temperature ranged from 25 oC to 150 oC. As a result of increasing the content of CCTO, the dielectric constant and dielectric loss of composites are increased. The increase of dielectric loss at high frequencies is due to the relaxation process in the polymer matrix.
Nanocoating GDZ is compared with Conventional YSZ coating for Hot Corrosion Resistance in presence of V2O5 and Na2SO4 salt which are formed at high temp in gas turbines.
Low Cost Synthesis of Single Walled Carbon Nanotubes from Coal Tar Using Arc ...IOSRJAP
There are various methods such as arc discharge, laser ablation, chemical vapour deposition (CVD), template-directed synthesis for the growth of CNTs in the presence of catalyst particles. The production of carbon nanotubes in large quantities is possible with inexpensive coal as the starting carbon source by the arc discharge technique. It is found that a large amount of carbon nanotubes of good quality can be obtained in the cathode deposits in which carbon nanotubes are present in nest-like bundles. For more than two decades, now, there has been extensive research on the production of carbon nanotubes (CNT) and optimization of its manufacture for the industrial applications. It is believed that they are the strong enough but most flexible materials known to mankind. They have potential to take part in new nanofabricated materials. It is known that, carbon nanotubes could behave as the ultimate one-dimensional material with remarkable mechanical properties. Moreover, carbon nanotubes exhibit strong electrical and thermal conducting properties. This paper primarily concentrates on the optimising such parameters related to the mass production of the product. It has been shown through Simplex process that based on the cost of the SWNT obtained by the arc discharge technique, the voltage and the current should lie in the range of 30 - 42 V and 49 - 66 A respectively. Any combination above the given values will lead to a power consumption cost beyond the final product cost, in turn leading to infeasibility of the process. Strong expectations exist for future use of carbon nanotubes as composite materials in a large number of industries. Production cost and control of the purity and properties of such materials will influence the impacts nanotubes on the chemical, computer and construction industries. Coal properties in this case are also important. Weak bonds and mineral matter in the coal play an important role in the formation of the nanotubes
Carbon nanotubes are allotropes of carbon that have a nanostructure that is a hollow cylinder of graphene. There are two main types: single-walled nanotubes consisting of a single layer of graphene and multi-walled nanotubes containing multiple layers of graphene. Carbon nanotubes are synthesized using methods such as arc discharge, laser ablation, and chemical vapor deposition. They are characterized using techniques like scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Carbon nanotubes have remarkable mechanical, thermal, and electrical properties that make them promising for applications in materials science, electronics, and other fields.
2. does not produce pure tungsten films but instead a tungsten oxicarbide in the following reaction: W(CO)6 + Heat →WOxCy +
5 CO. This unbalanced equation does not represent a stoichiometric reaction[4]. For the remainder of this paper CVD
tungsten will refer to the tungsten oxycarbide film produced by the CVD process. The CVD tungsten can be reduced to a
pure tungsten film by annealing it at 800 °C in the presence of hydrogen gas.
METHODS
Patterned CNT Growth
The VACNT growth process is as described previously [1-3]. First a pattern or “footprint” of the structure is created in
photoresist on a substrate (silicon wafer) through standard photolithography. The surface is then coated with a 30 nm thin
film of alumina coating by e-beam evaporation. Next a 2-6 nm layer of iron is added (Figure 2a); this bilayer acts as the
catalyst for VACNT growth. The photoresist (and the bilayer on its surface) is removed leaving the catalyst pattern. The
CNTs grow vertically from the catalyst forming sharp boundaries, this type of growth is called vertically aligned carbon
nanotubes (figure 2b and figure 1a ). The vertical growth transforms the 2-D footprint into a 3-D structure.
Tungsten Infiltration
The infiltration reactor configuration is illustrated in figure 3. The tungsten carbonyl [W(CO)6] source compound was placed
in a cylindrical aluminum block (called the heated source chamber) which was inserted into the reaction chamber via a 2 inch
Ultra-Torr fitting. A cartridge heater was used to heat the source chamber; a K-type thermocouple and Omron E5K
temperature controller was used to regulate the temperature. The source chamber (containing the carbonyl) was heated to
160 °C which causes the [W(CO)6]to volatilize. It was held at this temperature for the duration of the deposition process to
ensure a constant rate of carbonyl vapor entering the reaction chamber. The carbonyl vapor was carried into the cold-wall
reaction chamber by preheated hydrogen gas (50-150 sccm). The hydrogen gas was preheated by passing through the heated
source chamber. The reaction chamber was held at low pressure (3-6 torr) with a roughing pump. The VACNT samples were
heated on a graphite susceptor plate which was heated electrically. The electrical power was supplied by a Variac
autotransformer connected to a 100:1 step down transformer which delivers current in excess of 200 amps to the susceptor
plate during heating. The VACNTs were heated to above the decomposition temperature of the carbonyl vapor. When the
Figure 2 CNT-M process (a) A catalyst bilayer consisting of a 2 nm Fe film on a 30 nm Al2O3 film is patterned by lift-off
on a silicon wafer. (b) A forest of VACNT’s is grown from the patterned catalyst. (c) Chemical vapor infiltration coats the
individual nanotubes, filing in the patterned carbon nanotube framework with secondary material. A floor layer (indicated
by the white circle) of the secondary material is deposited on the exposed substrate (d) The floor layer is removed by
reactive ion etching(RIE). (e) A sacrificial layer is etched to release part or all of the structure from the substrate. (f)
Electron micrograph of structures fabricated in silicon nitride by the CNT-M process.
500 µm
a
ed
cb
f
34
3. carbonyl vapor contacted the heated VACNTs it decomposed and the tungsten film was deposited on the nanotubes. The
byproducts are evacuated and exhausted through the vacuum pump in gaseous form.
The primary goal of this project was to uniformly infiltrate patterned VACNT forests with tungsten. In an effort to
maximize infiltration, various geometries were explored. Initially the substrate was placed upright in the middle of a graphite
susceptor plate, approx. 6 inches from the source of heated carbonyl (Figure 3a). A inverted sample mount was also created
which allowed the sample to be much closer to the source in an inverted geometry (within 2 inches). This inverted mount
consisted of a block of aluminum with an angle on one end and placed on the suseptor plate (Figure 3b). A clip was used to
hold the sample at the angle. Other parameters that were varied were the gas flow rate and the temperature.
RESULTS
Figure 4 shows scanning electron microscope (SEM) images of samples infiltrated in different geometries and temperatures.
All three samples were infiltrated with an H2 carrier gas at 50 sccm and the same initial amount of carbonyl (3 g). The
inverted geometry places the sample closer to the source as seen in figure 3b and results in more deposition as seen in figure
4a (some deposition in interior) relative to figure 4b(no detectable deposition on interior). Higher temperature (530 °C vs
290°C) also results in increased deposition and a significant capping layer as seen in figure 4c.
Figure 5 shows SEM images of a sample was infiltrated in the inverted position at 300 °C. The initial amount of
carbonyl was 6 grams. There is significantly more infiltration than at 290 °C resulting in a robust structure that appears to be
more than 50% solid. A thick solid cap has formed on the surface and is clearly visible. The coated VACNTs below the cap
have an average diameter of 100 nm. The cap is 3 microns thick.
The sample in figure 6 was done at 300 C while inverted. The initial amount of carbonyl was 5 grams. The images are of
a section of the VACNTs that have been broken to reveal the inner nanotubes. The average diameter of the CNTs is 100 nm.
A 2 micron cap also formed on top of the VACNTs.
Figure 3 Tungsten infiltration reactor a) The tungsten infiltration process takes place in a cold-wall reaction chamber. A
heated source chamber was connected to the reaction chamber via an Ultra Torr fitting. Sample is shown in upright
configuration. b) sample is shown in inverted configuration.
Thermocouple
a) Cold-wall reaction Chamber,
Upright Sample Configuration
Gas
Heated Source
Chamber
Ultra-torr
fitting
Tungsten
Carbonyl
Cartridge heater
Heating Electrode
VACNTs in upright
configuration
b) Cold-wall reaction Chamber,
Inverted Sample Configuration Heated Sourc
Chamber
Ultra-torr
fitting
Cartr
Heating Electrode
VACNTs in inverted
configuration
Aluminum Heat
Transfer Block
a) Low Temp Inverted c) High Temp Uprightb) Low Temp Upright
30µm 20µm 2µm
Figure 4. Scanning electron micrograph cross sectional views of samples infiltrated in different geometries at low
and high temperatures. a) infiltrated at 290 °C in the inverted geometry b) infiltrated at 290 °C in the upright
geometry c) infiltrated at 530 °C in the upright geometry.
35
4. DISCUSSION
The above results show that
tungsten infiltration can vary from almost
no infiltration to near full (but still porous)
infiltration. Geometry and temperature are
both critical variables in tuning infiltration.
Of the two geometries, the inverted (fig 4a)
geometry seems best for infiltration.
However at lower temperature, even the
inverted geometry gave non-uniform
infiltration; the sample in figure 4a seems
to have been partially infiltrated, with the
inside of the sample being more infiltrated
than the region near the surface. This non-
uniformity may be caused by a temperature
gradient across the CNTs where the bottom
of the VACNTs were hotter than the tops
resulting in preferential deposition on the
bottom. Samples at slightly higher
temperatures (such as those in figure 5 and
6) have a much more uniform infiltration
top to bottom. The upright geometry at
high temperature (fig 4. right) resulted in a
cap (although incomplete). The incomplete
cap formation is probably due to the
limited material in the source chamber as
the deposition was dome until the source
material was depleted. The sample in figure 6 was done on shorter VACNT growth, this may explain the full infiltration and
subsequent cap. Also, it appears that the sample broke due to stress and infiltration began to take place at the bottom of the
sample as well, this resulted in the encapsulation of the CNTs.
CONCLUSIONS
We have explored conditions for infiltrating patterned VACNTs for CNT-M. We have observed regimes for both uniform
infiltration and capping of forest features depending on temperature and reactor geometry. The metal infiltrated VACNT
structure forms a tungsten-carbon nanotube matrix capable of being manipulated and strong enough to be used in applications
such as MEMS. This tungsten-CNT composite may be used in conjunction with CNT-M to create metal MEMS that have the
high temperature and anticorrosive properties of tungsten. Other possible applications of the tungsten-CNT composites may
take advantage of its porosity in catalysis or as a micro-filter material. Future work is needed to determine the composition,
mechanical, andelectrical properties of this microstructured composite.
[1] D. N. Hutchison, Q. Aten, B. W. Turner, N. B. Morrill, L. L. Howell, B. D. Jensen, R. C. Davis, and R.R.
Vanfleet “High aspect ratio microelectromechanical systems: A versatile approach using carbon nanotubes as a
framework,” Solid-State Sensors, Actuators and Microsystems Conference, 2009. TRANSDUCERS 2009.
International, p. 1604-1607, 2009.
[2] D. N. Hutchison, N. Morrill, Q. Aten, B. Turner, L. L. Howell, B. D. Jensen, R. R. Vanfleet, and R. C.
Davis “Carbon Nanotubes as a Framework for High-Aspect-Ratio MEMS Fabrication,” Journal of Micro
Electromechanical Systems, vol. 19, no. 1, pp. 75-82, (2010)
[3] Jun Song, David S. Jensen, David N. Hutchison, Brendan Turner, Taylor Wood, Andrew Dadson, Michael
A. Vail, Matthew R. Linford, Richard R. Vanfleet, and Robert C. Davis “Carbon Nanotube Templated
Microfabrication of Porous Silicon Carbon Materials with Application to Chemical Separations,” Advanced
Functional Materials, p. 1-8, 2011.
[4] K. K. Lai and H. H. Lamb, “Tungsten chemical vapor deposition using tungsten hexacarbonyl - microstructure of as-
deposited and annealed films,” Thin Solid Films, vol. 270, p. 114-121, Jun. 2000.
* davis@byu.edu
** allred@byu.edu
Figure 5 Inverted configuration tungsten deposition at 300 °C. a) Top down
image of where the sample broke. b) Cross sectional view at the broken edge.
2µm
4µm
a b
10µm 500 nm
a b
Figure 6. Inverted depositonat 600 C from 5 grams of W(CO)6 a) A cross
sectional view of broken sample. b) A close-up of the infiltrated CNTs.
36