Enhancing quality of carbon nanotubes through a real-time controlled CVD process with application to next-generation nanosystems

Laxminarayana, Karthik; Jalili, Nader

doi:10.1117/12.539582

Cited by 3 publications

(3 citation statements)

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“…However, their electric properties have not been quantified well due to their broad range of properties, which change depending on the type of nanotube and the growth method. Control-based manufacturing of these nanotubes is under investigation to grow nanotubes of required properties (Laxminarayana and Jalili, 2004). Nanotubes are classified as single-walled or multiwalled, depending on the number of concentric layers of carbon present in the nanotube.…”

Section: Introductionmentioning

confidence: 99%

Reinforcement of Piezoelectric Polymers with Carbon Nanotubes: Pathway to Next-generation Sensors

Ramaratnam

Jalili

2006

Journal of Intelligent Material Systems and Structures

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Piezoelectric polymers such as poly(vinylidene fluoride) (PVDF) are being currently utilized as low-cost sensors in many structural vibration control applications and measurements. Their low electromechanical coupling coefficient, however, has always been a concern when utilized in different applications. In order to remedy this, carbon nanotubes, known for their extraordinary properties, can be mixed with such piezoelectric polymers as they have the potential to improve the electromechanical response of these polymers. Along this line of reasoning, different types of nanotubes; namely, single-walled and multiwalled are blended with a copolymer of PVDF. Through extensive experimental vibration testing and theoretical verification, it is found that the nanotube-based polymers yield better response characteristics than those of the plain piezoelectric polymers. More specifically, it is demonstrated that the dominant mechanism responsible for improved sensing performance is the increased Young’s modulus of elasticity of the nanotube-based polymer for the samples considered here. The significant change in properties of these piezoelectric polymers with different fabrication conditions and nanotube addition, though provokes doubts about standardization, creates a pathway for the development of next-generation sensors with enhanced or entirely new properties.

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Section: Introductionmentioning

confidence: 99%

Reinforcement of Piezoelectric Polymers with Carbon Nanotubes: Pathway to Next-generation Sensors

Ramaratnam

Jalili

2006

Journal of Intelligent Material Systems and Structures

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“…Future research of these novel sensors paradigm will include: nanotube addition in different percentages, changing the type of nanotubes, determining the piezoelectric constants of the novel sensors and comparison with the existing PVDF sensors. Growing nanotubes of required dimensions [15] will also help to generalize this novel sensor paradigm. Alignment of the nanotubes will also affect the properties of these novel films.…”

Section: Experimentalsetupmentioning

confidence: 99%

“…The equation relating the strain (assuming the strain to be averaged over the sensor length) to the voltage output ofthe sensor can be written as [14], (15) x E°hd31b…”

Section: Constitutive Equations Of the Piezoelectric Sensormentioning

confidence: 99%

Development of a novel strain sensor using nanotube-based materials with applications to structural vibration control

2004

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In many structural vibration control applications, strain sensors play a key role in the design and implementation of the vibration controller. Different types of sensors are commercially available, among which is the poled polyvinylidene difluoride (PVDF), an attractive sensor for large bandwidths and low costs. Despite such attractive features, PVDF-based sensors have limited use due to their low efficiency (mechanical energy to electrical energy conversion factor). To remedy this, nanocrystals and nanostructures have been recently cited as candidate materials that can be engineered to exhibit enhanced or entirely new properties for use in different applications. Particularly, carbon nanotubes (CNTs) have raised considerable interest in the scientific community due to their size and wide range of outstanding material properties. Given the moduli and strength values of CNTs, they are ideal filler materials for high performance (polymer) composite materials with unbeatable modulus-to-weight and strength-toweight ratios-the attributes that are essential for structural vibration control of a wide variety of industrial equipment and systems. Along this line of reasoning, this paper undertakes the development and implementation of a novel sensor paradigm based on proper fusion of CNTs with PVDF materials.

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Molecular Dynamics Investigation of Carbon Diffusivity in Metal Nanoparticles During CVD-Based Nanotube Fabrication Process

Hosseini

Jalili

2006

Heat Transfer, Volume 1

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In this paper, molecular dynamics technique is utilized to investigate carbon molecules diffusivity into iron oxide nanoparticles such as FeO and Fe2O3. Such nanoparticles can be used during carbon nanotube (CNT) synthesis process in a chemical vapor deposition (CVD) system. Several simulations are conducted in the atmospheric pressure condition and for different temperatures ranging from 500 to 1100°C, which is common range for multi-walled and single-walled CNT (MWCNT and SWCNT) fabrication. The mean square displacement (MSD) diagrams and their corresponding diffusivity of the carbon molecules into the nanoparticles are then plotted. The results are compared with those obtained after adding silicon molecular structure to the each nanoparticle as substrate. The results From NPT/NVE (pressure constant-temperature constant/velocity constant-energy constant) simulations show that for each nanoparticle, the diffusivity increases as higher temperatures considered in the simulation. However, the corresponding diffusivity rate doesn't necessarily increase. In the diffusivity diagrams, three distinctive temperature regions are observed. In the temperature regions where MWCNT and SWCNT are commonly produced, decreasing in diffusivity rate is observed, while in transition region where CNTs change from multi-walled to single-walled, the diffusivity increases for both simulated metal nanoparticles. Finally, by investigating and comparing diffusivity diagrams of each nanoparticle, before and after adding silicon as substrate, it is observed that the effects of silicon layer decreases the amount of carbon molecules diffusivity. This decrease is more considerable in higher temperatures. The obtained information from this study helps to understand the growth rate and formation mechanism of MWCNT/SWCNT and their relationship with carbon diffusivity in metal nanoparticles in great detail which are important keys in controlling nanotube properties.

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Enhancing quality of carbon nanotubes through a real-time controlled CVD process with application to next-generation nanosystems

Cited by 3 publications

References 0 publications

Reinforcement of Piezoelectric Polymers with Carbon Nanotubes: Pathway to Next-generation Sensors

Reinforcement of Piezoelectric Polymers with Carbon Nanotubes: Pathway to Next-generation Sensors

Development of a novel strain sensor using nanotube-based materials with applications to structural vibration control

Molecular Dynamics Investigation of Carbon Diffusivity in Metal Nanoparticles During CVD-Based Nanotube Fabrication Process

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