Bulletin of the American Physical Society
Annual Meeting of the Four Corners Section of the APS
Volume 55, Number 9
Friday–Saturday, October 15–16, 2010; Ogden, Utah
Session K2: Condensed Matter, Nano I |
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Chair: Jordan Gerton, University of Utah Room: 404A |
Saturday, October 16, 2010 11:30AM - 11:42AM |
K2.00001: Carbon Nanotube Templated Fabrication of High Strength Microsieves Andrew Davis, Richard Vanfleet, Robert Davis We developed a high strength, low cost microsieve for both liquid and gas filtration. Developed using infiltrated carbon nanotube (CNT) forests grown using CNT templated microfabrication (CNT-M), the microsieve can withstand pressures up to 200 psi. The pattern was created using photolithography with pore sizes of 5microns and may be used for absolute microfiltration of particles that size and over. [Preview Abstract] |
Saturday, October 16, 2010 11:42AM - 11:54AM |
K2.00002: Orientation of Vanadium Dioxide Grains on Various Substrates Felipe Rivera, Robert Davis, Richard Vanfleet Crystalline vanadium dioxide VO$_{2}$ experiences a fast and reversible semiconductor-to-metal structural phase transition near 68$^{\circ}$C. The changes exhibited during this phase transition comprise a well known change in resistivity of several orders of magnitude, as well as a significant drop in optical transmittance in the infrared. Due to the changes in these optical and electronic properties, vanadium dioxide shows promise as a material to be used in many applications ranging from thermochromic window coatings to optoelectronic devices. However, since there is a structural component to the phase transition of VO2, it is of interest to study the orientation of the crystalline grains deposited. Substrates such as glass, SiO$_{2}$, Sapphire, and TiO$_{2}$ have been used for the deposition of this material. We used orientation imaging microscopy to study and characterize the orientation of the grains deposited on several of these substrates. Here we present results on this study. [Preview Abstract] |
Saturday, October 16, 2010 11:54AM - 12:06PM |
K2.00003: Patterned Carbon Nanotube Applications for Transmission Electron Microscopy Kyle Zufelt, Jonathan Abbott, Robert Davis, Richard Vanfleet Transmission electron microscopy is a method for observing and characterizing thin films and other nanoscale samples. Carbon nanotubes were patterned and grown to function as disposable grids for transmission electron microscopy research. Patterned nanotube forests were infiltrated with carbon by chemical vapor deposition to provide greater strength. Carbon and polymer support films have been deposited in a batch process to provide a substrate for samples to be observed in the microscope. Grids are released from silicon wafer substrates by chemical etching. Carbon grids represent a significant improvement over traditional copper grids, which are not robust and must be individually coated in support films. These carbon support grids are also superior for use in spectroscopy applications (EELS, EDX) because of the low background signal. [Preview Abstract] |
Saturday, October 16, 2010 12:06PM - 12:18PM |
K2.00004: Fe$_{3}$O$_{4}$ nanoparticles: superparamagnetic behavior Matea Trevino, Karine Chesnel, Betsy Olsen, Julie Boerio-Goates Magnetite ( Fe$_{3}$O$_{4 })$ nanoparticles exhibit a superparamagnetic behavior when small, 1-50 nm in diameter. When cooling the sample, we reach a point called the blocking temperature (Tb), below which~the magnetic moments are frozen.~ Each particle carries a super macrospin and aligns with other macrospins in the presence of a magnetic field. We will show results obtained on the nanoparticles of two batches: 5-15nm and 40-50nm in diameter. We studied these particles with Vibrating Sample Magnetometry (VSM). We will show magnetization curves taken at different temperatures and Field Cooling versus Zero Field Cooling measurements, to determine Tb. We will show Atomic Force Microscopy (AFM) images of nanoparticles deposited on a substrate. The AFM images provide information about the structure and morphology of the nanoparticles assembly. We will include Magnetic Force Microscopy (MFM) images to show the local magnetic profile of individual particles. By comparing VSM data and AFM/MFM images, our goal is to understand the superparamagnetic behavior of nanoparticles. [Preview Abstract] |
Saturday, October 16, 2010 12:18PM - 12:30PM |
K2.00005: 3D Modeling of the Chemical Vapor Infiltration of Carbon Nanotube Forests Adam Konneker, David Wagner, Richard Vanfleet, Robert Davis, David Allred Carbon nanotube templated microfabrication (CNT-M) is a recently developed process for making high aspect ratio microstructures and microelectromechanical systems (MEMS). In this process vertically aligned carbon nanotube (VACNT) forests are infiltrated with other materials. This process has been used to construct high aspect ratio MEMS devices from a variety of materials that is not possible with other methods. We are trying to better understand how the mass transport and chemistry involved in thin film deposition are affected by the complex geometry within a nanotube forest. Without optimized parameters, deposition is nonuniform and the interior of the structures are riddled with voids which reduce the strength of the devices. In order to find optimal deposition conditions for a variety of materials and forest geometries, we are developing algorithms and tools to construct and analyze 3D nanotube forests. These 3D models are composed of many individual nanotube structures and provide a method to model the different length scales present in a patterned CNT forest. We have experimented with a variety of algorithms to generate the model nanotubes, including simple kinematic and dynamic methods. [Preview Abstract] |
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