Stine R.,Nova Research Inc. |
Lee W.-K.,U.S. Navy |
Whitener Jr. K.E.,U.S. Navy |
Robinson J.T.,Washington Technology |
Sheehan P.E.,U.S. Navy
Fluorination can alter the electronic properties of graphene and activate sites for subsequent chemistry. Here, we show that graphene fluorination depends on several variables, including XeF2 exposure and the choice of substrate. After fluorination, fluorine content declines by 50-80% over several days before stabilizing. While highly fluorinated samples remain insulating, mildly fluorinated samples regain some conductivity over this period. Finally, this loss does not reduce reactivity with alkylamines, suggesting that only nonvolatile fluorine participates in these reactions. © 2013 American Chemical Society. Source
Sutto T.E.,U.S. Navy |
Duncan T.T.,Nova Research Inc.
The electrochemical behavior of magnesium perchlorate in ionic liquids is characterized using Co 3O 4 as the working electrode and Mg foil as the anode material. The cations of the ionic liquids were 1,2-dimethyl-3-R-imidazolium with R = butyl (MMBI) or octyl (MMOI), and the anion was bis(trifluoromethanesulfonyl)imide (TFSI). The TFSI ionic liquids exhibited large electrochemical windows, with MMOITFSI possessing an electrochemical window of 5 V. Ionic conductivity studies indicated a higher ionic conductivity of 3.67 mS/cm for 1.0 M Mg(ClO 4) 2 in MMBITFSI when compared to 2.16 mS/cm for 1.0 M Mg(ClO 4) 2. MMOITFSI was selected as the electrolyte for the electrochemical characterizations of Co 3O 4, due to its larger electrochemical window and its inability to intercalate, and therefore degrade, graphitic material added to the Co 3O 4 electrode. Electrochemical results indicated that the maximum attainable value for x in Mg xCo 3O 4 was 0.33, with an initial capacity of only 78 mAh/g. X-ray diffraction studies of the Mg intercalated Co 3O 4 indicated a 20% expansion of the unit cell and a decrease in the symmetry of the metal oxide from cubic to orthorhombic symmetry. Charge/discharge experiments at a C/3 rate were performed vs. Mg metal. Results indicated that after 10 cycles, the capacity decreased linearly with cycling, most likely due to the inability to deintercalate the more strongly interacting Mg ++. © 2012 Elsevier Ltd. Source
Nova Research Inc. | Date: 2011-03-14
A composite armor plate includes a fracture layer placed adjacent to a ceramic layer. The ceramic layer provides a ballistic resistant layer that receives a ballistic impact and propagates a compression wave. The fracture layer is placed behind the ceramic layer and absorbs a portion of the compression wave propagating out in front of the ballistic impact. The absorbed compression wave causes the fracture layer to at least partially disintegrate into fine particles, which dissipates energy in the process. To cause a higher degree of fracturing (and thus larger dissipation of compression wave energy) the fracture layer includes a plurality of resonators embedded in a fracture material.
Nova Research Inc. | Date: 2011-02-23
An infrared camera system for low contrast employs a focal plane array (FPA) of a plurality of detector diodes. A read out integrated circuit (ROIC) including a plurality of integration switches is connected to the plurality of detector diodes. A frame mean calculator receives raw data from the FPA and an integration time servo receives a frame mean from the frame mean calculator and a preprogrammed target mean. The integration time servo compares the frame mean and target mean and provides an integration time output to the ROIC responsive to the comparison for control of the integration switches.
Nova Research Inc. | Date: 2010-09-28
A Read-In Integrated Circuit scene generator incorporates an array of unit cells, with each cell having a switching control circuit. An array of emitting elements is associated with the unit cells and each element is connected with a lead to the switching control circuit of the associated cell. A first electrically conducting overlayer is deposited substantially covering the array of unit cells and connected for current supply. Each emitting element is connected to the first conducting overlayer and the first conducting overlayer includes vias through which each connecting lead from the emitting element to the switching control circuit extends. A second electrically conducting overlayer is deposited substantially covering the array of unit cells and connected for current return. Each switching control circuit is connected to the second conducting overlayer. The second conducting overlayer also has vias through which each lead from the emitting element extends to the switching circuit.