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  • 1
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    Role of a Chemist in Modern Industries: Design and Development of Nanoengineered Multifunctional Materials (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: During the past fifteen years significant investment has been made for the applications of nanotechnology in almost every aspect of life. Almost every area of research has projected improvements including biotechnology, bioinspired electronic, optical and radiological sensors, or a promise for the emergence of some novel device technologies. For such applications major focus has been placed on research nanoparticles, nanotubes nanorods and two-dimensional structures similar to that of graphene. Some near- term applications of nano- particles and nanowires have produced very promising results for better synthesis of energy storage materials, design of biologically active composites like apatites, laser host crystals, photodetectors and sensor materials for radiation detection. To achieve desired morphologies, nanomaterials can be utilized some organic melt and orient the grains by the directional solidification method. The organic treated materials produce different characteristics than coarsened oxide materials. The focus is also understanding the morphology and performance function in human organs that occur because of aging or disease, and responses to interventions. We annealed to determine the changes in morphologies and hence effect of aging. In this presentation, we will discuss correlation between the designed composition, micromorphology and the performance parameters of nanomaterials. To understand the mechanism of formation of nanoparticles, nanoboloids, fibers experimental details and observations on the of multinary compounds will be presented. These observations on the transition of nanomorphology can highlight the mechanism of the phase transition in some oxides and selenides.
    Keywords: Chemistry and Materials (General)
    Type: M18-6600 , International Seminar on Green Chemistry: Synthesis, Processing & Devices; Apr 06, 2018 - Apr 07, 2018; Bihar; India
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  • 2
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    Surface Modification at Nanoscale; Nanoparticle-Nanowire Transition (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Binary, ternary and quaternary oxides and selenides have been developed and used in multiple applications including high power lasers, detectors, dielectric energy storage and variety of optical devices. These materials have been grown by Bridgman, physical vapor transport (PVT), chemical vapor transport (CVT) methods and flux methods in the form of bulk thin film, nanocrystals and nanowires. With increasing thrust of bio applications, nanoparticles it is essential to understand nucleation and nanomorphological transition during drug delivery, growth of nanoengineered bio composites in body, grain growth and final morphology. Addition of fluorides and selenides have increased significantly in synthetic tissue constituents because of some advantages in adhesion and stability. We have performed experiments on multinary oxides Sr-Ba-O-F, Se-Tl-As and Se-Pb-Sn-Se using several growth methods to demonstrate nanoparticle and nanowire transition. This study has great potential to increase surface area and also provides understanding to the mechanism of nanowire growth.
    Keywords: Composite Materials; Solid-State Physics
    Type: M18-6490 , SPIE (Defense + Commercial Sensing and Imaging); Apr 15, 2018 - Apr 19, 2018; Orlando, FL; United States
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  • 3
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    Low Size, Weight and Power Concept for Mid-Wave Infrared Optical Communication Transceivers Based on Quantum Cascade Lasers (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept presented, realized and tested in the laboratory environment. Resilience to atmospheric impairments analyzed with simulated turbulence. Performance compared to typical telecom based Short Wavelength Infra-Red transceiver.
    Keywords: Lasers and Masers; Communications and Radar
    Type: GSFC-E-DAA-TN27691 , Applied Optics
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  • 4
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    Growth Mechanism of Nanowires: Ternary Chalcogenides (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: In the past two decades there has been a large rise in the investment and expectations for nanotechnology use. Almost every area of research has projected improvements in sensors, or even a promise for the emergence of some novel device technologies. For these applications major focuses of research are in the areas of nanoparticles and graphene. Although there are some near term applications with nanowires in photodetectors and other low light detectors, there are few papers on the growth mechanism and fabrication of nanowire-based devices. Semiconductor nanowires exhibit very favorable and promising optical properties, including high transparency and a several order of magnitude better photocurrent than thin film and bulk materials. We present here an overview of the mechanism of nanowire growth from the melt, and some preliminary results for the thallium arsenic selenide material system. Thallium arsenic selenide (TAS) is a multifunctional material combining excellent acousto-optical, nonlinear and radiation detection properties. We observed that small units of (TAS) nanocubes arrange and rearrange at moderate melt undercooling to form the building block of a nanowire. In some cases very long wires (less than mm) are formed. Since we avoided the catalyst, we observed self-nucleation and uncontrolled growth of wires from different places.
    Keywords: Inorganic, Organic and Physical Chemistry; Solid-State Physics
    Type: M16-4931 , SPIE Defense and Commercial Sensing; Apr 17, 2016 - Apr 21, 2016; Baltimore, MD; United States
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  • 5
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    Development of Large Bandgap Materials Using Reactive Growth in Al-SI Eutectic for Optical and RF Applications (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Carbon was utilized as reactive element to modify the microstructure using forced mixing during crystallization of the Al-Si alloy by rotation and stirring. We nucleated the material on SiC substrates while the Al-Si melt was rotated with a speed of 30rpm in a graphite crucible. Several experiments were performed and parameters such as time of mixing, soaking temperature, rotation rate of the substrate and rate of cooling during the solidification was changed. We observed dendrite and cell morphologies during the solidification of rotating melt. The microstructure was characterized by optical microscopy and SEM-EDX and compositional spectroscopy. The effect of carbon impurities was studied on the solidifying microstructure. When we used the longer soak time of the melt in presence of carbon impurities we observed the destruction of dendritic morphology and the formation of cellular and colony structures. Similar approach has been used for Ga2O3, a novel large bandgap material also.
    Keywords: Inorganic, Organic and Physical Chemistry
    Type: M18-6926 , Materials Science & Technology (MS&T) 2018; Oct 14, 2018 - Oct 18, 2018; Columbus, OH; United States
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  • 6
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    Effect of Radiation on Biologically Active Glasses (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Multifunctional hydroxyapatites single crystals have been studied for their applications as the laser host material since past several decades. It is only recently their potential has been evaluated for bioactive materials. In the past researches, Czochralski and flux growth methods have been utilized to achieve single crystals. We have used low temperature processing techniques for synthesis. Organic melt was used to achieve oriented fibers by the directional solidification method. This organic treated material has different characteristics than coarsened oxide materials. Our approach involved low temperature processing using nano engineered powders of the material system Na2O-K2O-CaO- MgO-SrO-SiO2. Also, borates were processed by sintering and grain growth. Effect of -ray was studied by measuring the electrical characteristics of radiated samples. Our experiments to further improve mechanical characteristics indicate that substitution of calcium with some other elements such as gallium have great potential to improve the radiation hardening and mechanical properties of bones.
    Keywords: Inorganic, Organic and Physical Chemistry
    Type: M18-6925 , Materials Science & Technology (MS&T) 2018; Oct 14, 2018 - Oct 18, 2018; Columbus, OH; United States
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  • 7
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    Design and Characteristics of Hydroxyapatites: Effect of Radiation (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Hydroxyapatites single crystals have been investigated their applications as the laser host material. Czochralksi and flux growth methods have been utilized to achieve single crystals. Because of their bioactivities with tissues these have attracted interest for bone applications. For low temperature processing we have used several techniques. We utilized some organic melt and oriented the grains by the directional solidification method. This organic treated material has different characteristics than coarsened oxide materials. Our approach involved low temperature processing using nano-engineered powders of the material system MgO-Na2O-K2O-CaO-SrO-SiO2 and also borates were processed by sintering and grain growth. Our results indicate that substitution of calcium and strontium with some other elements such as gallium and magnesium have great potential to improve the mechanical properties of bones.
    Keywords: Aerospace Medicine
    Type: M18-6491 , SPIE (Defense + Commercial Sensing and Imaging) 2018; Apr 15, 2018 - Apr 19, 2018; Orlando, FL; United States
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  • 8
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    Nanoengineered Materials for SWIR HOT Detectors (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Heavy metal Selenide has been investigated for more than half century for high operating temperature (HOT) mid wave infrared (MWIR) applications. Most of the efforts have been devoted to make detector arrays on high-resistivity Si substrates for operating wavelengths in the 1.5 to 5.0 m region using physical vapor transport grown poly crystalline materials. For most of the biological spectral and imaging applications, short wave infrared (SWIR) detectors have shown better performance. Recent growth materials have shown variation in morphology with slight change in growth conditions and hence variation in performance parameters such as bandgap, mobility and resistivity from sample to sample. We have performed growth and optical characterization of pure and doped PbS and PbSe and have determined bandgap using available theoretical models for different morphologies.
    Keywords: Engineering (General)
    Type: M18-6488 , SPIE (Defense + Commercial Sensing and Imaging); Apr 15, 2018 - Apr 18, 2018; Orlando, FL; United States
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  • 9
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    Design of Multifunctional Materials: Chalcogenides and Chalcopyrites (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: There is a strong need for developing multifunctional materials to reduce the cost of applied material without compromising the performance of the detectors, devices and sensors. The materials design, processing, growth and fabrication of bulk and nanocrystals and fabrication into devices and sensors involve huge cost and resources including a multidisciplinary team of experts. Because of this reason, prediction of multifunctionality of materials before design and development should be evaluated. Chalcogenides and chalcopyrites are a very exciting class of materials for developing multifunctionality. Materials such as Gallium selenide GaSe and zinc selenide ZnSe have been proven to be excellent examples. GaSe is a layered material and very difficult to grow in large crystal. However, it's ternary and quaternary analogs such as thallium gallium selenide TlGaSe2, thallium gallium selenide sulfide TlGaSe2-xSs, thallium arsenic selenide Tl3AsSe3, silver gallium selenide AgGaGe3Se8, AgGaGe5Se12 and several others have shown great promise for multifunctionality. Several of these materials have shown good efficiency for frequency conversion (nonlinear optical NLO), electro-optic modulation, and acousto-optic tunable filters and imagers suitable for the visible, near-infrared wavelength, mid wave infrared (MWIR), long wave infrared (LWIR) and even up to Tera hertz wavelength (THW) regions. In addition, this class of materials have demonstrated low absorption coefficients and power handling capability in the systems. Also, these crystals do not require post growth annealing, show very large transparency range and fabricability.
    Keywords: Metals and Metallic Materials; Chemistry and Materials (General)
    Type: M17-6098 , Annual Materials Science & Technology (MS&T) Conference 2017; Oct 08, 2017 - Oct 12, 2017; Pittsburg, PA; United States
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  • 10
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    Solidification and Morphological Evolution of Al-Si Eutectics in Convector-Diffusive Conditions (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: The Al-Si material system is an important and has been studied for over half century with a focus on industrial applications in high strength and high conductivity alloys. A great deal of researches have been focused on controlling the morphology and hence performance through the addition of small impurities and by processing conditions. Most of the structure-property correlations are based on the post solidified micromorphology and growth conditions. This material system is unique and has been explored for heat spreader, controlling coefficient of expansion by adjusting composition of silicon and in designing composites. The Al-Si system is very interesting system for understanding the dendritic (Al-rich side) eutectic transition. Recently this system has been of great interest because of its applications in designing heat spreader, low temperature flux to grow SiC large substrates and in controlling the coefficient of expansion of Al-based alloys. We have performed extensive experiments to understand eutectic transition and to understand the morphological evolution in presence of impurities. We will discuss the results of dendritic transition into faceted long grains in convector-diffusive conditions. In this presentation we will present morphological transition in presence of carbon impurity and development of novel morphology.
    Keywords: Metals and Metallic Materials
    Type: M17-6099 , Materials Science & Technology 2017 (MS&T-17); Oct 09, 2017 - Oct 12, 2017; Pittsburgh, PA; United States
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