6 results
Hydrothermal synthesis and characterization of the eulytite phase of bismuth germanium oxide powders
- Timothy J. Boyle, Eric Sivonxay, Pin Yang, Mark A. Rodriguez, Bernadette A. Hernandez-Sanchez, Nelson S. Bell, Andrew Velazquez, Bryan Kaehr, Marlene Bencomo, James J.M. Griego, Patrick Doty
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- Journal:
- Journal of Materials Research / Volume 29 / Issue 10 / 28 May 2014
- Published online by Cambridge University Press:
- 16 May 2014, pp. 1199-1209
- Print publication:
- 28 May 2014
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A simple hydrothermal route to the eulytite phase of bismuth germanium oxide (E-BGO: Bi4(GeO4)3) that required no post-processing has been developed. The E-BGO material was isolated from a mixture of bismuth nitrate pentahydrate and a slight excess of germanium oxide in water under hydrothermal conditions (185 °C for 24 h). The resultant materials were characterized by powder x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and luminescence measurements to verify the particle's phase (eulytite), morphology, size, and response to a variety of excitation energy sources, respectively. Photoluminescence spectroscopic response from E-BGO pellets indicated that the samples exhibited a strong emission peak consistent with an x-ray induced luminescence of a E-BGO single crystal (500 nm excited at 285 nm). Cathodoluminescent properties of the E-BGO displayed a broadband spectrum with a maximum at 487 nm. The growth process was consistent with a standard Oswald ripening and LaMer growth processes.
Contributors
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- By Lenard A. Adler, Pinky Agarwal, Rehan Ahmed, Jagga Rao Alluri, Fawaz Al-Mufti, Samuel Alperin, Michael Amoashiy, Michael Andary, David J. Anschel, Padmaja Aradhya, Vandana Aspen, Esther Baldinger, Jee Bang, George D. Baquis, John J. Barry, Jason J. S. Barton, Julius Bazan, Amanda R. Bedford, Marlene Behrmann, Lourdes Bello-Espinosa, Ajay Berdia, Alan R. Berger, Mark Beyer, Don C. Bienfang, Kevin M. Biglan, Thomas M. Boes, Paul W. Brazis, Jonathan L. Brisman, Jeffrey A. Brown, Scott E. Brown, Ryan R. Byrne, Rina Caprarella, Casey A. Chamberlain, Wan-Tsu W. Chang, Grace M. Charles, Jasvinder Chawla, David Clark, Todd J. Cohen, Joe Colombo, Howard Crystal, Vladimir Dadashev, Sarita B. Dave, Jean Robert Desrouleaux, Richard L. Doty, Robert Duarte, Jeffrey S. Durmer, Christyn M. Edmundson, Eric R. Eggenberger, Steven Ender, Noam Epstein, Alberto J. Espay, Alan B. Ettinger, Niloofar (Nelly) Faghani, Amtul Farheen, Edward Firouztale, Rod Foroozan, Anne L. Foundas, David Elliot Friedman, Deborah I. Friedman, Steven J. Frucht, Oded Gerber, Tal Gilboa, Martin Gizzi, Teneille G. Gofton, Louis J. Goodrich, Malcolm H. Gottesman, Varda Gross-Tsur, Deepak Grover, David A. Gudis, John J. Halperin, Maxim D. Hammer, Andrew R. Harrison, L. Anne Hayman, Galen V. Henderson, Steven Herskovitz, Caitlin Hoffman, Laryssa A. Huryn, Andres M. Kanner, Gary P. Kaplan, Bashar Katirji, Kenneth R. Kaufman, Annie Killoran, Nina Kirz, Gad E. Klein, Danielle G. Koby, Christopher P. Kogut, W. Curt LaFrance, Patrick J.M. Lavin, Susan W. Law, James L. Levenson, Richard B. Lipton, Glenn Lopate, Daniel J. Luciano, Reema Maindiratta, Robert M. Mallery, Georgios Manousakis, Alan Mazurek, Luis J. Mejico, Dragana Micic, Ali Mokhtarzadeh, Walter J. Molofsky, Heather E. Moss, Mark L. Moster, Manpreet Multani, Siddhartha Nadkarni, George C. Newman, Rolla Nuoman, Paul A. Nyquist, Gaia Donata Oggioni, Odi Oguh, Denis Ostrovskiy, Kristina Y. Pao, Juwen Park, Anastas F. Pass, Victoria S. Pelak, Jeffrey Peterson, John Pile-Spellman, Misha L. Pless, Gregory M. Pontone, Aparna M. Prabhu, Michael T. Pulley, Philip Ragone, Prajwal Rajappa, Venkat Ramani, Sindhu Ramchandren, Ritesh A. Ramdhani, Ramses Ribot, Heidi D. Riney, Diana Rojas-Soto, Michael Ronthal, Daniel M. Rosenbaum, David B. Rosenfield, Durga Roy, Michael J. Ruckenstein, Max C. Rudansky, Eva Sahay, Friedhelm Sandbrink, Jade S. Schiffman, Angela Scicutella, Maroun T. Semaan, Robert C. Sergott, Aashit K. Shah, David M. Shaw, Amit M. Shelat, Claire A. Sheldon, Anant M. Shenoy, Yelizaveta Sher, Jessica A. Shields, Tanya Simuni, Rajpaul Singh, Eric E. Smouha, David Solomon, Mehri Songhorian, Steven A. Sparr, Egilius L. H. Spierings, Eve G. Spratt, Beth Stein, S.H. Subramony, Rosa Ana Tang, Cara Tannenbaum, Hakan Tekeli, Amanda J. Thompson, Michael J. Thorpy, Matthew J. Thurtell, Pedro J. Torrico, Ira M. Turner, Scott Uretsky, Ruth H. Walker, Deborah M. Weisbrot, Michael A. Williams, Jacques Winter, Randall J. Wright, Jay Elliot Yasen, Shicong Ye, G. Bryan Young, Huiying Yu, Ryan J. Zehnder
- Edited by Alan B. Ettinger, Albert Einstein College of Medicine, New York, Deborah M. Weisbrot, State University of New York, Stony Brook
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- Book:
- Neurologic Differential Diagnosis
- Published online:
- 05 June 2014
- Print publication:
- 17 April 2014, pp xi-xx
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Scintillating Metal Organic Frameworks: A New Class of Radiation Detection Materials
- Mark Allendorf, Ronald Houk, Raghu Bhakta, Ida Beck Nielsen, Patrick Doty
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1164 / 2009
- Published online by Cambridge University Press:
- 31 January 2011, 1164-L07-01
- Print publication:
- 2009
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The detection and identification of subatomic particles is an important scientific problem with implications for medical devices, radiography, biochemical analysis, particle physics, and astrophysics. In addition, the development of efficient detectors of neutrons generated by fissile material is a pressing need for nuclear nonproliferation and counterterrorism efforts. A critical objective in the field of radiation detection is to develop the physical insight necessary to rationally design new scintillation materials for specific applications. However, none of the material types currently used in has sufficient synthetic versatility to exert systematic control over the factors controlling the light output and its dynamics. Here we describe a spectroscopic investigation of two stilbene-based metal-organic frameworks (MOFs) we synthesized, demonstrating that they emit light in response to ionizing radiation, creating the first completely new class of scintillation materials since the advent of plastic scintillators in 1950. This highly novel and unexpected property of MOFs opens a new route to rational design of radiation detection materials, since the spectroscopy shows that both the luminescence spectrum and its timing can be varied by altering the local environment of the chromophore within the MOF. Therefore, the inherent synthetic flexibility of MOFs, which enables both the chromophore structure and its local environment to be systematically varied, suggests that this class of materials can serve as a controlled “nanolaboratory” for probing a broad range of photophysical and radiation detection phenomena. In this presentation we report on the time-dependent fluorescence and radioluminescence of these MOFs and related structures. Multiple decay characteristics have been observed for some materials under study, including fast (ns) exponential and slow (microsecond) non-exponential components. We interpret the results in terms of the electronic states, crystal structures, intermolecular interactions, and transport effects mediating the luminescence. The potential for particle discrimination schemes and large scale production of MOFs and will be discussed.
The Synthesis and Structures of Elpasolite Halide Scintillators
- Pin Yang, F. Patrick Doty, Mark A. Rodriguez, Margaret R. Sanchez, Xiaowong Zhou, Kanai S. Shah
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1164 / 2009
- Published online by Cambridge University Press:
- 31 January 2011, 1164-L11-05
- Print publication:
- 2009
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Low-cost, high-performance gamma-ray spectrometers are urgently needed for nonproliferation and homeland security applications. Available scintillation materials fall short of the requirements for energy resolution and sensitivity at room temperature. The emerging lanthanide halide based materials, while having the desired luminosity and proportionality, have proven difficult to produce in the large sizes and low cost required due to highly anisotropic properties caused by the non-cubic crystal structure. New cubic materials, such as the recently discovered elpasolite family (A2BLnX6; Ln-lanthanide and X-halogen), hold promise for scintillator materials due to their high light output, proportionality, and toughness. The isotropic nature of the cubic elpasolites leads to minimal thermomechanical stresses during single-crystal solidification, and eliminates the problematic light scattering at the grain boundaries. Therefore, it may be possible to produce these materials in large sizes as either single crystals or transparent ceramics with high production yield and reduced costs. In this study, we investigated the “cubic” elpasolite halide synthesis and studied the structural variations of four different compounds, including Cs2NaLaBr6, Cs2LiLaBr6, Cs2NaLaI6, and Cs2LiLaI6. Attempts to produce a large-area detector by a hot forging technique were explored.
Organic Semiconductors for Detection of Ionizing Radiation
- Tiffany M.S. Wilson, Douglas A. Chinn, Michael J. King, F. Patrick Doty
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1038 / 2007
- Published online by Cambridge University Press:
- 01 February 2011, 1038-O03-02
- Print publication:
- 2007
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Organic semiconductors are increasingly common in electronics and sensors, and are now under investigation for a novel type of radiation sensors at Sandia National Laboratories. This class of materials can offer wide band gaps, high resistivities, low dielectric constants, and high dielectric strengths, suggesting they may be suitable for solid-state particle counting detectors. A range of solution cast materials have been evaluated for this application, primarily in the family of poly(p-phenylene vinylene)s, or PPVs. The high ratio of hydrogen to carbon offers neutron sensitivity, while the low Z material provides some natural gamma discrimination. Compared to existing detectors, these materials could potentially offer large-scale radiation detection at a substantially reduced cost.
While PPVs hold promise for radiation detection, the mechanical and electrical properties must be optimized and the processing effects understood. Polymers can offer significantly simplified processing compared to the more common crystals used in solid state detection, which can be size limited and fragile. However, organic semiconductors are very sensitive to processing conditions, and mobility can be affected by orders of magnitude by processing variables, without altering any chemistry. Additives can also have dramatic effects on both electrical and mechanical properties. We report on nanoparticle additives that cause an increase in photoresponse of approximately three orders of magnitude as compared to a polymer film without additives. We separately show an order of magnitude increase in photoresponse by exposing the polymer/fullerene composite to sub-bandgap light.
Future work will analyze the feasibility of single particle detection and various geometries for optimization. Additional processing variables will also be investigated for further improvement of mobility and reduction of trap density.
Transport Properties of Stretch-Oriented PPV Films
- Tiffany Wilson, F. Patrick Doty, Douglas Chinn, A. Alec Talin, Michael King, Luke L. Hunter, Frank E. Jones, Christine Cuppoletti, H. Rouchanian, C. Munoz
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- Journal:
- MRS Online Proceedings Library Archive / Volume 937 / 2006
- Published online by Cambridge University Press:
- 01 February 2011, 0937-M03-04
- Print publication:
- 2006
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Organic semiconductors are under investigation for radiation sensors at Sandia National Laboratories. The wide band gaps, high resistivities, low dielectric constants, and high dielectric strengths of conjugated polymers suggest these materials may be suitable for solid-state particle counting detectors. A range of solution cast materials have been evaluated for this application, including polythiophenes and poly(p-phenylene vinylene)s, or PPVs.
Films were prepared by novel solution casting and mechanical stretching methods. Device structures including interdigital metal electrodes on glass and thin film transistors on SiO2 on silicon were fabricated by drop casting from solution and lamination of solid films. Transient and DC responses were recorded and analyzed. Experiments include laser stimulus for photoconductive pulse response, and field effect transistor testing. Mechanical stretching was shown to dramatically alter electrical properties of polymer films.
Future work will analyze the feasibility of single particle detection and analyze various geometries for optimization. The effects of traps and methods for reduction of trapping effects will be analyzed.