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Seasonally stable temperature gradients through supraglacial debris in the Everest region of Nepal, Central Himalaya
- Ann V. Rowan, Lindsey I. Nicholson, Duncan J. Quincey, Morgan J. Gibson, Tristram D.L. Irvine-Fynn, C. Scott Watson, Patrick Wagnon, David R. Rounce, Sarah S. Thompson, Philip R. Porter, Neil F. Glasser
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- Journal:
- Journal of Glaciology / Volume 67 / Issue 261 / February 2021
- Published online by Cambridge University Press:
- 03 December 2020, pp. 170-181
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Rock debris covers ~30% of glacier ablation areas in the Central Himalaya and modifies the impact of atmospheric conditions on mass balance. The thermal properties of supraglacial debris are diurnally variable but remain poorly constrained for monsoon-influenced glaciers over the timescale of the ablation season. We measured vertical debris profile temperatures at 12 sites on four glaciers in the Everest region with debris thickness ranging from 0.08 to 2.8 m. Typically, the length of the ice ablation season beneath supraglacial debris was 160 days (15 May to 22 October)—a month longer than the monsoon season. Debris temperature gradients were approximately linear (r2 > 0.83), measured as −40°C m–1 where debris was up to 0.1 m thick, −20°C m–1 for debris 0.1–0.5 m thick, and −4°C m–1 for debris greater than 0.5 m thick. Our results demonstrate that the influence of supraglacial debris on the temperature of the underlying ice surface, and therefore melt, is stable at a seasonal timescale and can be estimated from near-surface temperature. These results have the potential to greatly improve the representation of ablation in calculations of debris-covered glacier mass balance and projections of their response to climate change.
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- By Yohance M. Allette, Christophe Altier, Charles E. Argoff, Nadine Attal, Paul J. Austin, Didier Bouhassira, Ian Carroll, Kristine M. Chapman, Stephen Coleman, Lynn Kerene Cooper, Michael R. Due, Mary-Ann Fitzcharles, Robyn Flynn, Andrea D. Furlan, Vishal Gupta, Maija Haanpää, Jennifer Hah, Steven H. Horowitz, John Hughes, Mark R. Hutchinson, Scott Jarvis, Maan Kattan, Manpreet Kaur, Bradley J. Kerr, Krishna Kumar, Yuen Hei Kwok, Wojciech Leppert, Liang Liu, Angela Mailis-Gagnon, Gila Moalem-Taylor, Dwight E. Moulin, Harsha Nagaraja, Dontese Nicholson, Lauren Nicotra, Anne Louise Oaklander, John Xavier Pereira, Syed Rizvi, Stephan A. Schug, Michael Serpell, Amanda Sherwin, Howard S. Smith, Peter A. Smith, Pam Squire, Peter A. Ste-Marie, Patrick L. Stemkowski, Nicole M. Sumracki, Cory Toth, Krista van Steeg, Jan H. Vranken, Bharati Vyawahare, Mark A. Ware, Linda R. Watkins, C. Peter N. Watson, Fletcher A. White
- Edited by Cory Toth, Dwight E. Moulin
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- Neuropathic Pain
- Published online:
- 05 December 2013
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- 07 November 2013, pp vii-x
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- By Rose Teteki Abbey, K. C. Abraham, David Tuesday Adamo, LeRoy H. Aden, Efrain Agosto, Victor Aguilan, Gillian T. W. Ahlgren, Charanjit Kaur AjitSingh, Dorothy B E A Akoto, Giuseppe Alberigo, Daniel E. Albrecht, Ruth Albrecht, Daniel O. Aleshire, Urs Altermatt, Anand Amaladass, Michael Amaladoss, James N. Amanze, Lesley G. Anderson, Thomas C. Anderson, Victor Anderson, Hope S. Antone, María Pilar Aquino, Paula Arai, Victorio Araya Guillén, S. Wesley Ariarajah, Ellen T. Armour, Brett Gregory Armstrong, Atsuhiro Asano, Naim Stifan Ateek, Mahmoud Ayoub, John Alembillah Azumah, Mercedes L. García Bachmann, Irena Backus, J. Wayne Baker, Mieke Bal, Lewis V. Baldwin, William Barbieri, António Barbosa da Silva, David Basinger, Bolaji Olukemi Bateye, Oswald Bayer, Daniel H. Bays, Rosalie Beck, Nancy Elizabeth Bedford, Guy-Thomas Bedouelle, Chorbishop Seely Beggiani, Wolfgang Behringer, Christopher M. Bellitto, Byard Bennett, Harold V. Bennett, Teresa Berger, Miguel A. Bernad, Henley Bernard, Alan E. Bernstein, Jon L. Berquist, Johannes Beutler, Ana María Bidegain, Matthew P. Binkewicz, Jennifer Bird, Joseph Blenkinsopp, Dmytro Bondarenko, Paulo Bonfatti, Riet en Pim Bons-Storm, Jessica A. Boon, Marcus J. Borg, Mark Bosco, Peter C. Bouteneff, François Bovon, William D. Bowman, Paul S. Boyer, David Brakke, Richard E. Brantley, Marcus Braybrooke, Ian Breward, Ênio José da Costa Brito, Jewel Spears Brooker, Johannes Brosseder, Nicholas Canfield Read Brown, Robert F. Brown, Pamela K. Brubaker, Walter Brueggemann, Bishop Colin O. Buchanan, Stanley M. Burgess, Amy Nelson Burnett, J. Patout Burns, David B. Burrell, David Buttrick, James P. Byrd, Lavinia Byrne, Gerado Caetano, Marcos Caldas, Alkiviadis Calivas, William J. Callahan, Salvatore Calomino, Euan K. Cameron, William S. Campbell, Marcelo Ayres Camurça, Daniel F. Caner, Paul E. Capetz, Carlos F. Cardoza-Orlandi, Patrick W. Carey, Barbara Carvill, Hal Cauthron, Subhadra Mitra Channa, Mark D. Chapman, James H. Charlesworth, Kenneth R. Chase, Chen Zemin, Luciano Chianeque, Philip Chia Phin Yin, Francisca H. Chimhanda, Daniel Chiquete, John T. Chirban, Soobin Choi, Robert Choquette, Mita Choudhury, Gerald Christianson, John Chryssavgis, Sejong Chun, Esther Chung-Kim, Charles M. A. Clark, Elizabeth A. Clark, Sathianathan Clarke, Fred Cloud, John B. Cobb, W. Owen Cole, John A Coleman, John J. Collins, Sylvia Collins-Mayo, Paul K. Conkin, Beth A. Conklin, Sean Connolly, Demetrios J. Constantelos, Michael A. Conway, Paula M. Cooey, Austin Cooper, Michael L. Cooper-White, Pamela Cooper-White, L. William Countryman, Sérgio Coutinho, Pamela Couture, Shannon Craigo-Snell, James L. Crenshaw, David Crowner, Humberto Horacio Cucchetti, Lawrence S. Cunningham, Elizabeth Mason Currier, Emmanuel Cutrone, Mary L. Daniel, David D. Daniels, Robert Darden, Rolf Darge, Isaiah Dau, Jeffry C. Davis, Jane Dawson, Valentin Dedji, John W. de Gruchy, Paul DeHart, Wendy J. Deichmann Edwards, Miguel A. De La Torre, George E. Demacopoulos, Thomas de Mayo, Leah DeVun, Beatriz de Vasconcellos Dias, Dennis C. Dickerson, John M. Dillon, Luis Miguel Donatello, Igor Dorfmann-Lazarev, Susanna Drake, Jonathan A. Draper, N. Dreher Martin, Otto Dreydoppel, Angelyn Dries, A. J. Droge, Francis X. D'Sa, Marilyn Dunn, Nicole Wilkinson Duran, Rifaat Ebied, Mark J. Edwards, William H. Edwards, Leonard H. Ehrlich, Nancy L. Eiesland, Martin Elbel, J. Harold Ellens, Stephen Ellingson, Marvin M. Ellison, Robert Ellsberg, Jean Bethke Elshtain, Eldon Jay Epp, Peter C. Erb, Tassilo Erhardt, Maria Erling, Noel Leo Erskine, Gillian R. Evans, Virginia Fabella, Michael A. Fahey, Edward Farley, Margaret A. Farley, Wendy Farley, Robert Fastiggi, Seena Fazel, Duncan S. Ferguson, Helwar Figueroa, Paul Corby Finney, Kyriaki Karidoyanes FitzGerald, Thomas E. FitzGerald, John R. Fitzmier, Marie Therese Flanagan, Sabina Flanagan, Claude Flipo, Ronald B. Flowers, Carole Fontaine, David Ford, Mary Ford, Stephanie A. Ford, Jim Forest, William Franke, Robert M. Franklin, Ruth Franzén, Edward H. Friedman, Samuel Frouisou, Lorelei F. Fuchs, Jojo M. Fung, Inger Furseth, Richard R. Gaillardetz, Brandon Gallaher, China Galland, Mark Galli, Ismael García, Tharscisse Gatwa, Jean-Marie Gaudeul, Luis María Gavilanes del Castillo, Pavel L. Gavrilyuk, Volney P. Gay, Metropolitan Athanasios Geevargis, Kondothra M. George, Mary Gerhart, Simon Gikandi, Maurice Gilbert, Michael J. Gillgannon, Verónica Giménez Beliveau, Terryl Givens, Beth Glazier-McDonald, Philip Gleason, Menghun Goh, Brian Golding, Bishop Hilario M. Gomez, Michelle A. Gonzalez, Donald K. Gorrell, Roy Gottfried, Tamara Grdzelidze, Joel B. Green, Niels Henrik Gregersen, Cristina Grenholm, Herbert Griffiths, Eric W. Gritsch, Erich S. Gruen, Christoffer H. Grundmann, Paul H. Gundani, Jon P. Gunnemann, Petre Guran, Vidar L. Haanes, Jeremiah M. Hackett, Getatchew Haile, Douglas John Hall, Nicholas Hammond, Daphne Hampson, Jehu J. Hanciles, Barry Hankins, Jennifer Haraguchi, Stanley S. Harakas, Anthony John Harding, Conrad L. Harkins, J. William Harmless, Marjory Harper, Amir Harrak, Joel F. Harrington, Mark W. Harris, Susan Ashbrook Harvey, Van A. Harvey, R. Chris Hassel, Jione Havea, Daniel Hawk, Diana L. Hayes, Leslie Hayes, Priscilla Hayner, S. Mark Heim, Simo Heininen, Richard P. Heitzenrater, Eila Helander, David Hempton, Scott H. Hendrix, Jan-Olav Henriksen, Gina Hens-Piazza, Carter Heyward, Nicholas J. Higham, David Hilliard, Norman A. Hjelm, Peter C. Hodgson, Arthur Holder, M. Jan Holton, Dwight N. Hopkins, Ronnie Po-chia Hsia, Po-Ho Huang, James Hudnut-Beumler, Jennifer S. Hughes, Leonard M. Hummel, Mary E. Hunt, Laennec Hurbon, Mark Hutchinson, Susan E. Hylen, Mary Beth Ingham, H. Larry Ingle, Dale T. Irvin, Jon Isaak, Paul John Isaak, Ada María Isasi-Díaz, Hans Raun Iversen, Margaret C. Jacob, Arthur James, Maria Jansdotter-Samuelsson, David Jasper, Werner G. Jeanrond, Renée Jeffery, David Lyle Jeffrey, Theodore W. Jennings, David H. Jensen, Robin Margaret Jensen, David Jobling, Dale A. Johnson, Elizabeth A. Johnson, Maxwell E. Johnson, Sarah Johnson, Mark D. Johnston, F. Stanley Jones, James William Jones, John R. Jones, Alissa Jones Nelson, Inge Jonsson, Jan Joosten, Elizabeth Judd, Mulambya Peggy Kabonde, Robert Kaggwa, Sylvester Kahakwa, Isaac Kalimi, Ogbu U. Kalu, Eunice Kamaara, Wayne C. Kannaday, Musimbi Kanyoro, Veli-Matti Kärkkäinen, Frank Kaufmann, Léon Nguapitshi Kayongo, Richard Kearney, Alice A. Keefe, Ralph Keen, Catherine Keller, Anthony J. Kelly, Karen Kennelly, Kathi Lynn Kern, Fergus Kerr, Edward Kessler, George Kilcourse, Heup Young Kim, Kim Sung-Hae, Kim Yong-Bock, Kim Yung Suk, Richard King, Thomas M. King, Robert M. Kingdon, Ross Kinsler, Hans G. Kippenberg, Cheryl A. Kirk-Duggan, Clifton Kirkpatrick, Leonid Kishkovsky, Nadieszda Kizenko, Jeffrey Klaiber, Hans-Josef Klauck, Sidney Knight, Samuel Kobia, Robert Kolb, Karla Ann Koll, Heikki Kotila, Donald Kraybill, Philip D. W. Krey, Yves Krumenacker, Jeffrey Kah-Jin Kuan, Simanga R. Kumalo, Peter Kuzmic, Simon Shui-Man Kwan, Kwok Pui-lan, André LaCocque, Stephen E. Lahey, John Tsz Pang Lai, Emiel Lamberts, Armando Lampe, Craig Lampe, Beverly J. Lanzetta, Eve LaPlante, Lizette Larson-Miller, Ariel Bybee Laughton, Leonard Lawlor, Bentley Layton, Robin A. Leaver, Karen Lebacqz, Archie Chi Chung Lee, Marilyn J. Legge, Hervé LeGrand, D. L. LeMahieu, Raymond Lemieux, Bill J. Leonard, Ellen M. Leonard, Outi Leppä, Jean Lesaulnier, Nantawan Boonprasat Lewis, Henrietta Leyser, Alexei Lidov, Bernard Lightman, Paul Chang-Ha Lim, Carter Lindberg, Mark R. Lindsay, James R. Linville, James C. Livingston, Ann Loades, David Loades, Jean-Claude Loba-Mkole, Lo Lung Kwong, Wati Longchar, Eleazar López, David W. Lotz, Andrew Louth, Robin W. Lovin, William Luis, Frank D. Macchia, Diarmaid N. J. MacCulloch, Kirk R. MacGregor, Marjory A. MacLean, Donald MacLeod, Tomas S. Maddela, Inge Mager, Laurenti Magesa, David G. Maillu, Fortunato Mallimaci, Philip Mamalakis, Kä Mana, Ukachukwu Chris Manus, Herbert Robinson Marbury, Reuel Norman Marigza, Jacqueline Mariña, Antti Marjanen, Luiz C. L. Marques, Madipoane Masenya (ngwan'a Mphahlele), Caleb J. D. Maskell, Steve Mason, Thomas Massaro, Fernando Matamoros Ponce, András Máté-Tóth, Odair Pedroso Mateus, Dinis Matsolo, Fumitaka Matsuoka, John D'Arcy May, Yelena Mazour-Matusevich, Theodore Mbazumutima, John S. McClure, Christian McConnell, Lee Martin McDonald, Gary B. McGee, Thomas McGowan, Alister E. McGrath, Richard J. McGregor, John A. McGuckin, Maud Burnett McInerney, Elsie Anne McKee, Mary B. McKinley, James F. McMillan, Ernan McMullin, Kathleen E. McVey, M. Douglas Meeks, Monica Jyotsna Melanchthon, Ilie Melniciuc-Puica, Everett Mendoza, Raymond A. Mentzer, William W. Menzies, Ina Merdjanova, Franziska Metzger, Constant J. Mews, Marvin Meyer, Carol Meyers, Vasile Mihoc, Gunner Bjerg Mikkelsen, Maria Inêz de Castro Millen, Clyde Lee Miller, Bonnie J. Miller-McLemore, Alexander Mirkovic, Paul Misner, Nozomu Miyahira, R. W. L. Moberly, Gerald Moede, Aloo Osotsi Mojola, Sunanda Mongia, Rebeca Montemayor, James Moore, Roger E. Moore, Craig E. Morrison O.Carm, Jeffry H. Morrison, Keith Morrison, Wilson J. Moses, Tefetso Henry Mothibe, Mokgethi Motlhabi, Fulata Moyo, Henry Mugabe, Jesse Ndwiga Kanyua Mugambi, Peggy Mulambya-Kabonde, Robert Bruce Mullin, Pamela Mullins Reaves, Saskia Murk Jansen, Heleen L. Murre-Van den Berg, Augustine Musopole, Isaac M. T. Mwase, Philomena Mwaura, Cecilia Nahnfeldt, Anne Nasimiyu Wasike, Carmiña Navia Velasco, Thulani Ndlazi, Alexander Negrov, James B. Nelson, David G. Newcombe, Carol Newsom, Helen J. Nicholson, George W. E. Nickelsburg, Tatyana Nikolskaya, Damayanthi M. A. Niles, Bertil Nilsson, Nyambura Njoroge, Fidelis Nkomazana, Mary Beth Norton, Christian Nottmeier, Sonene Nyawo, Anthère Nzabatsinda, Edward T. Oakes, Gerald O'Collins, Daniel O'Connell, David W. Odell-Scott, Mercy Amba Oduyoye, Kathleen O'Grady, Oyeronke Olajubu, Thomas O'Loughlin, Dennis T. Olson, J. Steven O'Malley, Cephas N. Omenyo, Muriel Orevillo-Montenegro, César Augusto Ornellas Ramos, Agbonkhianmeghe E. Orobator, Kenan B. Osborne, Carolyn Osiek, Javier Otaola Montagne, Douglas F. Ottati, Anna May Say Pa, Irina Paert, Jerry G. Pankhurst, Aristotle Papanikolaou, Samuele F. Pardini, Stefano Parenti, Peter Paris, Sung Bae Park, Cristián G. Parker, Raquel Pastor, Joseph Pathrapankal, Daniel Patte, W. Brown Patterson, Clive Pearson, Keith F. Pecklers, Nancy Cardoso Pereira, David Horace Perkins, Pheme Perkins, Edward N. Peters, Rebecca Todd Peters, Bishop Yeznik Petrossian, Raymond Pfister, Peter C. Phan, Isabel Apawo Phiri, William S. F. Pickering, Derrick G. Pitard, William Elvis Plata, Zlatko Plese, John Plummer, James Newton Poling, Ronald Popivchak, Andrew Porter, Ute Possekel, James M. Powell, Enos Das Pradhan, Devadasan Premnath, Jaime Adrían Prieto Valladares, Anne Primavesi, Randall Prior, María Alicia Puente Lutteroth, Eduardo Guzmão Quadros, Albert Rabil, Laurent William Ramambason, Apolonio M. Ranche, Vololona Randriamanantena Andriamitandrina, Lawrence R. Rast, Paul L. Redditt, Adele Reinhartz, Rolf Rendtorff, Pål Repstad, James N. Rhodes, John K. Riches, Joerg Rieger, Sharon H. Ringe, Sandra Rios, Tyler Roberts, David M. Robinson, James M. Robinson, Joanne Maguire Robinson, Richard A. H. Robinson, Roy R. Robson, Jack B. Rogers, Maria Roginska, Sidney Rooy, Rev. Garnett Roper, Maria José Fontelas Rosado-Nunes, Andrew C. Ross, Stefan Rossbach, François Rossier, John D. Roth, John K. Roth, Phillip Rothwell, Richard E. Rubenstein, Rosemary Radford Ruether, Markku Ruotsila, John E. Rybolt, Risto Saarinen, John Saillant, Juan Sanchez, Wagner Lopes Sanchez, Hugo N. Santos, Gerhard Sauter, Gloria L. Schaab, Sandra M. Schneiders, Quentin J. Schultze, Fernando F. Segovia, Turid Karlsen Seim, Carsten Selch Jensen, Alan P. F. Sell, Frank C. Senn, Kent Davis Sensenig, Damían Setton, Bal Krishna Sharma, Carolyn J. Sharp, Thomas Sheehan, N. Gerald Shenk, Christian Sheppard, Charles Sherlock, Tabona Shoko, Walter B. Shurden, Marguerite Shuster, B. Mark Sietsema, Batara Sihombing, Neil Silberman, Clodomiro Siller, Samuel Silva-Gotay, Heikki Silvet, John K. Simmons, Hagith Sivan, James C. Skedros, Abraham Smith, Ashley A. Smith, Ted A. Smith, Daud Soesilo, Pia Søltoft, Choan-Seng (C. S.) Song, Kathryn Spink, Bryan Spinks, Eric O. Springsted, Nicolas Standaert, Brian Stanley, Glen H. Stassen, Karel Steenbrink, Stephen J. Stein, Andrea Sterk, Gregory E. Sterling, Columba Stewart, Jacques Stewart, Robert B. Stewart, Cynthia Stokes Brown, Ken Stone, Anne Stott, Elizabeth Stuart, Monya Stubbs, Marjorie Hewitt Suchocki, David Kwang-sun Suh, Scott W. Sunquist, Keith Suter, Douglas Sweeney, Charles H. Talbert, Shawqi N. Talia, Elsa Tamez, Joseph B. Tamney, Jonathan Y. Tan, Yak-Hwee Tan, Kathryn Tanner, Feiya Tao, Elizabeth S. Tapia, Aquiline Tarimo, Claire Taylor, Mark Lewis Taylor, Bishop Abba Samuel Wolde Tekestebirhan, Eugene TeSelle, M. Thomas Thangaraj, David R. Thomas, Andrew Thornley, Scott Thumma, Marcelo Timotheo da Costa, George E. “Tink” Tinker, Ola Tjørhom, Karen Jo Torjesen, Iain R. Torrance, Fernando Torres-Londoño, Archbishop Demetrios [Trakatellis], Marit Trelstad, Christine Trevett, Phyllis Trible, Johannes Tromp, Paul Turner, Robert G. Tuttle, Archbishop Desmond Tutu, Peter Tyler, Anders Tyrberg, Justin Ukpong, Javier Ulloa, Camillus Umoh, Kristi Upson-Saia, Martina Urban, Monica Uribe, Elochukwu Eugene Uzukwu, Richard Vaggione, Gabriel Vahanian, Paul Valliere, T. J. Van Bavel, Steven Vanderputten, Peter Van der Veer, Huub Van de Sandt, Louis Van Tongeren, Luke A. Veronis, Noel Villalba, Ramón Vinke, Tim Vivian, David Voas, Elena Volkova, Katharina von Kellenbach, Elina Vuola, Timothy Wadkins, Elaine M. Wainwright, Randi Jones Walker, Dewey D. Wallace, Jerry Walls, Michael J. Walsh, Philip Walters, Janet Walton, Jonathan L. Walton, Wang Xiaochao, Patricia A. Ward, David Harrington Watt, Herold D. Weiss, Laurence L. Welborn, Sharon D. Welch, Timothy Wengert, Traci C. West, Merold Westphal, David Wetherell, Barbara Wheeler, Carolinne White, Jean-Paul Wiest, Frans Wijsen, Terry L. Wilder, Felix Wilfred, Rebecca Wilkin, Daniel H. Williams, D. Newell Williams, Michael A. Williams, Vincent L. Wimbush, Gabriele Winkler, Anders Winroth, Lauri Emílio Wirth, James A. Wiseman, Ebba Witt-Brattström, Teofil Wojciechowski, John Wolffe, Kenman L. Wong, Wong Wai Ching, Linda Woodhead, Wendy M. Wright, Rose Wu, Keith E. Yandell, Gale A. Yee, Viktor Yelensky, Yeo Khiok-Khng, Gustav K. K. Yeung, Angela Yiu, Amos Yong, Yong Ting Jin, You Bin, Youhanna Nessim Youssef, Eliana Yunes, Robert Michael Zaller, Valarie H. Ziegler, Barbara Brown Zikmund, Joyce Ann Zimmerman, Aurora Zlotnik, Zhuo Xinping
- Edited by Daniel Patte, Vanderbilt University, Tennessee
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- The Cambridge Dictionary of Christianity
- Published online:
- 05 August 2012
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- 20 September 2010, pp xi-xliv
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Instability of Si3N4/, SiC/, and MoSi2/ethanol suspensions
- Yoko Fukada, Patrick S. Nicholson
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- Journal of Materials Research / Volume 18 / Issue 1 / January 2003
- Published online by Cambridge University Press:
- 31 January 2011, pp. 45-52
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- January 2003
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Time-dependent suspension behavior is reported for nonoxide ceramic powders (Si3N4, SiC, and MoSi2) in ethanol. The suspension pH (and therefore the stability) changed with time. X-ray photoelectron spectroscopy, inert gas fusion, inductively coupled plasma, and high-resolution transmission electron microscopy were used to track changes of surface chemistry. The adsorption of the base, tetramethyl ammonium hydroxide (TMAH), is examined. The pH drop on powder addition to pure EtOH was used to gain insight into the role of TMAH coverage of the powder surfaces.
Diffusion calculations for the 80-K-to-110-K Bi(Pb)SrCaCuO superconducting phase transformation
- Wen Zhu, Chu Kun Kuo, Patrick S. Nicholson
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- Journal:
- Journal of Materials Research / Volume 14 / Issue 11 / November 1999
- Published online by Cambridge University Press:
- 31 January 2011, pp. 4143-4147
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- November 1999
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A diffusion model is proposed to fit the measured chemical-transformation rates of the Bi(Pb)CaCuSrO 80-K phase to 110-K phase. Diffusion coefficients and activation energies in PO2 = 0.08 and 0.21 atm are reported. The low diffusion rates and high activation energies suggest cation diffusion controls the transformation.
33 - Synthesis of polycrystalline H3O+ and NH4+ -β″/β-Al2O3 and potential applications in steam-electrolysis/fuel-cells
- Edited by Philippe Colomban, Centre National de la Recherche Scientifique (CNRS), Paris
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- Book:
- Proton Conductors
- Published online:
- 04 May 2010
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- 25 September 1992, pp 499-510
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Summary
Introduction
Proton conduction in β- and (β″-Al2O3 is of interest because of potential use in steam-electrolysis/H2/O2 fuel-cells. Single crystal H30+/-β″-Al2O3 was reported by Farrington & Briant to be a fast ion conductor with a proton conductivity of 10–4–10–5 (Ω cm)–1 at 25 °C. These encouraging results led to the first fabrication, characterization and use of polycrystalline H3O + -β″ /β-A12O32.
A second electrolyte with a higher conductivity but a lower thermal stability is NH4+ -β″-Al2032. This system, NH4+/H30+ -β″-Al203, is the best conductor of protons (σ = 7 × 10–4 (Ω cm)–1 rising to 2 × 10–2 (Ω cm)–1 at 200 °C). All previous work has been on single crystals (see Chapters 13 & 23) or powders. This chapter describes the synthesis of NH4+O + -β″-Al2O3 polycrystals.
Ion conducting structure of β″- and β-aluminas
The β-A12O3 family of compounds is constructed from oxygen and aluminium ‘spinel blocks’ with intervening ‘conduction planes’. In βA12O3 there are two spinel blocks per unit cell and in β″-A12O3 there are three. The upper oxygen layer of the spinel block is mirrored across the conduction plane in β-Al2O3 but this symmetry is lost in β″-A12O3. The alkali ion ‘Beevers-Ross’ site in the β-Al2O3 conduction planes is octahedral. The equivalent site in β″-A12O3 is tetrahedral and smaller. Thus K+ (r = 0.28 nm) promotes formation of β-A12O3 and Na+ (r = 0.196 nm), β″- A12O3.
The effect of oxygen partial pressure on the formation of (Bi, Pb)2Sr2Ca2Cu3O10−x
- Wen Zhu, Patrick S. Nicholson
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- Journal:
- Journal of Materials Research / Volume 7 / Issue 1 / January 1992
- Published online by Cambridge University Press:
- 29 June 2016, pp. 38-42
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- January 1992
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The effect of atmosphere on the formation of the 110 K (Bi2Sr2Ca2Cu3O10, 2223) superconductor phase was studied at different oxygen partial pressures and temperatures. Step heating at low oxygen partial pressures with intermediate grinding promoted 110 K phase formation. With this synergy the shortest time for single-phase 110 K superconductor formation was found to be 12 h between 845 and 865°C at Po2 = 0.078 atmosphere. The activation energy of 110 K phase formation is 1513 KJ/mole in air.
Microstructural Design and Conductivity and Ultrasonic Activation in the Ion Exchange of H3O+ and NH4+β"-Aluminas
- Patrick S. Nicholson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 210 / 1990
- Published online by Cambridge University Press:
- 28 February 2011, 541
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- 1990
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H3O+- and NH4 + -A12O3 polycrystals have been conductivity-optimised by eliminating metastable grain-boundary phases (NaA1O2 and MgAl2O4) and texturing the microstructure. The grain-boundary conductivity is considerably improved (up to 5x10-5(Ω-cm)-i) from 10–6 (Ω-cm)-l). The dc-field-assisted, H3O+ ion exchange process for K+/Na+-β"-A12O3 in HAC has been accelerated by cyclic switching of the dc field (cycle = 3secs) or injecting ultrasonic energy. The formeroubles the steady-state ion-exchange current to 12 μA by dispersing the HAC/electrolyte, interfacial, H3O+ polarisation layer. The ion-exchange currentefficiency is not improved from 0.15. The ultrasound (23 MHz) markedly shortens the time to complete ion-exchange (400 hrs.vs. > 700 hrs), more than doubles the final ion-exchange current (360 μA.vs. 150 μA) and improves the ion-exchange current efficiency to 0.24. These results are interpreted in terms of ionic “activation ”in the electrolyte. Evidence is presented of a mixed-cation-effect in H3O+-K-β"-AI2O3.
Structural Design and Synthesis of H3O+-β”/βAl2O3 and NH4-β”/β-Al2O3 Polycrystals
- Patrick S. Nicholson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 135 / 1988
- Published online by Cambridge University Press:
- 21 February 2011, 511
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- 1988
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The synthesis and characterization of H3Oβ”/β-Al2O3 and NH4 + -H3O+β”/β-Al2O3 poly-crystals is described. The role of stress development and control in the intermediate stages of ion-exchange of the NaK-β”/βA12O3 ceramics is analysed and identifies the β-Al2O3 phase as acting as inert reinforcement for the two-phase composite. The Rb + ion-exchange of the intermediate K + β”/β-Al2O3 requisite for NH4+/H3O + ion-exchange to NH4-H3O+β”/βAl2O3 is described as also is the NH4NO3 exchange to the final ceramic. The total weight loss on heating NH4-H3O+β”/βAl2O3 polycrystals to 810°C is 7.4% which agrees with the value expected from the chemical formula. The 25°C conductivity of the grains of NH4 +-H3O + β”/βAl2O3 was 1.7 × 10−4 (ω-cm)−1 and the bulk conductivity was 3 × 10−5(ω-cm)−1.
Electrical Relaxation Studies in Fluorite Oxides
- Partho Sarkar, Patrick S. Nicholson
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- Journal:
- MRS Online Proceedings Library Archive / Volume 135 / 1988
- Published online by Cambridge University Press:
- 21 February 2011, 271
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- 1988
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Electric relaxation in CeO2-M203 (M34 sY3+, La3+) solid solutions has been investigated as a function of temperature (373K-673K) using the electric modulus formalism in the frequency range 5 to 107Hz. Two relaxation processes are observed in dilute solid solutions. The low frequency process is identified as a long range migration of free oxygen-vacancies (Process A) and the high frequency process is due to reorientation relaxation of the (MceVo) charged associates (Process B). The relaxation process is analysed using a non-exponential decay function, ø(t)=exp[-(t/τo)B] for O<β≤1, of the electric field. The observed activation enthalpy minimum as a function of dopant concentration for the Process A is explained using the concept of incomplete dissociation of oxygen-vacancies from (MceVo) defect associates and the formation of higher-order defect clusters at higher mole% M203.