Electric field effect on chemical and phase equilibria in nano-TiB2-TiO2-TiBO3 system at < 650 degrees C: an in situ time-resolved energy dispersive x-ray diffraction study with an ultrahigh energy synchrotron probe
| Autor: | Hülya Biçer, Tevfik E. Özdemir, Thomas Tsakalakos, Zhong Zhong, İlyas Şavklıyıldız, Metin Örnek, E. K. Akdogan |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Materials science Mechanical Engineering Analytical chemistry 02 engineering and technology Electrolyte 021001 nanoscience & nanotechnology Condensed Matter Physics Electrochemistry 01 natural sciences Synchrotron law.invention Reaction rate Mechanics of Materials law Phase (matter) Electric field 0103 physical sciences General Materials Science Energy-dispersive X-ray diffraction 0210 nano-technology Joule heating |
| Popis: | WOS: 000397467200022 Nano-TiB2 powder of 58 nm size with TiO2 and TiBO3 as secondary phases was heated with 20 degrees C to,650 degrees C in argon while applying an electric field. The powder became conductive at 520 and 305 degrees C (T-onset) for 16 and 40 V/cm, respectively, at which point current bursts of 4.5 and 10.0 A (peak value) were observed. Current bursts were accompanied by >1% TiB2 unit cell expansion, exceeding zero field thermally induced expansion. The current bursts also induced nonisothermal reaction between TiB2 and TiO2, yielding TiBO3 that is absent with no field. Increase from 16 to 40 V/cm shifts the TiB2 -> TiBO3 reaction forward, decreases Tonset but increases reaction rate. Analysis using Van't Hoff relation, including electrochemical effects, precluded possibility of appreciable Joule heating, which was supported with adiabatic internal temperature calculations. The observed low temperature oxidation of TiB2 to TiBO3 that is electrochemically driven and is mediated by the TiO2 solid electrolyte. Office of Naval Research (ONR)Office of Naval Research [N00014-10-1-042]; U.S. Department of Energy, Division of Material SciencesUnited States Department of Energy (DOE) [DE-AC02-76CH00016]; U.S. Department of Energy, Division of Chemical SciencesUnited States Department of Energy (DOE) [DE-AC02-76CH00016] The authors wish to express their gratitude for the financial support provided by the Office of Naval Research (ONR) under Contract No. N00014-10-1-042. The authors wish to thank Dr. Lawrence Kabacoff of the ONR for his valuable technical feedback and support to this project. E.K.A. thanks Dr. L. Fabris various technical discussions. This research was carried out in part at the National Synchrotron Light Source at Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Division of Material Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-76CH00016. |
| Databáze: | OpenAIRE |
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