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dc.contributor.authorSalamat, Ashkanen_US
dc.contributor.authorHector, Andrew L.en_US
dc.contributor.authorGray, Benjamin M.en_US
dc.contributor.authorKimber, Simon A. J.en_US
dc.contributor.authorBouvier, Pierreen_US
dc.contributor.authorMcMillan, Paul F.en_US
dc.date.accessioned2014-02-18T18:11:14Z
dc.date.issued2013en_US
dc.identifier.citationSalamat, Ashkan, Andrew L. Hector, Benjamin M. Gray, Simon A. J. Kimber, Pierre Bouvier, and Paul F. McMillan. 2013. “Synthesis of Tetragonal and Orthorhombic Polymorphs of Hf3N4 by High-Pressure Annealing of a Prestructured Nanocrystalline Precursor.” Journal of the American Chemical Society 135 (25): 9503-9511. doi:10.1021/ja403368b. http://dx.doi.org/10.1021/ja403368b.en
dc.identifier.issn0002-7863en
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:11717553
dc.description.abstractHf3N4 in nanocrystalline form is produced by solution phase reaction of Hf(NEtMe)4 with ammonia followed by low-temperature pyrolysis in ammonia. Understanding of phase behavior in these systems is important because early transition-metal nitrides with the metal in maximum oxidation state are potential visible light photocatalysts. A combination of synchrotron powder X-ray diffraction and pair distribution function studies has been used to show this phase to have a tetragonally distorted fluorite structure with 1/3 vacancies on the anion sites. Laser heating nanocrystalline Hf3N4 at 12 GPa and 1500 K in a diamond anvil cell results in its crystallization with the same structure type, an interesting example of prestructuring of the phase during preparation of the precursor compound. This metastable pathway could provide a route to other new polymorphs of metal nitrides and to nitrogen-rich phases where they do not currently exist. Importantly it leads to bulk formation of the material rather than surface conversion as often occurs in elemental combination reactions at high pressure. Laser heating at 2000 K at a higher pressure of 19 GPa results in a further new polymorph of Hf3N4 that adopts an anion deficient cottunite-type (orthorhombic) structure. The orthorhombic Hf3N4 phase is recoverable to ambient pressure and the tetragonal phase is at least partially recoverable.en
dc.language.isoen_USen
dc.publisherAmerican Chemical Societyen
dc.relation.isversionofdoi:10.1021/ja403368ben
dc.relation.hasversionhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3715886/pdf/en
dash.licenseLAAen_US
dc.subjectArticleen
dc.titleSynthesis of Tetragonal and Orthorhombic Polymorphs of Hf3N4 by High-Pressure Annealing of a Prestructured Nanocrystalline Precursoren
dc.typeJournal Articleen_US
dc.description.versionVersion of Recorden
dc.relation.journalJournal of the American Chemical Societyen
dash.depositing.authorSalamat, Ashkanen_US
dc.date.available2014-02-18T18:11:14Z
dc.identifier.doi10.1021/ja403368b*
dash.contributor.affiliatedSalamat, Ashkan


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