Institutional Research Information Service
UCL Logo
Please report any queries concerning the funding data grouped in the sections named "Externally Awarded" or "Internally Disbursed" (shown on the profile page) to your Research Finance Administrator. Your can find your Research Finance Administrator at https://www.ucl.ac.uk/finance/research/rs-contacts.php by entering your department
Please report any queries concerning the student data shown on the profile page to:

Email: portico-services@ucl.ac.uk

Help Desk: http://www.ucl.ac.uk/ras/portico/helpdesk
Publication Detail
Synthesis of tetragonal and orthorhombic polymorphs of Hf3N 4 by high-pressure annealing of a prestructured nanocrystalline precursor
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Journal Article
  • Authors:
    Salamat A, Hector AL, Gray BM, Kimber SAJ, Bouvier P, McMillan PF
  • Publication date:
  • Pagination:
    9503, 9511
  • Journal:
    Journal of the American Chemical Society
  • Volume:
  • Issue:
  • Status:
  • Print ISSN:
Hf 3 N 4 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 pho tocatalysts. 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 Hf 3 N 4 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 Hf 3 N 4 that adopts an anion deficient cottunite-type (orthorhombic) structure. The orthorhombic Hf 3 N 4 phase is recoverable to ambient pressure and the tetragonal phase is at least partially recoverable. © 2013 American Chemical Society.
Publication data is maintained in RPS. Visit https://rps.ucl.ac.uk
 More search options
UCL Researchers
Dept of Chemistry
University College London - Gower Street - London - WC1E 6BT Tel:+44 (0)20 7679 2000

© UCL 1999–2011

Search by