Reply to comment on Couzi et al. (2018): A phenomenological model for structural phase transitions in incommensurate alkane/urea inclusion compounds

Kirsten Christensen, P. Andrew Williams, Rhian Patterson, Benjamin A. Palmer, Michel Couzi, François Guillaume, Kenneth D.M. Harris

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

In a recent paper (Couzi et al. 2018 R. Soc. open sci. 5, 180058. (doi:10. 1098/rsos.180058)), we proposed a new phenomenological model to account for the I↔II↔“III” phase sequence in incommensurate n-alkane/urea inclusion compounds, which represents an alternative interpretation to that proposed in work of Toudic et al. In a Comment (Toudic et al. 2019 R. Soc. open sci. 6, 182073. (doi:10.1098/rsos.182073)), Toudic et al. have questioned our assignment of the superspace group of phase II of n-nonadecane/urea, which they have previously assigned, based on a (3 + 2)-dimensional superspace, as C2221(00γ)(10δ). In this Reply, we present new results from a comprehensive synchrotron single-crystal X-ray diffraction study of n-nonadecane/urea, involving measurements as a detailed function of temperature across the I↔II↔“III” phase transition sequence. Our results demonstrate conclusively that “main reflections” (h, k, l, 0) with h+k odd are observed in phase II of n-nonadecane/urea (including temperatures in phase II that are just below the transition from phase I to phase II), in full support of our assignment of the (3+1)-dimensional superspace group P212121(00γ) to phase II. As our phenomenological model is based on phase II and phase “III” of this incommensurate material having the same (3+1)-dimensional superspace group P212121(00γ), it follows that the new X-ray diffraction results are in full support of our phenomenological model.

Original languageEnglish
Article number190518
JournalRoyal Society Open Science
Volume6
Issue number8
DOIs
StatePublished - 1 Aug 2019

Keywords

  • Incommensurate composite materials
  • Solid-state phase transitions
  • Superspace groups
  • Urea inclusion compounds

ASJC Scopus subject areas

  • General

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