title: A critical analysis of calcium carbonate mesocrystals.
abstract: The term mesocrystal has been widely used to describe crystals that form by oriented assembly, and that exhibit nanoparticle substructures. Using calcite crystals co-precipitated with polymers as a suitable test case, this article looks critically at the concept of mesocrystals. Here we demonstrate that the data commonly used to assign mesocrystal structure may be frequently misinterpreted, and that these calcite/polymer crystals do not have nanoparticle substructures. Although morphologies suggest the presence of nanoparticles, these are only present on the crystal surface. High surface areas are only recorded for crystals freshly removed from solution and are again attributed to a thin shell of nanoparticles on a solid calcite core. Line broadening in powder X-ray diffraction spectra is due to lattice strain only, precluding the existence of a nanoparticle sub-structure. Finally, study of the formation mechanism provides no evidence for crystalline precursor particles. A re-evaluation of existing literature on some mesocrystals may therefore be required.
authors.affiliation: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
authors.forename: Yi-Yeoun
authors.initials: YY
authors.lastname: Kim
authors.affiliation: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Schenk
authors.affiliation: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
authors.forename: Johannes
authors.initials: J
authors.lastname: Ihli
authors.affiliation: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
authors.forename: Alex N
authors.initials: AN
authors.lastname: Kulak
authors.affiliation: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
authors.forename: Nicola B J
authors.initials: NB
authors.lastname: Hetherington
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK.
authors.forename: Chiu C
authors.initials: CC
authors.lastname: Tang
authors.affiliation: Ludwig-Maximilians-Universität München, Department für Geo- und Umweltwissenschaften, Sektion Kristallographie, Theresienstrasse 41, 80333 München, Germany.
authors.forename: Wolfgang W
authors.initials: WW
authors.lastname: Schmahl
authors.affiliation: Ludwig-Maximilians-Universität München, Department für Geo- und Umweltwissenschaften, Sektion Kristallographie, Theresienstrasse 41, 80333 München, Germany.
authors.forename: Erika
authors.initials: E
authors.lastname: Griesshaber
authors.affiliation: Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Hyett
authors.affiliation: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
authors.forename: Fiona C
authors.initials: FC
authors.lastname: Meldrum