posted on 2020-04-01, 15:34authored byYuzhe Zhang, Li Qiao, Hejin Yan, Ivo Zizak, Paul Zaslansky, Yingfeng Li, Limin Qi, Yurong Ma
Vaterite
is the thermodynamically least stable phase of the three
anhydrous calcium carbonate phases. So far there have been no reports
showing the synthesis of pure phase vaterite single crystals exposing
the (001) facet without the aid of any additive. Herein, single crystalline
vaterite microdiscs exposing the (001) facet with high surface energy
have been successfully obtained for the first time in isopropanol
without the presence of any additives. The process progresses via
amorphous calcium carbonate (ACC) precursors. To study this, Ca K-edge
extended X-ray absorption fine structure characterization was performed
under cryo-condition. The results indicate that the ACC precursor
has a short-range order structure similar to that of vaterite, previously
named “proto-vaterite ACC”. Molecular dynamic (MD) simulations
indicate that the binding energy between the (001) facet of vaterite
and isopropanol is much higher than those of other facets of vaterite
with isopropanol, which might be the reason for the formation of vaterite
microdiscs exposing the (001) facet. In summary, the thermodynamically
less stable phase vaterite microdiscs exposing the (001) facet were
realized for the first time without the presence of any additive,
and its formation mechanism was investigated in detail based on the
experimental results and MD simulations.