10.1021/acs.cgd.5b00187.s004
Qi Jiang
Qi
Jiang
Alexander G. Shtukenberg
Alexander G.
Shtukenberg
Michael D. Ward
Michael D.
Ward
Chunhua Hu
Chunhua
Hu
Non-Topotactic Phase Transformations in Single Crystals
of β‑Glycine
American Chemical Society
2015
Single Crystals
reference frame
nucleation event
growth front
domain crystals
parent phase
transformation rate increases
glycine exhibits
β parent phase
SCSCT
parent β phase
transformation rates
γ phase
24 form
crystal habit
27 β parent crystals
orientation matrix
daughter phases
2015-06-03 00:00:00
Dataset
https://acs.figshare.com/articles/dataset/Non_Topotactic_Phase_Transformations_in_Single_Crystals_of_Glycine/2206315
The
metastable β polymorph of glycine exhibits a single-crystal-to-single-crystal
transformation (SCSCT) to either the α or γ phase with
retention of the crystal habit of the parent β phase. X-ray
diffraction and optical microscopy reveal that of 51 single crystals
of the β parent phase, 24 form single domain crystals of α
or γ with a single orientation matrix, confirming an SCSCT.
The remaining 27 β parent crystals transform to crystals with
a few domains of either α and/or γ, each domain arising
from a single nucleation event. In three cases the β →
α and β → γ transformations occurred within
the same glycine single crystal. In all cases, regardless of the number
of domains, the transformation occurred with retention of the original
habit of the parent phase. Both β → α and β
→ γ transformations proceed in a non-topotactic manner,
as evident from the random orientations of the daughter phases in
the crystallographic reference frame of the parent β phase.
The transformation rates, as measured by advancement of the growth
front with polarized optical microscopy, vary from crystal to crystal
as well as for different regions within the same crystal. Moreover,
the transformation rate increases substantially with relative humidity,
and at a relative humidity of 90% α-glycine was observed as
the only product.