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Structural and Kinetic Analysis of BaCl 2 Nanocrystals in Fluorochlorozirconate Glass‐Ceramics
Author(s) -
Alvarez Carlos J.,
Leonard Russell L.,
Gray Sharon K.,
Johnson Jacqueline A.,
PetfordLong Amanda K.
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13410
Subject(s) - nanocrystal , orthorhombic crystal system , materials science , nucleation , ostwald ripening , transmission electron microscopy , crystallography , phase (matter) , crystallization , mineralogy , chemical engineering , crystal structure , nanotechnology , chemistry , organic chemistry , engineering
The presence of BaCl 2 nanocrystals and the crystallographic phase that they adopt controls the optical behavior of fluorochlorozirconate glass‐ceramics. We have used in situ X‐ray diffraction heating experiments and ex situ transmission electron microscopy to follow the BaCl 2 nanocrystal nucleation and growth processes as a function of heating rate and isothermal hold temperature. The BaCl 2 nanocrystals nucleate with the hexagonal crystal structure and grow as spherical particles to a size of ~10 to 20 nm. They then undergo a structural transformation to the orthorhombic phase and their shape changes to rounded disks, with diameters ranging from 150 to 250 nm, and thicknesses ranging from 80 to 120 nm. The change in size results from Ostwald ripening of the hexagonal BaCl 2 nanocrystals to form the orthorhombic BaCl 2 nanocrystals.