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Synthesis of High Aspect Ratio PbBi 4 Ti 4 O 15 and Topochemical Conversion to PbTiO 3 ‐Based Microplatelets
Author(s) -
Poterala Stephen F.,
Meyer, Jr. Richard J.,
Messing Gary L.
Publication year - 2011
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/j.1551-2916.2010.04369.x
Subject(s) - ostwald ripening , nucleation , tetragonal crystal system , phase (matter) , dissolution , perovskite (structure) , materials science , chemical engineering , particle size , aurivillius , diffusion , crystallography , chemistry , nanotechnology , thermodynamics , ferroelectricity , organic chemistry , optoelectronics , dielectric , engineering , physics
Perovskite microplatelets of the composition 0.4(Na 1/2 Bi 1/2 ) TiO 3 –0.6PbTiO 3 (0.4NBT–0.6PT) were synthesized by topochemical conversion of the Aurivillius phase PbBi 4 Ti 4 O 15 in a NaCl/Bi 2 O 3 /PbO flux system. To facilitate morphologic control, we investigate the effects of TiO 2 particle size on molten salt growth of the PbBi 4 Ti 4 O 15 phase. We find that the initial nucleation density and [100] thickness of this phase are controlled by the TiO 2 dissolution rate, while the platelet diameter is determined by Ostwald ripening. PbBi 4 Ti 4 O 15 microplatelets produced using these methods can be converted entirely to a tetragonal perovskite phase ( c / a =1.051) while retaining the dimensions of the precursor PbBi 4 Ti 4 O 15 phase. We propose that the resulting 0.4NBT–0.6PT composition is favored thermodynamically due to the lower free energy of this composition relative to pure PbTiO 3 . In addition, partial (Na 1/2 Bi 1/2 )TiO 3 substitution is kinetically favored as it reduces A‐site diffusion during the topochemical conversion process.