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Coarsening Induced Phase Transformation of Hafnia in Polymer‐Derived Si–Hf–C–N–O Ceramics
Author(s) -
Sujith Ravindran,
Kousaalya Adhimoolam Bakthavachalam,
Kumar Ravi
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.1551-2916.2011.04719.x
Subject(s) - hafnia , materials science , crystallite , tetragonal crystal system , nanocrystalline material , amorphous solid , monoclinic crystal system , ceramic , transmission electron microscopy , phase (matter) , crystallography , mineralogy , composite material , crystal structure , chemistry , nanotechnology , metallurgy , cubic zirconia , organic chemistry
Coarsening induced reverse phase transformation of hafnia in polymer‐derived Si–Hf–C–N–O ceramics was studied experimentally. X‐ray diffraction and high resolution transmission electron microscopy were used to obtain information regarding nanocrystalline structure. Hafnia crystallites precipitated out from the amorphous ceramic matrix on heat treatment were observed to remain as tetragonal hafnia below a critical crystallite radius of 4 nm. Prolonged heat treatment has resulted in coarsening, as explained by Lifshitz–Slyozov–Wagner model, resulting in reverse phase transformation from tetragonal to monoclinic hafnia.