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Thermodynamically Stable Si w C x N y O z Polymer‐Like, Amorphous Ceramics Made from Organic Precursors
Author(s) -
Morcos Riham M.,
Navrotsky Alexandra,
Varga Tamas,
Ahn Dongjoon,
Saha Atanu,
Poli Fabrizia,
Müller Klaus,
Raj Rishi
Publication year - 2008
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.1551-2916.2008.02427.x
Subject(s) - amorphous solid , enthalpy , nanoclusters , stoichiometry , cristobalite , ceramic , materials science , nitrogen , oxygen , standard enthalpy of formation , polymer , carbon fibers , crystallography , analytical chemistry (journal) , chemistry , organic chemistry , nanotechnology , thermodynamics , metallurgy , physics , quartz , composite material , composite number
This communication reports new results on the enthalpy of formation of pseudo‐amorphous ceramic compounds constituted from silicon, carbon, oxygen, and nitrogen (SiCNO), made from the polymer route. Again, like the SiCO materials, although with one exception, the enthalpy of formation from crystalline components (SiO 2 cristobalite, β‐Si 3 N 4 , SiC, and excess C) is negative. Some of the alloyed oxygen–nitrogen compositions yield enthalpies that are much more negative (∼100 kJ/g·atom) in comparison with compositions that contain mainly oxygen or nitrogen (∼20 kJ/g·atom). The exception, having a N/O ratio near 2, has a positive value for the enthalpy. This may reflect the presence of nanoclusters of stoichiometric Si 2 N 2 O instead of the pseudo‐amorphous nanodomain structure seen for the other samples.