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On the thermodynamically stable amorphous phase of polymer-derived silicon oxycarbide.

Yu L, Raj R - Sci Rep (2015)

Bottom Line: In this article we employ first-principles calculations to estimate how the interfacial energy of the graphene networks is favorably influenced by having mixed bonds attached to them.We analyze the ways in which this reduction in interfacial energy can stabilize the amorphous phase.In addition we discover a two-dimensional lattice structure, with the composition Si2C4O3 that is constructed from a single layer of graphene congruent with silicon and oxygen bonds on either side.

View Article: PubMed Central - PubMed

Affiliation: University of Colorado at Boulder Boulder, Colorado 80309, USA.

ABSTRACT
A model for the thermodynamic stability of amorphous silicon oxycarbide (SiCO) is presented. It builds upon the reasonably accepted model of SiCO which is conceived as a nanodomain network of graphene. The domains are expected to be filled with SiO2 molecules, while the interface with graphene is visualized to contain mixed bonds described as Si bonded to C as well as to O atoms. Normally these SiCO compositions would be expected to crystallize. Instead, calorimetric measurements have shown that the amorphous phase is thermodynamically stable. In this article we employ first-principles calculations to estimate how the interfacial energy of the graphene networks is favorably influenced by having mixed bonds attached to them. We analyze the ways in which this reduction in interfacial energy can stabilize the amorphous phase. The approach highlights how density functional theory computations can be combined with the classical analysis of phase transformations to explain the behavior of a complex material. In addition we discover a two-dimensional lattice structure, with the composition Si2C4O3 that is constructed from a single layer of graphene congruent with silicon and oxygen bonds on either side.

No MeSH data available.


Related in: MedlinePlus

The methodology for combining first principles computations with closed form models to analyze the behavior of a complex material, in this instance the amorphous state of polymer-derived SiCO constructed from nanodomains created by networks of graphene.
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f7: The methodology for combining first principles computations with closed form models to analyze the behavior of a complex material, in this instance the amorphous state of polymer-derived SiCO constructed from nanodomains created by networks of graphene.

Mentions: The procedure and the equations that lead to the comparison between theory and experiment are outlined in Fig. 7. The interfacial energies, γf and γe are obtained from the computed values for and using Eq. (9) and (10). We use the lowest (the most negative) values of γf and γe for comparison with experimental data. The lowest value for γf, as calculated above is −0.76 J m–2, and the lowest value for γe is −0.77 × 10–10 J m–1.


On the thermodynamically stable amorphous phase of polymer-derived silicon oxycarbide.

Yu L, Raj R - Sci Rep (2015)

The methodology for combining first principles computations with closed form models to analyze the behavior of a complex material, in this instance the amorphous state of polymer-derived SiCO constructed from nanodomains created by networks of graphene.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588588&req=5

f7: The methodology for combining first principles computations with closed form models to analyze the behavior of a complex material, in this instance the amorphous state of polymer-derived SiCO constructed from nanodomains created by networks of graphene.
Mentions: The procedure and the equations that lead to the comparison between theory and experiment are outlined in Fig. 7. The interfacial energies, γf and γe are obtained from the computed values for and using Eq. (9) and (10). We use the lowest (the most negative) values of γf and γe for comparison with experimental data. The lowest value for γf, as calculated above is −0.76 J m–2, and the lowest value for γe is −0.77 × 10–10 J m–1.

Bottom Line: In this article we employ first-principles calculations to estimate how the interfacial energy of the graphene networks is favorably influenced by having mixed bonds attached to them.We analyze the ways in which this reduction in interfacial energy can stabilize the amorphous phase.In addition we discover a two-dimensional lattice structure, with the composition Si2C4O3 that is constructed from a single layer of graphene congruent with silicon and oxygen bonds on either side.

View Article: PubMed Central - PubMed

Affiliation: University of Colorado at Boulder Boulder, Colorado 80309, USA.

ABSTRACT
A model for the thermodynamic stability of amorphous silicon oxycarbide (SiCO) is presented. It builds upon the reasonably accepted model of SiCO which is conceived as a nanodomain network of graphene. The domains are expected to be filled with SiO2 molecules, while the interface with graphene is visualized to contain mixed bonds described as Si bonded to C as well as to O atoms. Normally these SiCO compositions would be expected to crystallize. Instead, calorimetric measurements have shown that the amorphous phase is thermodynamically stable. In this article we employ first-principles calculations to estimate how the interfacial energy of the graphene networks is favorably influenced by having mixed bonds attached to them. We analyze the ways in which this reduction in interfacial energy can stabilize the amorphous phase. The approach highlights how density functional theory computations can be combined with the classical analysis of phase transformations to explain the behavior of a complex material. In addition we discover a two-dimensional lattice structure, with the composition Si2C4O3 that is constructed from a single layer of graphene congruent with silicon and oxygen bonds on either side.

No MeSH data available.


Related in: MedlinePlus