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Meeting Materials Science & Technology 2009
Symposium Phase Equilibria Symposium in Memory of Dr. Richard Spriggs
Presentation Title Novel Phase Relations in the Wurtzite-Structure Based SiC-AlN Phase Diagram: Miscibility Gaps with Lower Critical Points in a Non-Polymer System
Author(s) Benjamin P Burton, Axel van de Walle, Marcel Sluiter
On-Site Speaker (Planned) Benjamin P Burton
Abstract Scope Preliminary results of first principles phase diagram calculations for the quasibinary system SiC-AlN suggest a phase diagram in which there are three miscibility gaps, two of which have lower critical points (LCP). We do not know of any other non-polymer system that exhibits an LCP miscibility gap. These unusual phase relations derive from highly anisotropic energetics: (1) it is energetically cheap (<8 kJ/mol; mole = one Si or Al + one C or N) to construct ordered intermediate configurations (supercells) of the form (SiC)<SUB>m</SUB>(AlN)<SUB>n</SUB> in which (SiC)<SUB>m</SUB> represents m SiC-layers perpendicular to c<SUB>Hex</SUB>, and similarly for (AlN)<SUB>n</SUB>; (2) it is energetically expensive (20-125 kJ/mol) however, to construct intermediate superstructures that do not share this characteristic crystallography. Calculations were performed by using VASP-GGA-PAW supercell formation energies as input for the ATAT package (mmaps and memc2): http://www.its.caltech.edu/~avdw/atat/manual/manual.html.
Proceedings Inclusion? Definite: A CD-only volume

OTHER PAPERS PLANNED FOR THIS SYMPOSIUM

Ab Initio Thermodynamic Modeling of Multicomponent Alloys
First-Principles Calculations and Thermodynamic Modeling of the B-C System
First-Principles Calculations and Thermodynamic Modeling of the Hf-Re System
High Temperature X-Ray Diffraction Studies of Monoclinic to Tetragonal Phase Transformation in HfO2
In-situ Studies of Phase Transitions Driven by Oxygen Activity
In situ, High Temperature, Synchrotron Studies of Phase Transformations in Oxide Ceramics
Nanoscale Effects on Phase Equilibria
Novel Phase Relations in the Wurtzite-Structure Based SiC-AlN Phase Diagram: Miscibility Gaps with Lower Critical Points in a Non-Polymer System
On the Configuration of Closed Two–Phase Regions in Equilibrium Phase Diagrams
Phase Composition, Lattice Parameters, and Chemical Stability of Sr2Ga(1-X)Al(X)TaO6
Phase Equilibria and Crystal Chemistry in the Systems BaO-TiO2-MnOx and BaO-TiO2-CoO
Phase Equilibria in Spinel Coatings for Solid Oxide Fuel Cell Interconnects
Phase Equilibria in the Refractory Oxide Systems of Zirconia, Hafnia and Yttria with Rare-Earth Oxides
Phase Relation Studies of Energy Materials for Coated Conductor and Waste Heat Recovery Applications
Phase Relationships of Ceramics by Combination of Cluster Expansion Method and First Principles Calculations
The Effect of Zirconium Impurities on the Melting Points of Near Eutectic Alloys in the Cr-Hf System
Thermodynamic Assessment of Ce-Mo, Mo-La, Mo-Y, Ce-V, La-V, V-Y Systems
Thermodynamic Modeling and First-Principles Calculations of Hf-Cr-Y
What Phase Diagrams Can Teach Us about Transparent Conducting Oxides
X-Ray Studies of Phase Transformations in Tantalum Pentoxide

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