Abstracts Book - IMRC 2018

• SC2-O015 Invited Talk
PHASE STABILITY ANALYSIS OF MIXED-CATION METAL
HEXABORIDES: INSIGHTS FROM DFT CALCULATIONS AND
EXPERIMENTAL CHARACTERIZATION
Kevin Schmidt 1 , Olivia Graeve 2 , Scott Misture 3 , Victor R Vasquez 1
1 University of Nevada, Reno, Chemical and Materials Engineering, United States. 2 University of
California, San Diego, Mechanical and Aerospace Engineering, United States. 3 Alfred University,
Materials Science and Engineering, United States.
Metal hexaborides (MB6) are refractory ionic crystals with unique
thermophysical properties including low work functions, chemical inertness,
and high hardness values among other. Also, they have a broad variety of
potential applications such as thermionic emitters, corrosion-resistant coatings,
sensors, and catalysis among many other. Ternary mixtures of metal
hexaborides offer additional possibilities to tune material properties for many
of the applications aforementioned. In this work, we use density functional
theory (DFT) calculations to stability of the solid solutions of mixed-cation
hexaborides and to study how the spatial arrangement of cations within the
mixture can affect properties related to stability. Bond-lengths within the boron
framework are found to be heavily dependent upon the local cationic
environment, and energies calculated at zero Kelvin suggest certain
stoichiometries naturally lead to phase separation. Some of these calculations
and conclusions are also complemented with recent experimental
characterization of solid solutions of these materials using X-ray diffraction
analysis.
Acknowledgment:
This project was funded by Grant No. 1360561 the National Science Foundation
(USA).
Keywords: Metal Hexaborides, DFT, Mixture Stability
Presenting authors email: victor.vasquez@unr.edu