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Meeting MS&T23: Materials Science & Technology
Symposium Phase Transformations in Ceramics: Science and Applications
Presentation Title Structural Evolution of MgAl2O4 and NiAl2O4 Disordered Spinel Oxides Studied via In Situ Neutron Total Scattering
Author(s) John M. Hirtz, Eric C O'Quinn, Igor Gussev, Joerg C Neuefeind, Maik Lang
On-Site Speaker (Planned) John M. Hirtz
Abstract Scope Complex oxides that adopt the isometric spinel structure (AB2O4) are regularly used in energy storage technologies. Using neutron total scattering experiments at the Spallation Neutron Source (Oak Ridge National Laboratory), we elucidated both the long-range repeating structure and the short-range local atomic arrangements of disordered and defective spinels. We have characterized MgAl2O4 and NiAl2O4 disordered through chemical substitution (Mg1-xNixAl2O4), external heating (up to 1000C), and dense electronic excitation through swift heavy ion irradiation (2.2-GeV Au ions). Locally, the isometric Fd3 ̅m spinel structure re-arranges to a tetragonal P4122 atomic configuration with changes in chemistry or during heating to maintain local charge balance, consistent with Pauling’s rules. Interestingly, this behavior is distinct from spinels that are irradiated with swift heavy ions. In this case, the resulting defect structure includes also cations trapped at sites that are ordinarily unoccupied when the structure is disordered by chemical substitution or high temperature.

OTHER PAPERS PLANNED FOR THIS SYMPOSIUM

Computational Study of Site-disordered AgSbI4
Crystal Structure Solution and Phase Transformations of CaZr4(PO4)6 and SrZr4(PO4)6
Effect of Cations Decoration on Ti3C2Tx MXene, its Stability and Phase Transformation at High Temperatures
Elevated Temperature Phase Control of Two-dimensional Mo2TiC2Tx Carbide Through Defect Engineering
Enhancing Oxidation Resistance of Silicon Nitride Using Ca2+ Stabilizer
Microstructural Evolution and Associated Kinetics of Seeded Solid State Single Crystal Growth of CoTi2O5
Phase Stability and Cation Partitioning in Multi-rare Earth Aluminates and Zirconates
Phase Transformations in Ceramic Materials under Extreme External Forcing
Progress on Phase Stability of Substituted Rare Earth Disilicate Compositions for Environmental Barrier Coatings
Spinodal Decomposition in Ferroelectric Crystals
Structural Evolution of MgAl2O4 and NiAl2O4 Disordered Spinel Oxides Studied via In Situ Neutron Total Scattering
Using Total Scattering Techniques to Explore Fundamental Aspects of the Structural Organization in Weberite-type Tantalate Oxides

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