| About this Abstract |
| Meeting |
Materials Science & Technology 2011
|
| Symposium
|
Phase Stability, Diffusion, Kinetics and their Applications (PSDK-VI)
|
| Presentation Title |
Phase Stability of NixMg1-xAl2O4 Spinel under Reducing Conditions and the Influence of Stabilizing Elements |
| Author(s) |
Brenden E. Hill, Michelene E. Miller, Scott T Misture |
| On-Site Speaker (Planned) |
Brenden E. Hill |
| Abstract Scope |
Treatment of Ni<sub>x</sub>Mg<sub>1-x</sub>Al<sub>2</sub>O<sub>4</sub> with H<sub>2</sub> results in the progressive reduction of Ni<sup>2+</sup> to Ni<sup>0</sup>, along with a charge compensating oxygen vacancy. For compositions x<0.5, it has been shown that the vacancy rich spinel structure remains stable with all Ni<sup>2+</sup> removed. For compositions x=0.75 and x=1, the spinel phase becomes unstable when approaching full reduction, and transitions to a θ or α alumina phase. The addition of ZrO<sub>2</sub> (2.5 weight %) has been found to suppress this phase transition. Other additives with similar ionic radii are being investigated for additional insight as to the nature of the stabilization mechanism. The nature of the system encourages the use of complementary techniques. Refined phase fractions and site occupancies aid in the deconvolution of the complicated Ni2p electron emission spectra. A detailed picture of structural changes, vacancy formation and phase development as a function of composition, reduction temperature, and stabilizing additives will be demonstrated. |
| Proceedings Inclusion? |
Definite: A CD-only volume |