| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
Thermodynamics of Materials in Extreme Environments
|
| Presentation Title |
Energetics of K-,Ga- Titanate Hollandites |
| Author(s) |
Nancy Birkner, Mingyang Zhao , Kyle S. Brinkman |
| On-Site Speaker (Planned) |
Nancy Birkner |
| Abstract Scope |
Hollandites show promise for immobilization of alkali metal radionuclides (e.g. 137Cs fission product of nuclear reactors). The Center for Hierarchical Waste Form Materials previously measured the thermodynamic stability of A-site (Ba,Cs)-containing titanate hollandites of the general form BaxCsyZnx+y/2Ti8-x-y/2O16 and BaxCsyB2x+yTi8-2x-yO16 (x + y = 1.33 and B = Al, Fe, Ga). Enthalpies of formation in order of increasing stability are Ga<Zn<Fe≈Al (notation based on B-sites). Additionally, greater [Cs] increases stability resulting in fractional Cs retention increase under aqueous leaching conditions. Recently, K,Ga - titanate hollandites, (KxGayTi8-x-yO16, x = y) were measured using high temperature oxide melt solution calorimetry. Like previous titanate hollandites, their formation enthalpies are strongly exothermic indicating thermodynamic stability relative to their binary oxides and elements at 25 °C. |