Thermochemistry of Lanthana- and Yttria- Doped Thoria

Journal Article · Wed Sep 29 04:00:00 EDT 2010 · Journal of the American Ceramic Society (Online)

DOI:https://doi.org/10.1111/j.1551-2916.2010.04001.x· OSTI ID:1064906

Aizenshtein, Michael ^[1]; Shvareva, Tatiana Y. ^[2]; Navrotsky, Alexandra ^[2]

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1. NRC-Negev, Beer-Sheva (Israel); Univ. of California, Davis, CA (United States)
2. Univ. of California, Davis, CA (United States)

Lanthanide-doped thoria is relevant both to nuclear energy and to solid oxide fuel cell technology. It is also a simple model system in which oxygen vacancy concentration is directly proportional to doping with no complication from oxidation–reduction reactions, ordered phases, or phase transitions in the tetravalent oxide. Despite this relevance, only few thermodynamic data are available for such systems. In the present study, La _xTh_1-xO_2-0.5x (0< x <0.50) and Y_x Th_1-x O_2-0.5x (0 < x < 0.18) have been synthesized, characterized, and systematically studied for the first time using high-temperature oxide melt solution calorimetry. Two competing effects contribute to the energetics: endothermic deviation from ideality related to cation size difference and partial stabilization of the system due to the exothermic formation of defect clusters. The former can be described by endothermic regular solution interaction parameters of 119.3 ± 11.4 kJ/mol for the yttria system and 27.8 ± 4.1 kJ/mol for the lanthana system. The latter can be described by exothermic vacancy clustering or defect association energies of –116.3 ± 23.3 kJ/mol for yttria-doped thoria and –98.6 ± 19.7 kJ/mol for lanthana-doped thoria.

• Research Organization: Energy Frontier Research Centers (EFRC); Materials Science of Actinides (MSA)
• Sponsoring Organization: USDOE SC Office of Basic Energy Sciences (SC-22)
• DOE Contract Number: SC0001089
• OSTI ID: 1064906
• Journal Information: Journal of the American Ceramic Society (Online), Journal Name: Journal of the American Ceramic Society (Online) Journal Issue: 12 Vol. 93; ISSN 1551-2916
• Publisher: American Ceramic Society
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
materials and chemistry by design
nuclear (including radiation effects)
synthesis (novel materials)
synthesis (self-assembly)