TY - JOUR
T1 - Synthesis of (Ca,Ce3+,Ce4+)2Ti 2O7
T2 - A pyrochlore with mixed-valence cerium
AU - Garvie, Laurence
AU - Xu, Huifang
AU - Wang, Yifeng
AU - Putnam, Robert L.
N1 - Funding Information:
We thank two anonymous reviewers for their constructive criticism. This work is based upon research conducted at the Transmission Electron Microscopy Laboratory in the Department of Earth and Planetary Sciences of the University of New Mexico, which is partially supported by NSF (CTS 98-71292) and the State of New Mexico. This work was supported by grants from the National Science Foundation (EAR 00-87714, 01-13345, and 02-10820). The EELS was performed at the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University.
PY - 2005/5
Y1 - 2005/5
N2 - Pyrochlore with mixed-valence Ce was synthesized by firing and annealing Ce(NO3)4, TiO2, and Ca(OH)2 with a stoichiometry of CaCeTi2O7 at 1300 °C. The product contains Ce-pyrochlore, Ce-rich perovskite, CeO2 (cerianite), and minor CaO. Electron energy-loss spectroscopy (EELS) revealed both Ce 4+ and Ce3+ in the Ce-pyrochlore with a Ce4+ to total Ce (Ce4+/ΣCe) of 0.80 giving (Ca0.87Ce0.213+Ce0.864+) Ti2.05O7. Cerium in the perovskite and cerianite is dominated by Ce3+ and Ce4+, respectively. High-resolution transmission electron microscope (HRTEM) images show that the boundary between Ce-pyrochlore and Ce-rich perovskite is semi-coherently bonded. The orientational relationship between the neighboring Ce-pyrochlore and Ce-rich perovskite is not random. Ce-pyrochlore (CaCeTi2O7) is a chemical analogue for CaPuTi2O7, which is a proposed ceramic waste form for deposition of excess weapons-usable Pu in geological repositories. It is postulated, based on the presence of Ce3+ in the Ce-pyrochlore, that neutron poisons such as Gd can be incorporated into the CaPuTi2O 7 phase.
AB - Pyrochlore with mixed-valence Ce was synthesized by firing and annealing Ce(NO3)4, TiO2, and Ca(OH)2 with a stoichiometry of CaCeTi2O7 at 1300 °C. The product contains Ce-pyrochlore, Ce-rich perovskite, CeO2 (cerianite), and minor CaO. Electron energy-loss spectroscopy (EELS) revealed both Ce 4+ and Ce3+ in the Ce-pyrochlore with a Ce4+ to total Ce (Ce4+/ΣCe) of 0.80 giving (Ca0.87Ce0.213+Ce0.864+) Ti2.05O7. Cerium in the perovskite and cerianite is dominated by Ce3+ and Ce4+, respectively. High-resolution transmission electron microscope (HRTEM) images show that the boundary between Ce-pyrochlore and Ce-rich perovskite is semi-coherently bonded. The orientational relationship between the neighboring Ce-pyrochlore and Ce-rich perovskite is not random. Ce-pyrochlore (CaCeTi2O7) is a chemical analogue for CaPuTi2O7, which is a proposed ceramic waste form for deposition of excess weapons-usable Pu in geological repositories. It is postulated, based on the presence of Ce3+ in the Ce-pyrochlore, that neutron poisons such as Gd can be incorporated into the CaPuTi2O 7 phase.
KW - A. Ceramics
KW - B. Chemical synthesis
KW - C. Electron energy loss spectroscopy (EELS)
KW - C. Electron microscopy
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U2 - 10.1016/j.jpcs.2004.10.012
DO - 10.1016/j.jpcs.2004.10.012
M3 - Article
AN - SCOPUS:13844309861
SN - 0022-3697
VL - 66
SP - 902
EP - 905
JO - Journal of Physics and Chemistry of Solids
JF - Journal of Physics and Chemistry of Solids
IS - 5
ER -