Self-propagating high-temperature synthesis of ZrO2 incorporated Gd2Ti2O7 pyrochlore
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In this research, Zr-doped Gd2Ti2O7 pyrochlores, with the composition of Gd2(Ti1-xZr x )2O7, were firstly synthesized by self-propagating high-temperature synthesis plus quick pressing (SHS/QP) using CuO as the oxidant and Ti as the reductant. To improve the radiation resistance of titanate–pyrochlore, up to 35 at% Zr was incorporated to substitute the Ti site of Gd2Ti2O7 pyrochlore (Gd2(Ti0.75Zr0.35)2O7). XRD and SEM microstructural characterizations showed the formation of a composite ceramic with the major pyrochlore phase and the minor Cu phase. The generated temperature of samples decreased from 1702 to 1011°C with increasing Zr content. The effects of sintering temperature and pressure time on phase composition and microstructure were systematically studied. Besides, the influence of thermal transmission on the whole combustion process was also explored. The pyrochlore-based waste form possessed high bulk density of 6.25 g/cm3 and Vickers hardness of 10.81 GPa. The MCC-1 leaching test showed the normalized elemental leaching rates (42 d) of Cu, Gd, and Zr are 1.27×10-2, 1.33×10-3, and 8.44×10-7 g·m-2·d-1, respectively.
Keywordsself-propagating high-temperature synthesis plus quick pressing (SHS/QP) pyrochlore thermal transmission waste form aqueous leachability
We sincerely appreciate the projects supported by the National Natural Science Foundation of China (Nos. 51672228 and 51202203), the Open Project of State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials (No. 11zxfk26), the Young Outstanding Scientist Fund of Southwest University of Science and Technology (No. 13zx9108), and the Postgraduate Innovation Fund Project by Southwest University of Science and Technology (No. 16ycx010).
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