In this study, Nd-bearing zirconolite-rich ceramics were prepared by solid-state reaction process using CaF2,ZrO2, Ti,TiO2, Fe2 O3 and Nd2O3 as the raw materials. Neodymium was used as trivalent actinide surrogate and...In this study, Nd-bearing zirconolite-rich ceramics were prepared by solid-state reaction process using CaF2,ZrO2, Ti,TiO2, Fe2 O3 and Nd2O3 as the raw materials. Neodymium was used as trivalent actinide surrogate and designed to substitute the Ca and Zr sites of zirconolite with general stoichiometry of Ca1-xZr1-xNd2 xTi2O7（0≤x≤0.3）. Density of Fe-Nd-O sample reaches a maximum value of 4.13 g/cm^2 after being sintered at 1325 ℃ for 42 h. Three major phases, namely zirconolite, perovskite and pseudobrookite, are observed in all these samples. The EDX result shows that Nd2O3 can be successfully incorporated into the lattice structure of the prepared zirconolite-rich minerals and replace the Ca sites of zirconolite and perovskite with Fe3＋ as the charge-compensating ion. Furthermore, the thermal conductivities are all in the range of 1.51-1.67 W/（m·K）. The normalized elemental leaching rates of Ca and Nd in the Fe-Nd-0.2 sample keep in low values of 6.20 × 10^-2 and 4.86 × 10^-4 g/（m^2·d） after 42 d.展开更多
Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich mineral...Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich minerals. Petrography and mineralogy of these two lunar meteorites are consistent with previous investigations. The zirconolite Pb/Pb age of MIL 05035 is 3851±8 Ma (2σ), in excellent agreement with previous reports. This age suggests that MIL 05035 could be paired with Asuka 881757, a low-Ti mare basalt meteorite. The magmatic event related to MIL 05035 was probably due to the late heavy impact bom- bardment on the moon around 3.9 Ga. One baddeleyite grain in LAP 02224 shows a large variation of Pb/Pb age, from 3109±29 to 3547±21 Ma (2σ), much older than the whole-rock age of the same meteorite (~3.02±0.03 Ga). The other baddeleyite grain in LAP 02224 has an age of 3005±17 Ma (2σ). The result indicates that the minimum crystallization age of LAP 02224 is ~3.55 Ga and the younger ages could reflect late thermal disturbance on U-Pb system.展开更多
Zirconolite is recognized as one of the most durable waste matrices for the disposal of high-level radioactive wastes(HLWs).In this study,HfO2 was employed as the surrogate of tetravalent actinides.Hf-bearing zirconol...Zirconolite is recognized as one of the most durable waste matrices for the disposal of high-level radioactive wastes(HLWs).In this study,HfO2 was employed as the surrogate of tetravalent actinides.Hf-bearing zirconolite-based composite waste forms(CaZr1–xHfxTi2O7)were rapidly prepared by combustion synthesis(CS)using CuO as the oxidant,where quick pressing(QP)was introduced to obtain densified samples.Similar as solid state reaction process,the Zr site of zirconolite can be totally occupied by Hf(x=1.0)under the CS reaction.The original 2M zirconolite structure was maintained and a small amount of perovskite impurity phase was generated in the final products.The aqueous durability of representative sample(Cu-Hf-0.6)was tested,where the 42-day normalized leaching rates(LRi)of Ca,Cu,and Hf are 0.25,3.10×10–2,and 1.11×10–8 g·m–2·d–1.展开更多
Zirconolite is one of the most important matrix materials for nuclear waste immobilization.In this study,Sm was employed as the surrogate of trivalent actinides.Sm-doped zirconolite-rich waste forms were readily prepa...Zirconolite is one of the most important matrix materials for nuclear waste immobilization.In this study,Sm was employed as the surrogate of trivalent actinides.Sm-doped zirconolite-rich waste forms were readily prepared by combustion synthesis(CS)using CuO as the oxidant.Two different schemes with or without Al2O3 as the charge compensator were carried out simultaneously.The results demonstrate that Al2O3 addition results in complex phase composition.On the other hand,the samples without Al2O3 addition show desirable products of zirconolite and pyrochlore.The EDX analysis shows that Sm is concurrently incorporated into the Ca and Zr sites of zirconolite,which transforms to pyrochlore structure with high Sm2O3 contents.The aqueous durability of representative Sm-doped sample(Sm-0.6)was investigated.The 42 days normalized leaching rate of Sm is as low as 6.41×10-7 g/(m2 d),which exhibits high durability of Sm-doped sample.展开更多
基金Project supported by the National Natural Science Foundation of China(51672228)the Open Project of State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials(11zxfk26)Science Development Foundation of China Academy of Engineering Physics
文摘In this study, Nd-bearing zirconolite-rich ceramics were prepared by solid-state reaction process using CaF2,ZrO2, Ti,TiO2, Fe2 O3 and Nd2O3 as the raw materials. Neodymium was used as trivalent actinide surrogate and designed to substitute the Ca and Zr sites of zirconolite with general stoichiometry of Ca1-xZr1-xNd2 xTi2O7（0≤x≤0.3）. Density of Fe-Nd-O sample reaches a maximum value of 4.13 g/cm^2 after being sintered at 1325 ℃ for 42 h. Three major phases, namely zirconolite, perovskite and pseudobrookite, are observed in all these samples. The EDX result shows that Nd2O3 can be successfully incorporated into the lattice structure of the prepared zirconolite-rich minerals and replace the Ca sites of zirconolite and perovskite with Fe3＋ as the charge-compensating ion. Furthermore, the thermal conductivities are all in the range of 1.51-1.67 W/（m·K）. The normalized elemental leaching rates of Ca and Nd in the Fe-Nd-0.2 sample keep in low values of 6.20 × 10^-2 and 4.86 × 10^-4 g/（m^2·d） after 42 d.
基金supported by State Key Laboratory of Lithospheric Evolution at the Institute of Geology and Geophysics, Chinese Academy of Sciences, National Natural Science Foundation of China (Grants Nos. 40703015, 40773046)Minor Planet Foundation of China
文摘Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich minerals. Petrography and mineralogy of these two lunar meteorites are consistent with previous investigations. The zirconolite Pb/Pb age of MIL 05035 is 3851±8 Ma (2σ), in excellent agreement with previous reports. This age suggests that MIL 05035 could be paired with Asuka 881757, a low-Ti mare basalt meteorite. The magmatic event related to MIL 05035 was probably due to the late heavy impact bom- bardment on the moon around 3.9 Ga. One baddeleyite grain in LAP 02224 shows a large variation of Pb/Pb age, from 3109±29 to 3547±21 Ma (2σ), much older than the whole-rock age of the same meteorite (~3.02±0.03 Ga). The other baddeleyite grain in LAP 02224 has an age of 3005±17 Ma (2σ). The result indicates that the minimum crystallization age of LAP 02224 is ~3.55 Ga and the younger ages could reflect late thermal disturbance on U-Pb system.
基金the projects supported by the National Natural Science Foundation of China (Nos. 51202203 and 51672228)the Project of State Key Laboratory of Environment-friendly Energy Materials (Nos. 16kffk05 and 17FKSY0104, Southwest University of Science and Technology)Science Development Foundation of China Academy of Engineering Physics
文摘Zirconolite is recognized as one of the most durable waste matrices for the disposal of high-level radioactive wastes(HLWs).In this study,HfO2 was employed as the surrogate of tetravalent actinides.Hf-bearing zirconolite-based composite waste forms(CaZr1–xHfxTi2O7)were rapidly prepared by combustion synthesis(CS)using CuO as the oxidant,where quick pressing(QP)was introduced to obtain densified samples.Similar as solid state reaction process,the Zr site of zirconolite can be totally occupied by Hf(x=1.0)under the CS reaction.The original 2M zirconolite structure was maintained and a small amount of perovskite impurity phase was generated in the final products.The aqueous durability of representative sample(Cu-Hf-0.6)was tested,where the 42-day normalized leaching rates(LRi)of Ca,Cu,and Hf are 0.25,3.10×10–2,and 1.11×10–8 g·m–2·d–1.
基金Projects supported by the National Natural Science Foundation of China(51202203,51672228)the Project of State Key Laboratory of Environment-friendly Energy Materials(17FKSY0104)Science Development Foundation of China Academy of Engineering Physics
文摘Zirconolite is one of the most important matrix materials for nuclear waste immobilization.In this study,Sm was employed as the surrogate of trivalent actinides.Sm-doped zirconolite-rich waste forms were readily prepared by combustion synthesis(CS)using CuO as the oxidant.Two different schemes with or without Al2O3 as the charge compensator were carried out simultaneously.The results demonstrate that Al2O3 addition results in complex phase composition.On the other hand,the samples without Al2O3 addition show desirable products of zirconolite and pyrochlore.The EDX analysis shows that Sm is concurrently incorporated into the Ca and Zr sites of zirconolite,which transforms to pyrochlore structure with high Sm2O3 contents.The aqueous durability of representative Sm-doped sample(Sm-0.6)was investigated.The 42 days normalized leaching rate of Sm is as low as 6.41×10-7 g/(m2 d),which exhibits high durability of Sm-doped sample.
