The compound CeNi 5Sn was studied by means of X ray powder diffraction technique and refined by Rietveld method. It has a hexagonal structure with space group P 6 3/ mmc (No.194), Z =4, the lattice constant...The compound CeNi 5Sn was studied by means of X ray powder diffraction technique and refined by Rietveld method. It has a hexagonal structure with space group P 6 3/ mmc (No.194), Z =4, the lattice constants a =0 48912(3) nm, c =1 973(2) nm and D x=8 974 g·cm -3 . The Rietveld structural refinement was performed, leading to R p=0 138 and R wp =0 185. The figure of merit F N for the XRD data is F 30 =82 1(0 0068, 54). The X ray powder diffraction data are presented.展开更多
オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3typ...オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3type structure, space group I4mm (No.107) a=0.42961(2) nm, c=098147(4) nm, V=0.018114 nm3, Z=2 and Dx=7.717 g·cm-3. The figure of merit FN for the powder data is F30=623 (0.0107, 45). Structure refinement was performed with 110 reflections and led to Rp=11.78% and Rwp=16.56%.展开更多
The phase of pyrochlore Gd_2Zr_2O_7 used for immobilization of Pu （Ⅳ） was investigated, tetravalent cerium was used as the simulacrum for plutonium with tetravalence, and the compounds in the system Gd_2Zr_2-_xCe_x...The phase of pyrochlore Gd_2Zr_2O_7 used for immobilization of Pu （Ⅳ） was investigated, tetravalent cerium was used as the simulacrum for plutonium with tetravalence, and the compounds in the system Gd_2Zr_2-_xCe_xO_7 （0.0≤x≤2.0） were synthesized via a high temperature solid reaction method with Gd_2O_3 and ZrO_2 powders being used as the starting materials. Based on the collected XRD data of the gained samples, the phase and microstructural change of compounds were calculated by means of rietveld structural refinement method. The experimental results indicated that the phases of compounds were changed from pyrochlore to fluorite-type phase with the increasing x. The linear relation between a and x was discovered in the range of fluorite-type phase, which accorded with a = 0.52748 ＋ 0.00825 x （0.2≤x≤2.0）, while V= 0.14668 ＋ 0.00711 x （0.2≤x≤2.0） was also achieved.展开更多
In this work,we reported an exceptionally high selectivity of a NaA zeolite(for which the framework type code of LTA was assigned by the Structure Commission of the International Zeolite Association)towards radioactiv...In this work,we reported an exceptionally high selectivity of a NaA zeolite(for which the framework type code of LTA was assigned by the Structure Commission of the International Zeolite Association)towards radioactive ^(90)Sr^(2+)and explained the origin of this high selectivity by combining structural Rietveld refinements and density functional theory(DFT)calculations.Nuclear wastewater with a ^(90)Sr^(2+)radioactive concentration of 400 Bq L^(-1)(7.75×10^(-2) ppt)and highly concentrated NaNO_(3) and NH_(4)NO_(3)(0.03 M Na^(+) and 0.4 M NH_(4)+,Na+/^(90)Sr^(2+)=3.48×10^(10),and NH_(4)^(+/90)Sr^(2+)=4.64×10^(11))was treated with NaA zeolite.The resultant ^(90)Sr^(2+)radioactive concentration was as low as 0.62±0.12 Bq L^(-1),close to the upper limit of 90Sr-induced radioactive activity in drinking water,and the distribution coefficient,Kd,was as high as 421.56±13.39 L g^(-1).The NaA zeolite showed fast adsorption kinetics(ca.5 min),high capture capacity(294.12 mg g^(-1)),a broad working pH range(4-12),and excellent radiation resistance.The crystallinity and performance of NaA zeolite were not affected by 1000 kGy 60Coγirradiation.Structural Rietveld refinements revealed that all Sr^(2+)ions are located at the center of the single 6-membered rings(s6rs)of the NaA zeolite.DFT calculations showed the free energy difference of exchanging different cations with Na+located in the 8-membered ring(s8r)of the NaA zeolite,and predicted the sequence of Sr^(2+)(-8.17 eV)>Ca^(2+)(-6.17 eV)>K^(+)(-2.13 eV)>Mg^(2+)(-1.94 eV)>NH_(4)+(-0.65 eV)>Cs+(-0.11 eV).The strong tendency of Sr^(2+)replacing Na+explains the exceptionally high selectivity of the NaA zeolite for ^(90)Sr^(2+)in high concentrations of Na^(+)and NH_(4)^(+).Along with the ion-exchange process,structural Rietveld refinements revealed that the Sr^(2+) ions at the s8rs center migrated to the s6rs center.展开更多
文摘The compound CeNi 5Sn was studied by means of X ray powder diffraction technique and refined by Rietveld method. It has a hexagonal structure with space group P 6 3/ mmc (No.194), Z =4, the lattice constants a =0 48912(3) nm, c =1 973(2) nm and D x=8 974 g·cm -3 . The Rietveld structural refinement was performed, leading to R p=0 138 and R wp =0 185. The figure of merit F N for the XRD data is F 30 =82 1(0 0068, 54). The X ray powder diffraction data are presented.
文摘オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3type structure, space group I4mm (No.107) a=0.42961(2) nm, c=098147(4) nm, V=0.018114 nm3, Z=2 and Dx=7.717 g·cm-3. The figure of merit FN for the powder data is F30=623 (0.0107, 45). Structure refinement was performed with 110 reflections and led to Rp=11.78% and Rwp=16.56%.
基金Funded Partly by the Key Project of National High Technology Research and Development Program-"863"Program(No.2009AA050703)the National Natural Science Foundation of China(Nos.41302028,41272050,and 21007052)the Open Foundation of Joint Laboratory for Extreme Conditions Matter Properties,Southwest University of Science and Technology and Research Center of Laser Fusion,CAEP(No.12zxjk04)
文摘The phase of pyrochlore Gd_2Zr_2O_7 used for immobilization of Pu （Ⅳ） was investigated, tetravalent cerium was used as the simulacrum for plutonium with tetravalence, and the compounds in the system Gd_2Zr_2-_xCe_xO_7 （0.0≤x≤2.0） were synthesized via a high temperature solid reaction method with Gd_2O_3 and ZrO_2 powders being used as the starting materials. Based on the collected XRD data of the gained samples, the phase and microstructural change of compounds were calculated by means of rietveld structural refinement method. The experimental results indicated that the phases of compounds were changed from pyrochlore to fluorite-type phase with the increasing x. The linear relation between a and x was discovered in the range of fluorite-type phase, which accorded with a = 0.52748 ＋ 0.00825 x （0.2≤x≤2.0）, while V= 0.14668 ＋ 0.00711 x （0.2≤x≤2.0） was also achieved.
基金financial support from the National Key Research and Development Program of China(2021YFA1500401,2021YFA1501202)the National Natural Science Foundation of China(U1967215,21835002,21621001,21903058,22173066)+9 种基金the 111 Project(B17020)Dr Peng Guo acknowledges financial support from the National Natural Science Foundation of China(No.21972136)the CAS Pioneer Hundred Talents Program(Y706071202)Dalian National Laboratory for Clean Energy,(DNL)Cooperation Fund,and the Chinese Academy of Sciences(DNL201908)Dr Nana Yan acknowledges financial support from the National Natural Science Foundation of China(No.22102177)the CAS Special Research Assistant Program and a scholarship from STOEDr Tao Cheng acknowledges support from Suzhou Key Laboratory of Functional Nano&Soft Materialsthe Collaborative Innovation Center of Suzhou Nano Science&Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 Project,and the Natural Science Foundation of Jiangsu Province(BK20190810).
文摘In this work,we reported an exceptionally high selectivity of a NaA zeolite(for which the framework type code of LTA was assigned by the Structure Commission of the International Zeolite Association)towards radioactive ^(90)Sr^(2+)and explained the origin of this high selectivity by combining structural Rietveld refinements and density functional theory(DFT)calculations.Nuclear wastewater with a ^(90)Sr^(2+)radioactive concentration of 400 Bq L^(-1)(7.75×10^(-2) ppt)and highly concentrated NaNO_(3) and NH_(4)NO_(3)(0.03 M Na^(+) and 0.4 M NH_(4)+,Na+/^(90)Sr^(2+)=3.48×10^(10),and NH_(4)^(+/90)Sr^(2+)=4.64×10^(11))was treated with NaA zeolite.The resultant ^(90)Sr^(2+)radioactive concentration was as low as 0.62±0.12 Bq L^(-1),close to the upper limit of 90Sr-induced radioactive activity in drinking water,and the distribution coefficient,Kd,was as high as 421.56±13.39 L g^(-1).The NaA zeolite showed fast adsorption kinetics(ca.5 min),high capture capacity(294.12 mg g^(-1)),a broad working pH range(4-12),and excellent radiation resistance.The crystallinity and performance of NaA zeolite were not affected by 1000 kGy 60Coγirradiation.Structural Rietveld refinements revealed that all Sr^(2+)ions are located at the center of the single 6-membered rings(s6rs)of the NaA zeolite.DFT calculations showed the free energy difference of exchanging different cations with Na+located in the 8-membered ring(s8r)of the NaA zeolite,and predicted the sequence of Sr^(2+)(-8.17 eV)>Ca^(2+)(-6.17 eV)>K^(+)(-2.13 eV)>Mg^(2+)(-1.94 eV)>NH_(4)+(-0.65 eV)>Cs+(-0.11 eV).The strong tendency of Sr^(2+)replacing Na+explains the exceptionally high selectivity of the NaA zeolite for ^(90)Sr^(2+)in high concentrations of Na^(+)and NH_(4)^(+).Along with the ion-exchange process,structural Rietveld refinements revealed that the Sr^(2+) ions at the s8rs center migrated to the s6rs center.
