The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration...The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca（HzPO4）2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient （Kn） increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg（OH）z＇MgCIz＇8H20 in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.展开更多
The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consi...The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa （discrete variational Xa） method. The ground-state calculation showed that only the lowest 5d level Ed of Ce^3＋ ion lies around the BCB （bottom of the conduction band） while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4d of Y mixed with 5d of Ce, even for the wavefunctions （WFS） with energy Ed under BCB there are still 24% of Y-4d and 9% of F-2p as components. So, they are not pure crystal-field states at all. Furthermore, transition state （TS） calculation was performed to obtain the 4f→5d transition energies Efd, to improve the previous calculation performed by Andriessen et al, in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare with the observed 4f→5 d transition energies. The ionic radius of Ce^3＋ is larger than that of y^3＋ , so we had also modeled approximately the lattice relaxation. As results, the CeY4Li8F24 cluster with 4.56 % outward relaxation （of the nearest-neighbor and next nearest-neighbor eight fluorines） has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the ground-state calculated Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure （including zero-phonon line） of the lowest 5 d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is some how around 4. 56% -7.36% outward, not as large as 10% proposed by Andriessen et al.展开更多
The title complex 1,{[CuEu（Hbidc）2（H2O）4]·H2O}n（H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid）,has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Comple...The title complex 1,{[CuEu（Hbidc）2（H2O）4]·H2O}n（H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid）,has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Complex 1 crystallizes in triclinic,space group P1,with a = 7.791（2）,b = 12.058（3）,c = 12.109（3）,α = 82.189（5）,β = 72.407（5）,γ = 89.184（4）°,V = 1073.7（5）3,C18H18CuEuN4O13,Mr = 713.86,Dc = 2.208 g/cm3,μ（MoKα） = 3.967 mm-1,F（000） = 700,GOOF = 0.950,Z = 2,the final R = 0.0531 and wR = 0.1068 for I 2σ（I）.Complex 1 possess a tape-like chain structure consisting of Eu2C8O4 and Cu2Eu2C18N4O4 metallic rings alternatively arranged and is the first 3d-4f heterometallic complex based on the 1H-ben-zimidazole-5,6-dicarboxylato ligand（Hbidc）.Plenty of hydrogen-bonding and π...π stacking interactions connect the 1D chains to construct a 3D supramolecular architecture.展开更多
The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consi...The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa （discrete variational Xa） method. The ground-state calculation showed that only the lowest 5d level Ed of Ce^3＋ ion lies around the BCB （bottom of the conduction band） while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4d of Y mixed with 5d of Ce, even for the wavefunctions （WFS） with energy Ed under BCB there are still 24% of Y-4d and 9% of F-2p as components. So, they are not pure crystal-field states at all. Furthermore, transition state （TS） calculation was performed to obtain the 4f→5d transition energies Efd, to improve the previous calculation performed by Andriessen et al, in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare with the observed 4f→5 d transition energies. The ionic radius of Ce^3＋ is larger than that of y^3＋ , so we had also modeled approximately the lattice relaxation. As results, the CeY4Li8F24 cluster with 4.56 % outward relaxation （of the nearest-neighbor and next nearest-neighbor eight fluorines） has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the ground-state calculated Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure （including zero-phonon line） of the lowest 5 d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is some how around 4. 56% -7.36% outward, not as large as 10% proposed by Andriessen et al.展开更多
Eight comptexes (RC_5H_4)_2Ti(O_2CA_r)_2(R=H,CH_3;Ar= with 2 equiv.N_aO_2CA_r.The carboxytate ligands in the complexes coordinate to titan^um atom in monodentate mode.(CH_3C_5H_4)_2Ti(O_2CC_4H_3S-2)_2 has four-coordin...Eight comptexes (RC_5H_4)_2Ti(O_2CA_r)_2(R=H,CH_3;Ar= with 2 equiv.N_aO_2CA_r.The carboxytate ligands in the complexes coordinate to titan^um atom in monodentate mode.(CH_3C_5H_4)_2Ti(O_2CC_4H_3S-2)_2 has four-coordinate bent titanocene in which the thiophencarboxyaltes are a monodeotate ligand(Ti-0=1.981(8)A,1.926(3)A;) 0-Ti-0:91.6(8)~ ; Ti-C:2.333-2.440A).展开更多
基金Project(B0210)supported by One Hundred Talent Project of Chinese Academy of SciencesProject(2008-G-158)supported by Science and Technology Tackling Key Program of Qinghai Province,China
文摘The effects of H3PO4 and Ca（H2PO4）2 on compressive strength, water resistance, hydration process of thermally decomposed magnesium oxychloride cement （TDMOC） pastes were studied. The mineral composition, hydration products and hydration heat release were analyzed by XRD, FT-IR, SEM and TAM air isothermal calorimeter, etc. After being modified by H3PO4 and Ca（HzPO4）2, the properties of the TDMOC are improved obviously. The compressive strength increases from 14.8 MPa to 48.1 MPa and 37.1 MPa, respectively. The strength retention coefficient （Kn） increases from 0.38 to 0.99 and 0.94, respectively. The 24 h hydration heat release decreases by 10% and 4% and the time of hydration peak appearing is delayed from 1 h to about 10 h. The XRD, FT-IR and SEM results show that the main composition is 5Mg（OH）z＇MgCIz＇8H20 in the modified TDMOC pastes. The possible mechanism for the strength enhancement was discussed. The purposes are to extend the potential applications of the salt lake magnesium resources and to improve the mechanical properties of TDMOC.
文摘The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa （discrete variational Xa） method. The ground-state calculation showed that only the lowest 5d level Ed of Ce^3＋ ion lies around the BCB （bottom of the conduction band） while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4d of Y mixed with 5d of Ce, even for the wavefunctions （WFS） with energy Ed under BCB there are still 24% of Y-4d and 9% of F-2p as components. So, they are not pure crystal-field states at all. Furthermore, transition state （TS） calculation was performed to obtain the 4f→5d transition energies Efd, to improve the previous calculation performed by Andriessen et al, in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare with the observed 4f→5 d transition energies. The ionic radius of Ce^3＋ is larger than that of y^3＋ , so we had also modeled approximately the lattice relaxation. As results, the CeY4Li8F24 cluster with 4.56 % outward relaxation （of the nearest-neighbor and next nearest-neighbor eight fluorines） has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the ground-state calculated Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure （including zero-phonon line） of the lowest 5 d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is some how around 4. 56% -7.36% outward, not as large as 10% proposed by Andriessen et al.
基金Supported by the Nanjing University of Posts and Telecommunications(No.NY209032)the National Natural Science Foundation of China(No.21001065)the Major State Basic Research Development Program of China (973 Program,No.2009CB930600)
文摘The title complex 1,{[CuEu（Hbidc）2（H2O）4]·H2O}n（H3bidc = 1H-benzimidazole-5,6-dicarboxylic acid）,has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction.Complex 1 crystallizes in triclinic,space group P1,with a = 7.791（2）,b = 12.058（3）,c = 12.109（3）,α = 82.189（5）,β = 72.407（5）,γ = 89.184（4）°,V = 1073.7（5）3,C18H18CuEuN4O13,Mr = 713.86,Dc = 2.208 g/cm3,μ（MoKα） = 3.967 mm-1,F（000） = 700,GOOF = 0.950,Z = 2,the final R = 0.0531 and wR = 0.1068 for I 2σ（I）.Complex 1 possess a tape-like chain structure consisting of Eu2C8O4 and Cu2Eu2C18N4O4 metallic rings alternatively arranged and is the first 3d-4f heterometallic complex based on the 1H-ben-zimidazole-5,6-dicarboxylato ligand（Hbidc）.Plenty of hydrogen-bonding and π...π stacking interactions connect the 1D chains to construct a 3D supramolecular architecture.
文摘The electronic structures of LiYF4：Ce^3＋ and LiYF4 crystal simulated by an embedded （in a microcrystal containing 1938 ions） cluster CeY4Li8F24, and Y5LisF24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa （discrete variational Xa） method. The ground-state calculation showed that only the lowest 5d level Ed of Ce^3＋ ion lies around the BCB （bottom of the conduction band） while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4d of Y mixed with 5d of Ce, even for the wavefunctions （WFS） with energy Ed under BCB there are still 24% of Y-4d and 9% of F-2p as components. So, they are not pure crystal-field states at all. Furthermore, transition state （TS） calculation was performed to obtain the 4f→5d transition energies Efd, to improve the previous calculation performed by Andriessen et al, in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare with the observed 4f→5 d transition energies. The ionic radius of Ce^3＋ is larger than that of y^3＋ , so we had also modeled approximately the lattice relaxation. As results, the CeY4Li8F24 cluster with 4.56 % outward relaxation （of the nearest-neighbor and next nearest-neighbor eight fluorines） has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the ground-state calculated Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure （including zero-phonon line） of the lowest 5 d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is some how around 4. 56% -7.36% outward, not as large as 10% proposed by Andriessen et al.
文摘Eight comptexes (RC_5H_4)_2Ti(O_2CA_r)_2(R=H,CH_3;Ar= with 2 equiv.N_aO_2CA_r.The carboxytate ligands in the complexes coordinate to titan^um atom in monodentate mode.(CH_3C_5H_4)_2Ti(O_2CC_4H_3S-2)_2 has four-coordinate bent titanocene in which the thiophencarboxyaltes are a monodeotate ligand(Ti-0=1.981(8)A,1.926(3)A;) 0-Ti-0:91.6(8)~ ; Ti-C:2.333-2.440A).
