The title compound, Cs 2[Mg(CO 3) 2(H 2O) 4], was synthesized by the dropwise addition of an aqueous solution of Mg(NO 3) 2 to a stirred aqueous Cs 2CO 3/CsHCO 3 solution. A colorless needle shaped crystal was formed ...The title compound, Cs 2[Mg(CO 3) 2(H 2O) 4], was synthesized by the dropwise addition of an aqueous solution of Mg(NO 3) 2 to a stirred aqueous Cs 2CO 3/CsHCO 3 solution. A colorless needle shaped crystal was formed by slow evaporation. The crystal structure was established on the basis of the single crystal X ray diffraction data. Cs 2[Mg(CO 3) 2(H 2O) 4] crystallized in the orthorhombic space group Pbca (No. 61) with a =0.658 4(1) nm, b =1.257 9(1) nm, c =1.301 3(1) nm, \{ V =1.077 8 nm 3, Z =4, D x=2.971 g·cm -3 , μ =69.20 cm -1 , F (000)=888, T =298 K, final R =0.029 and R w=0.024 for 1 037 observed reflections. The crystal consists of Cs + cations and the complex trans [Mg(CO 3) 2(H 2O) 4] 2- anions with each Mg atom coordinated by the six oxygens of two carbonate groups and four water molecules [ d (Mg_O)=0.203 6(4), 0.207 4(4), 0.213 4(4) nm]. The complex trans [Mg(CO 3) 2(H 2O) 4] 2- anions are arranged in a strongly compressed bcc pattern. A 3D network was formed through the intermolecular hydrogen bonds. The Cs + cations are located in cavities, each being surrounded by nine oxygens of five complex anions with d (Cs_O)=0.306 1-0.348 8 nm. The CO 2- 3 group reveals a lowering of D 3h symmetry due to site and coordination effects, but not any observable deviation from co planarity [ d (C_O)=0.127 2(6), 0.127 5(7) , 0.130 5(6) nm and O_C_O=119.6(5)°, 120.1(5)°, 120.4(5)°].展开更多
The attractive utilization route for one-step catalytic oxidation of dimethyl ether to dimethoxymethane was successfully carried out over the H3PW12O40（40%）/SiO2 catalyst, modified by Cs, K, Ni, and V. The Cs modifi...The attractive utilization route for one-step catalytic oxidation of dimethyl ether to dimethoxymethane was successfully carried out over the H3PW12O40（40%）/SiO2 catalyst, modified by Cs, K, Ni, and V. The Cs modification of H3PW12O40（40%）/SiO2 gave the most promising result of 20% dimethyl ether conversion and 34.8% dimethoxymethane selectivity. Dimethoxymethane could be synthe- sized via methoxy groups decomposed from dimethyl ether through the synergistic effect between the acid sites and the redox sites of Cs modified H3PW12O40（40%）/SiO2.展开更多
The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC cryst...The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.展开更多
The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF...The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF3(M=K,Cs)systems with molar ratios<1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF6^(3-),AlF5^(2-),and AlF4^-,the systems also contained Al2F-7^-.The characteristic bands in the Raman spectra belonging to Al2F-7^-were located at about 225 cm^-1,315 cm^-1,479 cm^-1,and 720 cm^-1.There are two possible structures of Al2F-7^-,which belong to the D3d and D3hpoint groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.展开更多
文摘The title compound, Cs 2[Mg(CO 3) 2(H 2O) 4], was synthesized by the dropwise addition of an aqueous solution of Mg(NO 3) 2 to a stirred aqueous Cs 2CO 3/CsHCO 3 solution. A colorless needle shaped crystal was formed by slow evaporation. The crystal structure was established on the basis of the single crystal X ray diffraction data. Cs 2[Mg(CO 3) 2(H 2O) 4] crystallized in the orthorhombic space group Pbca (No. 61) with a =0.658 4(1) nm, b =1.257 9(1) nm, c =1.301 3(1) nm, \{ V =1.077 8 nm 3, Z =4, D x=2.971 g·cm -3 , μ =69.20 cm -1 , F (000)=888, T =298 K, final R =0.029 and R w=0.024 for 1 037 observed reflections. The crystal consists of Cs + cations and the complex trans [Mg(CO 3) 2(H 2O) 4] 2- anions with each Mg atom coordinated by the six oxygens of two carbonate groups and four water molecules [ d (Mg_O)=0.203 6(4), 0.207 4(4), 0.213 4(4) nm]. The complex trans [Mg(CO 3) 2(H 2O) 4] 2- anions are arranged in a strongly compressed bcc pattern. A 3D network was formed through the intermolecular hydrogen bonds. The Cs + cations are located in cavities, each being surrounded by nine oxygens of five complex anions with d (Cs_O)=0.306 1-0.348 8 nm. The CO 2- 3 group reveals a lowering of D 3h symmetry due to site and coordination effects, but not any observable deviation from co planarity [ d (C_O)=0.127 2(6), 0.127 5(7) , 0.130 5(6) nm and O_C_O=119.6(5)°, 120.1(5)°, 120.4(5)°].
基金Foundation items:the National Natural Science Foundation of China(No.20373085)the Natural Science Foundation of Shanxi Province(No.20051023)
文摘The attractive utilization route for one-step catalytic oxidation of dimethyl ether to dimethoxymethane was successfully carried out over the H3PW12O40（40%）/SiO2 catalyst, modified by Cs, K, Ni, and V. The Cs modification of H3PW12O40（40%）/SiO2 gave the most promising result of 20% dimethyl ether conversion and 34.8% dimethoxymethane selectivity. Dimethoxymethane could be synthe- sized via methoxy groups decomposed from dimethyl ether through the synergistic effect between the acid sites and the redox sites of Cs modified H3PW12O40（40%）/SiO2.
基金supported by the National Natural Science Foundation of China(No.11575145)
文摘The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.
基金the National Natural Science Foundation of China(grant no.51474060)the National Key R&D Program of China(grant no.2017 YFC0805100)+1 种基金the National Natural Science Foundation of Liaoning Province(China)(grant no.2019-MS-129)the Fundamental Research Funds for the Central Universities of China(grant no.N162502002).
文摘The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF3(M=K,Cs)systems with molar ratios<1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF6^(3-),AlF5^(2-),and AlF4^-,the systems also contained Al2F-7^-.The characteristic bands in the Raman spectra belonging to Al2F-7^-were located at about 225 cm^-1,315 cm^-1,479 cm^-1,and 720 cm^-1.There are two possible structures of Al2F-7^-,which belong to the D3d and D3hpoint groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.
