A series of title compounds as well as their precursors were synthesized by precursor route. Their PXRD patterns were characterized with ZrW2O8 or ZrMo2O8 model by Rietveld method. The thermal contractions of the com... A series of title compounds as well as their precursors were synthesized by precursor route. Their PXRD patterns were characterized with ZrW2O8 or ZrMo2O8 model by Rietveld method. The thermal contractions of the compounds were determined according to the variable-temperature PXRD data and NTE coefficients were presented. The two-phase mixture of ZrW0.4Mo1.6O8 was also analyzed individually.展开更多
In this work, surface-mazelike Zn O, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol- mediated solvothermal method. The structure evolution of these materials bore striking similari...In this work, surface-mazelike Zn O, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol- mediated solvothermal method. The structure evolution of these materials bore striking similarities, including(1) initial formation of metal alkoxides precursors and(2) subsequent structural evolution of products from tiered plates to jigsaw puzzles; then to extrusion ridges, nests and spindles; and thereafter to final mazelike structures driven by persistent thermal decomposition of preformed precursors. Based on their unique surface morphologies in sinuous asymmetry, it is anticipated that such mazelike hierarchical structures may shed new light on the development of morphology-controlled adsorption and heterogeneous catalysts.展开更多
The mechanism of the precursor dehydration route was revealed for the synthesis of NTE c-ZrW_ 1.6 Mo_ 0.4 O_8. The hydrate precursor was dehydrated at 473 K and transformed to a NTE cubic compound above 800 K. A nov...The mechanism of the precursor dehydration route was revealed for the synthesis of NTE c-ZrW_ 1.6 Mo_ 0.4 O_8. The hydrate precursor was dehydrated at 473 K and transformed to a NTE cubic compound above 800 K. A novel intermediate phase o-ZrW_ 1.6 Mo_ 0.4 O_8 occurs between the temperature range of 573—800 K. The XRD pattern of novel intermediate was refined with the structural model of LT-ZrMo_2O_8 by using Rietveld method. The residuals are R_ wp =7.80% and R_p=5.79%. The space group is Pmn2_1 and the lattice parameters are a=0.5917(4) nm, b=0.7273(4) nm, c=0.9148(6) nm, and Z=2.展开更多
Al foam sandwich panel(AFS) with metallic bonding was fabricated by foaming a hotpressed three-layer composite with two steel facesheets and a melt route precursor as core. The melt route precursor was fabricated by d...Al foam sandwich panel(AFS) with metallic bonding was fabricated by foaming a hotpressed three-layer composite with two steel facesheets and a melt route precursor as core. The melt route precursor was fabricated by dispersing undecomposed blowing agent into molten Al, followed by solidification. Microstructures of the joints during fabrication process were analyzed by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS). Static three-point bending was conducted to evaluate joint quality of the AFS. It was found that a primary bonding was achieved by hot-pressing and significant diffusion layer of Fe-Al intermetallic compounds was sustained between steel and Al foam core by foaming. Damage modes of the AFS under three-point bending were dominated by indentation, plastic hinges, core shear and crack. Delamination between steel and foam was absent, implying that reliable metallic bonding was achieved. This method allows for producing large-scale AFS with steel facesheets.展开更多
Manganese nickel ferrite (Mn0.2Ni0.8Fe2O4) powder was synthesized through oxalate precursor route. The effect of annealing temperature (400℃ - 1100℃) on the formation, crystalline size, morphology and magnetic prope...Manganese nickel ferrite (Mn0.2Ni0.8Fe2O4) powder was synthesized through oxalate precursor route. The effect of annealing temperature (400℃ - 1100℃) on the formation, crystalline size, morphology and magnetic properties was systematically studied. The resultant powders were investigated by thermal analyzer (TG-DTG-DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Based on thermal analysis results, the oxalate mixture decomposed thermally in multisteps weight loss up to about 680℃. XRD indicated that Mn0.2Ni0.8Fe2O4 formed at much lower annealing temperature (≤400℃) but contained α-Fe2O3 impurity. The hematite phase decreased by increasing the annealing temperature. The lattice parameters were increased with increasing annealing temperature up to 1000℃. The average crystalline size increased by increasing the annealing temperature. Single well crystalline ferrite was obtained at 800℃with crystallite size about 109 nm. The saturation magnetization of the ferrites powders continuously increased with the increase in annealing temperature. Maximum saturation magnetization 48.2 emu/g was achieved for the formed Mn0.2Ni0.8Fe2O4 phase at annealing temperature 1100℃.展开更多
Nanocrystallite δ ′ ZrW 1.6 Mo 0.4 O 8 was prepared in the precursor route synthesis. The characterization by means of powder X ray diffraction (XRD) and selected area electron diffraction (SAED) showe...Nanocrystallite δ ′ ZrW 1.6 Mo 0.4 O 8 was prepared in the precursor route synthesis. The characterization by means of powder X ray diffraction (XRD) and selected area electron diffraction (SAED) showed it crystallized in a orthorhombic crystal system with a =0.896 9(7) nm, b =0.701 1(8) nm, c =0.596(1) nm. The possible space group is Pnnm (58) or Pnn2 (34). The compound crystallizes in a metastable phase during the synthesis process depending on temperature and crystallization time.展开更多
Zirconium tungsten oxyfluoride,ZrWO4F2,was firstly synthesized with the pr ecursor route.The composition of the compound was determined by combi ning the results of ICP and XPS.The in dexed powder X-ray diffraction pa...Zirconium tungsten oxyfluoride,ZrWO4F2,was firstly synthesized with the pr ecursor route.The composition of the compound was determined by combi ning the results of ICP and XPS.The in dexed powder X-ray diffraction pattern of this compound indicates t hat it is a pure phase,orthorhombic c rystal system,space group D 22 =P2 1 22and a=15.32（2）*!,b=13.877（7）*!,c=8.42（2）*!.Combining the results of the DTA-T GA curves from room temperature to 700℃and XRD patterns in different temperatures the mechanism was revealed during the solid precursor（1）been heated to 700℃.The zirconium tu ngsten oxyfluoride was considered t o be a metastable com-pound.The ascertaining of annealin g time and temperature is the key of handling.展开更多
基金Project (No. 29871006) supported by the National Natural Science Foundation of China.
文摘 A series of title compounds as well as their precursors were synthesized by precursor route. Their PXRD patterns were characterized with ZrW2O8 or ZrMo2O8 model by Rietveld method. The thermal contractions of the compounds were determined according to the variable-temperature PXRD data and NTE coefficients were presented. The two-phase mixture of ZrW0.4Mo1.6O8 was also analyzed individually.
基金supported by the National Natural Science Foundation of China(51072087)Specialized Research Fund for the Doctoral Program of Higher Education(20113719110001)
文摘In this work, surface-mazelike Zn O, Cu, and Ni hierarchical structures were synthesized via a versatile ethylene glycol- mediated solvothermal method. The structure evolution of these materials bore striking similarities, including(1) initial formation of metal alkoxides precursors and(2) subsequent structural evolution of products from tiered plates to jigsaw puzzles; then to extrusion ridges, nests and spindles; and thereafter to final mazelike structures driven by persistent thermal decomposition of preformed precursors. Based on their unique surface morphologies in sinuous asymmetry, it is anticipated that such mazelike hierarchical structures may shed new light on the development of morphology-controlled adsorption and heterogeneous catalysts.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 98710 0 6)
文摘The mechanism of the precursor dehydration route was revealed for the synthesis of NTE c-ZrW_ 1.6 Mo_ 0.4 O_8. The hydrate precursor was dehydrated at 473 K and transformed to a NTE cubic compound above 800 K. A novel intermediate phase o-ZrW_ 1.6 Mo_ 0.4 O_8 occurs between the temperature range of 573—800 K. The XRD pattern of novel intermediate was refined with the structural model of LT-ZrMo_2O_8 by using Rietveld method. The residuals are R_ wp =7.80% and R_p=5.79%. The space group is Pmn2_1 and the lattice parameters are a=0.5917(4) nm, b=0.7273(4) nm, c=0.9148(6) nm, and Z=2.
基金Funded by the National Natural Science Foundation of China(51174060 and 51301109)the Science and Technology Department of Liaoning Province of China(2013223004)the Fundamental Research Funds for the Central Universities(140203004)
文摘Al foam sandwich panel(AFS) with metallic bonding was fabricated by foaming a hotpressed three-layer composite with two steel facesheets and a melt route precursor as core. The melt route precursor was fabricated by dispersing undecomposed blowing agent into molten Al, followed by solidification. Microstructures of the joints during fabrication process were analyzed by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS). Static three-point bending was conducted to evaluate joint quality of the AFS. It was found that a primary bonding was achieved by hot-pressing and significant diffusion layer of Fe-Al intermetallic compounds was sustained between steel and Al foam core by foaming. Damage modes of the AFS under three-point bending were dominated by indentation, plastic hinges, core shear and crack. Delamination between steel and foam was absent, implying that reliable metallic bonding was achieved. This method allows for producing large-scale AFS with steel facesheets.
文摘Manganese nickel ferrite (Mn0.2Ni0.8Fe2O4) powder was synthesized through oxalate precursor route. The effect of annealing temperature (400℃ - 1100℃) on the formation, crystalline size, morphology and magnetic properties was systematically studied. The resultant powders were investigated by thermal analyzer (TG-DTG-DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Based on thermal analysis results, the oxalate mixture decomposed thermally in multisteps weight loss up to about 680℃. XRD indicated that Mn0.2Ni0.8Fe2O4 formed at much lower annealing temperature (≤400℃) but contained α-Fe2O3 impurity. The hematite phase decreased by increasing the annealing temperature. The lattice parameters were increased with increasing annealing temperature up to 1000℃. The average crystalline size increased by increasing the annealing temperature. Single well crystalline ferrite was obtained at 800℃with crystallite size about 109 nm. The saturation magnetization of the ferrites powders continuously increased with the increase in annealing temperature. Maximum saturation magnetization 48.2 emu/g was achieved for the formed Mn0.2Ni0.8Fe2O4 phase at annealing temperature 1100℃.
基金Supported by the National Natural Science Foundation of China(No. 2 98710 0 6 ) .
文摘Nanocrystallite δ ′ ZrW 1.6 Mo 0.4 O 8 was prepared in the precursor route synthesis. The characterization by means of powder X ray diffraction (XRD) and selected area electron diffraction (SAED) showed it crystallized in a orthorhombic crystal system with a =0.896 9(7) nm, b =0.701 1(8) nm, c =0.596(1) nm. The possible space group is Pnnm (58) or Pnn2 (34). The compound crystallizes in a metastable phase during the synthesis process depending on temperature and crystallization time.
文摘Zirconium tungsten oxyfluoride,ZrWO4F2,was firstly synthesized with the pr ecursor route.The composition of the compound was determined by combi ning the results of ICP and XPS.The in dexed powder X-ray diffraction pattern of this compound indicates t hat it is a pure phase,orthorhombic c rystal system,space group D 22 =P2 1 22and a=15.32（2）*!,b=13.877（7）*!,c=8.42（2）*!.Combining the results of the DTA-T GA curves from room temperature to 700℃and XRD patterns in different temperatures the mechanism was revealed during the solid precursor（1）been heated to 700℃.The zirconium tu ngsten oxyfluoride was considered t o be a metastable com-pound.The ascertaining of annealin g time and temperature is the key of handling.
