The compression behavior of the heavy RE-based BMC Gd40Y16Al24Co20 under high pressure has been investigated by in situ high pressure angle dispersive X-ray diffraction measurements using synchrotron radiation in the ...The compression behavior of the heavy RE-based BMC Gd40Y16Al24Co20 under high pressure has been investigated by in situ high pressure angle dispersive X-ray diffraction measurements using synchrotron radiation in the pressure range of 0-33.42 GPa at room temperature. By fitting the static equation of state at room temperature, we find the value of bulk modulus B is 61.27±4 GPa which is in good agreement with the experimental study by pulse-echo techniques of 58 GPa. The results show that the amorphous structure in the heavy RE-based BMG Gd40Y16Al24Co20 keeps quite stable up to 33.42 GPa although its compressibility is as large as about 33%. The coexistence of normal local structure similar to that of other BMGs and covalent bond structure similar to those of oxide glasses may be the reason for the anomalous property under high pressure of the Gd4oY16Al24Co2o BMG.展开更多
The thermodynamics structural relaxation of Fe73Cu1.5Nd3Si13.5B9 amorphous alloy from room temperature to 400℃ has been investigated by measuring the structure factor with in situ X-ray diffraction. The structural in...The thermodynamics structural relaxation of Fe73Cu1.5Nd3Si13.5B9 amorphous alloy from room temperature to 400℃ has been investigated by measuring the structure factor with in situ X-ray diffraction. The structural information of the atomic con-figuration such as radial distribution function (RDF) and neighbor atomic distance was gained by Fourier transformation. The research result shows that the amor-phous structure remains stable in the temperature range of 30 to 400℃ but exhibits distinct changes in local atomic configuration with the increase of temperature. The quantitative determination of the neighbor atomic distance suggests that the de-gree of short-range order changes by the temperature altering the second nearest neighbor local atomic configuration of the amorphous when structural relaxation occurs.展开更多
采用碳酸盐共沉淀法合成出前驱体,然后通过高温固相法制备了富锂锰基材料0.6Li[Li1/3Mn2/3]O2·0.4Li NixMnyCo1-x-yO2（x〈0.6,y〉0）.使用扫描电镜（SEM）、X射线衍射（XRD）以及电化学方法等手段进行了表征.高温原位XRD测试结果...采用碳酸盐共沉淀法合成出前驱体,然后通过高温固相法制备了富锂锰基材料0.6Li[Li1/3Mn2/3]O2·0.4Li NixMnyCo1-x-yO2（x〈0.6,y〉0）.使用扫描电镜（SEM）、X射线衍射（XRD）以及电化学方法等手段进行了表征.高温原位XRD测试结果表明,随着温度和Ni含量增加,材料的晶胞参数发生较大变化,温度达800 o C时,高Ni组成的材料阳离子混排现象严重,并伴有尖晶石相生成.电性能测试结果表明,在充放电电压为2.0~4.6 V、电流密度20m A·g-1条件下,低Ni含量材料表现出较好的电化学性能,首周放电容量达260.1 m Ah·g-1,首次效率为83.2%,经过50次循环后放电容量保持率高达99.7%,且在电池循环过程中,放电电压平台下降较少.展开更多
In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs t...In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700°C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO<sub>2</sub>. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample;this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characterized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO<sub>2</sub> nanotub展开更多
基金Supported by Chinese Academy of Sciences (KJCX2-SW-N20, KJCX2-SW-N03)NSFC (50731005)+1 种基金SKPBRC(2007CB616915/2006CB605201)PCSIRT (IRT0650)
文摘The compression behavior of the heavy RE-based BMC Gd40Y16Al24Co20 under high pressure has been investigated by in situ high pressure angle dispersive X-ray diffraction measurements using synchrotron radiation in the pressure range of 0-33.42 GPa at room temperature. By fitting the static equation of state at room temperature, we find the value of bulk modulus B is 61.27±4 GPa which is in good agreement with the experimental study by pulse-echo techniques of 58 GPa. The results show that the amorphous structure in the heavy RE-based BMG Gd40Y16Al24Co20 keeps quite stable up to 33.42 GPa although its compressibility is as large as about 33%. The coexistence of normal local structure similar to that of other BMGs and covalent bond structure similar to those of oxide glasses may be the reason for the anomalous property under high pressure of the Gd4oY16Al24Co2o BMG.
基金the Natural Science Foundation of Hebei Province of China (Grant No. A2007000296)the National Natural Science Foundation of China (Grant No. 50731005)+1 种基金SKPBRC (Grant Nos. 2007CB616915 and 2006CB605201)PCSIRT (Grant No. IRT0650)
文摘The thermodynamics structural relaxation of Fe73Cu1.5Nd3Si13.5B9 amorphous alloy from room temperature to 400℃ has been investigated by measuring the structure factor with in situ X-ray diffraction. The structural information of the atomic con-figuration such as radial distribution function (RDF) and neighbor atomic distance was gained by Fourier transformation. The research result shows that the amor-phous structure remains stable in the temperature range of 30 to 400℃ but exhibits distinct changes in local atomic configuration with the increase of temperature. The quantitative determination of the neighbor atomic distance suggests that the de-gree of short-range order changes by the temperature altering the second nearest neighbor local atomic configuration of the amorphous when structural relaxation occurs.
文摘采用碳酸盐共沉淀法合成出前驱体,然后通过高温固相法制备了富锂锰基材料0.6Li[Li1/3Mn2/3]O2·0.4Li NixMnyCo1-x-yO2（x〈0.6,y〉0）.使用扫描电镜（SEM）、X射线衍射（XRD）以及电化学方法等手段进行了表征.高温原位XRD测试结果表明,随着温度和Ni含量增加,材料的晶胞参数发生较大变化,温度达800 o C时,高Ni组成的材料阳离子混排现象严重,并伴有尖晶石相生成.电性能测试结果表明,在充放电电压为2.0~4.6 V、电流密度20m A·g-1条件下,低Ni含量材料表现出较好的电化学性能,首周放电容量达260.1 m Ah·g-1,首次效率为83.2%,经过50次循环后放电容量保持率高达99.7%,且在电池循环过程中,放电电压平台下降较少.
文摘In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700°C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO<sub>2</sub>. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample;this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characterized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO<sub>2</sub> nanotub
