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高温高压下氧化锌纳米晶的晶粒演化动力学 总被引:3,自引:0,他引:3
用GS-1B型六面顶压机研究了ZnO纳米晶高温高压下的晶粒演化动力学, 用MDI/JADE5 X射线衍射仪(Cu靶)和XL30S-FEG场发射扫描电子显微镜对高压样品的相组成、晶粒尺寸及微观形貌进行了表征. 实验发现300 ℃(包括300 ℃)以下, ZnO纳米材料中晶粒生长速率随着压力的升高先增大后减小, 1~3 GPa烧结体晶粒尺寸随着压力的升高而增大, 4~6 GPa烧结体晶粒尺寸随着压力的升高而减小. 利用高压下晶粒生长速率方程求出1~3 GPa, 4~6 GPa的激活体积分别为-5.82, 9.66 cm3/mol. 400 ℃(包括400 ℃)以上, 1~6 GPa烧结体的晶粒尺寸随着压力的升高而不断增大. 相似文献
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Cylinder-shaped CusoNi20 alloy melt is undercooled and solidified by the combination of the electromagnetic levitation technique and the flux treatment method. Nearly constant temperature gradient of 8-10 K/cm is realized for the cylindrical melts with differen~ undercooling levels at the bottom ends. The experimental results reveal that with the increase of the undercoo]ing of the melts from 35 to 220 K, the microstructures undergo transition from coarse dendrites to granular grains, unidirectional dendrites, and finally to equiaxed grains. 相似文献
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利用密度泛函理论的B3LYP/LanL2DZ方法,对AgGe_n(n=1~17)团簇进行了系统的研究,较小的AgGe_m(n=1~11)和相对较大的AgGe_n(n=12~17)团簇出现了不同的生长方式.从n=12开始,形成了银原子被锗原子完全包围的笼状结构.根据AgGe_n团簇的分裂能和二阶能量差分,预测了AgGe_n(n=1~17)团簇的幻数为n=5、10、12和15.Mulliken电荷布局分析显示电荷转移的方向和团簇的大小与掺杂的金属种类有关.通过分析振动光谱,研究了团簇的动态稳定性,在实验中明显的红外谱和拉曼谱能被用来区别团簇结构. 相似文献
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The structural,elastic, and electronic properties of ZrxNbl-xC alloys from first principle calculations* 下载免费PDF全文
The structural, elastic, electronic, and thermodynamic properties of ZrxNbl xC alloys are investigated using the first principles method based on the density functional theory. The results show that the structural properties of Zr~.Nb1 xC alloys vary continuously with the increase of Zr composition. The alloy possesses both the highest shear modulus (215 GPa) and a higher bulk modulus (294 GPa), with a Zr composition of 0.21. Meanwhile, the Zr0.2! Nb0.79C alloy shows metallic conductivity based on the analysis of the density of states. In addition, the thermodynamic stability of the designed alloys is estimated using the calculated enthalpy of mixing. 相似文献
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Elastic stability and electronic structure of low energy tetragonal and monoclinic PdN2 and PtN2 下载免费PDF全文
This paper studies the elastic and electronic structure properties of two new low-energy structures of PdN2 and PtN2 by first-principles calculations.It finds that tetragonal and monoclinic structures are more stable than a pyrite one.The always positive eigenvalues of the elastic constant matrix confirm that both the tetragonal and monoclinic structures are elastically stable.The origin of the low bulk modulus of the two structures is discussed.The results of the calculated density of states show that both of the two low-energy structures are metallic. 相似文献
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利用六面顶高压设备制备了高密度、低脆性、纳米级的ZnO块体材料,用MDI/JADE5 X射线衍射仪(Cu靶)和XL30S-FEG场发射扫描电子显微镜对高压样品的相组成、晶粒尺寸及微观形貌进行了表征.利用E55+FRA106/5傅里叶变换激光拉曼光谱仪通过ZnO块体样品位于50—500cm-1之内的拉曼光谱, 研究了极性半导体纳米材料的拉曼光谱学特征.发现在极性半导体ZnO纳米块体材料中,没有出现明显的尺寸限制效应.
关键词:
ZnO纳米块体
拉曼光谱
尺寸限制效应 相似文献
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The compression behaviour of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using in-situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. The equation of state is determined by fitting the experimental data according to the Birch-Murnaghan equation. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa. Within the pressure range from zero to the experimental one, the pressure-induced structural relaxation is reversible. 相似文献
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采用基于密度泛函理论的第一性原理方法系统地研究了Au12M(M=Na,Mg,Al,Si,P,S,Cl)团簇的结构、稳定性和电子性质.对团簇的平均结合能、镶嵌能、垂直离化势、最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO)的能级差、电荷布居分析、自然键轨道(NBO)进行了计算和讨论.对于Au12M(M=Na,Mg,Al)团簇,它们形成了内含M原子的最稳定的笼状结构.然而对于Au12M(M=Si,P,S,Cl)团簇,它们却形成了以M元素为顶点的稳定锥形结构.在这些团簇中发现Au12S团簇相对是最稳定的,这是由于Au12S团簇形成了稳定的满壳层的电子结构.自然电荷布居分析表明:对于所有的Au12M(M=Na,Mg,Al,Si,P,S,Cl)团簇电荷总是从Au原子转向M原子.自然键轨道和HOMO分析表明Au12M团簇中发生了Au原子的s-d轨道和M原子的p轨道间的杂化现象. 相似文献