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941.
利用 X射线衍射和 Rietveld 结构精修的方法,研究了 Pr_(1 x)Ba_(2-x)Cu_3O_(7±δ)体系固相线下的相关系和晶体结构。研究表明:Pr123 单相可以在 950℃、空气气氛、富 Pr的条件下获得。Pr_(1 x)Ba_(2-x)Cu_3O_(7±δ)固溶区的范围为0.08≤x≤0.80。0.08≤x≤0.30 时 Pr_(1 x)Ba_(2-x)Cu_3O_(7±δ)的结构为正交晶系;0.30≤x≤0.80时为四方晶系。获得 Pr123的条件是在Pr123结构中Ba的位置必须被部分Pr代替、其最小量为 x=0.08;而Ba离子不能占据Pr的位置。 相似文献
942.
Effects of Nano-Particles on the Tribological and Thermal Properties of Piston Ring-Cylinder Liner 总被引:2,自引:0,他引:2
The effects of ultra-dispersed diamond (UDD) on the friction force, wear, and temperature of tribological pairs have been investigated. The experimental tests were carried out on a modified piston ringcylinder liner bench tester with different particle mass fractions of 0, 0.02%, and 0.10%. The results show that compared with a pure fluid, the mixture of the fluid and UDD not only reduces the friction and wear, but also reduces the bulk temperature of the specimen. The mechanism by which the UDD lubricant improves the tribological properties has some relationship with surface topography, because it can increase the bearing capability of surfaces. 相似文献
943.
Liquid structure of molten pure Cu, Cu-12Al, Cu-12Al-4Ni (mass fraction, %) alloys has been investigated using the X-ray diffraction method. It is found that the main peak of the structure factor of pure Cu is symmetrical. In the front of main peak, the curve takes on a shape of parabola, whereas a distinct pre-peak has been found around a scattering vector magnitude of 18.5 nm?1 in the structure factor of the liquid Cu-12Al alloy. This pre-peak increases its intensity with the addition of Ni in the liquid Cu-12Al-4Ni alloy. The appearance of a pre-peak is a mark of the mediate-range order. Based on Daken-Gurry theory and according to mutual interaction between unlike atoms, the analysis of correlation between different composition and liquid structure was done: the strong interaction exists between Cu and Ni, so Cu-Al can form strong chemical bond which causes compound-forming behavior. Therefore, the medium-range size clusters can form in melt. The presence of the pre-peak corresponds to these clusters. The addition of Ni can strengthen the interaction between unlike atoms and increase the sizes of clusters, thus result in the height of pre-peak increasing. 相似文献
944.
Ta/NiOx/Ni81Fe19/Ta and Co/AiOx/Co multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field (Hex) and the coercivity (Hc)of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that when the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1and the valence of nickel is +2. At this point, NiOx is antiferromagnetic NiO and the corresponding Hex is the largest.As the ratio of Ar/O2 deviates from 7, the Hex will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiOx /NiFe, while the Hc will increase due to the metallic Ni. Al layers in Co/AIOx/Co multilayers were also studied by angle-resolved XPS. Our finding is that the bottom Co could be completely covered by depositing an Al layer about 1.8 nm. The thickness of AIOx was 1.2 nm. 相似文献
945.
Ta is often used as a buffer layer in magnetic multilayers. In this study, Ta/Ni81Fe19/Ta multilayers were deposited by magnetron sputtering on sing-crystal Si with a 300-nm-thick SiO2 film. The composition and chemical states at the interface region of SiO2/Ta were studied using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that there is an "intermixing layer" at the SiO2/Ta interface due to a thermodynamically favorable reaction: 15 SiO2 + 37 Ta = 6 Ta2O5 + 5 Ta5Si3. Therefore, the Ta buffer layer thickness used to induce NiFe (111) texture increases. 相似文献
946.
MA Zhongyuan BAO Yun CHEN Kunji SHI Jianjun LI Wei XU Jun Liu Jiayu FENG DUAN 《自然科学进展(英文版)》2002,12(4)
Ultrathin SiO 2 layers on Si (100) wafers were prepared by plasma oxidation at a low temperature (250℃). The analyses of X-ray photoelectron spectroscopy (XPS) and TEM reveal that the chemical composition of the oxide layer is stoichiometric SiO 2 and the SiO 2/Si interface is abrupt. The thickness of the ultrathin oxide layer obtained from XPS, capacitance-voltage (C-V) and ellipsometry measurements indicate a nonlinear time dependence. The high frequency C-V characterization of MOS structure shows that the fixed charge density in SiO 2 film is about 10 11 cm -2 . It is also shown that the strength of breakdown electrical field of SiO 2 film with 6 nm thickness is of the order of 10 6 Vcm -1 . These properties of the ultrathin SiO 2 layer ensure its application in silicon quantum devices. 相似文献
947.
Ta/NiO
x
/Ni81Fe19/Ta and Co/AlO
x
/Co multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field (H
ex) and the coercivity (H
c) of NiO
x
/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied. The composition and chemical states at the interface region of NiO
x
/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results
show that when the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is +2. At this point, NiO
x
is antiferromagnetic NiO and the corresponding Hex is the largest. As the ratio of Ar/O2 deviates from 7, the H
ex will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiO
x
/NiFe, while the H
c will increase due to the metallic Ni. Al layers in Co/AlO
x
/Co multilayers were also studied by angle-resolved XPS. Our finding is that the bottom Co could be completely covered by
depositing an Al layer about 1.8 nm. The thickness of AlO
x
was 1.2 nm. 相似文献
948.
测定了TAP晶体中铊离子的价态,发现TAP晶体中除了一价的铊离子Tl+外,还有少量三价铊离子Tl3+的存在.实验还测定TAP晶体中存在的金属离子杂质,总量为0207mg/g.联系TAP结构的特点讨论了TAP晶体存在Tl3+和金属离子杂质是产生TAP晶体结构缺陷的重要原因,并分析了TAP晶体位错线基本走向平行于c轴的原因 相似文献
949.
在各物相的质量吸收系数已知时,对一种新的无标定量相分析法(QPAWS)作了探讨.在QPAWS中应用了最小二乘法,文中提出了新的推导方法并得到新的表达式,应用含有三种物相的混合物所作的验证实验得到较满意的结果 相似文献
950.
刘小君 《合肥工业大学学报(自然科学版)》1997,(3)
将粗糙表面视为随机过程,通过表面频谱分析,给出了包含关于表面轮廓高度、梯度、曲率方面信息的表征参数,该方法是对以往仅考虑表面高度的表征方法的改进。此外,还研究了轮廓的统计特性,这些统计特性与轮廓的功率谱密度有关。 相似文献