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测量了块体金属玻璃Zr46.75Ti8.25Cu7.5Ni10Be27.5在退火前后其电阻值随温度的变化,测量的温度范围为1.5—300K.样品在退火前后都发现有超导现象.零磁场下其超导转变温度Tc分别为1.84和3.76K.在5—300K温度范围内,原始样品具有负的电阻温度系数.如果取Zr, Ti, Cu, Ni及Be分别贡献出1.5, 1.5, 0.5, 0.5及两个传导
关键词:
块体金属玻璃
超导
电阻温度系数 相似文献
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铋(Bi)和铅(Pb)都是重元素,有很强的自旋-轨道耦合作用,由于原子半径接近,可形成丰富的原子取代合金结构.尽管对高温合金相有了较深入的研究,但对其低温物相的结构和超导物性的认识还很不全面.本文采用低温共沉积和低温退火的方法,在Si(111)-(7×7)衬底上制备了一种基于Bi(110)单晶结构中部分Bi原子被Pb取代的铅铋合金低温相超薄膜新结构,利用扫描隧道显微术(STM)对其结构和电子学性质进行了表征.通过结构表征,确定了合金薄膜表面呈现21/2×21/2R45°重构的PbBi3合金相,其母体Bi(110)结构中25%的Bi原子被Pb取代了.通过STM谱学测量,发现合金相PbBi3为超导相.变温实验表明, PbBi3相的超导转变温度为6.13 K.在外加垂直磁场下出现的磁通涡旋结构表明PbBi3薄膜是第Ⅱ类超导体,估算出上临界磁场的下限为0.92 T.测量了由Bi(110)-PbBi3组成的共面型和台阶型正常金属-超导体异质结中... 相似文献
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利用我们设计的一套光学变换传输系统实现了激光束在超导靶上一定范围内扫描消融来淀积高Tc超导薄膜。实验表明用这种激光扫描消融方法可使大尺寸超导薄膜的厚度均匀性得到较大的改善。我们采用激光扫描半径为9mm在12mm×33mm的Y-ZrO2基片上淀积出零电阻温度Tc≥90K,临界电流密度Jc(零磁场,77K)≥1×106A/cm2,薄膜c轴择优取向,厚度均匀性较好的YBa
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本文报道,通过对Y1-xCaxBa2Cu3-xMxO7-δ(M=Fe,Ni)体系样品的晶体结构、氧含量、正常态电阻率与温度的关系,以及超导转变温度等测量,并与YBa2Cu3-xMxO7-δ(M=Fe,Ni)体系进行比较,发现Y1-xCaxBa2Cu3-xFexO7-δ体系的Tc显著地高于相应x值的YBa2Cu3-xFexO7-δ体系,而Y1-xCaxBa2Cu3-xNixO7-δ体系则相反,Tc低于仅Ni替代的体系,表明Ca和Fe同时替代时两者引起的载流子浓度(nH)变化相互补偿,抑制了仅Fe替代时引起的nH和Tc急剧下降;而作Ca和Ni同时替代时主要的不是两者引起载流子浓度变化的相互补偿,Ca和Ni替代效应之间的关联较弱。作者认为,对Y1-xCaxBa2Cu3-xFexO7-δ体系属于CuO2平面外的元素替代,这时载流子浓度是决定Tc的主要因素;而对Y1-xCaxBa2Cu3-xNixO7-δ体系,由于Ni2+离子主要占据Cu(Ⅱ)位,它导致磁拆对效应,Ni2+离子的拆对效应是引起Tc下降的直接原因。
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应用同步辐射x射线小角散射法在原位对块体非晶合金Zr55Cu30Al 10Ni5在等温退火过程中的微结构变化进行研究.实验表明:在等温退火过程中电子 密度涨落反映了晶化之前的结构弛豫过程;在一定的退火温度下、随退火时间的增加,拓扑短程序弛豫与化学短程序弛豫之间存在一个电子密度均匀化的过程;导致这两种弛豫过程转变的退火时间与退火温度有关,温度越高,所需的退火时间越短.
关键词:
原位x射线小角散射
块体非晶合金
等温退火
结构弛豫 相似文献
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N.D. Tho N. Chau S.C. Yu H.B. Lee N.D. The L.A. Tuan 《Journal of magnetism and magnetic materials》2006
Effect of annealing on the soft magnetic properties of Fe73.5Si13.5B9Nb3Au1 amorphous ribbon has been investigated by means of structure examination, magnetoimpedance ratio (MIR) and incremental permeability ratio (PR) spectra measured in the frequency range of 1–10 MHz at a fixed current of 10 mA X-ray diffraction analysis showed that the as-cast sample was amorphous and it became nanocrystalline under a proper heat treatment. When annealing amorphous alloy at 530 °C for 30, 60, 90 min, soft magnetic properties have been improved drastically. Among the samples investigated, the sample annealed at 530 °C for 90 min showed the softest magnetic behavior. The MIR and PR curves revealed the desirable changes in anisotropy field depending upon annealing. 相似文献
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M. Nabiałek J. Zbroszczyk J. Olszewski M. Hasiak W. Ciurzyńska K. Sobczyk J. Świerczek J. Kaleta A. Łukiewska 《Journal of magnetism and magnetic materials》2008
The microstructure and magnetic properties, i.e. the initial magnetic susceptibility, its disaccommodation, core losses and approach to ferromagnetic saturation of the bulk amorphous and partially crystallized Fe61Co10Zr2.5Hf2.5Nb2W2B20 alloy are studied. From X-ray, Mössbauer spectroscopy and electron microscopy studies we have stated that all samples in the as-quenched state are fully amorphous. However, after annealing the samples at 850 K for 30 min the crystalline α-FeCo grains embedded in the amorphous matrix are found. Moreover, from Mössbauer spectra analysis we have stated that the crystalline phase in those samples exhibits the long-range order. The alloy in the as-quenched state shows good thermal stability of the initial magnetic susceptibility. Furthermore, the intensity of the magnetic susceptibility disaccommodation in the rod is lower than in the ribbon. It is due to low quenching rate during the rod preparation which involves the reduction of free volumes. From the analysis of the isochronal disaccommodation curves, assuming the Gaussian distribution of relaxation times, we have found that activation energies of the elementary processes responsible for this phenomenon range from 1.2 to 1.4 eV. After the annealing of the samples the initial susceptibility slightly enhances and disaccommodation drastically decreases. From high-field magnetization studies we have learned that the size of structural defects depends on the quenching rate (the shape of the samples) and changes after annealing. 相似文献
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应用同步辐射小角x射线散射和差示扫描量热分析对块体非晶合金Zr5555Cu 3030Al1010Ni55结构弛豫进行了研究.实验结果表 明:经340℃、不同时间退火后的非晶内 部的电子密度涨落随退火时间的延长先增大而后减小;玻璃转变温度附近焓弛豫峰的表观激 活能则随退火时间的延长先减小而后增大.结果反映了随退火时间的延长,块体非晶合金内 部类液体区不断减少及类固体区不断增加的过程.
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小角x射线散射
块体非晶合金
结构弛豫 相似文献
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利用X射线衍射技术、差示扫描量热分析技术和透射电子显微镜研究了非晶态Cu56Zr44合金的结构及其等温退火条件下的晶化过程.实验结果表明,非晶态Cu56Zr44合金在室温下的短程结构类似于硬球无规密堆积分布.在703K过冷液相区内等温退火时发现,当退火时间为3min时,晶化产物主要为Cu8Zr3相;当退火时间为6min时,Cu8Zr3关键词:
非晶态
56Zr44合金')" href="#">Cu56Zr44合金
结构
等温退火 相似文献
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The amorphous Fe40Ni40P14B6 alloy (Metglas 2826) has been annealed under magnetic field at several temperatures. The kinetics of induced magnetic anisotropy exhibits a broad spectrum (β = 4) of time constants; it obeys exactly an Arrhenius law with an activation energy of 1.74 ± 0.04 eV. These values are identical to those determined by resistivity measurements. This suggests the formation of short range directional order. 相似文献
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X-ray diffraction experiments have been performed on amorphous sputtered Zr76Cu24 alloy in order to investigate the structural relaxation induced by thermal annealing below the crystallization temperature. Contrary to the low-temperature thermal properties which are very sensitive to heat treatments, only weak modifications affect the short-range structural order as defined by the total radial distribution function. 相似文献
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The magnetic after-effect spectrum of hydrogen-charged amorphous Co75Si15B10 and its annealing behaviour was measured in the temperature range between 2.1 and 450 K. A hydrogen related relaxation peak was observed at 190 K with a mean activation energy of 0.42 eV. 相似文献
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在室温下和4.2K下测定了非晶Fe80B20-xMx合金(M=P,C)的穆斯堡尔吸收谱。利用分布参数拟合程序得到了超精细内场Hi和同质异能移IS同类金属成份的变化关系。利用这些结果考察了非晶合金的微观结构,比较了两类结构模型:Bernal-Polk模型和微晶模型。对比非晶合金和它们的相应晶相的行为得知,这类非晶合金中不存在微晶近程序,Bernal-Polk模型对描述TM-M类非晶合金的微观结构优于微晶模型。
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TiO2 nanoparticles have been prepared by simple chemical precipitation method and annealed at different temperatures. The as-prepared TiO2 are amorphous, and they transform into anatase phase on annealing at 450 °C, and rutile phase on annealing at 900 °C. The X-ray diffraction results showed that TiO2 nanoparticles with grain size in the range of 21–24 nm for anatase phase and 69–74 nm for rutile phase have been obtained. FESEM images show the formation of TiO2 nanoparticles with small size in structure. The FTIR and Raman spectra exhibited peaks corresponding to the anatase and rutile structure phases of TiO2. Optical absorption studies reveal that the absorption edge shifts towards longer wavelength (red shift) with increase of annealing temperature. 相似文献