共查询到18条相似文献,搜索用时 62 毫秒
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报道了利用蓝宝石介质谐振器技术测量MgB2超导薄膜的微波表面电阻Rs sub>、0K时的穿透深度λ(0)和超导能隙Δ(0).λ(0)和Δ(0)的值是通过先测量样品穿透深度λ(T)的变化量Δλ(T),然后由BCS理论模型拟合Δλ(T)的实验数据得到的.测试样 品是利用化学气相沉积技术在MgO(111)基片上制备的c轴织构的MgB2超导薄膜, 薄膜的超导转变温度和转变宽度分别为38K和01K.微波测试结果表明在10K,18GHz下M gB2薄膜的Rs约为100μΩ,可以和高质量的YBCO薄膜的Rs值相比拟;BCS理论拟合得到的MgB2超导薄膜的λ(0)=102nm,Δ(0)=113k Tc. 相似文献
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在新型超导体MgB2 发现 (2 0 0 1年 )的初期 ,大部分的研究工作是基于多晶样品 .但MgB2 是一种结构上高度各向异性的化合物 (具有六方对称的层状结构 ) ,为了认识它的本征特性 ,有必要制备出高质量的单晶样品并加以研究 .对于MgB2 ,在熔点处的固相和液相 ,其化学组成是不同的 .因此 ,不可能从化学计算比的熔液中生长MgB2 单晶 .较大尺寸的MgB2 单晶可用两种办法生长 :(1)基于压力砧技术的高压方法 ;(2 )在密封的金属容器中对Mg和B的混合物进行加热 .最近 ,来自瑞士ETH -苏黎世固态物理实验室的KarpinskiJ等使用上述第一种方法 ,成功… 相似文献
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用微波传输法测量高Tc超导薄膜的表面电阻 总被引:1,自引:0,他引:1
当有微波入射至厚度为d的高温超导薄膜时,测量透射波(或反射波)的幅度及相位,便可定出材料的复数电导率σ=σ1-jσ2,进而计算表面电阻Ra和穿透深度λL,本对于薄膜样品置于矩形波导中的实际情况,给出了一般情况下,波导中透射系数和反射系数的正确解表达式。在诸如σ1<<σ2,d<<λL等近似条件下,这些正确解表达式可以奶化为目前献中的常用公式。本指出了这些常用公式的缺陷,并用数值方法对正确解、近 相似文献
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在多晶Al2O3衬底上化学气相沉积MgB2超导薄膜 总被引:1,自引:0,他引:1
报道了制备MgB2超导薄膜的一种新方法和测量结果,MgB2超导薄膜的制备采用的是两步异位退火方法,但在现有报道的方法不同的是,制备硼(B)先驱膜采用的是化学气相沉积方法,在460℃温度下热分解乙硼烷(B2H6)沉积的,然后镁(Mg)蒸气中分别在730℃、780℃和830℃条件下退火,生成MgB2超导薄膜,扫描电子显微镜观察表明制备薄膜是多晶的,MgB2晶料小于2μm。X衍射分析发现所生长的薄膜是随机取向的。800℃条件下退火生成的MgB2超导薄膜起始转变温度和零电阻温度分别达到35K和24K,结果表明,采用B2H6热分解化学气相沉积B先驱膜的方法在优化的沉积条件和退火条件下可制备高质量的MgB2超导薄膜,我们这种化学气相沉积MgB2超导薄膜方法在大面积的MgB2超导薄膜制备方面较脉冲激光沉积方法具有优势,并且与现有的半导体工艺技术相兼容,有利用实现MgB2超导薄膜在电子器件方面的应用。 相似文献
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本文报导用磁控离子溅射和后热处理方法在LaAlO3(001)衬底上制作2英寸双面Tl2Ba2CaCu2O8(Tl-2212) 超导薄膜的方法和薄膜的特性.XRD测试表明薄膜具有纯的Tl-2212相和c轴垂直于膜面的织构.衬底两侧薄膜的结晶形貌和超导电性均匀,超导转变温度Tc一般为105 K左右,液氮温度下临界电流密度Jc>2×106A/cm2,10GHz频率下表面电阻最小达到350μΩ,可满足超导微波滤波器实用的需要. 相似文献
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我们用混合物理化学气相沉积法(hybrid physical-chernical vapor deposition简称为HPCVD)以氩气为背景气体,在不锈钢衬底上于不同条件下制备了一批MgB2超导薄膜样品.用扫描电子显微镜获取了相关的SEM图像,并对膜的成分进行了能谱分析(EDX)的.当把不锈钢衬底MgB2超导薄膜弯曲不同角度之后,膜面上均出现了裂纹.裂纹的数量和宽度随弯曲的角度的增大而增加,但是膜始终紧紧地覆着在衬底上不脱落.因此我们可以说覆着在不锈钢衬底上的MgB2超导薄膜具有了很好的韧性.在膜中我们也发现有大量的数十纳米大小的晶粒.这个尺寸的纳米粒子的作用可以用来平衡MgB2膜内结构和表面晶粒的活性之间的相互作用.MgB2纳米粒子的存在是MgB2超导膜表现出韧性的关键角色. 相似文献
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Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small pore structure and size of porous SiO2 thin film produced by sputtered Al-Si thin film and etched Al-Si thin film. The film is prepared by an Al/Si 75:25 at.-% (A175Si25) target with the radiofrequency (RF) power of 66 W at room temperature. A 5 wt.-% phosphoric acid solution is used to etch the Al cylinders. All the A1 cylinders dissolved in the solution after 15 h at room temperature, and the sample is subsequently rinsed in pure water. In this way, the porous SiO2 on the Si substrate is produced. From our results, the values of all lifetime components in the spectra of Al-Si thin film are less than 1 ns, but the value of one of the lifetime components in the spectra of porous SiO2 thin film is τ = 7.80 ns. With these values of lifetime, RTE (Rectangular Pore Extension) model has been used to analyze the pore size. 相似文献
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本介绍了基于混合物理化学气相沉积法(HPCVD),以B2H6为硼源,在(000l)取向的Al2O3单晶衬底上,制备了MgB2超导体厚膜样品.该样品平均厚度约为40μm.其Tc(onset)=39K,Tc(0)=37.2K.X光衍射图显示该膜沿(101)方向生长,具有少量Mg和MgO杂相.SEM图像、X射线能量损失谱以及背散射电子衍射图证实了这两种杂相的存在,并显示该样品成分富镁.样品表面的镁与空气接触形成MgO膜,在一定程度上阻止了MgB2样品进一步被氧化.对于MgB2厚膜成膜过程及反应机理,我们提出了一种新的推断. 相似文献
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ZHANG Zhe QIN Xiu-Bo WANG Dan-Ni YU Run-Sheng WANG Qiao-Zhan MA Yan-Yun WANG Bao-Yi 《中国物理C(英文版)》2009,33(2)
Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small pore structure and size of porous SiO2 thin film produced by sputtered A1-Si thin film and etched Al-Si thin film. The film is prepared by an Al/Si 75:25 at.-% (A175Si25) target with the radiofrequency (RF) power of 66 W at room temperature. A 5 wt.-% phosphoric acid solution is used to etch the A1 cylinders. All the Al cylinders dissolved in the solution after 15 h at room temperature, and the sample is subsequently rinsed in pure water. In this way, the porous SiO2 on the Si substrate is produced. From our results, the values of all lifetime components in the spectra of Al-Si thin film are less than 1 ns, but the value of one of the lifetime components in the spectra of porous SiO2 thin film is T = 7.80 ns. With these values of lifetime, RTE (Rectangular Pore Extension) model has been used to analyze the pore size. 相似文献
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MK Bhide RM Kadam MD Sastry Ajay Singh Shashwati Sen Manmeet Kaur DK Aswal SK Gupta VC Sahni 《Pramana》2002,58(5-6):799-802
Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for
polycrystalline (grain size ∼ 10 μm) samples suggested the absence of weak-link character. The field dependent direct microwave
absorption has been found to obey a ✓H dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime. 相似文献