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在多晶A l2O3衬底上,以B2H6作为硼源,化学气相沉积先驱B薄膜,采用Mg扩散方法,在不同退火时间条件下制备了MgB2超导薄膜。通过电阻-温度曲线测量、X射线衍射分析和扫描电子显微镜形貌观测方法,研究了退火时间对MgB2薄膜的超导特性、晶体结构、表面形貌的影响。 相似文献
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采用脉冲激光方法,先在YSZ(yttria stablized zirconia)衬底上制备(YBa2Cu3O7-y)/YSZ高温超导薄膜,再用较低的激光能流密度(1.2-1.0Jcm^-2)沉积一层NBCO(NdB2Cu3O7-x)薄膜,形成NBCO/YBCO/YSZ双层超导薄膜。在制备完当时,存放40天和存放400天后分别对薄膜进行了X射线衍射分析和电阻-温度曲线测量。结果表明,NBCO/YBCO/YSZ双层膜的转变温度、结晶度和表面稳定性及光滑度都优于YBCO/YSZ薄膜的。在YBCO/YSZ上使用较低的激光能量可以制备出优质的c轴取向NBCO高温超导薄膜。 相似文献
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We report on a new preparation method for magnesium diboride (MgB2) films by chemical vapour deposition (CVD) from diborane (B2H6).It is two-step ex situ approach,with the precursor boron films grown by CVD from B2H6 at 460℃,followed by a post-annealing process in magnesium (Mg) vapour at 830℃.The prepared MgB2 thin films on Al2O3 polycrystalline substrates have an onset transition temperature of 35K and a zeroresistance temperature of about 24K.Well-crystallized MgB2 grains have clearly been observed in the SEM images and confirmed by x-ray diffraction analysis.The advantages of the proposed method are the feasibility to prepare large-area superconducting films and the compatibility with semiconductor technology. 相似文献
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采用超声波制备出不同含水率的水包油型原油乳状液样品,采用CPMG自旋回波法测量了核磁共振T_2谱。根据实验结果分析,提出了分别基于水包油型原油乳状液T_2谱中T_2N峰的弛豫时间T_(23),T_2谱各峰面积和加入过量MnCl_2·4H_2O后T_2谱总峰面积测量含水率的3种可能方法。验证实验表明:两种基于T_2谱峰面积的测量方法具有较强的可行性和有效性;基于横向弛豫时间的测量方法因受原油乳状液乳化程度的影响较大,可行性较差。该研究成果为测量水包油型原油乳状液的含水率提供了新的方法。 相似文献
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Polarization effect in (e, 2e) reaction process for Ar (3s) in coplanar asymmetric geometry 下载免费PDF全文
The (e, 2e) triple differential cross sections (TDCSs) of Ar (3s) are calculated by using distorted-wave Born approx- imation under coplanar asymmetric geometry. The incident electron energy is 113.5 eV, and the scattering electron angle 01 is -15~. The ejected electron energy is set at 10 eV, 7.5 eV, 5 eV, and 2 eV, respectively. The polarization effects have been discussed and the polarization potential Vpol changing from a second-order to a fourth-order term has been analyzed. Our calculated TDCSs have been compared with reported experimental and theoretical results, and the calculated TDCSs of polarization potential up to the fourth order could give a good fit with experimental results in the binary region, but fail to predict the correct recoil-to-binary ratio in most cases. 相似文献