Investigation of the Parameters of Superconducting and Insulating Elements of Structures Obtained on YBCO Films by Master Mask with Decreasing Their Size

Physics of the Solid State - This study is devoted to the investigation of the electrophysical parameters of superconducting and insulating elements of planar structures manufactured by master mask...     

Superconducting properties of polycrystalline YBCO prepared by a pyrolytic process

Il Nuovo Cimento D - Polycrystalline YBCO was prepared by a pyrolytic process starting from citrate and tartrate precursors. The effect of the precursor on the superconducting properties was...     

YBCO带材无阻连接热退火效应研究

超导焊接是第二代高温超导(2G-HTS)带材研究的重要内容,在两根超导带材中间生长超导连接层可实现无阻连接.在超导连接层的生长过程中,原来的两根超导带材需再次经历热处理,目前这方面的研究甚少.本文系统研究了780℃热退火中,时间、气氛对带材性能的影响.分析了样品的显微结构、表面形貌以及临界电流密度(Jc),结果表明.2...     

Problems in the low-temperature synthesis of 92K Superconducting YBCO

Il Nuovo Cimento D - YBCO with high granulometric perfection and low dispersion can be obtained by a low-temperature reaction (≈800°C) of atomic-scale dispersed powders, produced through...     

Nanocrystals of CdSe Formed by the Pressure Cycle Method

CdSe nanocrystals were prepared by the pressure cycle method using the Paris-Edinburgh cell up to 7 GPa. The recovered samples are nanocrystals in the cubic phase (zinc-blende structure) and were characterized using transmission electron microscopy (TEM), electron diffraction and Raman scattering. Transmission electron micrographs shows that these nanocrystals are nearly spherical with diameters ranging from 20 to 50 nm. The Raman scattering measurement confirm the existence of CdSe nanocrystals in the cubic phase (ZB).     

飞秒激光形成的半导体低维结构与发光

采用飞秒激光辐照硅和硅锗样品,用扫描电子显微镜(SEM)观察样品同,发现样品上产生了某低维结构.用飞秒激光作用产生等离子体相干驻波对硅和硅锗表面的融蚀模型来解释低维结构的形成机制,发现硅的表面周期约为400 nm的光栅结构在波长719 nm处有较强的光致荧光(PL)峰.该光致荧光的发光强度较小,其机制可从激光的脉宽和重复率两个方面来分析.当激光辐照的能量明显超过硅的融蚀阈值时,光栅形状消失,另一种锥状结构开始形成.控制加工条件,可以获得用于衍射和微分束的纳米光栅.     

Analysis of Absorbing Periodic Structures Formed by Cylindrical Electromagnetic Black Holes

Technical Physics - A 2D problem of electromagnetic plane wave scattering by 1D-periodic structures with cylindrical elements of electromagnetic black hole type arranged on a semi-infinite...     

电子束蒸发制备YBCO超导薄膜研究

采用电子束沉积制备YBCO超导薄膜,研究了760℃—840℃的不同退火温度下高温热处理对YBCO薄膜双轴织构、表面形貌及超导性能的影响。超导临界电流密度测试、X射线衍射(XRD)和扫描电镜(SEM)的结果表明,退火温度在在800℃时,YBCO薄膜具有良好的织构和平整致密的表面形貌,在77K自场下的临界电流密度J可达4.2×106/cm2。     

TFA-MOD法制备YBCO薄膜生长速率研究

采用原位电阻法对TFA-MOD法高温热处理阶段YBCO薄膜生长速率进行了研究。实验结果和分析表明原位电阻测量法是一种估算YBCO层生长速率的有效方法,不同条件下的测量结果表明薄膜生长速率随管式炉内的温度、水分压、气体流量的上升而明显增加,但随薄膜面积的增加而减小。实验结果为进一步探索和优化热处理过程提供了重要的基础。     

化学修饰的溶胶-凝胶(Sol-Gel)法制备YBCO薄膜图形的研究

化学修饰的Sol-Gel法因无需光刻胶、腐蚀液被用于YBCO薄膜图形的制备。以丙烯酸(AA)、苯酰丙酮(BzAcH)作为化学修饰剂制备YBCO薄膜图形,研究了化学修饰剂、光源、前烘温度和时间、溶洗剂对薄膜图形的最小线宽和质量的影响。     

矩量法研究平面波导点缺陷引起的散射损耗

对平面波导工艺过程里出现的点缺陷,如气泡、灰尘颗粒等对平面波导内光场造成的散射提供了一种简单而又实用的计算方法。计算基于格林函数方法,并利用矩量法求解积分方程,采用分块矩阵优化算法,使得算法的计算时间直接与点缺陷大小相关,提高了效率。证明了一定大小的点缺陷在特定的波长处会产生很大的散射损耗,证明点缺陷的散射损耗依赖于缺陷大小和光学性质而与其在波导中的位置无直接关系。以二氧化硅平面波导为例,分析了对中心波长1．55μm的入射光场,分别存在气泡和灰尘颗粒两种点缺陷时,散射损耗随点缺陷大小的关系特性,指出工艺过程特别应该避免某些孔径的点缺陷。     

Potential Images of Ferroelectric Domain Structures Formed by Electron Beam in Lithium Niobate Crystals

Ferroelectric domain structures formed by an electron beam in lithium niobate crystals are studied using low-voltage SEM microscopy. The structures are formed in crystals with different conductivity, including samples with high-resistance congruent composition (CLN) and samples with conductivity increased by reductive annealing (RLN). The potential nature of the contrast of the domain structures observed in the secondary electron mode depending on the conductivity of the samples and the direction of spontaneous polarization of the domains is analyzed. It is assumed that the domain contrast in CLN crystals is associated with long-lived charges localized near domain walls and in the irradiated areas. The recorded domain structures in the CLN crystals are visualized on polar and nonpolar cuts. In the RLN crystals with improved conductivity compared to CLN, the potential contrast of the periodic domain structures is found only on the polar cuts, where vector P_s of the domains is perpendicular to the irradiated surface. This contrast is likely because the field of the spontaneous electric polarization charges influences the secondary electrons.     

快速前处理TFA-MOD制备YBCO超导薄膜的研究

三氟乙酸盐金属有机物沉积(TFA-MOD)方法是制备YBa2Cu3O7(YBCO)超导薄膜最有应用前景的方法之一。采用快速前处理TFA-MOD的方法在LaAlO3单晶基片上生长YBCO薄膜并与常规的TFA-MOD方法进行对比研究。XRD分析表明用快速前处理TFA-MOD方法制备的YBCO薄膜的c轴取向一致性,没有常规的TFA-MOD制备的YBCO薄膜好。SEM的分析表明快速前处理TFA-MOD制备的YBCO超导薄膜表面有孔洞和YBCO(103)取向生长的晶粒,常规方法制备的YBCO薄膜表面比较光滑,孔洞较少。虽然较常规方法制备的薄膜的临界电流密度(JC)低,但超导电性能分析表明,快速前处理方法制备的YBCO薄膜JC达到1mA/cm2以上,且前处理时间大幅缩短,对于提高YBCO薄膜制备的效率非常有效。     

A Study of Ultrathin Superconducting Films of Niobium Nitride Obtained by Atomic Layer Deposition

Technical Physics - A method is presented for the deposition of ultrathin superconducting NbNx films by atomic layer deposition enhanced by plasma from an organometallic precursor and an H2/Ar gas...     

Shear Elastic Properties of HTSC Ceramics in the Region of Superconducting Transition

Technical Physics - The shear elastic properties of YBa2Cu3O7 –x high-temperature superconducting (HTSC) ceramics are studied near the superconducting transition at a temperature of 91.3 K...