共查询到14条相似文献,搜索用时 93 毫秒
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用高TcGdBa2Cu3O7-δ薄膜设计并研制了单元及2×2阵列型红外探测器。其中2×2阵列型器件的四个单元探测器的Tc值及R-T特性相差≤3%。使用500K黑体及He-Ne激光作为辐照源。单元及阵列器件最好的结果为噪声等效功率NEP(500,10,1)分别为3.6×10-12和4.1×10-12W/Hz1/2,归一化探测率分别为1.6×1010和1.2×1010cmHz1/2/W;响应率分别为8.2×104和7.2×104V/W。 相似文献
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我们在运用高分辨电子显微术,在T_c为90K通过固态反应制备的YBaCuO超导体中观察到两种类型的层错,其层错面均为(001)面。结构象衬度及晶体周期性分析表明层错均为附加Cu-O链插入包含基本Cu-O面的两层Ba-O层之间所致,两种层错分别具有位移矢量R_1=[0,/2,c/b]和R_2=[a/2,b/2,c/b]。图1为[100]带轴的高分辨象,图中显示了R_1型层错并标出了层错附近原子排列情况,结构模型在[100]方向的投影如图4A区所示。图2是与图1同一样品稍不同区域不同欠焦量的[100]带轴高分辨象。图中B区沿水平方向晶格参数与A区相同,故A、B两区具有相同的晶带轴B区显示的层错与A区不同,具有位移矢量R_2,图中标出了原子排列情况,结构模型如图4B区所示。(001)层错可以穿过整个晶粒,也可中止在其中。在层错中止处,存在伯格斯矢量和层错位移矢量相同的不全位错。图 相似文献
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证实只要测得直流电导率,即可由测量正常相的远红外(波数v<120cm~(-1))透射率直接求得等离子体频率v_(p')发现在实验误差范围内正常相的v_p为常数,由于直流电阻率与温度成线性关系,所以碰撞频率v_c也是温度的线性函数。在波数大于120cm~(-1)的高频范围,透射率减小,而在简单的Drude模式中透射应该是增加的。为了解释这种透射率减小,以及在近红外区观察到的小的透射率值,假定中红外区存在非常强的阻尼振子。最简单的模型是一个中心为v_0=360cm~(-1)的过阻尼振子,对于温度为7K的超导相,只要保持正常态的等离子体频率,并设v_c=0,便可以得到远红外透射率值的数量级。 相似文献
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YBa2Cu3O7/PBa2Cu3O7多层膜微结构的高分辨电镜研究刘维张云孙吉军*赵柏儒*李林*(中国科学院物理研究所,*国家超导实验室,北京100080)通过改变非超导层的厚度,可以有效地调节超导薄膜的各向异性,所以多层膜的制备和研究能够加深对层状... 相似文献
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本研究采用电子通道技术(ECP)对单晶和双晶外延生长的YBa_2Cu_3O_7(YBCO)超导薄膜的结构、取向和表面完好性作检测,并证实对衬底的预处理可改善外延超导薄膜的质量;还对YBCO/CeO_2/MgO/SrTiO3的双外延薄膜作研究。 相似文献
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高度(100)取向的BST薄膜及其高介电调谐率 总被引:2,自引:0,他引:2
用脉冲激光沉积法制备(Ba1-xSrx)TiO3(x=0.35,0.50简称BST35和BST50)介电薄膜。在650℃原位退火10min,获得高度(100)取向柱状生长的晶粒。BST35薄膜的平均晶粒尺寸为50nm,BST50薄膜的晶粒尺寸为150~200nm。在室温和1MHz条件下,BST35的最大εr和调谐率分别达到810和76%,其介电调谐率高于国内外同类文献报道的数据;BST50的εr和调谐率最大分别达到875和63%。薄膜为(100)取向生长,因为薄膜沿平面c轴极化而产生应力,在电场作用下,而获得高介电调谐率。 相似文献
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Detailed investigation of superconducting films of YBa2Cu3O7-δ (YBCO) prepared from solution-based precursors have been performed. Two precursors have been compared in this study: the
presently used trifluoroacetate (TFA) solution and a recently developed colloidal suspension containing nanoparticles of mixed
oxide. Detailed analyses of the evolution of microstructure and chemistry of the films have been performed, and process parameters
have been correlated with final superconducting properties. Both films need two heating steps: a low temperature calcination
and a higher temperature crystallization step. For TFA films, it was seen that the heating rate during calcination needs to
be carefully optimized and is expected to be slow. For the alternate process using a nanoparticle precursor, a significantly
faster calcination rate is possible. In the TFA process, the Ba ion remains as fluoride and the Y remains as oxyfluoride after
calcination. This implies that, during the final crystallization stage to form YBCO, fluorine-containing gases will evolve,
resulting in residual porosity. On the other hand, the film from the nanoparticle process is almost fully oxidized after calcination.
Therefore, no gases evolve at the final firing (crystallization) stage, and the film has much lower porosity. The superconducting
properties of both types of films are adequate, but the nanoparticle films appear to have persistently higher J
c values. Moreover, they show improved flux pinning in higher magnetic fields, probably due to nanoscale precipitates of a
Cu-rich phase. In addition, the nanocolloid films seem to show additionally enhanced flux pinning when doped with minute amounts
of second phase precipitates. It therefore appears that, whereas the TFA process is already quite successful, the newly developed
nanoparticle process has significant scope for additional improvement. It can be scaled-up with ease, and can be easily adapted
to incorporate nanoscale flux pinning defects for in-field performance. 相似文献