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混合物理化学气相沉积法制备Al2O3衬底MgB2薄膜性质的研究 总被引:1,自引:0,他引:1
我们用混合物理化学气相沉积(Hybrid Physical-Chemical Vapor Deposition简称为HPCVD)法在Al2O3(00l)衬底上原位制备了MgB2超导薄膜样品.样品厚度约为1μm左右,最高的超导起始转变温度Tc(onset)=40.3K,转变宽度ΔT为0.3K.ρ50K=2.3μΩcm,剩余电阻比率RRR=R300K/R50K=10.样品的X射线衍射分析表明,MgB2薄膜具有较好的c轴取向,晶粒大小约200nm.由毕恩模型计算求得在5K和零场条件下,样品的临界电流密度Jc=7.6×106A/cm2,不同磁场下测得R~T曲线可以外推得到Hc2(0K)约10T.这些结果表明HPCVD技术在MgB2薄膜原位制备方面有着很大的优势,从而有利于实现MgB2薄膜在电子器件方面的应用. 相似文献
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《低温物理学报》2015,(4)
利用混合物理化学气相沉积法(Hybrid physical-chemical vapor deposition简称为(HPCVD)在(0001)SiC衬底上制备了干净的MgB2超导超薄膜.在背景气体、压强、载气氢气流量以及B2H6的流量一定的情况下,改变沉积时间,制得一系列MgB2超薄膜样品。通过观察样品的表面形貌变化探究了MgB2超薄膜的生长过程.该系列超薄膜的生长遵循Volmer-Weber岛状生长模式且沿c轴外延生长.以20nm超薄膜作为例子,可知其表面连接性良好,超导转变温度Tc(0)≈38.5K,临界电流密度Jc≈0.82×107 A/cm2,表明了利用HPCVD在(0001)SiC衬底上制备的MgB2超薄膜有很好的性能.这预示其在超导电子器件上具有广阔的应用前景. 相似文献
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本文报道了利用混合物理化学气相沉积方法(HPCVD)在SiC衬底上制备出约150 nm厚,结构均匀的MgB2薄膜.由R~T曲线知道样品TC(0)高达40.1K.由M~T曲线知道其TC=40.4K,且曲线转变十分陡峭.X射线衍射分析表明薄膜具有较好的C轴取向,没有氧污染,却存在Mg的杂峰.由M~H曲线,利用毕恩模型计算得到了5 K零场条件下JC(0T,5K)=2.7×106A/cm2,Hc2=19.5 T.这些结果表明过量的Mg对MgB2薄膜的转变温度以及有些性质有较大的影响. 相似文献
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本文报导了利用混合物理化学气相沉积法(Hybrid physical-chemical vapor deposition,HPCVD)在SiC(0001)衬底上制备干净的MgB2超薄膜.在背景气体压强、载气H2流量等条件一定的情况下,改变B2H6流量及沉积时间,制备不同厚度的MgB2超薄膜样品,并研究了超导转变温度Tc、剩余电阻率ρ(42K)、上临界场Hc2等与膜厚的关系.这系列超薄膜生长沿c轴外延,随膜厚度的变小Tc(0)降低,ρ(42K)升高.膜在衬底上的生长遵循Volmer-Weber岛状生长模式.对于10nm厚的膜,Tc(0)~32.4K,ρ(42K)~124.92μΩ·cm,其表面连接性良好,平均粗糙度为2.72nm,上临界磁场Hc2(0K)~12T,零场4K时的临界电流密度Jc~107A/cm2,为迄今为止所观测到的10nm厚MgB2超薄膜的最高Jc值,这也证明了10nm厚的MgB2膜在超导纳米器件上具有很强的应用潜力. 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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Neutron diffraction study of polycrystalline HoRu2Si2, HoRh2Si2, TbRh2Si2, and TbIr2Si2 was performed in the temperature range between 4.2 and 300 K. For HoRu2Si2 the magnetic spin alignment of a linear transverse wave mode below the Néel temperature 19 K is observed. This static moment wave is propagating along the b-axis with k=(0, 0.2, 0) and is polarized in the c-axis. The root-mean-square and maximum saturation moments per Ho atom are 9.26 and 13.09μB, respectively. HoRh2Si2, TbRh2Si2 an TbIr2Si2 are simple collinear antiferromagnets of +-+- type with Néel temperatures of (27±1), (98±2) and (72±3) K, respectively. For TbRh2Si2 and TbIr2Si2 magnetic moments are localized on RE ions only and are aligned along the tetragonal axis, while for HoRh2Si2 they form an angle ø = (28±3)°. 相似文献
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The CO2 TEA laser irradiation of CBr2F2 in the presence of Cl2 yielded 13C-enriched CBrClF2 and 13C-enriched CCl2F2 under selected experimental conditions. As the photolysis proceeded, the 13C concentration of CBrClF2 decreased gradually and that of CCl2F2 increased up to 90% or higher. These results can be explained by the mechanism involving the secondary 13C-selective IRMPD of the primary product CBrClF2. On the other hand, the carbon-containing product for a CCl2F2/Br2 system was only CBrClF2; the further IRMPD of which probably regenerated CBrClF2 in the presence of Br2. The decomposition probabilities of 12C- and 13C-containing molecules in both systems were measured as functions of laser line, laser fluence, and reactant pressures. 相似文献
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P. Dalmas de Réotier B. Licciardi A. Yaouanc B. Chevalier P. Chaudouët R. Madar J. P. Sanchez 《Hyperfine Interactions》1990,59(1-4):317-320
Muon spin relaxation experiments have been carried out in the paramagnetic and magnetically ordered states of URh2Si2 and CeRh2Si2. As the magnetic structure of these compounds is well known, these measurements can help to characterise their magnetic properties
probed by μSR and to understand the μSR results of the heavy fermion compounds of the same crystallographic family. Our measurements
show that the muons occupy two different crystallographic sites. The spectra of URh2Si2 and CeRh2Si2 in the magnetically ordered states are very different, probably reflecting their different magnetic structures. The spectra
obtained on CeRh2Si2 are similar to the published spectra of the heavy fermion compound CeCu2.1 Si2. Muon spin rotation measurements on LaNi2As2 indicate that the muon is diffusing at 150 K. 相似文献
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采用固相反应法合成了组成为Ca1-xEuxSi2O2N2的Eu2+掺杂CaSi2O2N2荧光粉.通过荧光光谱对样品的发光性能进行了研究,发现Eu2+掺杂CaSi2O2N2荧光粉发射光谱为宽波段的单峰结构,主要包含绿光和黄光区,发射峰在556~568 nm.从发射光谱的宽带特征来看,CaSi2O2N2:Eu2+的发射主要对应着Eu2+离子4f65d→4f7跃迁.从激发光谱所覆盖的范围还可以看到,样品可以有效的被UV蓝-光激发,这意味着该类荧光粉在白光LED方面有可能得到广泛的应用.另外,样品的发光性能与激发离子的浓度有着很大关系.激发离子浓度增大时,发射光谱会发生明显红移.利用这一性质,可以通过改变Eu2+浓度来调节荧光粉的发光范围,从而满足不同场合的需要.同时,Eu2+浓度提高,样品发射光谱的强度也会随之增强,在x=0.06时发射强度达到最大值,之后继续增加Eu2+浓度,强度不仅没有增加反而降低,即出现浓度猝灭现象. 相似文献
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J. Petzelt I. Mayerová Č. Bárta L. D. Kislovskii 《Czechoslovak Journal of Physics》1973,23(8):845-854
Far infrared (30–430 cm?1) reflectivity measurements of Hg2Cl2 and Hg2Br2 single crystals have been performed in polarized light. The spectra, which are in agreement with group-theoretical predictions, were analyzed by the oscillator fitting procedure and Kramers-Kronig method. The results are compared with the existing data from other measurements and the large anisotropy of polar modes is briefly discussed. The polarization vectors of all long-wavelength symmetry modes were determined group-theoretically. 相似文献
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Guo Guanghua R. Z. Levitin V. V. Snegirev D. V. Filippov 《Physics of the Solid State》2001,43(3):496-500
Longitudinal and transverse magnetostrictions of polycrystalline samples of intermetallic compounds RMn2Ge2 (R=Sm or Gd) are measured in pulsed magnetic fields up to 250 kOe. It is found that linear magnetostrictive strains of about 10?3 arise in a temperature range in which the magnetic field causes a change in the magnetic state of a manganese magnetic subsystem. The results obtained are described within the model of a two-sublattice ferrimagnet with a negative exchange interaction in the manganese subsystem in terms of a strong dependence of this interaction on interatomic distances. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2018,(12)
正Since the discovery of superconductivity in LaFeAsO_(1-x)F_x,the high-T_c iron-based superconductors have been extensively studied from both experimental and theoretical viewpoints [1-8]. However, the mechanism of the unconventional superconductivity is still to be resolved. To 相似文献
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X-ray photoemission spectra, resistivity and susceptibility of CeNi2Sb2 and CeCu2Sb2 were measured and are discussed. The results indicate that these alloys are Kondo systems. For comparison of the valence band properties, the spectra of the isostructural alloys of RT2X2-type with R = La, Gd, T = Cu, Ni and X = Sn, Sb were investigated, too. 相似文献