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首页> 外文期刊>Journal of materials science >Enhanced superconducting properties of Ti doped (Cu_(0.5)Tl_(0.5)) Ba_2(Ca_(2-x)Ti_x)Cu_3O_(10-δ) samples
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Enhanced superconducting properties of Ti doped (Cu_(0.5)Tl_(0.5)) Ba_2(Ca_(2-x)Ti_x)Cu_3O_(10-δ) samples

机译：Ti掺杂（Cu_（0.5）Tl_（0.5））Ba_2（Ca_（2-x）Ti_x）Cu_3O_（10-δ）样品的增强超导性能

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摘要

Ti-doped (Cu~(0.5)Tl~(0.5))Ba~(2)(Ca~(2−x)Ti~(x))Cu~(3)O~(10−δ)(x = 0, 0.25, 0.50, 0.75, 1.0) superconductors have been synthesized by solid state reaction method. The prepared samples are characterized by XRD, electrical resistivity, AC susceptibility and FTIR techniques. XRD analysis showed that the lattice parameters are marginally altered but there is no substantial change with the doping of Ti. All the samples are found with orthorhombic crystal structure following PMMM space group. T~(c)(R = 0) is enhanced with the doping of Ti except for x = 1.0 sample. The magnitude of diamagnetism in the AC-susceptibility measurements is enhanced up to x = 0.5 and decreased beyond. The FTIR measurements show that the apical oxygen phonon modes are softened. The planar oxygen phonon modes are softened but their intensity is raised with the enhanced Ti contents. This softening of the planar oxygen phonon modes may be arising due to the heavier Ti ions (47.9 amu) at the lighter Ca (40.07 amu) sites. Variation in the lattice parameters in the XRD data and shifting of various oxygen phonon modes in the FTIR data show that Ti is incorporated at Ca sites in the unit cell. Increase in the superconducting properties up to certain doping level (x = 0.75) may be arising due to the improved interplane coupling caused by the smaller sized Ti at Ca sites. While the decrease in T~(c)and magnitude of diamagnetism beyond x = 0.75 and x = 0.5 respectively, is attributed to the suppressed density of a particular type of phonons required for optimum superconductivity. This suppression in the density of the desired phonons is brought about by the substitution of heavier Ti ions at the lighter Ca sites. This study signifies the role of electron–phonon interaction in mechanism of high T~(c)superconductivity.
机译：掺钛（Cu〜（0.5）Tl〜（0.5））Ba〜（2）（Ca〜（2-x）Ti〜（x））Cu〜（3）O〜（10−δ）（x = 0固态反应法合成了0.25、0.50、0.75、1.0）超导体。制备的样品通过XRD，电阻率，交流磁化率和FTIR技术进行表征。 XRD分析表明，晶格参数略有变化，但Ti的掺杂基本没有变化。发现所有样品都遵循PMMM空间群具有正交晶体结构。除x = 1.0样品外，掺杂Ti可以提高T〜（c）（R = 0）。交流磁化率测量中的抗磁强度提高到x == 0.5，然后降低到。 FTIR测量表明，顶端的氧声子模式被软化了。平面氧声子模式被软化，但是随着Ti含量的增加，它们的强度增加。平面氧声子模式的这种软化可能是由于较轻的Ca（40.07 amu）处的Ti离子（47.9 amu）重而引起的。 XRD数据中晶格参数的变化以及FTIR数据中各种氧声子模式的移动表明，Ti掺入了晶胞的Ca位置。由于在Ca位置处较小的Ti导致平面间耦合的改善，可能会导致超导性能提高到一定的掺杂水平（x = 0.75）。分别使T〜（c）和抗磁强度的下降分别超过x = 0.75和x = 0.5，这是由于最佳超导性所需的特定类型声子的密度被抑制。所需声子密度的这种抑制是通过在较轻的Ca位置取代较重的Ti离子而实现的。该研究表明电子-声子相互作用在高T〜（c）超导机理中的作用。

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