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The doping effects of transition metals(TMs = Mn, Co, Ni, and Cu) on the superconducting critical parameters are investigated in the films of iron selenide(Li,Fe)OHFe Se. The samples are grown via a matrix-assisted hydrothermal epitaxy method. Among the TMs, the elements of Mn and Co adjacent to Fe are observed to be incorporated into the crystal lattice more easily. It is suggested that the doped TMs mainly occupy the iron sites of the intercalated(Li,Fe)OH layers rather than those of the superconducting Fe Se layers. We find that the critical current density Jc can be enhanced much more strongly by the Mn dopant than the other TMs, while the critical temperature Tc is weakly affected by the TM doping. 相似文献
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Single crystal growth and characterizations of iron arsenide superconductor BaFe2-xNixAs2(0.0≤x≤0.12)
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A series of big single crystals of BaFeFe2-xNixAs2 have been prepared by the FeAs self-flux method,
with nominal nickel doping x = 0--0.12. The dimensions of the
cleaved crystals are over 10~mm along ab plane and ~ 2~mm
in maximum along the c direction. The measurements of x-ray
diffraction, electrical resistance and magnetic property are carried
out on the crystals. For the undoped parent compound
BaFe2As2, both resistance and magnetization data display
an anomaly associated with spin density wave and/or structural phase
transition, with the transition temperatures at ~ 138~K. For
Ni-doped BaFe2-xNixAs2 crystals, the
superconducting critical temperature Tc ranges from 4.3~K
for x=0.06 sample to 20~K for the optimally doped x=0.10
crystal. 相似文献
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Structural and physical properties of undoped and nickel-doped BaFe2-xNixAs2(x = 0,0.04) single crystals
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<正>Single crystals of undoped and nickel-doped BaFe_(2-x)Ni_xAs_2(x=0,0.04) have been grown by FeAs self-flux method.The maximum dimension of the crystal is as large as ~ 1 cm along the ab plane.The crystalline topography of a cleaved crystal surface is examined by scanning electron microscope(SEM).By x-ray powder diffraction(XRD) experiments using pure silicon as an internal standard,precise unit cell parameters(tetragonal at room temperature) are determined:a = 3.9606(4) A(1 A=0.1 nm),c = 13.015(2) A for BaFe_(1.96)Ni_(0.04)As_2 and a = 3.9590(5) A,c = 13.024(1) A for BaFe_2As_2.DC magnetization and transport measurements are performed to check superconducting transition(T_c=15 K for x=0.04) and other subtle anomalies.For BaFe_(0.96)Ni_(0.04)As_2 crystal,the resistance curve at normal state shows two distinct anomalies associated with spin and structure transitions,and its magnetization data above ~ 91 K exhibit a linear temperature dependence due to spin density wave(SDW) instability. 相似文献
100.
Floating-zone growth and property characterizations of high-quality La2-хSrхCuO4 superconductor crystals
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We have grown underdoped(x=0.11,0.12) and optimally doped(x=0.16) La2 x SrxCuO4 single crystals by the traveling-solvent floating-zone technique.In order to prepare good quality cuprate crystals,we have made much effort to optimize the preparation procedures.For example,we haveadopted the sol-gel route to prepare a highly fine and homogeneous La2xSrxCuO4 precursor powder for fabricating a very dense ceramic feed rod used for the floating-zone growth,and we have also used quite a slow growth rate.The high quality of the grown crystals has been verified by double-crystal x-ray rocking curves,with the full-width-at-half-maximum being only 113-150 arcseconds,which are the best data reported so far for La2xSrxCuO4 crystals.The superconducting critical temperatures of the grown crystals are 30,31 and 38.5 K for x=0.11,0.12 and 0.16 samples,respectively,according to magnetic measurements. 相似文献