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arXiv 0711.4174cond-mat.supr-con
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纳米金刚石掺杂MgB2超导体的高场性能

High Field Performance of Nano-Diamond Doped MgB2 Superconductor

Arpita Vajpayee, V. P. S. Awana*, H. Kishan, A. V. Narlikar, G. L. Bhalla, X. L. Wang

摘要:

以Mg、B和n-Diamond为原料,采用固相法合成了MgB 2-nDx(x= 0 ~ 0.1)多晶样品。报道了纳米金刚石掺杂MgB 2-nDx的磁输运和磁化强度的研究结果。超导转变温度(Tc)在x = 0.05之前不受x的显著影响,并且当x > 0.05时,后者略微降低。R(T)对H测量显示对于添加纳米金刚石的样品在相同的施加磁场下具有更高的Tc值,从而导致更高的估计Hc 2值。从磁化测量中发现,原始样品的不可逆场值Hirr在4 K下为7.5特斯拉,并且对于3重量%的nD添加样品在相同温度下增加到13.5特斯拉。在所有温度下的Jc(H)图显示,对于原始MgB 2,在所有施加的场下Jc值最低,并且掺杂有3-wt% nD的样品在所有场下给出最佳Jc值。对于纯样品,Jc值在较低的磁场下为105 A/cm 2的量级,但随着施加磁场,其下降非常快,并且在7特斯拉以上变得可忽略不计。在10 K和6 T场下,3%nD掺杂样品的Jc比纯MgB_2高40倍,在10 T场下,其值仍为103 A/cm ~ 2。另一方面,在20 K下,5%nD样品在较高场下显示出最佳性能。这些结果进行了讨论,在外在钉扎由于分散的n-金刚石在主机MgB 2矩阵随着内在钉扎由于可能的取代C在硼网站和增加带间散射高掺杂样品导致的掺杂系统的非凡性能。

英文摘要:

Polycrystalline MgB2-nDx (x= 0 to 0.1) samples are synthesized by solid-state route with ingredients of Mg, B and n-Diamond. The results from magneto-transport and magnetization of nano-diamond doped MgB2-nDx are reported. Superconducting transition temperature (Tc) is not affected significantly by x up to x = 0.05 and latter decreases slightly for higher x > 0.05. R(T) vs H measurements show higher Tc values under same applied magnetic fields for the nano-diamond added samples, resulting in higher estimated Hc2 values. From the magnetization measurements it was found that irreversibility field value Hirr for the pristine sample is 7.5 Tesla at 4 K and the same is increased to 13.5 Tesla for 3-wt% nD added sample at the same temperature. The Jc(H) plots at all temperatures show that Jc value is lowest at all applied fields for pristine MgB2 and the sample doped with 3-wt% nD gives the best Jc values at all fields. For the pure sample the value of Jc is of the order of 105 A/cm2 at lower fields but it decreases very fast as the magnetic field is applied and becomes negligible above 7 Tesla. The Jc is 40 times higher than pure MgB2 at 10 K at 6 Tesla field in case of 3%nD doped sample and its value is still of the order of 103 A/cm2 at 10 Tesla for the same sample. On the other hand at 20K the 5%nD sample shows the best performance at higher fields. These results are discussed in terms of extrinsic pinning due to dispersed n-Diamond in the host MgB2 matrix along with the intrinsic pinning due to possible substitution of C at Boron site and increased inter-band scattering for highly doped samples resulting in extraordinary performance of the doped system.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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