Suo Hongli

Study of Ta-doped CeO2 Buffer Layer for Coated Conductors

Abstract Ta-doped CeO 2 buffer layers were grown on the home-made textured Ni-5W substrates for YBCO coated conductors by a simple metal-organic deposition technique. The characterization of the samples was discussed. XPS results indicate that Ta 5+ is reduced into Ta 4+ prior to Ce 4+ , which is helpful to suppress the formation of holes and cracks in CeO 2 films from reducing Ce 4+ into Ce 3+ . Additionally, no new phase is found by doping Ta into CeO 2 , which indicates that Ta 4+ replaces the Ce 4+ position in CeO 2 lattice to form Ce 0.75 Ta 0.25 O 2 . The Ce 0.75 Ta 0.25 O 2 has a good out-of-plane and in-plane texture FWHM values for ω scan and ϕ scan are 4.38° and 6.67°, respectively. AES measurements show that no Ni element is detected on the surface of Ce 0.75 Ta 0.25 O 2 film, and a one-layer film has a thickness of about 70 nm. It is promising that the presently developed Ce 0.75 Ta 0.25 O 2 film can be used as a single multi-functional buffer layer for coated conductor.

Nb 5+ 掺杂对低氟MOD法制备的YBCO薄膜性能的影响

本研究通过低氟MOD法成功地制备了Nb 5+ 掺杂的YBa 2 Cu 3 O 7- x (YBCO)薄膜, Nb 5+ 在薄膜中生成了大小在20~30 nm之间的纳米颗粒; 纳米颗粒的生成不会对 YBCO薄膜的织构和临界温度( T c )构成明显的影响。由于纳米颗粒的引入, 掺杂后薄膜的临界电流密度( J c )在整个磁场范围内都要高于纯的YBCO, 自场下的Jc更是达到了3.4 MA/cm 2 。掺杂薄膜的钉扎力( F p )也远远大于纯YBCO, 最大钉扎力达到了3.25 GN/m 3 , 有效地提高了YBCO在外加磁下的超导性能。本研究通过低氟MOD法成功地制备了Nb 5+ 掺杂的YBa 2 Cu 3 O 7- x (YBCO)薄膜, Nb 5+ 在薄膜中生成了大小在20~30 nm之间的纳米颗粒; 纳米颗粒的生成不会对 YBCO薄膜的织构和临界温度( T c )构成明显的影响。由于纳米颗粒的引入, 掺杂后薄膜的临界电流密度( J c )在整个磁场范围内都要高于纯的YBCO, 自场下的Jc更是达到了3.4 MA/cm 2 。掺杂薄膜的钉扎力( F p )也远远大于纯YBCO, 最大钉扎力达到了3.25 GN/m 3 , 有效地提高了YBCO在外加磁下的超导性能。

Effect of F Doping on Fabrication and Superconductivity of SmO1-xFδFeAs Compound

Abstract We report the effect of fluorine doping on the fabrication and superconductivity of the iron-based arsenic oxide SmO1-xFδFeAs (δ≥x) compound. The fluorine over-doping can greatly reduce the heat treatment temperature and the heat treatment time, meanwhile the superconductivity of the SmO1-xFδFeAs samples does not reduce. The critical transition temperature (Tc) is as high as 56.5 K for the SmO0.7F0.3FeAs sample prepared by the two-step solid state reaction method at 1120 °C for 40 h, the Jc of the sample is 2.4×105 A/cm2 (10 K, 0 T). Tc of the fluorine over-doped SmO0.7F0.35FeAs and SmO0.7F0.4FeAs samples prepared by the two-step solid state reaction method at 1100 °C for 20 h are 56 and 55 K, respectively. Jc of the both samples are 1.9×105 and 1.7×105 A/cm2 (10 K, 0 T), respectively.