Mechanochemical synthesis of pnictide compounds and superconducting Ba0.6K0.4Fe2As2 bulks with high critical current density

Abstract

BaFe2As2 (Ba-122) and (Ba0.6K0.4)Fe2As2 (K-doped Ba-122) powders were successfully synthesized from the elements using a reaction method, which incorporates a mechanochemical reaction using high-impact ball milling. Mechanically-activated, self-sustaining reactions (MSR) were observed while milling the elements together to form these compounds. After the MSR, the Ba-122 phase had formed, the powder had an average grain size < 1 μm, and the material was effectively mixed. X-ray diffraction confirmed Ba-122 was the primary phase present after milling. Heat treatment of the K-doped MSR powder at high temperature and pressure yielded dense samples with high phase purity but only granular current flow could be visualized by magneto optical imaging. In contrast, a short, low temperature, heat treatment at ambient pressure resulted in global current flow throughout the bulk sample even though the density was lower and impurity phases were more prevalent. An optimized heat treatment involving a two-step, low temperature, heat treatment of the MSR powder produced bulk material with very high critical current density above 0.1 MAcm-2 (4.2 K, 0 T).

13 pages, 6 figures

References in corpus (13)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba(Fe1-xCox)2As2
• Advantageous grain boundaries in iron pnictide superconductors
• Superconductivity in SrFe_(2-x)Co_xAs_2: Internal Doping of the Iron Arsenide Layers
• High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2 wires and bulks
• Evidence for two distinct scales of current flow in polycrystalline Sm and Nd iron oxypnictides
• Atomically-flat, chemically-stable, superconducting epitaxial thin film of iron-based superconductor, cobalt-doped BaFe${}_2$As${}_2$
• Evidence for electromagnetic granularity in the polycrystalline iron-based superconductor LaO0.89F0.11FeAs
• Combined microstructural and magneto optical study of current flow in polycrystalline forms of Nd and Sm Fe-oxypnictides
• Mechanochemical synthesis of pnictide compounds and superconducting Ba0.6K0.4Fe2As2 bulks with high critical current density
• Evidence for electromagnetic granularity in polycrystalline Sm1111 iron-pnictides with enhanced phase purity
• Disorder effects and current percolation in FeAs based superconductors

Cited by in corpus (14)

• Recent advances in iron-based superconductors toward applications
• Hot pressing to enhance the transport Jc of Sr0.6K0.4Fe2As2 superconducting tapes
• Demonstration of an iron-pnictide bulk superconducting magnet capable of trapping over 1 T
• Mechanochemical synthesis of pnictide compounds and superconducting Ba0.6K0.4Fe2As2 bulks with high critical current density
• Development of very high Jc in Ba(Fe1-xCox)2As2 thin films grown on CaF2
• Grain boundary characteristics of Fe-based superconductors
• Strongly enhanced current densities in Sr0.6K0.4Fe2As2 superconducting tapes
• Synthesis of CaKFe${}_4$As${}_4$ bulk samples with high critical current density using a spark plasma sintering technique
• Enhanced upper critical field in Co-doped Ba122 superconductors by lattice defect tuning
• Enhancement of transport critical current density of SmFeAsO1-xFx tapes fabricated by an ex-situ powder-in-tube method with a Sn-presintering process
• Synthesis of Electron- and Hole-Doped Bulk BaFe2As2 Superconductors by Mechanical Alloying
• Synthesis of $c$-axis textured CaKFe${}_4$As${}_4$ superconducting bulk via spark plasma texturing technique
• Effect of spark plasma sintering on the superconducting properties of Sm-based oxypnictide
• Utilization of mechanical alloying method for flux growth of single crystalline BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$