α-FeAs-free SmFeAsO1-xFx by low temperature sintering with slow cooling

Abstract

We obtained amorphous-FeAs-free SmFeAsO1-xFx using a low temperature sintering with slow cooling. SmFeAsO1-xFx is sintered at 980 °C for 40 hours and cooled slowly down to 600 °C. The low temperature sintering suppresses the formation of amorphous FeAs, and the slow cooling introduces much fluorine into SmFeAsO1-xFx. The superconductivity of this sample appears at 57.8 K and the superconducting volume fraction reaches 96 %. To study the change of fluorine concentration during the cooling process, samples are quenched by water at 950 °C, 900 °C, 850 °C, 800 °C, 750 °C and 700 °C. It is found that fluorine is substituted not only at the maximum heating temperature but also during the cooling process. The low temperature sintering with slow cooling is very effective to obtain a homogeneous SmFeAsO1-xFx with high fluorine concentration.

17 pages, 7 figures

References in corpus (11)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• The superconductivity at 18 K in LiFeAs system
• Upper critical fields well above 100 T for the superconductor SmFeAsO${}_{0.85}$F${}_{0.15}$ with T${}_c$ = 46 K
• Evidence for two distinct scales of current flow in polycrystalline Sm and Nd iron oxypnictides
• Fabrication of the iron-based superconducting wire using Fe(Se, Te)
• Superconducting properties of SmO1-xFxFeAs wires with Tc = 52 K prepared by the powder-in-tube method
• Combined microstructural and magneto optical study of current flow in polycrystalline forms of Nd and Sm Fe-oxypnictides
• Transition Temperature and Upper Critical Field in SmFeAsO1-xFx Synthesized at Low Heating Temperatures
• Evidence for electromagnetic granularity in polycrystalline Sm1111 iron-pnictides with enhanced phase purity
• Effect of the indium addition on the superconducting property and the impurity phase in polycrystalline SmFeAsO1-xFx

Cited by in corpus (4)

• Recent advances in iron-based superconductors toward applications
• The effect of exceptionally high fluorine doping on the anisotropy of single crystalline SmFeAsO1-xFx
• Controlling Factors of Tc-Dome Structure in 1111-Type Iron Arsenide Superconductors
• Enhancement of transport critical current density of SmFeAsO1-xFx tapes fabricated by an ex-situ powder-in-tube method with a Sn-presintering process