Synthesis of electron- and hole-doped bulk BaFe2As2 superconductors by mechanical alloying

Abstract

Here, we report the successful synthesis of electron-(Ni) and hole-(K) doped bulk BaFe 2 As 2 compounds by means of mechanical alloying (MA) process. The MA technique allows one to obtain amorphous phase BaFe 2 As 2 with a homogeneous distribution of doping atoms at room temperature without continuous heating. We found the optimum time for high-energy milling is in the range between 1-1.5 hours. Using pre-synthesised FeAs and NiAs precursors, we successfully obtained BaFe 2−x Ni x As 2 and Ba 1−x K x Fe 2 As 2 superconducting bulk samples after shortrange heat treatment. This method can be easily scaled according to industrial needs to provide high-quality bulk superconducting material for wires, trappedfield magnets and other applications.

Phase Formation of Iron-Based Superconductors during Mechanical Alloying

“…Our data indicate that during MA, the peaks related to the initial materials are suppressed, whereas the peaks associated with the 122 phase appear. Similar behavior for the nickel- and potassium-doped samples were observed previously [ 43 , 46 ].…”

“…Taking that into account, an excess of arsenic and alkaline metals should be added. The magnetic susceptibility measurements of the powder after the MA process did not show any superconducting transition in SNFA, BNFA and Ca,Sm-1111, which is similar to BKFA and BFNA samples [ 43 ]. After the MA process, we pressed the obtained BNFA and SNFA powders into pellets and heat-treated them for 1 h at a temperature of 850 °C to restore long-range ordering of Ba/Sr-122 phases.…”

“…However, after the mechanical alloying has been applied, it is often necessary to carry out additional heat treatment of the mixed homogeneous material to provide long-range ordered crystal structure formation. Nevertheless, the heat treatment time after MA is much shorter rather than in the classical solid-state synthesis techniques [ 41 , 43 ]. Therefore, given that MA significantly reduces the subsequent heat treatment time and energy consumption, it seems appropriate to use this method for synthesizing bulk material in large amounts.…”

Enhanced critical current density in K-doped Ba122 polycrystalline bulk superconductors via fast densification

“…In this study, K-doped Ba122 polycrystalline bulks were synthesized via spark plasma sintering (SPS), a pressure-assisted sintering method expected to achieve fast densification, using a mechanically alloyed precursor powder prepared via high-energy ball milling ( Maltsev et al., 2019 ; Pervakov and Vlasenko, 2020 ; Tokuta et al., 2020 ; Tokuta and Yamamoto, 2019 ; Weiss et al., 2013 ). The density, microstructure, phase composition, and superconducting properties of the fabricated bulk samples were evaluated as a function of the sintering temperature.…”

Modeling Superconducting Critical Temperature of 122-Iron-Based Pnictide Intermetallic Superconductor Using a Hybrid Intelligent Computational Method

“…Therefore, superconductivity appears after applying external pressure or through doping in which the spin density wave order is suppressed. In order to achieve room pressure superconductor, hole doping, electron doping and iso-electronic substitutions are possible [ 8 ]. Iso-electronic substitution involves the replacement of arsenic by other elements such as phosphorus or the application of strong perturbation to Fe-As layer through perturbation of Fe environment since pnictogen tetrahedrally coordinates the Fe atoms.…”