Solution Fabrication of a Superconducting MgB₂ Coated Conductor on Stainless Steel

We report the solution fabrication of a MgB₂ coated conductor on a stainless steel substrate. The precursor solution of Mg(BH₄)₂ diethyl ether is initially synthesized by refluxing the milled mixture of NaBH₄ and MgCl₂ in diethyl ether. Then the Mg(BH₄)₂ diethyl ether is spin coated on a stainless steel substrate and annealed in Mg vapor, which yields a homogeneous MgB₂ coated conductor. X−ray diffraction indicates that the grown MgB₂ coated conductor is polycrystalline. It has a superconducting transition temperature of 34–37 K. The slope of the upper critical field H_C increases with decreasing temperature, and the extrapolated value of H_C(0) reaches ∼28 T. The critical current density estimated by the Bean model is J_C (25 K, 0 T)∼10⁶ A⋅cm⁻². These parameters indicate that the solution method is potentially able to produce MgB₂ coated conductors that can satisfy application purposes.