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Title: Facile synthesis of Ba1-xKxFe₂As₂ superconductors via hydride route

We have developed a fast, easy, and scalable synthesis method for Ba1-xKxFe₂As₂ (0 ≤ x ≤ 1) superconductors using hydrides BaH₂ and KH as a source of barium and potassium metals. Synthesis from hydrides provides better mixing and easier handling of the starting materials, consequently leading to faster reactions and/or lower synthesis temperatures. The reducing atmosphere provided by the evolved hydrogen facilitates preparation of oxygen-free powders. By a combination of methods we have shown that Ba1-xKxFe₂As₂ obtained via hydride route has the same characteristics as when it is prepared by traditional solid-state synthesis. Refinement from synchrotron powder X-ray diffraction data confirms a linear dependence of unit cell parameters upon K content as well as the tetragonal to orthorhombic transition at low temperatures for compositions with x < 0.2. Magnetic measurements revealed dome-like dependence of superconducting transition temperature Tc upon K content with a maximum of 38 K for x close to 0.4. Electron diffraction and high-resolution high-angle annular dark-field scanning transmission electron microscopy indicates an absence of Ba/K ordering, while local inhomogeneity in the Ba/K distribution takes place at a scale of several angstroms along [110] crystallographic direction.
 [1] ;  [2] ;  [2] ;  [1] ;  [1]
  1. Univ. of California at Davis, Davis, CA (United States)
  2. Univ. of Antwerp, Antwerp (Belgium)
Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 136; Journal Issue: 48
American Chemical Society (ACS)
Research Org:
Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Org:
Country of Publication:
United States