Facile synthesis of Ba(1-x)K(x)Fe2As2 superconductors via hydride route.
We have developed a fast, easy, and scalable synthesis method for Ba(1-x)K(x)Fe2As2 (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 Ba(1-x)K(x)Fe2As2 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.
Department of Chemistry and ‡Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis , One Shields Avenue, Davis, California 95616, United States.
Julia V
JV
Zaikina
Maria
M
Batuk
Artem M
AM
Abakumov
Alexandra
A
Navrotsky
Susan M
SM
Kauzlarich