Cation vacancy order in the K0.8+xFe1.6-ySe2 system: five-fold cell expansion accommodates 20% tetrahedral vacancies

Abstract

Ordering of the tetrahedral site vacancies in two crystals of refined compositions K0.93(1)Fe1.52(1)Se2 and K0.862(3)Fe1.563(4)Se2 produces a fivefold expansion of the parent ThCr2Si2 unit cell in the ab plane which can accommodate 20% vacancies on a single site within the square FeSe layer. The iron charge state is maintained close to +2 by coupling of the level of alkali metal and iron vacancies, producing a potential doping mechanism which can operate at both average and local structure levels.

5 pages 3 figures accepted for publication in Chemical Science Chem. Sci., DOI:10.1039/C1SC00070E

References in corpus (10)

• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• Pnictogen height as a possible switch between high-T_c nodeless and low-T_c nodal pairings in the iron based superconductors
• Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)
• Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln=La,Nd)
• Pressure evolution of low-temperature crystal structure and bonding of 37 K $T_c$ FeSe superconductor
• A review of Fe-chalcogenide superconductors: the simplest Fe-based superconductor
• Crystal structure of the new FeSe1-x superconductor
• Structure and superconductivity of LiFeAs
• Transport properties of the new Fe-based superconductor KxFe2Se2 (Tc = 33 K)

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