Phase transition, superstructure and physical properties of K2Fe4Se5

Abstract

The structural features and physical properties of the antiferromagnetic K0.8Fe1.6Se2 (so called K2Fe4Se5 phase) have been studied in the temperature range from 300K up to 600K. Resistivity measurements on both single crystal and polycrystalline samples reveal a semiconducting behavior. Structural investigations of K2Fe4Se5 by means of transmission electron microscopy and powder x-ray diffraction demonstrate the presence of a well-defined superstructure within the a-b plane originating from a Fe-vacancy order along the [130] direction. Moreover, in-situ heating structural analysis shows that K0.8Fe1.6Se2 undergoes a transition of the Fe-vacancy order to disorder at about 600K. The phase separation and the Fe-vacancy ordering in the superconducting materials of KxFe2-ySe2 (0.2 \leq y \leq 0.3) has been briefly discussed.

arXiv comment17pages, 5 figures, 1 table

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• Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity
• Fe-vacancy order and superconductivity in PbO-type tetragonal β-Fe1-xSe
• Reciprocal-space structure and dispersion of the magnetic resonant mode in the superconducting phase of Rb(x)Fe(2-y)Se2 single crystals
• Evolution of precipitate morphology during heat treatment and its implications for the superconductivity in KxFe1.6+ySe2 single crystals
• From antiferromagnetic insulator to correlated metal in pressurized and doped LaMnPO
• Structural, Magnetic and Electronic Properties of the Iron-Chalcogenide A${}_x$Fe${}_{2-y}$Se${}_2$ (A=K, Cs, Rb, Tl and etc.) Superconductors
• Spin reorientation in TlFe1.6Se2 with complete vacancy ordering
• Local structural disorder and superconductivity in KxFe2-ySe2
• (PI,0) antiferromagnetic spin excitations in superconducting Rb0.82Fe1.68Se2
• Superconductivity at 40 K in lithiation-processed [(Fe,Al)(OH)2][FeSe]1.2 with a layered structure
• Correlated disorder to order crossover in the local structure of K${}_x$Fe${}_{2-y}$Se${}_{2-z}$S${}_z$
• Evolution of the nuclear and magnetic structures of TlFe1.6Se2 with temperature
• Exploration of iron-chalcogenide superconductors
• Connection between ambient-pressure and pressure-induced superconducting phases in alkaline iron selenide superconductors