Soft chemical control of superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe

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SUN, Hualei, WOODRUFF, Daniel N., CASSIDY, Simon J., ALLCROFT, Genevieve M., SEDLMAIER, Stefan J., THOMPSON, Amber L., BINGHAM, Paul, FORDER, Sue, CARTENET, Simon, MARY, Nicolas, RAMOS, Silvia, FORONDA, Francesca R., WILLIAMS, Benjamin H., LI, Xiaodong, BLUNDELL, Stephen J. and CLARKE, Simon J. (2015). Soft chemical control of superconductivity in Lithium Iron Selenide Hydroxides Li1–xFex(OH)Fe1–ySe. Inorganic Chemistry, 54 (4), 1958-1964. [Article]

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Abstract

Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ∼ 0.2; 0.02 < y < 0.15) with a wide range of iron site vacancy concentrations in the iron selenide layers. This iron vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction, and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesized samples when the iron vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low vacancy concentration in the iron selenide layers is emphasized by the demonstration that reductive postsynthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer.

More Information

Official URL:

http://dx.doi.org/10.1021/ic5028702

Research Institute, Centre or Group - Does NOT include content added after October 2018:

Materials and Engineering Research Institute > Materials Analysis and Research Services

Page Range:

1958-1964

Identifiers

Identification Number:

10.1021/ic5028702

ORCID for Paul Bingham: