The recent discovery of superconductivity in iron arsenide compounds RFeAsO (R = rare earth) or AFe(2)As(2) (A = alkaline earth) has attracted great attention due to the unexpected high T-c in the system containing ferromagnetic elements like Fe. Similar to high T-c cuprates, the superconductivity in iron arsenide is related to a layered structure. Searching for new superconductors with FeAs layer, but of simpler structure will be of scientific significance either to build up new multilayered superconductors that may reach higher T-c or to study the mysterious underlined superconducting mechanism in iron arsenide compounds. Here we report that a new superconducting iron arsenide system LiFeAs was found. The compound crystallizes into a structure containing FeAs conducting layer that is interlaced with Li charge reservoir. Superconductivity was observed with T-c up to 18 K in the compounds.
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