Iodine as an Oxidant in the Topotactic Deintercalation of Interstitial Iron in Fe1+xTe

The layered telluride, Fe1+xTe, is a parent compound of the isostructural and superconducting phases, Fe1+x(Te, Se, S). Here we show that, through a simple reaction of I2 vapor with both powder and single crystal samples, the interstitial iron can be removed from the FeTe framework topotactically. Neutron powder diffraction and X-ray single crystal diffraction confirm that the iron being extracted is the partially occupied site that lies between the 2-D blocks of edge-sharing FeTe4 tetrahedra. The deintercalation process has consequences for both magnetic and crystallographic phase transitions in the compound at low temperatures. This technique could be of use for the tuning of stoichiometry of the superconducting phases and therefore enable more careful studies on how chemical composition affects magnetic and superconducting properties.