New graphite intercalation compounds with heavy alkali metal superoxides

The study of potassium-oxygen and cesium-oxygen graphite intercalation compounds (GICs) first synthesized by the authors is presented. It is shown that these GICs are formed in reactions of graphite with alkali metal/alkali superoxide mixtures or with alkali suboxide (in the case of cesium). Stage 1 and 2 potassium-oxygen GICs (interplanar distance 8.44 Angstrom), and stages 1, 2 and 5 cesium-oxygen GICs (interplanar distance 9.84 Angstrom) were isolated. X-ray diffraction, XPS, TEM electron diffraction and chemical analysis were used to characterize the content and constitution of the GICs synthesized. Metal-like temperature dependence of c-axis resistivity was obtained in the 1.5-300 K range where the resistivity values at room temperature are 0.07, 0.81, 2.6 and 0.089 Ohm cm for K-O stage1, K-O stage 2, Cs-O stage 1 and Cs-O stage 2 compounds, respectively. All the GICs exhibit low spin susceptibility (order of 10(-7) emu/g) which suggests the absence of magnetic species O-2(-).