LiCl-KCl eutectic molten salt as an original and efficient medium to intercalate metals into graphite: Case of europium

Abstract : We present the successful intercalation of europium into graphite by using an original method based on LiCl-KCl molten salts mixture. After solubilization of europium in the liquid chlorides mixture at 450 °C, reactivity toward graphite is investigated. We evidence the formation of the first stage EuC$_6$ Graphite Intercalation Compound (GIC) with a repeat distance Ic = 487 pm. Using 00$l$ X-ray diffraction and ion beam analysis, we show that europium is intercalated into the bulk with remarkable degree of homogeneity. This is also confirmed by magnetic measurements that clearly put in evidence the antiferromagnetic transition at about T$_N$ = 40 K. Below such temperature the characteristic step-like behavior of metamagnetic transitions was found by isothermal magnetization measurements, that is generally visible only in highly pure samples.