Preparation And Characterization Of Gadolinium Graphite Intercalation Compounds

Rare-earth graphite intercalation compounds, a new type of composite materials, are made by inserting particles containing rare earth elements into the graphite layers under certain conditions. Because of their special properties in electronics and magnetics and so on, they can be applied to electrode materials, catalyst supports, magnetic materials and many other materials. This not only saves rare earth resources, but also open a new way of raising the value of graphite.In this paper, natural flake graphite and gadolinium oxide were chosen as raw materials to prepare gadolinium exfoliated graphite intercalation compounds and gadolinium graphite oxide intercalation compounds. Morphologies, composition and structures of the products were characterized by field emission scanning electron microscopy(FESEM), energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), thermo gravimetric-differential thermal analysis (TG-DTA) and fourier transform infrared spectrometry(FT-IR).GdCl3-Gd2O3-EG-GICs were prepared using a simple liquid mixture adsorption method, and exfoliated graphite was obtained by mixed acid method. It is found that GdCl3-EG-GICs were of mixed structure of 2nd and 3rd stages at small W(Gd2O3)/W(EG) ratio, then of stable 3rd stage with increasing W(Gd2O3)/W(EG) ratio.Gd2O3 was obtained by the reaction between Gd3+ and oxygen groups from EG, and some Gd2O3 entered interlayers of expanded graphite, but Gd2O3-EG-GICs kept stable 4th stage structure, which was independent of W(Gd2O3)/W(EG) ratio.Graphite oxide was prepared by Hummers method, and gadolinium oxide carbonate hydrate-graphite oxide intercalation compounds were obtained through the reaction between suspension of graphite oxide and saturated solution of gadolinium chloride. Because some carboxyl, hydroxyl and other oxygen-containing polar functional groups on the graphite oxide layers easily adsorbed met al ions, Gd3+ was inserted into the graphite oxide layers, and combined with the oxygen-containing groups on the graphite oxide layers to form a new substances—gadolinium oxide carbonate hydrate.TG-DTA analysis confirmed that high-temperature reduction of graphite oxide occurs at 480℃. At this temperature, gadolinium oxide carbonate hydrate-graphite oxide intercalation compounds were reduced. Gadolinium oxide carbonate hydrate was transformed into Gd2O3 monoclinic crystal, rather than the cubic crystals of parent Gd2O3, the layer absorbed water was removed, C-O-C group, C-OH group, epoxy or peroxy groups were decomposed, oxygen content decreased, the crystal structure of graphite was resumed. Ultimately, Gd2O3-graphite intercalation compounds were obtained.