Transport and NMR study of the scandium boron carbide compound ScC2B1.1C3.2 with a boron and carbon mixed graphitelike layer

Transport properties and nuclear magnetic resonance (NMP) of the new scandium boron carbide compound Sc2B1.1C3.2 were investigated. Sc2B1.1C3.2 has a trigonal crystal structure [a = b = 23.710(9)A, c = 6.703(2)A. P3m1] and is composed of alternate [B1/3C2/3]-Sc-C-Sc-[B1/3C2/3] layers, with the boron and carbon mixed layer [B1/3C2/3] forming a very rare graphitelike structure. Physical properties similar to graphite intercalation compounds (GIC) were observed. The temperature dependence of the resistivity showed a large anisotropy. The in-plane resistivity showed a metallic quadratic dependence, also observed in some GIC's while the resistivity along the c axis, perpendicular to the layers, increased with decreasing temperature. From magnetic susceptibility and specific-heat measurements, the orbital susceptibility was indicated to take a paramagnetic value. At low temperatures an increase of the in-plane resistivity with log T dependence and negative magnetoresistance was observed. Two-dimensional Anderson localization was indicated, possibly originating from disorder in the [B1/3C2/3] graphitelike layer. B-11 magic angle spinning (MAS). nuclear magnetic resonance (NMR) results indicate a large distribution of the chemical shift of the boron nuclei, which is consistent with the existence of disorder within the graphitic layer.