Magnetic susceptibility of Alq3 powder, pure and Al-doped 8-hydroxyquinoline

Single-crystal nanowires several microns long and 100-200 nm in diameter were grown by physical vapour deposition from mixed Alq(3)/gamma-Al2O3 powder. The crystals are orthorhombic Al-doped 8-hydroxyquinoline. The molar susceptibility is -3 x 10(-9) at room temperature, and it shows a Curie-law up turn below about 50 K. The approach to saturation at low temperature indicates a density of S = 1/2 defects 4 x 10(-4) per formula unit. Pure 8-hydroxyquinoline and aluminium (Alq(3)) behave similarly. Pressed pellets exhibit much increased paramagnetic susceptibility due to iron ions scavanged from the steel die. Subsequent melting of these samples produces a ferromagnetic signal of order 0.01 A m(2) kg(-1), which is attributed to metallic iron nanoclusters in the organic material. (C) 2009 Elsevier B.V. All rights reserved.