Synthesis of layered hydroxides using controlled ammonia vapor diffusion

Layered hydroxides Co(OH)1.65Br0.35·0.5H2O (1), Co(OH)1.60(DDS)0.36Cl0.04·2.1H2O (2), Mg2Al(OH)6NO3·3H2O (3) and Mg(OH)2 (4) with unique morphologies have been synthesized by low temperature, controlled ammonia vapor diffusion. The materials were characterized by X-ray powder diffraction (XRD), field emission scanning microscope (FESEM) and SQUID magnetometry. Crystallites of (1) and (4) grow as thin films perpendicular to the air/water interface, while crystals of (2) and (3) share an unusual coral-like morphology. The magnetic data is consistent with a 3D ferrimagnet ground state at low temperature for both (1) and (2). The saturation magnetization (MSAT) at 5 K is observed to be 0.88 and 0.59 μB for (1) and (2), respectively. These values are consistent with a model containing two antiferromagnetically coupled magnetic sublattices, one comprising of octahedral cobalt atoms and one comprising tetrahedral cobalt atoms.