Simple manufacturing and metal type-dependent properties of M3(OH)2V2O7•nH2O (M; Co, Ni, Cu, Zn) nanostructures

M3(OH)2V2O7·nH2O ( M : Co, Ni, Cu, Zn) nanostructures were synthesized by a simple and economic chemical precipitation route. For Co and Ni compounds, very small (~9 nm), irregularly shaped and poor crystalline nanoparticles occurred, probably due to high tendency for complexing with ammonia molecules releasing from ammonium metavanadate. However, more crystalline Co compounds could be synthesized in high reactant concentrations, but not for Ni.  Zn and Cu compounds are well crystallized in the hexagonal and monoclinic unit cell, respectively. Their shapes were nanoflake or nanoplate and their thickness were about 20 nm and 25 nm, respectively. Both have an average diameter of less than 500 nm. The chemical formulas determined were Co3V2O7(OH)2·2.8H2O, Ni3V2O7(OH)2·5.6H2O, Cu3V2O7(OH)2·2H2O and Zn3V2O7(OH)2·2.8H2O. The band gaps of samples were found in the range from 3.22 to 4.34 eV. Magnetic measurements show that all Co samples have a magnetic transition from ferromagnetic (FM) to paramagnetic (PM) around 300 K, on the ground that samples with FM characteristics and coupling at 5 K temperature turn into PM samples at room temperature. These results are important for large-scale synthesis of nanovanadate structures.