Synthesis and magnetic property of cobalt hydroxide carbonate and cobalt oxide nanowires

Abstract

The present study is the first to report the successful synthesis of layered cobalt hydroxide carbonate nanowires templated by dodecyl sulfate assemblies by a homogeneous precipitation method using urea. The layered structure was composed of a cobalt hydroxide carbonate phase 1.9 nm thick and a dodecyl sulfate phase 2.3 nm thick. The width and length of the nanowires were tens of nm and greater than several micrometers, respectively. The layered cobalt hydroxide carbonate nanowires were transformed into Co3O4 and CoO nanowires by calcination in air and in vacuum, respectively, and were exfoliated to form ultrathin cobalt hydroxide carbonate nanowires approximately 3 nm wide. The present study also showed a dependence of the size and morphology on the magnetism of cobalt hydroxide carbonate. Although cobalt hydroxide carbonate nanorods synthesized in the presence of Na2SO4·10H2O and lamellar-shaped cobalt compound templated by a mixture of C16H33OSO3− and C18H37OSO3− were antiferromagnetic materials, the layered cobalt hydroxide carbonate nanowires exhibited ferrimagnetism. This expression of ferrimagnetism was considered to be due to the formation of ultrathin cobalt hydroxide carbonate phases in the nanowires. Moreover, the Neel temperature of the obtained Co3O4 nanowires, which exhibited antiferromagnetism, was lower than that of commercially available Co3O4 particles.