Synthesis and magnetic properties of β-Ni(OH)₂ and NiO nanosheets

In this report, we have synthesized hexagonal phase β-Ni(OH)₂ nanosheets through a facile hydrothermal route. NiO nanosheets were obtained by thermal decomposition of the obtained β-Ni(OH)₂ nanosheets at 450 °C for 3 h in air. The obtained samples were characterized by transmission electron microscopy (TEM), revealing that the obtained β-Ni(OH)₂ and NiO nanosheets have the length and width of several decade nanometers. Thermogravimetric (TG) measurement showed that β-Ni(OH)₂ nanosheets started to decompose at about 250 °C with the major weight loss that happened between 270 and 323 °C. The magnetic measurement results showed that β-Ni(OH)₂ nanosheets have ferromagnetic behavior at 5 K and paramagnetic behavior at 300 K. NiO nanosheets exhibited an obvious hysteresis loops both at 5 K and 300 K due to the magnetization relaxation process. At the same time, the origin of magnetic properties of the obtained β-Ni(OH)₂ and NiO nanosheets is discussed in detail. - highlights: • β-Ni(OH)₂ nanosheets were obtained through a facile hydrothermal method. • NiO was obtained by annealing β-Ni(OH)₂ at 450 °C for 3 h in air. • The morphology of NiO was unchanged through the annealing process. • β-Ni(OH)₂ has ferromagnetic behavior at 5 K and paramagnetic behavior at 300 K. • NiO exhibits an obvious hysteresis in M–H loops at 5 K and 300 K