Polymorphism induced magnetic transitions in Ni(OH)2 nanostructures

[Display omitted] •Novel Ni(OH)2 nanostructures were prepared by facile hydrothermal method and reported.•Polymorphism in Ni(OH)2 was induced by varying complexing agents.•C-axis of hexagonal Ni(OH)2 has significant influence on magnetic properties.•Paramagnetic to superparamagnetic transition was observed in α-Ni(OH)2 phase.•Paramagnetic to antiferromagnetic transition was observed in β-Ni(OH)2 phase. The article describes the impact of complexing agent on the phase changing property of Ni(OH)2 nanostructures (NSs). Ni(OH)2 was prepared by facile hydrothermal method and polymorphism have been obtained by employing two different complexing agent while keeping other parameters constant during synthesis. The α-and β-Ni(OH)2 NSs phase was formed confirmed by XRD and FTIR. FESEM and TEM images reveals that the 3D-flower like α-Ni(OH)2 nanostructure and formation randomly oriented nanopetals of β-Ni(OH)2 NSs. Magnetic features of both α-and β-Ni(OH)2 phases were studied using SQUID magnetometer. α-and β-Ni(OH)2 exhibit blocking temperature at 6 K and 25 K, correspondingly and irreversible hysteresis behavior below blocking temperature. α-Ni(OH)2 shows paramagnetic to superparamagnetic transition whereas β-Ni(OH)2 shows paramagnetic to antiferromagnetic transition as temperature varies from 2 to 50 K.