Structural, magnetic and dielectric studies of siderite nano-particles synthesized by hydrothermal method

Siderite or ferrous carbonate (FeCO3) is a well-known mineral and finds applications in various fields such as dietary supplement to treat anemia and in petroleum drilling fluids for H2S removal. The FeCO3 nano-particles are synthesized by hydrothermal method using aqueous solutions of iron sulfate, ascorbic acid and ammonium carbonate with a molar ratio of 1:1:3, respectively, and heating at 140 degrees C for 1.5 h in Teflon-lined stainless steel autoclave. The recovered sample is characterized by several techniques. The powder XRD indicates the hexagonal crystal system and the average crystallite size of 17.32 nm are obtained from the Scherrer's formula and 18.98 nm is obtained from the Williamson and Hall formula. The TEM images suggest the spherical nature of the nano-particles. The EDX confirms the elemental presence of iron, carbon and oxygen. The impedance and dielectric studies are carried out within 20 Hz-2 MHz range at room temperature. The complex impedance plot, i.e. the Nyquist plot, is composed of one semicircle indicating the contribution from the grain only. The Jonscher's power-law is applied to AC conductivity data. The VSM data at room temperature and at low temperature, i.e. 20-300 K range, suggests a weak antiferromagnetic nature of the sample.