Nanostructural, magnetic and electrical properties of Ag doped Mn-ferrite nanoparticles

• Effect of Ag doping has been investigated.
• Generally Ag increases the electrical conductivity of samples.
• Magnetization, activation energy and Curie temperature decreases by increasing the Ag doping level.
• Magnetization depends on measurement temperature as well as Ag content in samples.

Nano-crystalline MnFe2−xAgxO4 (x = 0, 0.1, 0.2, 0.3 and 0.6) samples with average grain size of 4–7 nm were synthesized by a simple method based on decomposition of metal nitrates in presence of citric acid. The samples were characterized by different structural, magnetic and electrical measurements. Rietveld refinement of X-ray diffraction data confirmed cubic spinel structure of the samples. Results show that Ag doping decreases the crystallite size, magnetization and coercivity of nanoparticles. By increasing the Ag content in the samples the saturation magnetization shows interesting temperature dependent behavior. It was realized that magnetization of smaller particles show higher sensitivity to temperature variations than larger particles. DC electrical resistivity measurements in the temperature range of 300–650 K show that the resistivity first increases and then decreases by increasing the Ag content in the samples. Curie temperature (Tc) and polaron activation energy in ferromagnetic and paramagnetic regions were estimated by using resistivity curves.