Effect of air annealing on the structure, dielectric and magnetic properties of (Co, Ni) co-doped SnO2 nanoparticles

After our discovery of room temperature ferromagnetism in the (Co, Ni) co-doped SnO2 nanoparticles by co-precipitation method, we successfully annealed all (Co, Ni) co-doped SnO2 diluted magnetic nanoparticles in air at 800 A degrees C. The effect of annealing on dielectric and magnetic properties of (Co, Ni) co-doped SnO2 diluted magnetic nanoparticles was investigated. The as-synthesized (Co, Ni) co-doped SnO2 nanoparticles were annealed in air at 800 A degrees C for 2 h in an electric furnace. The dielectric constant and dielectric loss values of all (Co, Ni) co-doped SnO2 samples decrease whereas, the electrical conductivity value increased with an increase in Ni co-doped concentration. Room temperature ferromagnetic behavior was observed in (Co, Ni) co-doped SnO2 samples. Increasing the Ni content up to 2 % leads to an increase ferromagnetic behavior and beyond that the ferromagnetic behavior decreased. A comparative study shows that (Co, Ni) co-doped SnO2 nanoparticles annealed in air at 800 A degrees C have an excellent dielectric, magnetic properties and higher electrical conductivity than that of the (Co, Ni) co-doped SnO2 annealed in air at 600 A degrees C, indicating that these nanoparticles can be used for high frequency devices, ultrahigh dielectric materials and spintronics.