The influence of transition metal doping on the thermoelectric and magnetic properties of microwave synthesized SnO2 nanoparticles

Abstract

Dilute magnetic semiconductors at the nanoscale size are of great importance for different applications. However, their performance depends on several factors including the synthesis route and type of dopants. In this work tin dioxide (SnO2) nanoparticles (NPs) doped with different transition metals (TM) were synthesized by the microwave method and evaluated for their thermoelectric and magnetic properties. These TM include Fe, Cu, Cd, Ni and Zn. No significant changes are observed in the rutile tetragonal structure or morphology of SnO2 NPs by incorporating these dopants. Slight increase in value of the energy band gap of SnO2 NPs was observed in some of these samples. Oxygen defects were also noticed as revealed from the photoluminescence emission spectra. The valences states of the used TM were indentified using the XPS analysis. The resistivity of these NPs was decreased by incorporating these dopants meanly Ni and Zn ions. The magnetic measurement result showed that all the doped SnO2 NPs including the pure one have noticeable hysteresis loops, indicating that samples have room-temperature ferromagnetism. Strong magnetism with wider hysteresis loop was observed in the Fe doped SnO2 NPs. The induced magnetism could be attributed to the presence of defects at the grain boundaries, NPs interfacing sites, atom vacancies and existence of these dopants. The Fe doped SnO2 NPs might be a good DMS candidate for spintronics applications.