Zn-Cu-codoped SnO_2 nanoparticles: Structural,optical, and ferromagnetic behaviors

Zn-Cu-codoped SnO₂ nanoparticles have been synthesized by chemical precipitation method. All nanoparticles are crystalline, with the average size increases from 2.55 nm to 4.13 nm as the calcination temperature increases from 400℃ to 600℃. The high calcination temperature can enhance the crystalline quality and grain growth. The oxygen content decreases with decreasing calcination temperature; at a low temperature of 400℃, Zn-Cu-codoped SnO₂ nanoparticles are in a rather oxygen-poor state having many oxygen vacancies. The optical band gap energies of Zn-Cu-codoped SnO₂ nanoparticles calcined at 400℃ and 600℃ are decreased from 3.93 eV to 3.62 eV due to quantum confinement effects. Both samples exhibit room-temperature ferromagnetism, with a larger saturation magnetization at 400℃ due to the presence of large density of defects such as oxygen vacancies. Zn-Cu-codoped SnO₂ nanoparticles exhibit large optical band gap energies and room temperature ferromagnetism, which make them potential candidates for applications in optoelectronics and spintronics.