Ni-Doped SnO2 Dilute Magnetic Semiconductors: Morphological Characteristics and Optical and Magnetic Properties

Ni-doped SnO2 dilute magnetic semiconductors were prepared by precipitation method. The obtained spherical nanoparticles are pure tetragonal rutile phase, and Ni ions promote the growth of SnO2 nanoparticles. The optical band gap energy of the SnO2 nanoparticles decreases from 3.14 to 2.84 eV when input x% Ni. The room-temperature photoluminescence (PL) spectra and X-ray photoelectron spectroscopy (XPS) confirm the existence of surface oxygen vacancies caused by the large specific surface area and the introduction of Ni ions. All the synthesized Ni-doped SnO2 nanoparticles achieve room-temperature ferromagnetism, with a saturation magnetization of up to 2.95 × 10−3 emu/g at a dopant concentration of 2%. The interaction between oxygen vacancies and Ni2+ realizes the magnetic transition of nanoparticles from diamagnetic to ferromagnetic.