Microstructure investigation, optical properties and magnetic phase transition of Tm3+ substituted nanocrystalline ZnO (Zn0.95Tm0.05O)

Abstract

The magnetic phase transition, optical and dielectric properties of nanocrystalline Tm³⁺-doped zinc oxide (Zn_0.95Tm_0.05O), prepared by the co-precipitation method, were determined for the first time. The oxygen vacancy of the as prepared sample was enhanced by annealing at 200 °C for 6 h in an argon atmosphere. The formation of defects/oxygen vacancy is reflected in the Raman, FTIR and PL spectral analyses of the doped sample. Paramagnetic to ferromagnetic phase transition of Zn_0.95Tm_0.05O was observed at and below ∼30 K. The onset of ordering is successfully explained by the vacancy assisted bound-magnetic-polaron (BMP) model. The results of dielectric measurements suggest that the dielectric response of Zn_0.95Tm_0.05O is significantly enhanced, compared to that of pristine ZnO, and this is due to the presence of large amounts of oxygen vacancies, and the nanostructure of the sample.