Characterization of single and doped zirconia with metal elements of the lanthanides group using the positron annihilation lifetime spectroscopy

In this article, single and doped zirconium oxide (ZrO₂) with metal ions (lanthanides group), which was synthesized by the co-precipitation method, was studied. The changes in crystal structure due to metal ions as dopants were investigated by X-ray diffraction (XRD). The results of XRD show that metal ions cause a change in the chemical phase structure, in the direction of crystal growth of ZrO₂. Defects, porosity, and lattice structure of pure and doped ZrO₂ were investigated by positron annihilation lifetime spectrometer (PALS). The results of PALS analysis show that the metal ions Pr³⁺, Sm³⁺, Dy³⁺, and Er³⁺ occupy the interstitial sites of the zirconia lattice, and Eu²⁺ replaces the vacancy of the Zr atom. The results of UV–Vis show that these metal ions cause a significant reduction in the band gap. Creating an energy band by metal ions plays the role of positron trapping centers that prevent electron–hole recombination and thus affect the conductivity of ZrO₂. (author)