Co_xMg_1-xGa₂O₄ (x = 0~0.6) nanoparticles were synthesized by citrate sol-gel method and characterized by X-ray powder diffraction. X-ray photoelectron spectroscopy was used to study the distribution of the cations in the tetrahedral and octahedral sites in Co_xMg_1-xGa₂O₄  nanoparticles as a function of composition. The results show that the as-synthesized samples exhibit spinel-type single phase when annealed at 800^oC (Fig.1). The crystallite size is about 8-40 nm, and increases with increasing cobalt content. The Ga 2p_3/2 XPS spectra are composed of two peaks for all the x values, indicating that Ga^3₊ ions occupy two different coordination sites (tetrahedral and octahedral) in the nanoparticles (Fig.2). The inversion parameter (two times the fraction of Ga^3₊  ions in tetrahedral sites) is estimated to be 0.48 for the pure MgGa₂O₄ (x=0) and the value increases to 0.72 when x is up to 0.6. The absorption spectra of Co-doped MgGa₂O₄ nanoparticles exhibit two absorption bands in the wavelength range 250-800 nm, which indicates that Co²⁺ ions are located in the tetrahedral sites as well as in the octahedral sites in the nanoparticles (Fig.3).

Fig.1 XRD patterns of Co_xMg_1-xGa₂O₄ nanoparticles annealed at 800^oC.

 Fig.2 Ga 2p_3/2 XPS spectra of Co_xMg_1-xGa₂O₄ (x=0~0.6) nanoparticles annealed at 800^oC.

Fig.3 Absorption spectra of Co_xMg_1-xGa₂O₄ (x=0~0.6) nanoparticles annealed at 800^oC.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/28874 must be provided.