Highlights

•

Co-doped MgGa₂O₄/SiO₂ nanocomposites have been synthesized by sol–gel method.

•

The chemical environments of cations and oxygen in the nanocomposites as a function of annealing temperature, cobalt content and SiO₂ content were studied.

•

Ga³⁺ and Mg²⁺ ions occupy both the tetrahedral and octahedral sites of spinel structure in the samples.

•

The inversion parameter decreases with the increase of annealing temperature and silica concentration, while increases with cobalt-enrichment.

•

The fraction of octahedral Co²⁺ ions increases with decreasing annealing temperature for Co_0.3Mg_0.7Ga₂O₄ nanocrystals.

Abstract

Co-doped ZnO–Ga₂O₃–SiO₂ nano-glass–ceramic composites were prepared by sol–gel method. X-ray diffraction patterns showed that the crystallization temperature was 800 °C. X-ray photoelectron spectroscopy (XPS) was used to study the effect of heat-treatment temperature on the electronic structure of Co-doped ZnO–Ga₂O₃–SiO₂ nano-glass–ceramic composites. The Zn (2p_3/2), Ga (2p_3/2) and O (1s) XPS spectra for the glass–ceramics heat-treated at 800–1000 °C could be deconvoluted into two peaks corresponding to these elements in glass network and in nanocrystals, respectively. The results indicate that the material is composed of an amorphous silicate network and ZnGa₂O₄ nanocrystalline particles. The amount of nanocrystals increases with the annealing temperature. The photoelectron peak of Si (2p) shifts to higher binding energy at higher annealing temperature, revealing the charge transfer from Si to O increased. The relationship between the microstructure of Co-doped ZnO–Ga₂O₃–SiO₂ sample and its absorption properties was discussed, and the suitable heat-treatment temperature was proposed.