Novel syntheses of wide-band gap semiconducting Cdx Znx-1 Co2O4 of spinel nanostructure: Characterization and optical properties

Abstract

<title>Abstract</title> Cadmium doped zinc cobaltite spinel structure in the form of Cd_{<italic>x</italic>}Zn_{<italic>x</italic>-1}Co₂O₄ (0 ≤ <italic>x</italic> ≤ 1) are synthesized by sol-gel method. A good crystallinity of the ZnCo₂O₄ and its dopants samples are indicated by the sharpness and strong peaks of X-ray diffraction patterns. The particle size is independent of the ratio of incorporated Cd into the ZnCo₂O₄ matrix. The FT-IR transmission spectrum of each Cd_{<italic>x</italic>} Zn_{1-<italic>x</italic>}Co₂O₄ complex shows two strong vibration peaks that are ascribed to the spinel structure's octahedral and tetrahedral. The occurrence of light absorption by Cd_{<italic>x</italic>} Zn_{<italic>x</italic>-1} Co₂O₄ is due to the photoexcitation of electrons from O 2<italic>p</italic> to Co 3<italic>d</italic> transitions and <italic>d</italic>-<italic>d</italic> transition of Co 3<italic>d</italic>. The obtained values of the optical band gap (<italic>E</italic>_{<italic>g</italic>}) for Cd_x Zn_1-xCo₂O₄ varies from 2.93 eV for ZnCo₂O₄ (<italic>x</italic> = 0) to 2.15 eV for CdCo₂O₄ (<italic>x</italic> = 1).