Structural, magnetic and optical behavior of pristine and Yb doped CoWO₄ nanostructure

Abstract

Nanocrystalline pure and Yb doped CoWO₄ nanostructures were synthesized successfully by single step chemical precipitation technique. The prepared sample was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal analysis (TGA). XRD pattern reveals the pure and doped CoWO₄ nanoparticles belongs to the monoclinic structure with the space group of P_2/c. Electron microscopy studies clearly evidence the formation of round edged nanocubes with an average particle size of 60–80 nm, emerges in the polycrystalline nature. UV–Visible absorption spectra of Yb³⁺ doped CoWO₄ nanocrystals shows a strong absorption peak at 278 nm due to CoWO₄ metal to ligand charge transfer within the [WO₆]⁶⁻ complex. Photoluminescence spectra of pure and doped CoWO₄ nanostructures substantiate the effect of Yb on the wolframite structure and its response for optical behavior. These results suggest that the addition of Yb into the Co-site on CoWO₄ has no significant contribution for luminescent enhancement when compared to pure one up to 5 % Yb concentration. Typical magnetization curve shows the mixed ferromagnetic and diamagnetic transition of CoWO₄ with respect to the Yb doping concentration.