Structural, morphological and optical properties of cobalt-substituted MgMoO4 ceramics prepared by pyrolysis of citric acid precursors

Abstract

Magnesium-cobalt molybdate composites (Mg1–xCoxMoO4: x = 0, 0.3, 0.4, 0.6, 0.8 and 1) were successfully synthesized through a facile sol-gel synthesis at low temperature, and characterized by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), UV-Vis spectroscopy and colorimetric measurements using the CIE L*a*b* colour system. The surface specific area was calculated using the Brunauer–Emmett–Teller analysis in the adsorption/desorption isotherm. The examination of the X-ray diffractograms of the unground milled solid solutions of Mg1–xCoxMoO4 (0 ≤ x ≤ 1) presented a single continuous system related to monoclinic β-MgMoO4. The absorbance spectra of the Mg1–xCoxMoO4 pigments confirmed the insertion of cobalt in the β- MgMoO4 matrix. The CIE-L*a*b* colour coordinates indicated that the intense purple colour was obtained for x = 0.6.