Purple nanometrics pigments based on cobalt-doped manganese molybdate: Synthesis, characterization, structural, thermal, optical, colorimetric and chemical properties

Hind Lakhlifi (1) , Youssef El Jabbar (1) , Sophie Guillemet-Fritsch (2) , Bernard Durand (2) , Lahcen Er-Rakho (1) , Rachida El Ouatib (1)

1 Laboratoire de Physico-Chimie des Matériaux Inorganiques
2 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

This work is related to the characterization of nanometrics materials of the βMnMoO 4-βCoMoO 4 system, prepared by co-precipitation and sol-gel routes from the corresponding metal salts. The structural, morphological and colorimetric characteristics of the obtained powders were studied using thermogravimetric and differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), infrared and Raman spectroscopy, scanning electron microscopy (SEM) and colorimetry (CIE-L * a * b * system). The surface specific area was calculated using the Brunauer-Emmett-Teller analysis (BET) in the adsorption/desorption isotherm. The X-ray diffraction patterns highlighted the formation of a continuous solid solution Mn 1-x Co x MoO 4 (0 ≤ x ≤ 1) of monoclinic symmetry (C 2 /m) isotype to β-MnMoO 4 and this regardless of the synthetic route adopted. FTIR and Raman spectroscopy analysis showed that the chemical bonds' nature in the Mn 1-x Co x MoO 4 compounds corresponded to the strong MoO -Mo, MoO and CoO -Mo vibrational modes. The micrographs (SEM) highlighted the form of nanorods with sizes ranging from 10 to 200 nm for compositions x = 0.3 and x = 0.6, prepared by co-precipitation. The specific surface area measurements indicated that the powders obtained by the sol-gel process present lower values than those prepared by co-precipitation, regardless the cobalt substitution rate. The specific surface area of the purple nanoscale powder (x = 0.6) obtained by co-precipitation was about 7.52 m 2 /g. Colorimetric parameters analysis of the powders heat treated at 1100 °C showed that the degree of the component (-b *) was significant for compositions x = 0.6, regardless of the synthesis method adopted.

Mots clés: Co-precipitation; Sol-Gel; Nanometrics materials; FTIR; Raman; CIE-L* a* b * system

Domaines: Sciences de l'ingénieur [physics]; Chimie

Hind Lakhlifi, Youssef El Jabbar, Sophie Guillemet-Fritsch, Bernard Durand, Lahcen Er-Rakho, et al.. Purple nanometrics pigments based on cobalt-doped manganese molybdate: Synthesis, characterization, structural, thermal, optical, colorimetric and chemical properties. Journal of Molecular Structure, 2022, 1248, pp.131458. ⟨10.1016/j.molstruc.2021.131458⟩. ⟨hal-03851465⟩