Black and green pigments based on chromium–cobalt spinels

Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co2−xCrx)O4 powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 °C. These powders were cha...

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Principais autores: Eliziário, Sayonara A., Andrade, Jeferson M. de, Lima, Severino Jackson Guedes, Paskocimas, Carlos Alberto, Soledade, Luiz Edmundo Bastos, Hammer, Peter, Silva, Elson Longo da, Souza, Antônio Gouveia de, Santos, Ieda Maria Garcia dos
Formato: article
Idioma:English
Publicado em: Elsevier
Assuntos:
Chemical synthesis
Optical materials
Oxides
X-ray photo-emission spectroscopy
Endereço do item:https://repositorio.ufrn.br/handle/123456789/32147
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spelling ri-123456789-321472021-12-16T12:49:28Z Black and green pigments based on chromium–cobalt spinels Eliziário, Sayonara A. Andrade, Jeferson M. de Lima, Severino Jackson Guedes Paskocimas, Carlos Alberto Soledade, Luiz Edmundo Bastos Hammer, Peter Silva, Elson Longo da Souza, Antônio Gouveia de Santos, Ieda Maria Garcia dos Chemical synthesis Optical materials Oxides X-ray photo-emission spectroscopy Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co2−xCrx)O4 powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 °C. These powders were characterized by X-ray diffraction, infrared spectroscopy, colorimetry, UV–vis absorption and X-ray photoelectron spectroscopies. Even with the addition of chromium, the XRD patterns revealed that all powders crystallize in a single spinel cubic structure. The spinels with higher cobalt amount, Co(CoCr)O4 and Co(Co1.75Cr0.25)O4, displayed a dark color, without the Co3+ reduction observed in Co3O4 between 900 and 950 °C. The spinel with higher chromium amount, CoCr2O4, was green. The colors were directly related to the occupation of tetrahedral and octahedral sites by the chromophores, as well as to the different oxidation states of chromium and cobalt. The different optical band gap values estimated from UV–vis spectra suggested the existence of intermediary energy levels within the band gap. X-ray photoelectron spectroscopy confirmed an increasing presence of Co(III) and a decreasing amount of Cr(VI) with cobalt enrichment 2021-04-09T20:50:45Z 2021-04-09T20:50:45Z 2011-09-15 article ELIZIÁRIO, Sayonara A.; ANDRADE, Jeferson M. de; LIMA, Severino J.G.; PASKOCIMAS, Carlos A.; SOLEDADE, Luiz E.B.; HAMMER, P.; LONGO, E.; SOUZA, Antônio G.; SANTOS, Ieda M.G.. Black and green pigments based on chromium–cobalt spinels. Materials Chemistry And Physics, [S.L.], v. 129, n. 1-2, p. 619-624, set. 2011. Disponível em: https://www.sciencedirect.com/science/article/abs/pii/S0254058411003932?via%3Dihub. Acesso em: 24 fev. 2021. http://dx.doi.org/10.1016/j.matchemphys.2011.05.001 0254-0584 https://repositorio.ufrn.br/handle/123456789/32147 10.1016/j.matchemphys.2011.05.001 en Attribution 3.0 Brazil http://creativecommons.org/licenses/by/3.0/br/ application/pdf Elsevier
institution Repositório Institucional
collection RI - UFRN
language English
topic Chemical synthesis
Optical materials
Oxides
X-ray photo-emission spectroscopy
spellingShingle Chemical synthesis
Optical materials
Oxides
X-ray photo-emission spectroscopy
Eliziário, Sayonara A.
Andrade, Jeferson M. de
Lima, Severino Jackson Guedes
Paskocimas, Carlos Alberto
Soledade, Luiz Edmundo Bastos
Hammer, Peter
Silva, Elson Longo da
Souza, Antônio Gouveia de
Santos, Ieda Maria Garcia dos
Black and green pigments based on chromium–cobalt spinels
description Chromium and cobalt oxides are widely used in the manufacture of industrial pigments. In this work, the Co(Co2−xCrx)O4 powders with different chromium concentrations (x = 0, 0.25 and 1) were synthesized by the polymeric precursor method, heat treatment between 600 and 1000 °C. These powders were characterized by X-ray diffraction, infrared spectroscopy, colorimetry, UV–vis absorption and X-ray photoelectron spectroscopies. Even with the addition of chromium, the XRD patterns revealed that all powders crystallize in a single spinel cubic structure. The spinels with higher cobalt amount, Co(CoCr)O4 and Co(Co1.75Cr0.25)O4, displayed a dark color, without the Co3+ reduction observed in Co3O4 between 900 and 950 °C. The spinel with higher chromium amount, CoCr2O4, was green. The colors were directly related to the occupation of tetrahedral and octahedral sites by the chromophores, as well as to the different oxidation states of chromium and cobalt. The different optical band gap values estimated from UV–vis spectra suggested the existence of intermediary energy levels within the band gap. X-ray photoelectron spectroscopy confirmed an increasing presence of Co(III) and a decreasing amount of Cr(VI) with cobalt enrichment
format article
author Eliziário, Sayonara A.
Andrade, Jeferson M. de
Lima, Severino Jackson Guedes
Paskocimas, Carlos Alberto
Soledade, Luiz Edmundo Bastos
Hammer, Peter
Silva, Elson Longo da
Souza, Antônio Gouveia de
Santos, Ieda Maria Garcia dos
author_facet Eliziário, Sayonara A.
Andrade, Jeferson M. de
Lima, Severino Jackson Guedes
Paskocimas, Carlos Alberto
Soledade, Luiz Edmundo Bastos
Hammer, Peter
Silva, Elson Longo da
Souza, Antônio Gouveia de
Santos, Ieda Maria Garcia dos
author_sort Eliziário, Sayonara A.
title Black and green pigments based on chromium–cobalt spinels
title_short Black and green pigments based on chromium–cobalt spinels
title_full Black and green pigments based on chromium–cobalt spinels
title_fullStr Black and green pigments based on chromium–cobalt spinels
title_full_unstemmed Black and green pigments based on chromium–cobalt spinels
title_sort black and green pigments based on chromium–cobalt spinels
publisher Elsevier
publishDate 2021
url https://repositorio.ufrn.br/handle/123456789/32147
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