Synthesis and characterization of pigments based on copper-zinc aluminate (CuxZn1-xAl2O4) by combustion

• Published in: Ceramics international Vol. 46; no. 2; pp. 2332 - 2343
• Main Authors: Santos, Thais Cristine de Sousa, Pinheiro, Darllan do Rosario, Costa, Cristiane Maria Leal, Estumano, Diego Cardoso, Ribeiro, Nielson Fernando da Paixão
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2020
• Subjects: Aluminate; Copper; Pigments; Spinel; Pigments; Aluminate; Spinel; Copper
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2019.09.224

New pigments with copper-zinc aluminate structures (CuxZn1-xAl2O4) were successfully produced by the combustion method. The materials synthesized were evaluated by TGA, SEM, XRD, FT-IR and the CIELab method in order to investigate the influence of chromophore ion content (x = 0, 0.1, 0.2, 0.4 and 1) and heat treatment temperatures of (600 °C, 800 °C and 1000 °C) on the structural, morphological and colorimetric properties of the pigments. Thermogravimetric analysis showed less than 6% mass loss, indicating that the combustion reaction was adequate. The XRD technique confirmed the presence of the spinel phase in all materials synthesized, except for samples with x = 1 without heat treatment or treated at 600 °C or 800 °C. Infrared spectroscopy showed that the addition of copper causes a small inversion in the assigned crystalline structure, verifying the presence of aluminium ions in the tetrahedral sites through monitoring of the 805 cm−1 band. The colorimetric data obtained from the dry powder pigments indicated coloration ranging from white (x = 0) to weak yellow (x = 0.1 and x = 0.2) and dark red (x = 1), which confirms the potential of copper-zinc aluminates in the production of diversified colours. The colour differences between the dried and dispersed powders in varnish were considered sharp. From the colorimetric experimental data, surface graphs were constructed, and empirical equations were obtained to predict the values of L*, a* and b*.