Highly Dispersed Re-Doped CoAl2O4 Nanopigments: Synthesis and Chromatic Properties

Journal of Nanomaterials, Mar 2016

Nanosized spinel complex oxides were prepared by self-propagation combustion method. The products have been characterized by XRD, SEM, and EDS. The results indicated that Al3

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Highly Dispersed Re-Doped CoAl2O4 Nanopigments: Synthesis and Chromatic Properties

Highly Dispersed Re-Doped CoAl2O4 Nanopigments: Synthesis and Chromatic Properties Yuping Tong, Hailong Zhang, Shun Wang, Zheng Chen, and Baixue Bian School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450011, China Received 16 December 2015; Revised 8 February 2016; Accepted 16 February 2016 Academic Editor: William Yu Copyright © 2016 Yuping Tong et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Nanosized spinel complex oxides were prepared by self-propagation combustion method. The products have been characterized by XRD, SEM, and EDS. The results indicated that Al3+ can be partly replaced by Re3+ when the doped amount is less than 10%, which forms single solid solution. The NIR reflectance and chromatic properties of samples have also been investigated. The substitution of Re3+ for Al3+ in CoAl2O4 can increase the blueness of pigments. SEM results revealed that the obtained pigments consisted of highly dispersed spherical-like nanoparticles with uniform size distribution. EDS results indicated that the distribution of element was considerably uniform with no chemical segregation phenomenon. 1. Introduction Spinel-type structure pigments with a general formula A2B2O4 have attracted extensive attention due to their chemical and thermal stability, which have been applied in decorating porcelains, ceramics, catalysts, paints, and so forth [1–3]. Among them, CoAl2O4 is one of the most important blue pigments, which has classic spinel-type structure and superior properties, such as high resistance to acids, and chemical, color, optical, and thermal stabilities [4–6]. Particularly, for application as optical devices like color filters or pigments, the presence of highly dispersed submicrometer or nano-CoAl2O4 particles is important and indispensable [7]. Recent efforts have focused on tailoring a controllable and simple synthetic method for high-quality CoAl2O4 nanopigment. Many new synthetic technologies have been developed to synthesize CoAl2O4 nanopigment, such as organic ligand-assisted supercritical water hydrothermal method [8], polyacrylamide gel method [9], coprecipitation process [6], sol-gel method [5, 10], autoignition technique [11], molten salts method [12], and combustion method [13]. The self-propagation combustion method has been developed by our team for preparation of pyrochlore-type and spinel-type nanoparticles [14, 15]. In this paper, we study synthesis and chromatics properties of rare earth ion doped CoAl2O4 nanopigment via self-propagation combustion method, based on the fact that rare earth element as doping ion can change the crystal structure and play an important role in stabilizing the color and changing the color of pigments. 2. Experimental2.1. Preparation of Materials All reagents were of analytical grade and used without further purification. In this work, all pigment samples of (Re = Y, La, Nd, Sm, and Eu) were synthesized by self-propagation combustion method. and were used as the precursors of Co and Al, respectively. was obtained by dissolving Re2O3 in concentrated HNO3. Urea was used as fuel. According to the formula (where , 0.1, 0.15, 0.2, and 0.3), stoichiometric amounts of , , and were added to urea aqueous solution in turn. After a series of steps of magnetic force stirring, evaporating, and self-propagating combustion, the loose precursor was obtained. The precursor was ground into powder and then submitted to calcination at 750°C for 4 h. The synthesis procedure and product of CoAl2O4 nanoparticles are shown in Figure 1. Figure 1: The synthesis procedure of CoAl2O4 nanoparticles. 2.2. Instrumentation The crystalline phase structure was determined by Bruker D8 Advance X-ray diffractometer (XRD) using Cu Kα radiation. Scanning electron microscopy (SEM) image was recorded on a JSM-7500F scanning electron microscope, and EDS was taken on INCAPentaFET-x3 energy dispersive X-ray detector. The CIE 1976 colorimetric method was used, as recommended by the Commission Internationale de l’Eclairage (CIE). In this method, is the lightness axis [black (0) to white (100)], is the green (−value) to red (+value) axis, and is the blue (−value) to yellow (+value) axis. The parameter (chroma) represents saturation of the color. For each colorimetric parameter of a sample, measurements were made in triplicate and an average value was chosen as the result. Typically, for a given sample, the standard deviation of the measured CIE- values is less than 0.10, and the relative standard deviation is not higher than 1%, indicating that the measurement error can be ignored. UV-vis-NIR reflectance of the obtained pigments was carried out by UV-vis-NIR spectrophotometer (Perkin Elmer Lambda 950), using polytetrafluoroethyle (...truncated)


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Yuping Tong, Hailong Zhang, Shun Wang, Zheng Chen, Baixue Bian. Highly Dispersed Re-Doped CoAl2O4 Nanopigments: Synthesis and Chromatic Properties, Journal of Nanomaterials, 2016, 2016, DOI: 10.1155/2016/4169673