Effective synthesis route for red-brown pigments based on Ce – Pr – Fe – O and their potential application for near infrared reflective surface coating

Abstract

New cerium-based ceramic pigments, displaying Ce 2 Pr 0.2 Fe x O 4.3+y stoichiometry, were obtained at low temperature using a sol-gel method. The powder precursor dissolved in 80% ethylene glycol was precipitated using ammonia and the obtained gel calcined at 800 • C for 2 h to yield homogeneous and crystalline particles with a diameter of around 150 nm. The oxide was composed of cerium in its +4 oxidation state and Pr in its +3 oxidation state. The oxides with varying Fe content had an intense red-brown colour, with bandgap energy of around 2.2 eV at 0.1 mol% Fe doping. The near infra red reflectance from these pigments, a measure of their ability to reflect rather than absorb heat waves from sunlight was found to be 82.7%, even in the absence of a white reflective base. Such high near infra red reflectance from these pigments qualify them for being ideal cool pigments for surface coating applications.

Solution combustion synthesis of FeCr 2 O 4 powders for pigment applications: Effect of fuel type

“…Brightness weakness (L * values), even in the case of glycine fuel samples, is due to the residual carbons, to the formation of acceptable greyish brown pigment, onestep without calcination. 40,42,43 As expected, the fuel mixture is intermediate and does not reach the brightness of the sample obtained by glycine and urea fuels. Contrary to popular belief, the simultaneous presence of glycine and urea did not have a synergistic effect and reduced the yellowness-redness color.…”

“…For example, in the case of glycine–urea fuel mixture, the conditions are better than urea, but it does not reach glycine, and as a result, no synergistic effect was observed from the fuel mixture. In another sense and compared to glycine fuel, the mixture of fuels reduced the quality of the hue and chroma, which can be due to the heterogeneity created by the addition of two fuels with different properties 40,41 …”

“…In another sense and compared to glycine fuel, the mixture of fuels reduced the quality of the hue and chroma, which can be due to the heterogeneity created by the addition of two fuels with different properties. 40,41 Chromatic properties of the sample synthesized in the presence of various fuels and fuel mixture are illustrated in Table 6. The a * and b * values of all samples are below 5 so the obtained color is grayish brown.…”

Synthesis and characterisation of SrY2−xCexO4 as environmentally friendly reddish-brown pigments

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In particular, development of novel red pigments has been required and several studies have been reported. [18][19][20][21][22][23][24][25][26][27] Among them, it has been reported that Ca 1Àx La x TaO 2Àx N 1+x and Ce 2 S 3 showed bright red colour. 18,19 But, unfortunately, harmful NO x and SO x are generated when these nitride and sulphide pigments are incinerated.…”

Templating Influence of Molecular Precursors on Pr(OH)3 Nanostructures

“…Among the lanthanides, praseodymium exhibits excellent optical characteristics manifested in several interesting praseodymium complexes of high luminescence efficiency or for applications as color pigments and in near-infrared reflective coatings . Moreover, praseodymium forms oxides with variable valence states (3+ and 4+) such as Pr 2 O 3 , PrO 2 , and Pr 6 O 11 that are stable under ambient conditions, making them promising functional oxide materials.…”