Solid solutions of ceramic pigments of red shade have been synthesized based on YAlO3 perovskite structure doped with chromium by means of conventional synthesis; that is, the “ceramic route”. To optimize this synthesis, an emphasis has been made on the study of stoichiometry, calcination conditions and mineralizer incorporation. Various studies have demonstrated the high stability of perovskite structures, which ensures stable coloration at high temperatures. This is a highly important factor in the ceramic sector, given the scarcity of red glazes functional at temperatures close to those required of porcelain stoneware and their environmental constraints. Such a limitation makes it impossible in the European community to manufacture using toxic materials such as Se and Cd (cadmium sulfoselenide) that offer interesting colors at low temperatures. Pigments have been synthesized within the Y_1−xCr_xAlO₃, YCr_xAl_1−xO₃ and Y_1−xAl_1−yCr_x+yO₃ chromium-doped systems in molar ratios between n = 0.01 molar and n = 0.10 molar. The pigments obtained have been characterized by X-ray diffraction to identify the crystalline phases responsible for the shade; that is, the formation of the perovskite crystalline structure YAlO₃ responsible for the red shade, together with lateral phases of garnet Y₃Al₅O₁₂ of lower intensity. Visible ultraviolet spectrophotometry shows absorption bands corresponding to Cr(III) in octahedral position and the appearance of Cr(IV) in both octahedral and tetrahedral positions. The morphology of the samples was studied using a scanning electron microscope, obtaining information from the secondary and back scattered electrons. The viability of its use in ceramic glazes was verified after applying them mixed at 4% by weight in a glaze to an industrial porous single-firing cycle, collecting the L*a*b* chromatic coordinates using a visible ultraviolet spectrophotometer based on the CIE L*a*b* system, giving rise to red colorations.

In this study, a new red ceramic pigment has been developed within a perovskite structure, and microwave heat treatments have been applied. Those red ceramic pigments within the YAlO₃ system doped with chromium with the nominal composition Y_0.98Al_0.98Cr_0.04O₃ were synthesized by traditional routes and alternative methods like coprecipitation. Also, heat treatment has been studied comparing a traditional electric and microwave kiln. Different flux agents have been incorporated to improve the synthesis reaction. Prepared pigments have been characterized by X-ray diffraction (XRD) as having a predominant phase of perovskite structure, which is responsible for the red shade, and a minority garnet phase that causes more brown colorations. Studies by Ultraviolet-Visible spectroscopy gave rise to a series of absorption bands that indicate the presence of Cr(III) in the octahedral position corresponding to perovskite and Cr(IV) corresponding to garnet in both the octahedral and tetrahedral positions. The perovskite phase is favored with the use of flux mix, corroborating the UV-visible results and being more pronounced in traditional high temperature thermal treatments. The coprecipitation route has been studied to increase the reactivity of the particles given their nanometric size; however, this reactivity favors a greater appearance of undesirable garnet phases with both types of flux. Scanning Electron Microscopy (SEM) micrographs offer information obtained from the secondary electrons of predominantly cubic crystalline phases with sizes between 1 µm and 2 µm in pigments synthesized via the traditional method and sizes less than 1µm together with the glassy phase in pigments synthesized via coprecipitation. Microwave thermal treatments have been studied, obtaining pigments with a majority structure of perovskite and garnet at lower temperatures and relatively short synthesis times. The feasibility of use in porous single-fired ceramic glazes has been studied, whose chromatic coordinates have been collected using an Ultraviolet-Visible Spectrophotometer based on the CIEL*a*b* system.