P.M. Pimentel

Preparação de pigmentos de aluminatos de cobalto para aplicação em vidrados cerâmicos

Inorganic pigments are the most widely used in industries, since they have greater chemical and thermal stability and can be produced with high purity and uniformity. These characteristics led to the development of different intense, stable and suitable colors for use as pigments. This paper aims to synthesize ceramic materials with spinel structure for use as ceramic pigment and apply them in ceramic frits. The synthesis procedure was performed by gelatin method and the powders were studied in terms of evolution of crystalline phases by X-ray diffraction (XRD), refinement of the structures through the Rietveld method, spectroscopy in the infrared region, scanning electron microscopy, UV-visible spectroscopy and colorimetric analysis. XRD patterns showed the characteristic reflections of the spinel structure. The average crystallite size and crystallinity increased with increasing calcination temperature. The color of pigments ranged from pale blue to blue violet.

Spectroscopic Properties of pigment Li2-xZn1-xPrxTi3O8

Inorganic compounds doped with rare earths (Ce3+, Pr3+, Nd3+, Sm3+, Eu 3+, Gd 3+, Tb 3+, Tm3+) have been used in various applications including light-emitting devices such as fluorescent lamps, cathode ray tubes, lasers and inorganic pigments. In this study, Pr3+ is doped in spinel Li2ZnTi3O8 system and synthesized by the polymeric precursor method, which is based on the process developed by the Pechini, and characterized by X-ray diffraction, UV-visible and CIE-L colorimetric measures * a * b *., in order to study the effect of doping and thermal treatment on its colorimetric properties. With three different samples of Pr3+ doping (0.01; 0.05 and 0.1 mol%) were prepared and calcined at 500°C, 600°C, 700°C, 800°C and 900°C for 4 h. The analysis of X-ray diffraction confirmed the formation of pure phases with spinel structure and average crystallite size of less than 46 nm. It was found that the colorimetric properties ranging from green to red, in accordance with the increase in the concentration of Pr3+ and thermal processing temperature.

Microstructural and Colour Analysis of CuCrO2 Delafossite Obtained by Gelatin Method

In this paper, CuCrO2 the compound was synthesized by a route new that uses gelatin as organic precursor in order to application as ceramic pigments. The type of compound delafossite CuCrO2 is known for its wide range of application, such as, thermoelectric devices, catalysts for the steam reforming process, ceramic pigments, NiO2 removal, among. The powders resulting from the synthesis process were calcined the 900 °C and characterized by X-ray diffraction (XRD), infrared spectroscopy, scanning electron microscopy (SEM), UV-Visible spectroscopy and colorimetry analysis. The results showed for the CuCrO2 have coloring green.

Combustion Synthesis of Cu1-xNixCr2O4 Spinel for Catalytic Applications

Transition-metal spinels are efficient catalysts in a number of heterogeneous processes, such as CO oxidation, catalytic combustion of hydrocarbons and oxychlorination of methane. The properties of catalytic materials are highly dependent on the synthesis route. Spinels are often produced at high temperatures by the calcination of precursors such as powder mixtures, slurries or resins. Combustion synthesis is a cost-efficient method used to produce homogeneous and fine particles with high reproducibility. Cu0.8Ni0.2Cr2O4 spinel was obtained by the combustion of metallic nitrates using urea as fuel. The resulting powders were calcinated at different temperatures and characterized by thermogravimetric and particle size analyses, X ray diffraction, and scanning electron microscopy. The effect of urea on the control of the process and particle morphology was investigated. The results revealed the formation of porous powders with increasing crystallinity as the calcination temperature increased. Crystallization of spinel started at 700 oC.