SOL-GEL PREPARATION AND CHARACTERIZATION OF NOVEL MIXED-METAL COBALTATES-ALUMINATES

Abstract

This article reports on the sol-gel synthesis and characteristic properties of novel mixed neodymium and neodymium-yttrium cobaltates and cobaltates-aluminates (NdCoO₃, NdCo_0.75Al_0.25O₃, NdCo_0.5Al_0.5O₃, NdCo_0.25Al_0.75O₃, (Nd_0.5Y_0.5)CoO₃, (Nd_0.5Y_0.5)Co_0.75Al_0.25O₃, (Nd_0.5Y_0.5)Co_0.5Al_0.5O₃, and (Nd_0.5Y_0.5)Co_0.25Al_0.75O₃). The polycrystalline powders were characterized by powder X-ray diffraction (XRD) analysis, Fourier transform-infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). Single-phase solid solutions NdCo_1-xAl_xO₃ and (Nd_0.5Y_0.5)Co_1-xAl_xO₃ were obtained after annealing precursor gels for 10 h at 1000°C. From the results obtained, it could be concluded that the NdCo_1-xAl_xO₃ and (Nd_0.5Y_0.5)Co_1-xAl_xO₃ solids are composed of spherical grains with uniform size (from 100 to 500 nm). The surface morphology changes slightly with substitution of cobalt by aluminium and neodymium by yttrium. With increasing amount of aluminium the crystalline particles formed with more pronounced agglomeration. The possible application of synthesized compounds as blue cobalt-based pigments was suggested.

Keywords:

• Cobalt-based pigments
• Cobaltates-aluminates
• Perovskites
• Sol-gel synthesis

Acknowledgments

This research was funded by a grant (No. TAP-04/2011) from the Research Council of Lithuania. The authors wish to thank Dalia Jonynaite for technical assistance.