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

This article reports on the sol-gel synthesis and characteristic properties of novel mixed neodymium and neodymium-yttrium cobaltates and cobaltates-aluminates (NdCoO3, NdCo0.75Al0.25O3, NdCo0.5Al0.5O3, NdCo0.25Al0.75O3, (Nd0.5Y0.5)CoO3, (Nd0.5Y0.5)Co0.75Al0.25O3, (Nd0.5Y0.5)Co0.5Al0.5O3, and (Nd0.5Y0.5)Co0.25Al0.75O3). 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 NdCo1-xAlxO3 and (Nd0.5Y0.5)Co1-xAlxO3 were obtained after annealing precursor gels for 10 h at 1000°C. From the results obtained, it could be concluded that the NdCo1-xAlxO3 and (Nd0.5Y0.5)Co1-xAlxO3 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.