Preparation and characterization of CuCr2O4/SiO2 and Cu2Cr2O4/SiO2 nanocomposites obtained from carboxylate complex combinations

Abstract

This study reports the preparation and characterization of CuCr2O4/SiO2 and Cu2Cr2O4/SiO2 nanocomposites. In order to obtain 50 mass% CuCr2O4/SiO2 and Cu2Cr2O4/SiO2 nanocomposites, we have used a method based on the thermal decomposition of the precursors Cu(II) and Cr(III) carboxylate type complexes inside the SiO2 matrix. The precursors were formed inside the gels during the redox reaction between Cu(II) and Cr(III) metal nitrates and 1,3-propanediol (1,3PD). As a result of the gels heating, the precursors decomposed at ~ 300 °C leading to the amorphous metal oxides CuO and Cr2O3+x. Cr2O3+x turned to crystalline α-Cr2O3 (crystalline) at 400 °C which subsequently interacted with CuO. Well crystallized Cu2Cr2O4 was obtained at 1000 °C as a result of the interaction between CuCr2O4 and residual CuO formed at 800 °C. In both samples the oxides were homogenously distributed within the amorphous silica matrix. The nanocomposite samples CuCr2O4/SiO2 and Cu2Cr2O4/SiO2 obtained at different annealing temperatures were characterized by thermal analysis, FT-IR spectrometry and powder x-ray diffraction. The results showed that the silica matrix plays a crucial role for the preparation of the desired chromite nanoparticles.