Study of Bandgap Energy of Novel Nanocomposite

In this novel work, we have studied the optical properties of CuBaM-CZFO nanocomposites. (Cu0.5Ba0.5Fe12O19)1-x/ (Co0.6Zn0.4 Fe2O4) x [where x=0.1,0.2] nanocomposites were synthesized individually by sol-gel citrate method and then made into nanocomposites by physical mixing technique. Further characterization over their structural, morphological and optical properties were carried out in detail. With the help of UV analysis, the optical properties such as, the band gap energy was discovered which is found using Tauc’s plot. The bandgap energy is 2.6503eV for CuBaM-CZFO 90-10 which is lesser than CuBaM-CZFO 80-20 (2.8456eV). The structural, morphological and optical properties of novel CuBaM-CZFO nanocomposite are reported and compared with, both among themselves and from the literature review.

Comparison of Precursor Preparation Routes on Final Density of Y3Fe5O12 Garnets Prepared via Reactive Sintering

Yttrium iron garnet was obtained using four methods of synthesis. A modified citrate method and a modified citrate method with YIG (yttrium iron garnet, Y3Fe5O12) nucleation were used. In two subsequent methods, YIP (yttrium iron perovskite, YFeO3) and α-Fe2O3 obtained in the first case by the citrate method and in the second by precipitation of precursors with an ammonia solution were used as the input precursors for reaction sintering. Differential scanning calorimetry (DSC) measurements of the output powders obtained by all methods allowed to identify the effects observed during the temperature increase. Dilatometric measurements allowed to determine the changes in linear dimensions at individual stages of reaction sintering. In the case of materials obtained by the citrate method, two effects occur with the increasing temperature, the first of which corresponds to the reaction of the formation of yttrium iron perovskite (YIP), and the second is responsible for the reaction of the garnet (YIG) formation. However, in the case of heat treatment of the mixture of YIP and α-Fe2O3, we observe only the effect responsible for the solid state reaction leading to the formation of yttrium iron garnet. The obtained materials were reaction sintered at temperatures of 1300 and 1400 °C. Only in the case of material obtained from a mixture of perovskite and iron(III) oxide obtained by ammonia precipitation at temperature of 1400 °C were densities achieved higher than 98% of the theoretical density. The use of Hot Isostatic Pressing (HIP) in the case of this material allowed to eliminate the remaining porosity and to obtain full density.

SYNTHESIS OF PEROFSKITE-LIKE Co-CONTAINING CATALYST

There are several approaches to the preparation of catalysts with a developed surface based on oxides with a perovskite structure. Perovskites, due to the possibility of easy variation of chemical composition, make it possible to choose the optimal composition of the catalyst and surface area, and as a result it is possible to influence effectively the selectivity. Perovskite-like LaMeO3 oxides are one of the most promising catalysts for many oxidation processes due to their high activity in oxidative reactions and the stability in aggressive environment. Pekini method (polymer complexes method) and its simplified variant - citrate method are the most widely used for the synthesis of perovskite-like oxides. This article reports about the synthesis of perovskite-like complex oxide LaCoO3 obtained in two ways: hydrothermal, using ethylene glycol, and the citrate method using the template – mesoporous silica KIT-6. The structure of the samples obtained was determined by the XRD method. As a result, it was found that the catalysts have a perovskite structure. Key words: LaCoO3 , perovskite, KIT-6.