شكيبا دانشجو

High-entropy ceramics are a new class of materials that were introduced to the world after the emergence of high-entropy alloys. However, until this moment, the exact mechanism of entropy effect on many of their characteristics remains unclear. Understanding the process of synthesis of high entropy materials is an important issue, mastering its dimensions can play a significant role in controlling the final properties of the material. In the upcoming research, to investigate the factors affecting the synthesis process, the high entropy compound (Mg, Ni, Co, Cu, Zn)O has been synthesized using the citrate sol-gel method. In this method, first, the sol resulting from the dissolution of nitrate precursors and citric acid was converted into a gel at a temperature of 80 °C and dried at a temperature of 120 °C, at temperatures of 800, 900 and 1000 °C, for three to eight hours and It was synthesized with one and two citrate to nitrate ratios in the furnace and the effect of time, temperature and citrate to nitrate ratio on its synthesis was investigated using XRD, SEM, FESEM, TEM and XRF analyses. The results indicate the existence of optimal temperature, time, and the ratio of precursors, which for this experiment, the temperature is 900 °C, the time is four hours and the ratio of citrate to nitrate is one. In the mentioned conditions, the XRD pattern of the synthesized material shows the formation of a single-phase material with the structure of rock salt, and FESEM, SEM, and TEM analysis also confirm the homogeneous dispersion of elements and the formation of a single-phase material. In the continuation of the experiments and to investigate one of the applications of the synthesized oxide, by using the TPR analysis and the catalytic activity test, the performance of the mentioned material as a methane combustion catalyst was eva‎luated. TPR analysis shows the presence of three peaks at temperatures around 900, 800, and 380 °C, which shows the reductive properties of the material and the reduction temperatures indicate the catalytic properties of the material. The methane oxidation reaction was completed at a temperature of 750 °C and a time of 1.5 hours, which indicates the catalytic property of this substance as a methane combustion catalyst.

اكسيد آنتروپي بالا , سنتز , كاتاليزگر , احتراق كاتاليزگري متان

high entropy oxide , synthesis , catalyst , methane catalytic combustion

shakiba daneshjoo

hosein sarpoolaki, hajar ghanbari