Correlation of heat treatment and the impurities accompanying Ag nanoparticles
A facile and rapid wet chemical flash method has been used for the formation of silver nanoparticles (Ag NPs). Silver nitrate, chromium nitrate and urea were used to form the as-prepared Ag NPs and two types of silver chromium oxide impurities due to the energy used in preparation (250 °C) is not enough to decompose these impurities. The types of impurities accompanied by Ag NPs were depended on the heat treatment. The experimental results show that the structural properties of the as-prepared Ag NPs at 250 °C, were accompanied by AgCrO2 and Ag2CrO4, however, at higher annealing temperature 400 °C, Ag NPs were accompanied by AgCrO2 only. X-ray diffraction patterns showed single-phase spinel structure of both samples. The morphology and the chemical composition of the samples are found out using field emission scanning electron microscopy with energy-dispersive X-ray analysis. The crystallite size and the particle size were found to increase with the increase of the annealing temperature. The magnetic behavior, using a vibrating sample magnetometer, indicated a decrease in the exchange bias happened in the hysteresis loop by increasing the annealing temperature. Moreover, the magnetization (Ms) of Ag NPs was improved by increasing the annealing temperature. The antimicrobial studies of Ag NPs at both temperatures showed strong effect against tested bacteria. The as-prepared Ag NPs showed a strong effective treatment against Candida albicans fungi. On the other hand, Ag NPs at 400 °C showed no effect on the tested fungi. Thus, heat treatment had a correlation on the impurities accompanied by Ag NPs, and also on the magnetic and antimicrobial studies.
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