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PbS nanopowder – synthesis, characterization and antimicrobial activity

Suganya M., Balu A. R.

Materials Science Poland

2017

Vol. 35, No. 2

322--328

Lead sulphide (PbS) nanopowder was synthesized by a simple soft chemical route using lead nitrate and thiourea as precursor salts. The as-synthesized nanopowder was characterized by XRD, SEM, EDX, FT-IR, PL, Raman and magnetic measurements. XRD studies reveal the polycrystalline nature of the powder. The powder exhibits face-centered cubic structure with a strong (2 0 0) preferential orientation. The presence of Pb and S in the powder is confirmed by energy dispersive X-ray analysis. The peaks observed at 1112 cm-1 and at 606 cm-1 in the FT-IR spectrum are related to heteropolar diatomic molecules of PbS. The Raman peak shift at 173 cm-1 might have originated from the combination of longitudinal and transverse acoustic phonon modes associated with PbS crystal. The M-H loop confirms the paramagnetic nature of the as-synthesized PbS nanopowder. The nanopowder has significant antimicrobial activity against certain bacteria and fungi strains which make it suitable as antimicrobial agent against pathogenic microorganisms.

Characterisation and preparation of sonochemically synthesised silver-silica nanocomposites

Askari S., Halladj R., Nasernejad B.

Materials Science Poland

2009

Vol. 27, No. 2

397--405

Properties of nanoparticles differ from those of bulk phase or individual molecules. The metal form of these particles shows chemical and physical properties that can be used in fields such as optics, optoelectronics and catalysis. Silver nanoparticles can be used as an antimicrobial agent in wound dressings and as surface coatings, e.g., catheters. In this work, silver nanoparticles were deposited on silica submicrospheres using ultrasounds. A mixture of silver nitrate solution with silica submicrospheres was sonificated under an atmosphere of argon gas in order to eliminate oxygen and decrease both the cavitational threshold as well as the intensity of the ultrasounds. Duration of irradiation was varied between 90 and 180 min at a the frequency of 24 kHz.The resulting silver-silica nanocomposites were characterized with Fourier transform infrared (FTIR), high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and X-ray florescence (XRF). The results of SEM micrographs show submicrospheres of silver-silica nanocomposites, with the 16-64 nm size distribution. Furthermore, HR-TEM micrographs show that the particle size distribution does not depend on time of irradiation. The particle size distribution of silver nanocomposite in all samples was approximately 4-30 nm. EDAX and FTIR measurements show that, with increasing AgNO3concentration, the percentage of deposited silver on silica increases. XRF patterns show that the amount of silver deposited on silica can be increased by increasing the ultrasound power.