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Effect of NaOH concentration on optical properties of zinc oxide nanoparticles

Koutu V., Shastri L., Malik M. M.

Materials Science Poland

2016

Vol. 34, No. 4

819--827

In the present work, powder zinc oxide samples were prepared by varying NaOH concentration (0.1 M – 0.4 M) using wet-chemical co-precipitation method. As-synthesized ZnO was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL) and Raman spectroscopy. Formation of hexagonal wurtzite structure of the ZnO samples has been revealed from XRD studies. This study further suggests reduction in crystallite size from 40 nm to 23 nm with an increase in NaOH concentration which is confirmed by FESEM. PL and Raman spectroscopy studies of these samples show significant peak shift towards the higher and lower energy respectively, with maximum PL emission between 400 nm and 470 nm region of the visible spectrum. Noticeable inverse relationship between optical properties of ZnO nanoparticles and NaOH concentration may be attributed to the rapid nucleation during the synthesis process. With these remarkable properties, ZnO nanoparticles may find applications in nanoelectronic devices, sensors, nanomedicine, GATE dielectrics, photovoltaic devices, etc.

Extraction mechanism of lead ion with p-allylcalix[4]arene tetracarboxylic acid

Ohto K., Yokomoto T., Higuchi H., Oshima T., Inoue K., Jumina

Ars Separatoria Acta

2004

No. 3

62-71

25,26,27,28-Tetrakis(carboxymethoxy)-5,11,17,23-tetraallylcalix[4]arene in a cone conformation has been synthesized for the selective extraction of divalent lead ions. The extraction of divalent metal ions, such as lead, copper, nickel and zinc with p-allycalix[4]arene tetracarboxylic acid was investigated. The extraction data and chemical shift of 1H-NMR for the extractant, caused by the complexation with lead, supports the conclusion that two lead ions are extracted stepwise. The complex structure was proposed.