Hydrothermal synthesis of nanocrystalline ZnSe: An in situ synchrotron radiation X-ray powder diffraction study |
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Authors: | J-E Jørgensen TR Jensen |
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Institution: | a iNANO and Department of Chemistry, University of Aarhus, DK-8000 Århus C, Denmark b Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA |
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Abstract: | The hydrothermal synthesis of nanocrystalline ZnSe has been studied by in situ X-ray powder diffraction using synchrotron radiation. The formation of ZnSe was studied using the following starting mixtures: Zn+Se+H2O (route A) and ZnCl2+Se+H2O+Na2SO3 (route B). The route A experiment showed that Zn powder starts reacting with water at 134 °C giving ZnO and H2 followed by the formation of ZnSe which takes place in temperature range from 167 to 195 °C. The route B experiment shows a considerably more complex reaction path with several intermediate phases and in this case the formation of ZnSe starts at 141 °C and ZnSe and Se were the only crystalline phases observed at the end of the experiment where the temperature was 195 °C. The sizes of the nanocrystalline particles were determined to 18 and 9 nm in the route A and B experiments, respectively. Nanocrystalline ZnSe was also synthesized ex situ using the route A and B methods and characterized by conventional X-ray powder diffraction and transmission electron microscopy. An average crystalline domain size of ca. 8 nm was determined by X-ray powder diffraction in fair agreement with TEM images, which showed larger aggregates of nanoparticles having approximate diameters of 10 nm. Furthermore, a method for purification of the ZnSe nanoparticles was developed and the prepared particles showed signs of anisotropic size broadening of the diffraction peaks. |
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Keywords: | Semi-conducting nanoparticles Hydrothermal synthesis In situ X-ray powder diffraction |
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