X-ray diffraction line profile analysis of chemically synthesized lead sulphide nanocrystals

Lead sulphide (PbS) nanocrystals with Pb:S molar ratios 1:1, 1:0.75, 0.75:0.75 and 0.75:1 are synthesized by chemical method. The structural properties are studied by X-ray diffraction line profile analysis using classical Williamson-Hall (WH) and modified Williamson-Hall (MWH) methods. A detailed fitting procedure of X-ray diffraction line profiles using MWH method for PbS nanocrystals is presented. The MWH method is found to fit better as compared to WH method indicating that strain broadening is caused by the presence of dislocations. Both these methods yield crystallite size of about 15 nm. The lattice strain (average dislocation density) as determined by WH (MWH) method is found to vary between 4.27 x 10(-3) and 6.23 x 10(-3) (1.72 x 10(17) m(-2) to 3.84 x 10(17) m(-2)). Further, the analysis indicates that edge dislocations are main contributors in inducing strain in the nanocrystals. (C) 2012 Elsevier B.V. All rights reserved.