Study of crystallization and spectral properties of PbS nanocrystals dopedin SiO2 aerogel matrix

PbS nanocrystallites with a diameter smaller than 15 nm doped in silica aer ogel matrix have been prepared by sol-gel route preceding supercritical dry ing technique and colloidal chemistry method. These PbS-nanocrystals-doped aerogels were characterized by optical absorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Blue shifts in optical absorpti on threshold indicate that the PbS crystallite sizes range from 5 to 15nm w ith an increase of annealing temperature from 298 to 1023 K. It has been sp eculated that three mechanisms exist during the growth of the PbS nanocryst allites, and various apparent growth excitation energies were calculated us ing an Arrhenius relation. (C) 2000 Elsevier Science B.V. All rights reserv ed.