The sodium borosilicate glass doped with indium nanocrystals have been successfully prepared by sol-gel route. The thermal stability behavior of the stiff gel is investigated by thermogravimetric (TG) and differential thermal (DTA) analysis. The crystal structure of the glass is characterized by X-ray powder diffraction (XRD). Particle composition is determined by X-ray photoelectron spectroscopy (XPS). Size and distribution of the nanocrystals are characterized by transmission electron microscopy (TEM) as well as high-resolution transmission electron microscopy (HRTEM). Results show that the iridium nanocrystals in tetragonal crystal structure have formed in glass, and the average diameter is about 30 nm. Further, the glass is measured by Z-scan technique to investigate the nonlinear optical (NW) properties. The third-order NLO coefficient chi((3)) of the glass is determined to be 2.81 x 10(-10) esu. The glass with large third-order NLO coefficient is promising materials for applications in optical devices. (c) 2012 Elsevier Ltd. All rights reserved.