Two sets, one deposited for similar to20 min and other for similar to1 h of diamond thin film samples are prepared following pretreatment of silicon substrates using mixed slurry containing different weight ratio of zirconium and diamond particles. The films are characterized ex situ using XRD, Raman spectroscopy, photoluminescence (PL), FTIR and atomic force microscopy (AFM). As evidenced from AFM topography, nucleation density as high as 2.5 x 10(9) particles/cm(2) could be achieved in spite of posttreatment cleaning of the substrates with methanol. It has been found that the nucleation density increases, while particle size and RMS surface roughness subsides with increasing metal concentration in the mixed slurry. Raman and PL spectra of both the 20 min and 1 h samples have been recorded to check the quality of the deposits. Although a significant amount non-diamond carbon impurities is found to be present mostly at the grain boundaries of the films, the concentration of defects due to [Si-V](0) complex reduces substantially for full-grown samples and also for 20 min samples pretreated with metal-rich slurries. The plausible role of the intermediate layers behind these effects has been explored. (C) 2004 Elsevier B.V. All rights reserved.