In this work, we will discuss the optical properties of NiO nanoparticles that we have investigated recently by photoluminescence (PL) spectroscopy. In particular, we will show the blue-shifts of PL, originating from the electron–hole recombination of the self-trapped exciton (STE), observed in smaller-sized NiO nanoparticles. To explain the size effect in relating to the STE PL shift, a question has been raised on whether it is appropriate to apply him quantum confinement (QC) theory usually used for the Mott-Winner type excitons in semiconductors to wide band-gap material, such as silica. Variations in several parameters and their effects on the structural (crystal size and morphology) properties of nanoparticles were investigated. Characterizations were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal stability (TGA and DTA), solid state UV and solid state florescent (PL)

Nanocrystalline diamond (NCD) films are being used in a large number of applications. Also, diamond nanorods (DNRs) exhibit distinctive features that are not present in diamond films, because of the tunable large surface-to-volume ratio and tubular configuration. In this work, we report on the synthesis of DNRs by means of the bottom-up and template-free method from NCD films by the hot filament chemical vapor deposition system. The substrate materials used for diamond deposition were stainless steel (AISI 316) and chromium nitride-coated stainless steel. On both substrates, NCD films and then DNRs have been synthesized. The micro-Raman confirms that the synthesized structure is NCD. In addition, the grazing incident x-ray diffraction pattern confirms the presence of cubic diamond and rhombohedral diamond as a film on the CrN and Cr₂N interlayer. Also, the DNRs are encased in an amorphous carbon (a-C) shell. The DNRs are grown on the NCD grains by a bottom-up technology and template-free method. Their orientations are almost random in the diamond thin-film surface. In addition, the density of DNRs on the NCD film for the CrN interlayer is more than for the stainless-steel substrate. The NCD/DNR films are dense, adhesive, continuous, and almost uniform on the CrN-coated stainless-steel substrate.