RESUMO
Chromium doped zinc gallium oxide (ZnGa2O4:Cr3+) microrods were synthesized by simple solid state reaction method. The transformation on crystal structure and optical properties with molar concentration of Cr3+ were analyzed. The cubic spinel nature of ZnGa2O4:Cr3+phosphor and their crystalline nature were confirmed from x- ray diffractogram. The average grain size of the samples range between 24 and 29â¯nm, with lattice parameter values greater than that of bulk. Lattice strain produced in the lattice on doping was estimated from the Williamson-Hall plot. It increases on Cr3+ doping up to 3â¯mol% and then decreases. Rod like nature of zinc gallate was observed from the surface morphological analysis using SEM. X-ray photoelectron spectroscopy was used for the chemical state identification of the constituent elements in the compound. The photoluminescense spectra consists of various emission lines originated from the chromium ion in the spinel lattice. The purity of red emissions were observed from chromaticity diagram with a concentration quenching initiated from the dipole-dipole interaction, with increase in dopant concentration. Band gap of the samples were estimated using Kubelka-Munk equation which exhibited red shift compared to bulk due to band tailing effect.
Assuntos
Cromo/química , Luminescência , Compostos de Zinco/química , Espectroscopia Fotoeletrônica , Termodinâmica , Difração de Raios XRESUMO
A surfactant-free, template-less and seed-less method, namely the thermal-assisted photoreduction (TAP) process, has been developed to synthesize vertically grown Au nanowires (30-80 nm in diameter and about 2 µm in length) on the surface of thin film titanium dioxide (TiO(2)), which is locally excited by blackbody radiation. The Au nanowires thus produced are single-crystalline with a preferred [Formula: see text] growth direction. The electrical behavior investigated using a nanomanipulation device indicates that the Au nanowires possess an excellent electrical resistivity of about 3.49 × 10(-8) Ω m.