Characterization of bismuth titanate ceramics derived by mechanochemical synthesis

Bismuth titanate, Bi(4)Ti(3)O(12) (BIT) nanosized powders have been successfully synthesized via high energy mechanochemical activation. The phase formation of BIT, crystal structure, microstructure, crystallite size and specific surface area were followed by XRD, scanning electron microscopy (SEM) and the BET specific surface area measurements. The BIT milled 2 h shows the orthorhombic crystalline structure with small amount of amorphous phase. The microstructure of Bi(4)Ti(3)O(12) ceramics sintered at 1000 degrees C for 12h exhibit plate-like grain structure

Ga-modified Nanostructured Zno: Characterization And Application In Dye-sensitized Solar Cells

ZnO has received great attention in many applications due to its electronic and optical properties. We report on the preparation of ZnO and gallium-containing ZnO (ZnO:Ga) nanoparticles by the precipitation method. The nanoparticles have the wurtzite structure and a high crystallinity. Gallium ions are present as Ga 3+, as evidenced by the binding energies through XPS. Porosity and surface area of the powder increased under increasing gallium level, explained by the smaller particle size of ZnO:Ga samples compared with ZnO. The estimated optical band gap of ZnO was 3.2 eV, comparable to ZnO:Ga.591-5931317O'Regan, B., Grätzel, M., (1991) Nature, 353, p. 737Kroon, J.M., Bakker, N.J., Smit, H.J.P., Liska, P., Thampi, K.R., Wang, P., Zakeeruddin, S.M., Tulloch, G.E., (2007) Progress in Photovoltaics, 15, p. 1Ma, T., Akiyama, M., Abe, E., Imai, I., (2005) Nano Lett, 5, p. 2543Ko, K.H., Lee, Y.C., Jung, Y.J., (2005) J. Colloid: Interface Sci, 283, p. 482Kakiuchi, K., Hosono, E., Fujihara, S., (2006) J. Photochem. Photobiol., A, 179, p. 81Keis, K., Vayssieres, L., Rensmo, H., Lindquist, S.-E., Hagfeldt, A., (2001) J. Electrochem. Soc, 148, pp. A149Gonçalves, A.S., Lima, S.A.M., Davolos, M.R., Antônio, S.G., Paiva-Santos, C.O., (2006) J. Solid State Chem, 179, p. 1330Roberts, N., Wang, R.P., Sleight, A.W., Warren, W.W., (1998) Phys. Rev. B, 57, p. 573

Contribution of structural order–disorder to the room-temperature photoluminescence of lead zirconate titanate powders

International audienceIntense and broad visible photoluminescent (PL) band was observed at room temperature in structurally disordered PbZr0:53Ti0:47O3 powders. The lead zirconate titanate PbZr0:53Ti0:47O3 powders prepared by the polymeric precursor method and heat treated at different temperatures were structurally characterized at long range by means of X-ray diffraction. The PL was measured at room temperature samples heat treated at different temperatures. Experimental measurements and quantum-mechanical calculations showed that the high structural order and the high structural disorder in PbZr0:53Ti0:47O3 lattice are not favorable to the intense PL emission. Only samples containing simultaneous structural order and disorder in their lattice present the intense visible PL emission at room temperature