Photoluminescence investigations of Eu~(3+) doped BaTiO_3 nanopowders fabricated using heterometallic tetranuclear alkoxide complexes

摘要

The synthesis of Ba-Ti precursors was achieved by a self-assembly synthesis starting from barium metal, titanium n-propoxide and 2,2,6,6-tetramethyl-heptanedione (Hthd) in ~nPrOH. The structure of the obtained Ba_2Ti_2(thd)_4(O~nPr)_8(~nPrOH)_2 compound is of the M_2M'_2X_(16) type-one of the most widespread for both the homo- and heterometallic tetranuclear alkoxide complexes. It remains unchanged in solution according to the NMR data, which are easily interpreted in terms of the same molecular structure as that revealed by crystallography for the solid state. In order to form BaTiO_3 phase doped with 1 percent of the Eu~(3+) the heterometallic alkoxide complex of barium and titanium with the necessary amount of Eu dissolved in the reaction mixture were hydrolyzed by moist ethanol on reflux in 1 M solution in n-propanol. The obtained gels were dried in vacuum and have been heat treated at different temperatures (700-1100 deg C). XRD measurements were performed in order to study the phase formation and grain size. TEM images have been taken for the morphology and grain size characterization. Emission spectra and decay times were measured for the description of the luminescence properties of the obtained system.