This project approach the preparation and electric and photocatalytic characterization of nanopowders of semiconductor ferroelectric oxides of strontium potassium niobate and theirs solid solutions content nickel cations. This project will give support to a new research line in implantation in the group of Composites and Functional Ceramics - LaCCeF, involving Nanoscale Effect, where the electrical and photocatalytic properties of nanoparticles will be investigated. In this project, from the tungsten bronze (TB)-type host structure of KSr2Nb5O15 will be studied the solid solutions content nickel atoms: KSr2(NixNb5-x)O15-delta, where x varies between 0.25 and 1, prepared by chemical synthesis, using the Modified Poliol method. These systems constitute a wide base of crystalline structures with distinct forms of occupation of specific sites. However, there is a lack of information about the substitution of non isomorphs cations in TB structure. The optimization of necessary parameters to obtaining the nanoparticles and nanostructured particles of KSr2Nb5O15 and theirs solid solutions will be monitored by X-ray diffraction. The diffraction pattern will be refined according to the Rietveld method using the Fullprof program. The nanoparticles will also be characterized by infrared (IR) and U.V-Visible spectroscopy, thermal analysis (TGA, DTA and DSC) and electric measurements, using the impedance spectroscopy technique, in the frequency range of 5 mHz to 13 MHz, in a wide temperature range (25 oC until 700 oC). Based on the a.c. measures will be investigated the electric conductivity and dielectric permittivity of the nanoparticles and dielectric loss phenomenon (tan x temperature and tan x frequency). A furnace attached to the sample holder will permit to performer the electric measurements since room temperature up to 700°C. The photocatalytic activity will be investigated using a photoreactor of low power developed in the LaCCeF. The study photocatalytic will be accomplished from heterogeneous photocatalysis with the addition of nanoparticles in solution containing phenol-red as substratum to be degraded. The analysis of the degradation degree will be accomplished by colorimetric analysis.
News published in Agência FAPESP Newsletter about the scholarship: