Investigation on Modified ZnO for Ferroelectric and Optical Applications

Abstract

In this approach undoped and doped (Samarium, Europium, Titanium, Niobium) ZnO samples were prepared via chemical route (co-precipitation) in the basic medium by adjusting the pH about 10.82. Undoped and doped samples were examined by XRD, FTIR, UV-Visible Spectroscopy, Photoluminescence spectroscopy , LCR meter, P-E loop tracer and SEM to investigate the structural, chemical, optical, dielectric, ferroelectric, and morphological nature of the samples. The XRD pattern of doped sample showed that no impurity peaks appeared and no change in the wurtzite hexagonal structure of ZnO, which confirming that dopant ions successfully substitute the Zinc ions. Chemical analysis is in good agreement with the structural analysis as only one reflection (455.54 cm-1) corresponding to Zn-O has been observed. Optical spectra infer that optical band gap decreased in doped ZnO in comparison to undoped. Photoluminescence investigation reveals the presence of green and blue colour emission in undoped and doped ZnO samples at 190 nm excitation wavelength; interestingly Europium doped system show orangish-yellow luminescence at 254 nm excitation wavelength. Temperature and frequency dependent dielectric measurements indicates transition at 710c for pure, 820c for 0.25 % and 1570c for 1% Titanium doped ZnO, which reflects certain shift in Tc , which gives an idea about presence of ferroelectricity in these systems. P-E loops for the Ti (0.25 and 1%) doped ZnO systems were found to be lossy in nature. Morphological study does not give any significant inference; only clusters of spherical particles have been found.