Sol-gel synthesized and microwave heated Pb0.8-yLayCo0.2TiO3 (y = 0.2-0.8) nanoparticles: Structural, morphological and dielectric properties

In this work, the Pb0.8-yLayCo0.2TiO3 (y = 0.2-0.8) (PLCT) nanoparticles were prepared by sol-gel method and further subjected to microwave heating. The formed tetragonal reflection planes of PLCT samples were on par with PbTiO3 (PT) and lanthanum cobalt titanate (LCT) tetragonal phases. Especially, for y = 0.2-0.4, PLCT attained the PT structure while for y = 0.6-0.8, PLCT acquired the LCT structure. That is, the structural transformation occurred from tetragonal PT to tetragonal LCT phases at higher La-contents. The high resolution transmission electron microscope (HRTEM) and field emission scanning electron microscopes (FESEM) showed complete formation of nanofibers at y = 0.8 which may reveal drug delivery system applications. The Fourier transform infrared spectra (FTIR) were recorded in order to find the presence of metal oxide bonds. The dielectric properties evidenced that the transition temperatures (Tc) were found to be increasing from 713 to 783 K with increase of y-value. Furthermore, the temperature and frequency dependence of dielectric constant (ε′), dielectric loss (ε′′), ac-electrical conductivity (σac), real (M′) and imaginary (M′′) parts of complex dielectric modulus (M*) was described. The Power law was used to fit the logσac versus logω plots in order to determine the dc-conductivity (σdc) and exponent (n) values of the samples at room temperature (RT). Later on, the Arrhenius plots (lnσac versus T−1 plots) were drawn to find the activation energies. The results expressed the existence of two activation energies at low and high temperature regions due to slope change before and after Tc.