Eu-doped ZnO nanoparticles for dielectric, ferroelectric and piezoelectric applications

Abstract

Europium doped ZnO nanorods were successfully synthesized using low cost wet-chemical precipitation method. The crystalline phases and structural analysis were investigated by powder X-ray diffraction (XRD) study. XRD analysis confirmed the formation of wurtzite hexagonal crystal system for both pure and Europium doped ZnO. The crystallite size, lattice strain, stress and energy density were evaluated by line broadening analysis methods such as Scherrer and Williamson-Hall (W-H) methods. Transmission electron microscopy (TEM) confirmed that pure and Europium doped ZnO nanoparticles were grown in the shape of rods. The average diameter of pure ZnO nanorods was found to be ∼85.79 nm. The average diameter (∼78.92 nm) of the Eu-doped ZnO nanorods measured using TEM analysis was found to be in co-relation with W-H methods. Detailed analyses of frequency and temperature dependence of dielectric constant, dielectric loss and AC conductivity of pure and Europium doped ZnO were performed. Improved ferroelectric to paraelectric phase transition temperature at Tc = 230 °C was observed for Eu-ZnO sample. In ferroelectric measurement of Europium doped ZnO, remnant polarization and coercive field were found to be 0.11 μC/cm2 and 5.81 kV/cm, respectively. In addition, butterfly loop and effective piezoelectric coefficient (d33) versus applied voltage curve were traced for Europium doped ZnO nanorods. The mean value of d33 was evaluated to be 43.38 pm/V. I-V studies were carried out to measure the effect of Europium doping on DC conductivity of ZnO.