AC and DC electrical transport studies of (Fe, Co) codoped ZnO nanoparticles

Abstract

High temperature ferromagnetism and optical properties of Co doped ZnO nanoparticles J. Appl. Phys. 108, 084322 (2010); 10.1063/1.3500380Microstructural and magnetic properties of ZnO:TM ( TM = Co , Mn ) diluted magnetic semiconducting nanoparticlesThe authors have presented microstructural, ac-and dc-electrical properties, and magnetic and optical studies of Zn 1-x Fe x/2 Co x/2 O (x ¼ 0.1 and 0.2) semiconducting nanoparticles, prepared through low temperature chemical "pyrophoric reaction process." Structural characterizations confirm the formation of single phase (at a calcination temperature of 300 C), chemically homogeneous, nanometric sample ($7 nm). Electrical studies on those samples have been carried out using an ac impedance spectroscopy and dc resistivity technique. Temperature dependent relaxation processes have been investigated by studying complex impedance spectroscopy. The authors have also estimated activation energy from both ac and dc resistivity data of those nanoparticles. Magnetic data clearly reveal the presence of some sort of magnetic behavior, even up to room temperature, in the x ¼ 0.2 sample, whereas for x ¼ 0.1 sample, there in no such magnetic behavior. This feature has been explained through magnetic polaron percolation theory. The authors have also estimated semiconducting band gap of those nanoparticles using recorded absorbance spectra.

Enhancement of dielectric constant in transition metal doped ZnO nanocrystals

“…1 show the corresponding HRTEM images, which clearly demonstrate that all the nanoparticles are single crystalline and free from any lattice defects. FE-SEM micrographs and EDAX spectra 16 correspond to absence of any phase segregation and good chemical homogeneity of these nanoparticles.…”

“…[11][12][13][14][15][16] Structural characterizations have been carried out using x-ray diffraction (XRD) with monochromatic Cu-K a radiation, transmission electron microscopy (TEM) (JEOL, JEM-2100, 200 kV), high resolution field emission scanning electron microscopy (FE-SEM), and energy dispersive x-ray analysis (EDAX). Detailed dielectric studies have been carried out using Agilent impedance analyser (4294A) along with a homemade Proportional-Integral-Derivative (PID)-controlled furnace.…”