Structure and electrical properties of Mg-doped ZnO nanoparticles

Mg_xZn_1-xO (x=0.01-0.3) nanoparticles were synthesized by the sol-gel technique using solutions of Mg and Zn based organometalic compounds. The electrical properties of Mg doped zinc oxide (ZnO) were studied within wide temperature range from 300 to 500 K under the N2 gas flow (flow rate: 20 sccm) and in the frequency range from 40 Hz to 1 MHz for ac electrical measurements. The dc conductivities and the activation energies were found to be in the range of 10^-9-10^-6 S/cm at the room temperature and 0.26-0.86 eV respectively depending on doping rate of these samples. The ac conductivity was well represented by the power law Aω^s. The conduction mechanism for all doped ZnO could be related to correlated barrier hopping (CBH) model. The complex impedance plots (Nyquist plot) showed the data points lying on a single semicircle, implying the response originated from a single capacitive element corresponding to the nanoparticle grains. The crystal structures of the Mg_xZn_1-xO nanoparticles were characterized using X-ray diffraction. The calculated average particle sizes values of Zn_1-xMg_xO samples are found between 29.72 and 22.43 nm using the Sherrer equation.