Structural, optical and electrical properties of Zn-doped SnO2 nanoparticles synthesized by the co-precipitation technique

Nanometric size Zn-doped SnO2 particles with Zn concentration varying from 1 to 6 % were prepared using the co-precipitation method. X-ray diffraction patterns show for all samples a typical rutile-type tetragonal structure of SnO2 without any additional peaks from spurious phases. These results together with transmission electron microscopy analyses have shown that the size of the nanoparticles decreases with Zn doping down to 4 nm. According to UV-visible absorption measurements this decrease of particle size is accompanied by a decrease of the band gap value from 3.34 eV for SnO2 down to 3.28 eV for 6 % Zn doping. The electrical conductivity of the system has been investigated between 473 and 718 K, in the 200 Hz-5 MHz frequency range, by means of impedance spectroscopy. The temperature dependence of the bulk conductivity was found to obey the Arrhenius law with activation energies of 0.74 eV for SnO2 and 0.69 eV for 6 % Zn doping.