Structural, optical and electrical properties of Zn-doped SnO_2 nanoparticles synthesized by the co-precipitation technique

摘要

Nanometric size Zn-doped SnO_2 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 SnO_2 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 SnO_2 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 SnO_2 and 0.69 eV for 6 % Zn doping.