Structural and electrical properties of sol-gel grown (1-x) (ZnO) plus (x) (SnO2) (x=0, 0.25, 0.5) nanocomposites

Semiconducting oxide nanocomposites of ZnO/SnO2 with different weight ratio, i.e. (i) ZnO:SnO2 = 100:0 (ZnO0), (ii) ZnO:SnO2 = 75:25 (ZnO25), and (iii) ZnO:SnO2 = 50:50 (ZnO50), were prepared by sol-gel method. X-ray diffraction (XRD) measurement reveals a rutile type tetragonal structure of SnO2 whereas hexagonal wurtzite structure of ZnO. Transmission electron microscopy (TEM) measurement suggests an effective role of SnO2 addition on the particle size of studied nanocomposites. Energy dispersive X-ray analysis (EDAX), carried out for elemental analysis for the studied nanocomposites, reveals the Sn deficiency in ZnO50 nanocomposite sample. Frequency dependent dielectric behavior recorded at different temperatures has been understood in the context of cole-cole plots for all the nanocomposites where variations in relaxation time and relaxation time distribution have been discussed in detail. Variation in ac conductivity has been discussed on the basis of Jonscher's universal power law and crossover from correlated barrier hopping (CBH) mechanism to Maxwell-Wagner (M-W) relaxation has been identified for the studies nanocomposites. Overall electrical properties have been discussed in the context of oxygen vacancies, defects, disorder, and thermal energy in details.