ZnO/TiO2 powders were synthesized by sol-gel method using ammonium hydroxide. The effects of calcination temperature (500–1000°C) and gamma rays (with doses from 25 to 150？kGy) on the phases present and their electrical properties were investigated. The results revealed that heating the system investigated at 500°C led to the formation of ZnTiO3-rohom and TiO2-rutile. The degree of crystallinity of the phases produced increased by increasing the calcination temperature. When heating at 1000°C, ZnTiO3-rohom turned to ZnTiO3-cubic but the rutile phase remained stable. γ-Irradiation decreased considerably the crystallite size of the rutile phase from 146 to 63？nm and that of ZnTiO3-cubic decreased from 101 to 39？nm. This treatment led also to the creation of holes in the matrix of irradiated solids which increased the mobility of charge carriers (electrons) leading to a significant increase in the electrical conductivity reaching to 102 to 103-fold. 1. Introduction Fundamental studies concerning the phase diagram and characterization of ZnO-TiO2 system have been published since 1960s. This system still attracts the attention of researchers because of its importance in practical applications [1–5]. TiO2 ceramics have been investigated for diverse applications in the optical and semiconductors industries because of their interesting semiconducting and dielectric properties. Semiconducting titania had especially been employed in producing different electronic devices, including oxygen sensors, varistors, and current collecting electrodes in Na-S batteries [6–8]. TiO2-ZnO-based compounds have been employed as promising catalysts in some chemical industries. Many attempts have been made to improve the photoelectrochemical (PEC) conversion efficiency of TiO2 ceramics by treatment with certain compounds including Al2O3 [9–14] and BeO [15]. The base of the phase diagram for this system was established by Dulin and Rase [1], who have reported that there are three compounds existing in the ZnO-TiO2 system, including Zn2TiO4 (cubic), perovskite metatitanate (hexagonal), and Zn2Ti3O8 (cubic) [16]. has perovskite structure and could be considered as a useful candidate for microwave resonator materials [17] and gas sensor [18] and as a catalyst for oxidation of ethanol NO, CO, and so forth …, [2] and colour pigments [11]. Yamaguchi et al. [3] claimed that Zn2TiO4 can be easily prepared by conventional solid-state reaction between 2 moles of ZnO and 1 mole of TiO2. However, preparation of pure from a mixture of equimolar proportion of zinc and titanium oxides has not
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