Structural, microstructural, and electrical transport properties of TiO2RuO2 ceramic materials obtained by polymeric sol-gel route

Materials belonging to the Ti1-xRuxO2 system, where 0 less than or equal to x less than or equal to 1 (mol), have been synthesized by a polymeric sol-gel route and calcined in air at 1300 degrees C by rapid firing. The crystalline evolution of the prepared materials has been investigated, as a function of temperature, by means of differential thermal analysis (DTA-TGA) and X-ray diffraction (XRD). Microstructures of the sintered materials were studied by scanning electron microscopy-energy-dispersive X-ray (SEM-EDX). Electrochemical impedance spectroscopy (EIS) and de four-point; methods were used to characterize electrically, in air, the ceramic materials obtained. For sintered materials, due to the partial volatilization of RuO2, the x real values were obtained by X-ray fluorescence (XRF) chemical analysis. Although, from 300 to 500 degrees C the solid solubility of RuO2 in rutile-TiO2 phase is located at x greater than or equal to 0.5, from 600 to 1300 degrees C, that value is located in the 0.05 less than or equal to x < 0.1 range. For higher contents of RuO2, two phases are observed: ruthenium-titanium oxide rutile solid solution and RuO2. Two types of electrical behavior are detected in sintered materials of this system: semiconductor and metallic. A wide transition semiconductor/metal is noted, which indicates the existence of a prepercolation effect. The metal/electrical percolation can be located at a chemical analyzed composition of x = 0.26. On the other hand, a microstructural/electrical approach is considered.