The influence of phases and phase's boundaries of TiO 2 and Ta 2 O 5 in the dielectric and electric response of TiTaO (100 nm thick) elaborated by RF magnetron sputtering was highlighted by complex impedance spectroscopy. Dielectric and electric modulus properties were studied over a wide frequency range (0.1-10 5 Hz) and at various temperatures (−160 to 120 • C). The diagram of Argand (ε ′′ versus ε ′ ) shows the contribution of phases, phases' boundaries and conductivity effect on the electric response of TiTaO thin films. Moreover, the resistance of the material decreases when the temperature increases, thus the material exhibits a negative temperature coefficient of resistance. The electric modulus plot indicates the presence of two peaks of relaxation. The first relaxation process appears at low temperature with activation energy of about 0.22 eV and it is related to the first ionization energy of oxygen vacancies. The second relaxation process appears at high temperature with activation energy of about 0.44 eV. This second peak is attributed to the Maxwell-Wagner-Sillars relaxation. The plots of the complex dielectric modulus and the impedance as a function of frequency allow concluding to a localized relaxation due to the long-range conductivity in the TiTaO film.

International audienceTwo relaxation processes have been identified in amorphous TiTaO thin films deposited by reactive magnetron sputtering. The parallel angle resolved x-ray photoelectron spectroscopy and field emission scanning electron microscopy analyses have shown that this material is composed of an agglomerates mixture of TiO2, Ta2O5, and Ti-Ta bonds. The first relaxation process appears at low temperature with activation energy of about 0.26 eV and is related to the first ionisation of oxygen vacancies and/or the reduction of Ti4+ to Ti3+. The second relaxation process occurs at high temperature with activation energy of 0.95 eV. This last peak is associated to the diffusion of the doubly ionized oxygen vacancies VÖ. The dispersion phenomena observed at high temperature can be attributed to the development of complex defect such as (VÖ − 2Ti3+)

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