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Effects of oxygen deficiency on the transport and dielectric properties of NdSrNbO
Authors: W. Hzez, A. Benali, H. Rahmouni, E. Dhari, K. Khirouni, B.F.O. Costa
Ref.: Phys. Chem. Solids 117, 1-12 (2018)
Abstract: In the present study, Nd0.7Sr0.3NbO3–y (y = 0.1, 0.15, 0.2) compounds were prepared via a solid–solid reaction route. The prepared samples were characterized by electrochemical impedance spectroscopy in order to establish the effects of temperature, frequency, and oxygen vacancies on both the transport and dielectric properties of NdSrNbO. We found that both the electrical and dielectric properties were highly sensitive to the concentration of oxygen vacancies. The conduction mechanism data were explained well according to the Mott model and adiabatic small polaronic hopping model. Electrochemical impedance spectroscopy analysis showed that one relaxation process was present in the Nd0.7Sr0.3NbO2.9 system whereas two relaxation processes were observed in the Nd0.7Sr0.3NbO2.85 and Nd0.7Sr0.3NbO2.8 systems, where the latter behavior indicated the presence of many active regions (due to the contributions of different microstructures). The temperature and frequency dependences of the dielectric constant confirmed the contributions of different polarization mechanisms. In particular, the high dielectric constant values at low frequencies and high temperatures were mainly related to the presence of different Schottky barriers, whereas the low dielectric constant values at high frequencies were essentially related to the intrinsic effect. The constant dielectric values obtained for the samples are greater than those in the NdSrFeO system, which makes them interesting materials for use in applications that require high dielectric constants.
