Electrical and dielectric properties study of CaZrO 3 -CaTiO 3 composite system by impedance spectroscopy
- PDF / 2,393,965 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 79 Downloads / 242 Views
ORIGINAL VPAPER
Electrical and dielectric properties study of CaZrO3-CaTiO3 composite system by impedance spectroscopy Khaoula Hkiri 1 & Mohamed Ben Salem 1 & Abdelhak Othmani 1 & Mouldi Zouaoui 1 Received: 2 March 2020 / Revised: 21 April 2020 / Accepted: 23 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract CaZrO3 mono-phase and (1-x)CaZrO3-xCaTiO3 composite systems, where x = 0.2, 0.25, and 0.3, were synthesized by a conventional solid-state method. XRD patterns of the synthesized composites reveal the formation of both phases, and no secondary phase was detected. The analysis of the internal stress in the composites systems by the William-Hall equation indicates that tensile stress is applied to the CaZrO3 grains, while compressive stress is applied to CaTiO3 grains. TEM analyses show that the CaTiO3 grain is surrounded by CaZrO3 grains, confirming the presence of the CaZrO3/CaTiO3 hetero-interfaces and confirming the results obtained by the William-Hall equation. Impedance spectra were well modelled by introducing electrical equivalent circuits. The obtained results show that the incorporation of the CaTiO3 phase favors the ionic conductivity in the composite and that the 0.75CaZrO3-0.25CaTiO3 composite exhibits the highest oxide ion conductivity among all the samples, where its total conductivity value is about 1.23 × 10−4 s cm−1 at 500 °C, which is higher than that of the CZO monophase (1.01 × 10−6 s cm−1 at 500 °C), and than that of the CTO mono-phase (2.1 × 10−7s cm−1 at 500 °C). The conductivity enhancement was explained based on the variation of the hetero-interface CaZrO3/CaTiO3 surface area. Furthermore, the 0 frequency and temperature dependence of dielectric constant (εr ) and dielectric loss tangent (tanδ) were investigated in detail and the dielectric response improvement was attributed to the improvement of the space charge polarization in the heterointerfaces. Keywords Composite systems . Internal stress . Hetero-interfaces . Electrical properties . Dielectric response
Introduction Perovskite oxides with the formula ABO3 have attracted much interest in the scientific community. Among the different perovskites, calcium zirconate (CaZrO3) has received much attention due to its good ionic conductivity, high thermal and chemical stability, and good thermal shock resistance, making its use in a wide range of applications such as solid oxide fuel cells [1], oxygen separation membranes [2], and oxygen sensors [3, 4]. Moreover, CaZrO3 is a potential candidate for mechanical filters, coating, and electrical applications such as resonators and capacitors, and can be used for dielectric resonators for microwave applications [5]. * Mohamed Ben Salem [email protected] 1
Faculté des Sciences de Bizerte, LR01ES15, Laboratoire de Physique des Matériaux: Structure et Propriétés, Université de Carthage, 7021 Zarzouna, Bizerte, Tunisia
Many efforts have been made to improve the electrical conductivity of CaZrO 3 perovskite. Incorporation of transition-metal elements such as S
Data Loading...
