Resumen de Characterisation of ferroelectric materials by impedance spectroscopy
Impedance spectroscopy, IS, is a powerful technique for the characterisation of electroceramics and particularly, for assessing the electrical microstructure, which may be similar to, or distinct from, the microstructure determined by electron microscopy. IS is particularly powerful when one of the electrical components of a ceramic shows a temperature dependent capacitance, such as is associated with ferroelectric materials above their Curie temperature, Tc. By analysing the température-dépendance of IS data, it is often possible to decide which of several plausible equivalent circuits provides the most reahstic model of the electrical properties of the material under investigation. To obtain a complete characterisation of electrical microstructure, particular attention to the methods of data analysis is necessary; data can be analysed in any of four formalisms: impedance, admittance, permittivity and electric modulus, and in order to extract the maximum amount of useful information, it is often important to present data in at least two of these formalisms. These points are illustrated with examples taken from the IS characterisation of ferroelectric BaTiO3 and LiTaO3.
