Eur. Phys. J. Plus (2018) 133: 69
https://doi.org/10.1140/epjp/i2018-11894-2

Regular Article

Structural and electrical properties of cobalt-doped 4H- perovskites obtained by the hydrothermal method

¹ Sfax University, Faculty of Sciences, B. P. 1171 - 3000, Sfax, Tunisia
² National School of Engineers of Sfax (ENIS), Laboratory of Electromechanical Systems (LASEM), B.P.W. 3038, Sfax, Tunisia
³ Dep. Química Inorgánica, Facultad de CC Químicas, Universidad Complutense de Madrid, E-28040, Madrid, Spain
⁴ Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, E-28049, Madrid, Spain

Received: 2 August 2017
Accepted: 19 January 2018
Published online: 22 February 2018

Abstract

A mild hydrothermal method was adapted to prepare the () compounds. They showed hexagonal-4H perovskite-type structure with space group , and cell parameters and Å, as deduced from X-ray and neutron diffraction data. The mean atomic concentrations indicated global stoichiometries close to the nominal ones whereas electron microscopy analyses pointed out to heterogeneity at the nanoscale. The characterization of the electrical response by means of impedance measurements, suggested a semiconductor behavior mainly ascribed to bulk contributions. Relaxation and conduction processes were analyzed. The materials showed mixed electronic-ionic conduction above K, when ionic conduction between intergrains becomes favored. Microstructural homogeneity was revealed as the key factor controlling the electrical response.