Effect of porosity on the electrical conductivity of LAMOX materials

• Published in: Solid state ionics Vol. 304; pp. 75 - 84
• Main Authors: El Khal, H., Cordier, A., Batis, N., Siebert, E., Georges, S., Steil, M.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-06-2017
• Subjects: Conductivity; Impedance spectroscopy; LAMOX; Microstructure; Porosity; Conductivity; Porosity; Impedance spectroscopy; LAMOX; Microstructure
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2017.03.028

Porous La2Mo1.5W0.5O9 (LMW05) samples with different levels of densification were obtained by varying the sintering temperature in the range of 750 to 1100°C. Impedance spectroscopy was used to evaluate the effect of porosity on the electrical response of LMW05-type compounds. The bulk conductivity was found to depend on the microstructure and the pore volume fraction. Effective medium theories (Bruggeman and Maxwell–Garnett approximations) were used to predict the macroscopic properties of the heterogeneous medium. The Bruggeman approximation proved to be better suited to predicting the bulk electrical response of porous LMW05 samples in the pore volume fraction range of 0 to 0.22. Compared with other ceramic materials, LMW05 was found to have a low blocking factor (αR). This characteristic of LMW05 could be related to the microstructure of ceramic materials. Two porous YSZ model samples with the same porosity but different pore morphologies were used to explain why microstructural defects (MD) have a small impact on the electrical properties of LMW05.
•Porous samples of tungsten-doped LAMOX ceramics were prepared by sintering.•Bulk conductivity was dependent on the pore volume fraction.•The Bruggeman approximation model predicted the bulk conductivity.•The observed low value of the blocking factor was attributed to the microstructure.