Utilisation of methylcellulose as a shaping agent in the fabrication of Ba0.95Ca0.05Ce0.9Y0.1O3 proton-conducting ceramic membranes via the gelcasting method

Magdalena Dudek,Dorota Majda,Michał Mosiałek,Sabrina Presto,Alicja Rapacz-Kmita,Antonio Barbucci,Marcin Gajek,Elwira Kocyło,Bartłomiej Lis,Maria Paola Carpanese,Massimo Viviani,Radosław Lach

doi:10.1007/s10973-019-08856-8

Abstract

The gelcasting method was used to form gastight Ba0.95Ca0.05Ce0.9Y0.1O3 samples proposed for use as proton-conducting electrolytes in solid oxide fuel cells. Methylcellulose was used as an environmentally friendly shaping agent for Ba0.95Ca0.05Ce0.9Y0.1O3 powder in an ethanol solution. Samples of Ba0.95Ca0.05Ce0.9Y0.1O3 were also prepared from the same powder via traditional isostatic pressing, as a reference for cast samples, and sintered in the same conditions. Comparative studies of the physicochemical properties of Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes, formed by means of these two methods and then sintered at 1550 °C for 2.5 h, were presented and discussed. Using the X-ray diffraction method, only the pure orthorhombic phase of BaCe0.9Y0.1O3 was detected in the Ba0.95Ca0.05Ce0.9Y0.1O3 powder, as well as in the Ba0.95Ca0.05Ce0.9Y0.1O3 sintered pellets formed via both gelcasting (A) and isostatic pressing (B). Thermal effects occurring during heating of methylcellulose, as well as ceramic Ba0.95Ca0.05Ce0.9Y0.1O3 powder, dried cast samples obtained from the prepared slurry, and sintered Ba0.95Ca0.05Ce0.9Y0.1O3 samples, were examined by differential scanning calorimetry, differential thermal analysis, thermogravimetric analysis, and evolved gas analysis of volatile products using a quadrupole mass spectrometer. The measurements were performed within the temperature range of 20–1200 °C in air. Based on dilatometric tests, it was found that the Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples exhibited slightly higher degree of sinterability than the 5CBCY samples obtained by isostatic pressing. In comparison with pressed pellets, higher values of total electrical conductivity in air or in a gas mixture of 5% H2 in Ar were also attained for Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples. The Ba0.95Ca0.05Ce0.9Y0.1O3 samples were used to construct oxygen–hydrogen electrolytes for solid oxide fuel cells. The results of the electrochemical performance of solid oxide fuel cells with Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes were comparable to the data in the literature on BaCe0.9Y0.1O3 electrolytes. An electrochemical study of a Ba0.5Sr0.5Co0.8Fe0.2O3−δ|Ba0.95Ca0.05Ce0.9Y0.1O3 interface was also performed. Ba0.5Sr0.5Co0.8Fe0.2O3−δ appears to be a suitable cathode material for a Ba0.95Ca0.05Ce0.9Y0.1O3 electrolyte.

Highlights

Ceramic proton conductors appear to be valuable components in the development of cost-effective solid oxide fuel cells (SOFCs) operating within an intermediate-temperature (IT) range of Extended author information available on the last page of the article500–700 °C and a low-temperature (LT) range of 350–600 °C
Thermal effects occurring during heating of methylcellulose, as well as ceramic Ba0.95Ca0.05Ce0.9Y0.1O3 powder, dried cast samples obtained from the prepared slurry, and sintered Ba0.95Ca0.05Ce0.9Y0.1O3 samples, were examined by differential scanning calorimetry, differential thermal analysis, thermogravimetric analysis, and evolved gas analysis of volatile products using a quadrupole mass spectrometer
The aim of this paper is to examine the potential for forming ceramic materials from modified calcium–barium– yttrium-doped cerate with the formula Ba0.95Ca0.05Ce0.9Y0.1O3 (5CBCY) via the gelcasting method, using methylcellulose as an environmental networking agent

Summary

Introduction

Ceramic proton conductors appear to be valuable components in the development of cost-effective SOFCs operating within an intermediate-temperature (IT) range of Extended author information available on the last page of the article. 500–700 °C and a low-temperature (LT) range of 350–600 °C. Protons are characterised by a higher level of mobility than oxygen ions because of their much smaller size. The diffusion of protons is much less temperature-dependent than that of oxygen ions. It is potentially easier to obtain greater conductivity for proton conductors than for oxygen ion conductors at lower temperatures [1, 2]. One of the main groups of ceramic proton conductors with perovskite structures (ABO3) currently under investigation comprises cerates [3].

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