Universität zu Köln

Malki, Mohammed, Hoo, Christopher M., Mecartney, Martha L. and Schneider, Hartmut (2014). Electrical Conductivity of Mullite Ceramics. J. Am. Ceram. Soc., 97 (6). S. 1923 - 1931. HOBOKEN: WILEY. ISSN 1551-2916

Full text not available from this repository.

Abstract

The electrical conductivity of a lab-produced homogeneous mullite ceramic sintered at 1625 degrees C for 10h with low porosity was measured by impedance spectroscopy in the 0.01Hz to 1MHz frequency range at temperatures between 300 degrees C and 1400 degrees C in air. The electrical conductivity of the mullite ceramic is low at 300 degrees C (approximate to 0.5x10-9Scm-1), typical for a ceramic insulator. Up to approximate to 800 degrees C, the conductivity only slightly increases (approximate to 0.5x10-6Scm-1 at 800 degrees C) corresponding to a relatively low activation energy (0.68eV) of the process. Above approximate to 800 degrees C, the temperature-dependent increase in the electrical conductivity is higher (approximate to 10-5Scm-1 at 1400 degrees C), which goes along with a higher activation energy (1.14eV). The electrical conductivity of the mullite ceramic and its temperature-dependence are compared with prior studies. The conductivity of polycrystalline mullite is found to lie in-between those of the strong insulator -alumina and the excellent ion conductor Y-doped zirconia. The electrical conductivity of the mullite ceramic in the low-temperature field (< approximate to 800 degrees C) is approximately one order of magnitude higher than that of the mullite single crystals. This difference is essentially attributed to electronic grain-boundary conductivity in the polycrystalline ceramic material. The electronic grain-boundary conductivity may be triggered by defects at grain boundaries. At high temperatures, above approximate to 800 degrees C, and up to 1400 degrees C gradually increasing ionic oxygen conductivity dominates.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Malki, Mohammed UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoo, Christopher M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mecartney, Martha L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schneider, Hartmut UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-437563
DOI:	10.1111/jace.12867
Journal or Publication Title:	J. Am. Ceram. Soc.
Volume:	97
Number:	6
Page Range:	S. 1923 - 1931
Date:	2014
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1551-2916
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language IMPEDANCE SPECTROSCOPY; STABILIZED ZIRCONIA; IONIC-CONDUCTIVITY; DOPED ZIRCONIA; SINGLE-CRYSTAL; GRAIN; RESISTIVITY; BLOCKING; BEHAVIOR Multiple languages Materials Science, Ceramics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/43756