Author:
Fritze H.,Schulz M.,Seh H.,Tuller H. L.
Abstract
ABSTRACTFactors limiting potential use of langasite as a gas sensor platform at elevated temperatures include excessive conductive and viscous damping, deviations from stoichiometry and chemical instability. This paper focuses on viscous damping which can be described by an effective viscosity of the resonator material. Based on a one-dimensional description of the resonator device, the material constants of langasite are determined as a function of temperature. Theeffective viscosity of the resonator material and the bulk conductivity are found to exhibit nearly the same activation energy at temperatures from 350 to 600 °C. Based on that fact, it is most likely that the predominant conduction mechanism, i.e. oxygen ion movement, controls the viscous damping in that temperature range. Therefore, intentional doping must suppress the oxygen conductivity to minimize losses. The effect of such dopants is presently under investigation. Further, pre-annealing specimens for several hours above 1050 °C is necessary, for the given sample dimensions, to establish reproducible materials properties. Based on oxygen diffusion data, it can be concluded that the oxygen stoichiometry of langasite specimens becomes equilibrated during the pre-annealing runs.
Publisher
Springer Science and Business Media LLC
Cited by
2 articles.
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