Abstract
There is a high demand for wireless sensing devices
in harsh environments for industrial applications. For temperatures above 250○C, silicon-based sensors cannot be used. In
contrast, bulk acoustic wave (BAW) and surface acoustic wave
(SAW) devices are still suitable for this purpose. Further high temperature applications include thermogravimetry on small
volumes and gas sensing based on stoichiometry change of
thin sensor films. Langasite (La3Ga5SiO14) is a piezoelectric
single crystal that preserves its piezoelectric properties and is
chemically stable up to its melting point at 1470○C without any
phase transition and, therefore, is a promising material for high temperature devices.
Using a resonance-antiresonance method based on bulk oscillations, all components of elastic and piezoelectric tensors of
langasite have been determined at temperatures up to 900○C. Resonance spectra of several langasite samples have been measured
and fitted with the impedance calculated from a one-dimensional
physical model of piezoelectric bodies vibrating in several modes.
In order to extract the electromechanical parameters, different
resonator geometries and orientations are used.
Also, the results of measurements are presented for SAW
devices on langasite at temperatures from 25 to 750○C. Two
cuts with Euler angles (0°, 138.5°, 26.6°) and (0°, 30.1°, 26.6°)
have been studied. The devices were fabricated with a platinum
(Pt) layer with different heights on a zirconium (Zr) adhesion
layer. The main material parameters relevant for SAW devices
such as phase velocity vp, propagation loss α and coupling
coefficient k² have been obtained. The measured SAW phase
velocities compare well with those calculated with the elastic and
piezoelectric tensors obtained by bulk-oscillation measurements.
in harsh environments for industrial applications. For temperatures above 250○C, silicon-based sensors cannot be used. In
contrast, bulk acoustic wave (BAW) and surface acoustic wave
(SAW) devices are still suitable for this purpose. Further high temperature applications include thermogravimetry on small
volumes and gas sensing based on stoichiometry change of
thin sensor films. Langasite (La3Ga5SiO14) is a piezoelectric
single crystal that preserves its piezoelectric properties and is
chemically stable up to its melting point at 1470○C without any
phase transition and, therefore, is a promising material for high temperature devices.
Using a resonance-antiresonance method based on bulk oscillations, all components of elastic and piezoelectric tensors of
langasite have been determined at temperatures up to 900○C. Resonance spectra of several langasite samples have been measured
and fitted with the impedance calculated from a one-dimensional
physical model of piezoelectric bodies vibrating in several modes.
In order to extract the electromechanical parameters, different
resonator geometries and orientations are used.
Also, the results of measurements are presented for SAW
devices on langasite at temperatures from 25 to 750○C. Two
cuts with Euler angles (0°, 138.5°, 26.6°) and (0°, 30.1°, 26.6°)
have been studied. The devices were fabricated with a platinum
(Pt) layer with different heights on a zirconium (Zr) adhesion
layer. The main material parameters relevant for SAW devices
such as phase velocity vp, propagation loss α and coupling
coefficient k² have been obtained. The measured SAW phase
velocities compare well with those calculated with the elastic and
piezoelectric tensors obtained by bulk-oscillation measurements.
Original language | English |
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Title of host publication | 2008 IEEE International Frequency Control Symposium |
Pages | 326-331 |
Number of pages | 6 |
DOIs | |
Publication status | Published - 2008 |
Keywords
- Langasite
- high temperature
- measurements