Precise measurements of BAW and SAW properties of Langasite in the temperature range from 25°C to 1000°C

There is a high demand for wireless sensing devices in harsh environments for industrial applications. For temperatures above 250degC, 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 1470degC 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 900deg 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 750deg C. Two cuts with Euler angles (0deg, 138.5deg,26.6deg) and (0deg,30.1deg,26.6deg) 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 alpha 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.

[1]  K. Ingebrigtsen.  Analysis of Interdigital Transducers , 1972 .

[2]  R Bechmann,et al.  Contour Modes of Square Plates excited Piezoelectrically and Determination of Elastic and Piezoelectric Coefficients , 1951 .

[3]  Tao Han,et al.  Investigation on SAW properties of LGS and optimal cuts for high-temperature applications. , 2005, IEEE transactions on ultrasonics, ferroelectrics, and frequency control.

[4]  L. Reindl,et al.  Wireless SAW based high-temperature measurement systems , 2006, 2006 IEEE International Frequency Control Symposium and Exposition.

[5]  J. Kosinski,et al.  A review of langasite material constants from BAW and SAW data: toward an improved data set , 2001, Proceedings of the 2001 IEEE International Frequncy Control Symposium and PDA Exhibition (Cat. No.01CH37218).

[6]  L. Solie,et al.  Optimal cuts of langasite, La/sub 3/Ga/sub 5/SiO/sub 14/ for SAW devices , 2001, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[7]  T. Ikeda.  Fundamentals of piezoelectricity , 1990 .

[8]  G. Borchardt,et al.  High temperature bulk acoustic wave properties of langasite , 2003 .

[9]  M. Redwood,et al.  Analysis of Generation and Detection of Surface and Bulk Acoustic Waves by Interdigital Transducers , 1977, IEEE Transactions on Sonics and Ultrasonics.

[10]  M. D. da Cunha,et al.  Investigation on recent quartz-like materials for SAW applications , 1999, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[11]  L. Reindl,et al.  Properties of radio frequency Rayleigh waves on langasite at elevated temperatures , 2004, IEEE Ultrasonics Symposium, 2004.

[12]  Allan D. Pierce,et al.  Physical acoustics : principles and methods , 1965 .

[13]  Kazuo Tanaka,et al.  A unified approach to controlling chaos via an LMI-based fuzzy control system design , 1998 .

[14]  A. Kaminskii,et al.  Investigation of trigonal (La1-xNdx)3Ga5SiO14 crystals. II. Spectral laser and electromechanical properties , 1983 .

[15]  H. Engan.  Surface Acoustic Wave Multielectrode Transducers , 1975, IEEE Transactions on Sonics and Ultrasonics.

[16]  Kiyoshi Shimamura,et al.  Growth of new langasite single crystals for piezoelectric applications , 1998, ISAF 1998. Proceedings of the Eleventh IEEE International Symposium on Applications of Ferroelectrics (Cat. No.98CH36245).

[17]  J. Schreuer.  Elastic and piezoelectric properties of La3Ga5SiO14 and La3Ga5.5Ta0.5O14: an application of resonant ultrasound spectroscopy. , 2002, IEEE transactions on ultrasonics, ferroelectrics, and frequency control.

[18]  D. J. Frankel,et al.  Performance of Zr and Ti adhesion layers for bonding of platinum metallization to sapphire substrates , 2001 .

[19]  On the existence of surface acoustic waves on piezoelectric substrates , 2001, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[20]  J. Schreuer.  Elastic and piezoelectric properties of La/sub 3/Ga/sub 5/SiO/sub 14/ and La/sub 3/Ga/sub 5.5/Ta/sub 0.5/O/sub 14/: an application of resonant ultrasound spectroscopy , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[21]  M. Pereira da Cunha,et al.  High temperature LGS SAW gas sensor , 2006 .

[22]  T. Moonlight,et al.  P4L-1 Enabling Very High Temperature Acoustic Wave Devices for Sensor & Frequency Control Applications , 2007, 2007 IEEE Ultrasonics Symposium Proceedings.