Sensor application-related defect chemistry and electromechanical properties of langasite

Fritze, Holger; Schulz, Michał; Seh, Huankiat; Tuller, Harry L.

doi:10.1016/j.ssi.2006.02.008

Cited by 20 publications

(16 citation statements)

References 4 publications

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“…The elements of the equivalent circuit can be used to express the total loss in form of the Q-factor which follows from the ratio of stored E S and dissipated energy E D multiplied by 2π according to [62] …”

Section: Electrical Equivalent Circuitmentioning

confidence: 99%

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High-temperature piezoelectric crystals and devices

Fritze

2011

J Electroceram

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Conventional piezoelectric materials such as quartz are widely used as high precision transducers and sensors based on bulk acoustic waves. However, their operation temperature is limited by the intrinsic materials properties to about 500 • C. High-temperature applications are feasible by applying materials that retain their piezoelectric properties up to higher temperatures. Here, langasite (La 3 Ga 5 SiO 14 ) and compounds of the langasite family are the most promising candidates, since they are shown to exhibit bulk acoustic waves up to at least 1400 • C. The mass sensitivity of langasite resonators at elevated temperatures is about as high as that of quartz at room temperature. Factors limiting potential use of those crystals include excessive conductive and viscous losses, deviations from stoichiometry and chemical instability. Therefore, the objective of this work is to identify the related microscopic mechanisms, to correlate electromechanical properties and defect chemistry and to improve the stability of the materials by e.g. appropriate dopants.Further application examples such as resonant gas sensors are given to demonstrate the capabilities of hightemperature stable piezoelectric materials. The electromechanical properties of langasite are determined and described by a one-dimensional physical model. Key properties relevant for stable operation of resonators are found to be shear modulus, density, electrical conductivity and effective viscosity. In order to quantify their impact on frequency and damping, a general-H. Fritze (B)

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Section: Electrical Equivalent Circuitmentioning

confidence: 99%

“…The shape of the symbols corresponds to different levels of hydrogen provided to the reaction chamber ( p RT H2 range: 2-18 mbar)[62,70] …”

mentioning

confidence: 99%

High-temperature piezoelectric crystals and devices

Fritze

2011

J Electroceram

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“…The feasibility of gas-sensing applications at the temperatures up to the 900 1C has been already demonstrated [4]. The diffusivity of its constituents and the electrical properties of langasite exposed to various atmospheres have been already studied [5,6]. It has been shown that the conductivity of langasite depends on both the oxygen and the water vapour pressure.…”

Section: Introductionmentioning

confidence: 99%

Electromechanical properties of langasite resonators at elevated temperatures

Schulz

Fritze

2008

Renewable Energy

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“…"Oxygen tunnels" may be formed [14] where water reacts easily with Si-O-Si bonds. Since a similar effect has been observed in case of LGS [15], its influence on the frequency and mass must be taken into account.…”

Section: Conductivity In Hydrogen Containing Atmospheresmentioning

confidence: 78%