The Proceedings of Mechanical Engineering Congress, Japan
Online ISSN : 2424-2667
ISSN-L : 2424-2667
2013
Session ID : J041035
Conference information
J041035 Discovery of a high-temperature thermally activated relaxation phenomenon in langasite by antenna transmission acoustic resonance method
Yuki TSUTSUIHirotsugu OGINobutomo NAKAMURAMasahiko HIRAO
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Abstract
Internal friction of langasite is necessary for optimal performance of acoustic resonators for high-temperature sensing applications, but it remains unknown over 500℃. In this report, internal friction Q^<-1> of langasite is measured from room temperature to about 900℃ by the antenna transmission acoustic resonance (ATAR) method, which we developed inimitably. ATAR method is free from electrodes or transducers, and can measure acoustic properties at elevated temperature over 900℃. Q^<-1> of langasite is caused by the phonon-phonon interactions, point-defect relaxations, piezoelectric/carrier relaxation, and so on, and it can be written by Q^<-1> = (Δ_i / T)(ωτ_i/1+Tω^2τ_i^2) with the relaxation time τ_i of individual mechanisms. With our measurement, we found out a new relaxation mechanism around 800℃ with the activation energy of 0.49eV.
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© 2013 The Japan Society of Mechanical Engineers
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