CTGS material parameters obtained by versatile SAW measurements

Biryukov, S. V.; Schmidt, H.; Сотников, А. В.; Weihnacht, M.; Sakharov, S.; Бузанов, О. А.

doi:10.1109/ultsym.2014.0217

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…This observation demonstrated that the above constants do not change linearly with increasing of Al content in the Al-doped CTGS. However, the constants of CTGS reported in [2] were significantly different from those obtained in [13], and the maximum difference of 55% was observed for the elastic constants. Based on our experience [10], this mismatch is associated with measurement method utilised in [2], but not with different crystal quality.…”

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confidence: 62%

Acoustical physical constants around room temperature for Ca ₃ TaGa _1.5 Al _1.5 Si ₂ O ₁₄ single crystal

et al. 2015

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A full set of acoustical physical constants was determined for Ca 3 TaGa 1.5 Al 1.5 Si 2 O 14 (CTGAS) single crystal from bulk wave velocities measured by the ultrasonic micro-spectroscopy method. Several plate specimens were cut perpendicular to the X-, Y-, Z-, 35.25°Y-, and 139.74°Y-directions from a CTGAS single crystal ingot grown by Czochralski technique. Following measurements of dielectric constants and density, elastic constants, piezoelectric constants, and their temperature coefficients were determined from longitudinal wave and shear wave velocities measured for the CTGAS specimens at around room temperature. It was demonstrated that the as found constants could provide calculation accuracy within ±0.15% in leaky surface acoustic wave velocity. The determined constants were used for numerical calculation of the cut angle, at which the temperature coefficient of shear wave velocity becomes zero. This angle corresponded to 147.9°Y-cut substrate that had electromechanical coupling factor of k 2 = 3.2%. This parameter is about four times greater than that of AT-cut α-quartz. Introduction: The langasite-type (La 3 Ga 5 SiO 14 : LGS) single crystals are promising materials for pressure sensors operating under high temperature environment as well as highly stable acoustic devices for future communication applications. In particular, the LGS-type crystals are candidate materials alternative to α-quartz from viewpoints of large electromechanical coupling factor, low impedance, and superior temperature stability. In 2000, ordered structure compounds, such as Ca 3 TaGa 3 Si 2 O 14 (CTGS) and Ca 3 NbGa 3 Si 2 O 14 (CNGS), have been developed because the crystals with disordered structure, such as LGS, La 3 Ta 0.5 Ga 5.5 O 14 (LTG) and La 3 Nb 0.5 Ga 5.5 O 14 (LNG) cause high acoustic losses and non-uniform mechanical properties [1]. Fortunately, CTGS and CNGS do not contain costly rare-earth elements unlike LGS, LTG, and LNG. Nevertheless, they still include quite expensive element of Ga. In 2008, Ca 3 TaAl 3 Si 2 O 14 (CTAS) single crystal was successfully developed by substituting 100% of Ga in CTGS with Al and its piezoelectric properties have been evaluated [2, 3]. However, temperature coefficients of the acoustical physical constants (including elastic, piezoelectric, and dielectric constants and density) were not yet reported. These parameters are rather important for designing acoustic devices such as bulk acoustic wave (BAW) resonators and surface acoustic wave (SAW) filters. In addition, physical performance of the mixed crystals formed as a result of partial substitution of Ga 3+ in CTGS with Al 3+ is also not clear. Therefore, examination of acoustic properties of the crystals having intermediate composition of Ca 3 Ta(Ga 1-x Al x) 3 Si 2 O 14 was considered to be important for further understanding of nature of LGS-type materials. Recently, Ca 3 TaGa 1.5 Al 1.5 Si 2 O 14 (CTGAS) bulk single crystals were produced by the Czochralski (CZ) technique [4]. Moreover, in the meantime, a number of single-cryst...

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confidence: 62%

Acoustical physical constants around room temperature for Ca ₃ TaGa _1.5 Al _1.5 Si ₂ O ₁₄ single crystal

et al. 2015

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“…There are many reports on determination of the material constants. [18][19][20][21] In previous works, we have measured the Al content dependence of acoustic properties of CTGAS(x) using the ultrasonic microspectroscopy (UMS) technology, [22][23][24] which showed a linear relationship between acoustic properties and Al content. 25) However, the temperature dependence of acoustic properties has not yet been clarified.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of acoustic property of Ca₃Ta(Ga,Al)₃Si₂O₁₄single crystals

Ohashi

Arakawa

Yokota

et al. 2017

Jpn. J. Appl. Phys.

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The temperature dependences of the acoustic properties of Ca3Ta(Ga1−xAlx)3Si2O14 [CTGAS(x)] were experimentally studied as a function of the Al substitution content x. Five specimens, i.e., one each of X-, Y-, and Z-, and two rotated Y-cut specimens, were prepared from each crystal ingot of CTGAS(x) (x = 0, 0.25, 0.50, and 0.75) grown by the Czochralski technique. The longitudinal wave and shear wave velocities of CTGAS(x) were measured at three temperatures ranging from 291 to 300 K, then acoustically related physical constants (elastic, piezoelectric, and dielectric constants and coefficient of thermal expansion) were determined at approximately room temperature. The results revealed that the temperature coefficients of all the constants linearly changed with Al content. By one of the calculations using the constants and their temperature coefficients determined in this study, we demonstrated their capability to predict suitable conditions (i.e., cut angle, propagation direction, and chemical composition) for acoustic wave devices although they were determined in a narrow temperature range.

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“…This material has better piezoelectric properties, such as higher effective piezoelectric coefficient at high temperature. The crystals have better quality due to the lower Ga content, higher electrical resistivity, higher mechanical strength and a lower thermal expansion anisotropy as compared to langasite [20,21,22,23]. This relatively newer substrate material is lesser known and thin films on it are not extensively studied yet.…”

Section: Introductionmentioning

confidence: 99%

Tungsten as a Chemically-Stable Electrode Material on Ga-Containing Piezoelectric Substrates Langasite and Catangasite for High-Temperature SAW Devices

et al. 2016

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Thin films of tungsten on piezoelectric substrates La3Ga5SiO14 (LGS) and Ca3TaGa3Si2O14 (CTGS) have been investigated as a potential new electrode material for interdigital transducers for surface acoustic wave-based sensor devices operating at high temperatures up to 800 °C under vacuum conditions. Although LGS is considered to be suitable for high-temperature applications, it undergoes chemical and structural transformation upon vacuum annealing due to diffusion of gallium and oxygen. This can alter the device properties depending on the electrode nature, the annealing temperature, and the duration of the application. Our studies present evidence for the chemical stability of W on these substrates against the diffusion of Ga/O from the substrate into the film, even upon annealing up to 800 °C under vacuum conditions using Auger electron spectroscopy and energy-dispersive X-ray spectroscopy, along with local studies using transmission electron microscopy. Additionally, the use of CTGS as a more stable substrate for such applications is indicated.

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CTGS material parameters obtained by versatile SAW measurements

Cited by 8 publications

References 7 publications

Acoustical physical constants around room temperature for Ca ₃ TaGa _1.5 Al _1.5 Si ₂ O ₁₄ single crystal

Acoustical physical constants around room temperature for Ca ₃ TaGa _1.5 Al _1.5 Si ₂ O ₁₄ single crystal

Temperature dependence of acoustic property of Ca₃Ta(Ga,Al)₃Si₂O₁₄single crystals

Tungsten as a Chemically-Stable Electrode Material on Ga-Containing Piezoelectric Substrates Langasite and Catangasite for High-Temperature SAW Devices

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CTGS material parameters obtained by versatile SAW measurements

Cited by 8 publications

References 7 publications

Acoustical physical constants around room temperature for Ca 3 TaGa 1.5 Al 1.5 Si 2 O 14 single crystal

Acoustical physical constants around room temperature for Ca 3 TaGa 1.5 Al 1.5 Si 2 O 14 single crystal

Temperature dependence of acoustic property of Ca3Ta(Ga,Al)3Si2O14single crystals

Tungsten as a Chemically-Stable Electrode Material on Ga-Containing Piezoelectric Substrates Langasite and Catangasite for High-Temperature SAW Devices

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Acoustical physical constants around room temperature for Ca ₃ TaGa _1.5 Al _1.5 Si ₂ O ₁₄ single crystal

Acoustical physical constants around room temperature for Ca ₃ TaGa _1.5 Al _1.5 Si ₂ O ₁₄ single crystal

Temperature dependence of acoustic property of Ca₃Ta(Ga,Al)₃Si₂O₁₄single crystals