Characterization of langasite for application in high temperature SAW sensors

Abstract

Experimental SAW resonator structures with iridium electrodes were fabricated on Y-cut of langasite with few different propagation directions and their characteristics were measured in a wide temperature interval, up to 700ºC, and compared with simulations. Between two sets of material constants reported by Bungo one set was selected as providing much better agreement with experiments, for the analyzed orientations. Further improvement of simulation accuracy was achieved via after-correction of the calculated temperature characteristics using auxiliary function extracted from experimental data. This approach was used to predict resonator characteristics in orientation with Euler angles (0º, 22º, 90º), in which Bluestein-Gulyaev wave propagates, and provided excellent agreement between experiments and simulations, in a wide temperature interval.

Experimental and theoretical investigations of some useful langasite cuts for high-temperature SAW applications

“…15). The results are consistent with data from Sakharov et al [17]. At higher temperatures (580°C and above), the signals of the latter cuts decrease slightly but signal analysis is still possible (Fig.…”

“…14). Small discrepancies between these results and the data coming from Sakharov et al [17] can be observed. Their origin can be likely attributed to the difference At higher temperatures (580°C and above), the signals of the latter cuts decrease slightly but signal analysis is still possible (Fig.…”

“…Therefore some prospective applications may be suggested. Thus, the (0°, 22°, 90°) SH-SAW cut and the (0°, 138.5°, 26.7°) cut are characterized by similar temperature Res 45 Res 50 Res 57 Exp [17] coefficient of frequency (TCF) value trends, which are close to zero at room temperature. They can subsequently be considered both for applications requiring thermal compensation (e.g.…”

“…A theoretical approach, based on a recent paper [16], considering interactions between STW and spurious SAW modes resulting from slight and unwilled misorientation of IDTs will be discussed in the next section of this paper. LGS cut, and those taken from [17].…”

Mode Analysis of Pt/LGS Surface Acoustic Wave Devices

“…However, their results were based on a numerical technique and were not compared with experimental results, so we are unable to verify the appropriateness of the analysis. Lots of experimental investigations on LGS SAW devices with Euler angles such as (0 , 138.5 , ), (0 , 90 , ) and (0 , 22 , ) have been conducted [ 12 , 22 , 23 , 24 ], however only one mode was investigated in these works. For example [ 12 ] studied the high temperature parameters of Pt LGS SAW devices with an Euler angle (0 , 138.5 , 26 ), which only referred to Rayleigh waves.…”