High temperature bulk acoustic wave properties of langasite

Thin Film Praseodymium-Cerium Oxide Langasite-Based Microbalance Gas Sensor

“…A similar resonator used in [6] had a mass sensitivity of approximately -21.9 cm 2 Hz µg −1 at 600 • C. Based on that mass sensitivity, the areal mass density change for the sensor used in this study would be 16.4 µg/cm 2 at 1%O 2 /Ar and lower oxygen partial pressure. The areal mass density of the PCO deposited, assuming a fully dense material (density at ∼7.1 g/cm 3 ), would be ∼320 µg/cm 2 .…”

“…Praseodymium-cerium oxide (PCO) was chosen as the active film, given its highly nonstoichiometric nature at high oxygen partial pressures [4]. These conditions lie well within the chemical stability regime of langasite [5,6].…”

Resonante Sensoren für die In‐situ‐Gasanalytik bei hohen Temperaturen

“…Aufgrund der starken Abhängigkeit der Resonanzfrequenz der Langasitresonatoren von der Temperatur ist eine Temperaturkompensation der Daten mit Hilfe des dritten Obertones notwendig [6]. Bei den angegebenen Resonanzfrequenzen handelt es sich stets um die temperaturkompensierten Werte.…”

Rare-Earth Calcium Oxyborate Piezoelectric Crystals ReCa4O(BO3)3: Growth and Piezoelectric Characterizations

“…Among these materials, the trigonal lithium niobate (LiNbO 3 , LN) crystals with 3m symmetry were reported to possess high piezoelectric coefficient, being on the order of 6-70 pC/N at room temperature, approximately 3-30 times that of commercial α-quartz (SiO 2 ) (2-3 pC/N). However, the maximum operating temperature of LN-based piezoelectric devices, restricted by their low electrical resistivity (a requirement of >10 6 Ohm· cm was proposed for comparison, where the materials with low resistivity yet can be used for high frequency applications [1]) at elevated temperature is limited to <600 °C, though the Curie temperature is above 1150 °C [5]. Other important trigonal piezoelectric crystals include the langasite family with the general formula of A 3 BC 3 D 2 O 14 [6][7][8][9][10][11][12] and gallium orthophosphate GaPO 4 , in the point group of 32 [13][14][15][16][17][18][19], these crystals were reported to show modest piezoelectric coefficients (5-7 pC/N) and high melting points (1300-1500 °C for langasite family crystals and ~1670 °C for GaPO 4 ), prior to which, there are no phase transitions observed for langasite family crystals (the phase transition for GaPO 4 is about 970 °C).…”

“…and fresnoite crystals (point group 4mm, such as Ba 2 TiSi 2 O 8 ) were investigated for piezoelectric applications. These crystals show the merits of high melting points (1400-1700 °C) and high effective piezoelectric coefficients d eff (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) pC/N) [20][21][22][23][24][25][26]; the evaluations of the temperature dependence of dielectric, piezoelectric and electromechanical properties, however, are limited. Of particular significance is that the monoclinic rare-earth calcium oxyborate crystals (ReCa 4 O(BO 3 ) 3 , ReCOB, Re: rare earth), which have been extensively investigated for nonlinear optical applications in the last two decades [27][28][29][30][31][32][33], were reported to exhibit good piezoelectric properties and high electrical resistivity at an elevated temperature of 1000 °C, with no phase transition prior to their melting points (~1400-1520 °C) [1][2][3][34][35][36][37][38].…”