Surface and volume defects in langasite crystals

High temperature bulk acoustic wave properties of langasite

“…The fundamental mode and the 3 rd overtone did not experience the same temperature dependence. This behaviour was already reported in the temperature range from 5 to 125 C. 14,15 Further, a theoretical approach by Tiersten et al 16 described the crystal orientation dependent resonance behaviour of quartz resonators. It was concluded that the nodal planes of the anharmonics of each harmonic family are oriented differently.…”

New Piezoelectric Substrates for Saw Devices

“…62 The perfection of as-grown langasite crystals has been studied by Raman spectroscopy, 72 IR spectroscopy, 62 X-ray diffraction, 47 ' 61 ' 73 X-ray topography, 10 ' 70 ' 74 and optical activity. 73 ' 75 The X-ray results are the most significant to date. X-ray diffraction has determined that the periodic growth striations commonly observed correspond to changes in the lattice constants on the order of Ac/c « 10" 4 with a period of 35 urn to 70 urn.…”

Growth and high-temperature characterization of langasite-family Ca3NbGa3−xAlxSi2O14single crystals

“…Many research studies have been focused on the crystal growth and piezoelectric properties for bulk and surface acoustic wave applications. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] Furthermore, because the langasite crystals have no phase transition until their melting point, high-performance pressure sensors operating under a high-temperature environment, for example, higher than 800 °C, have been expected for applications in automobile engines and turbines recently. [17][18][19][20][21][22][23][24] In our early work, 17) we have measured the dielectric, elastic, and piezoelectric constants of langasite-family singlecrystal La 3 Ta 0.5 Ga 5.3 Al 0.2 O 14 by the resonance-antiresonance method in a range from room temperature to 1000 °C.…”