Langasite - Lanthanum Gallium Silicate, is a piezoelectric crystal of gallogermanate family, having 32- symmetry class and described by the chemical formula: La3Ga5SiO14. Method for the production - the Czochralski method. It is used in the production of wafers for surface acoustic waves devices, direct piezoelectric effect sensors bulk acoustic waves devices. Due to the absence of pyroelectric effect, hysteresis of properties, the absence of a phase transition up to the melting temperature (1470°C) and the presence of temperature compensated cuts, Langasite is used where the temperature dependence of electrical signal is important.
| № | Characteristic | Value | Measurement units | |
|---|---|---|---|---|
| 1. | Hygroscopic property | N/A | - | |
| 2. | Hysteresis effect | N/A | - | |
| 3. | Dielectric capacity | ε11 = 19; ε33 = 50 | - | |
| 4. | Q-factor | 50000 | - | |
| 5. | Symmetry class | 32 | - | |
| 6. | Thermal-expansion coefficient | α11 = 5.630; α33 = 4.079 | mкK -1 | |
| 7. | EMC coefficient (BAW) | 15.8 | % | |
| 8. | EMC coefficient (SAW) | 0.34 (0°;138,5°;26,7°) | % | |
| 9. | Cell parameters | a = 8.170x10-10; c = 5.098x10-10 | m | |
| 10. | Density | 5.74 | g/cm 3 | |
| 11. | Pyroelectric effect | N/A | - | |
| 12. | Piezoelectric modulus | d12 = 6.1; d14 = 5.4 | pC/N | |
| 13. | Resonance spacing | 0.9 | % | |
| 14. | SAW velocity | 2723 (0°;138,5°;26,7°) | m/s | |
| 15. | Mohs hardness | 6.6 | - | |
| 16. | Debye temperature | 742 | K | |
| 17. | Curie temperature | N/A | оС | |
| 18. | Melting temperature | 1480 | оС | |
| 19. | Temperature Frequency Coefficient | 1.6х10-5 | °C-1 | |
| 20. | Resistivity | >1х1012 (25°C) | ohm*cm |