LGS can be used to fabricate piezoelectric and electro-optical devices. It has high temperature piezoelectric properties. The electromechanical coupling coefficient is 3 times of quartz, and the phase transition temperature is high (from room temperature to melting point 1470℃).
The use temperature is up to 900. It is available for manufacturing SAW, BAW, high temperature sensors and high power, high repetition rate electro-optic Q-switches.
Surface acoustic wave (SAW) devices using the recent langasite (LGS) family of crystals have been designed, fabricated and tested for high temperature (up to 750°C) gas sensor applications. The insertion loss of SAWF prepared by LGS is much smaller than that of SAWF prepared by quartz, which proves the advantages of LGS in the preparation of SAW devices and facilitates the miniaturization of devices.
Parameter
| Crystal structure | Trigeminal system |
| Point cloud | 32 |
| Space group | P321 |
| Lattice constant(Å) | a=b=0.8162, c=0.5087 |
| Melting point(℃) | 1470 |
| density( g/cm3) | 5.75 |
| Mohs hardness (Mohs) | 6.5 |
| Dielectric constant | ε11/ε0=18.27 ε33/ε0=56.26 |
| Piezoelectric strain constant (10-12)C/N | d11=6.3 d14=-5.4 |
| Orientation Tolerance | < 0.5° |
| Parallelism | <20〞 |
| Perpendicularity | 5ˊ |
| Surface Quality | 10-5 (MIL-O-13830A) |
| Wavefront Distortion | <λ/4@633 nm |
| Surface Flatness | <λ/8 @633 nm |
| Clear Aperture | >90% |
| Thickness/Diameter Tolerance | ±0.05 mm |
Characteristics\Crystals | Quartz, SiO2 | Langasite, La3Ga5SiO14 |
Electromechanical Coupling Factor K2emc, % (BAW) | 7.0 | 15.8 |
Frequency Spacing Δf, % | 0.25 | 0.90 |
Q-factor Q, ×103 | 100 | 50 |
Temperature Frequency Coefficient TFC, ×10-6/°C | 0.5 | 1.6 |
- High thermal stability
- Low equivalent series resistance
- Sensor
- SAW device
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