Introduction

Langasite – or “LGS” for short - is a piezoelectric crystal of the same crystal class as quartz. Its chemical formula is La3Ga5SiO14. Opposed to quartz it has no phase transition up to the melting point at 1475°C. Therefore LGS is an excellent candidate for high temperature applications in sensors - BAW (Bulk Acoustic Wave) and SAW (Surface Acoustic Wave) devices as well as sensors based on the direct piezoelectric effect.

LGS has a piezoelectric factor d11, which is about 2.7 times that of quartz, which allows to realize piezoelectric sensors with significantly higher sensitivity. As the piezoelectric coupling factor is 2.3 to 3 times that of quartz, resonators with high frequency pullability (i.e. low capacitance ratio C0/C1) can be manufactured with this material, having a temperature stability and a Q-factor, which are in the same order of magnitude as those of quartz resonators.

Langasite crystals are synthetically grown by the Czochralski method in boules up to 100 mm diameter. LGS has excellent thermal, piezoelectric and dielectric properties and is resistant to many chemicals.

The main applications of LGS include:

  • High-Temperature Surface Acoustic Wave (SAW) sensors
  • High-Temperature Bulk Wave (BAW) sensor
  • High -Temperature and High-Sensitivity piezo-static sensor elements
  • Crystal units as Bulk Wave (BAW) resonators with high motional capacitance
  • SAW devices for frequency control and selection
  • Wideband piezoelectric filters, both discrete and monolithic

For more detais please consult our Technical Notes on Novel Piezoelectric Materials

Langasite (LGS) Blanks & Wafers

Langasite (LGS) La3Ga5SiO14 Wafers
Product

Diameter

[mm]

Thickness

[mm]

Cut

(Euler notation)

Surface

Quality

Flat

[mm]

Remarks
AXLGSW-76.2-SAW 76.2 0.500 (0,138.5°,26.6°) SSP   SAW
AXLGSW-100-SAW 100 0.500 (0,138.5°,26.6°) SSP   SAW
AXLGSW-100-0-22-90 100 0.500 (0,22°,90°) SSP   SAW
AXLGSW-100-Y 100 0.500 Y-cut DSL   BAW
AXLGSW-76.2-Y 76.2 0.500 Y-cut DSP   BAW
  76.2 0.400 Y-cut DSL   BAW
  76.2 0.800 (0.0.1) DSL   Sensor
AXLGSW-60-Y 60 0.500 Y-cut DSL   BAW
  38.1 0.500 Y-57° DSL   Sensor
  25.4 0.280 Y-cut DSL   BAW
  20x20 0.500 X-cut DSL   Sensor
             

Caption:
SSP = Single Side Polished. Back side fine lapped
DSP = Double Side Polished
SAW = Surface Acoustic Wave Device
BAW = Bulk Acoustic Wave Device

Other dimensions, cut angles and other parameters on request. Please contact AXTAL