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Piezoelectric Langasite La<sub>3</sub>Ga<sub>5</sub>SiO<sub>14 </sub>(LGSO) Crystal,  MSE Supplies LLC

Piezoelectric Langasite La3Ga5SiO14 (LGSO) Crystal

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Product Name: Piezoelectric Langasite La3Ga5SiO14 (LGSO) Crystal

Langasite La3Ga5SiO14 crystals (LGSO or LGS), also known as Lanthanum gallium silicate, has its crystal structure belonging to the space group P321, point group 32. LGS is a promising piezoelectric material with no phase transitions up to its melting point of 1470 °C. LGSO has the value of electromechanical coupling coefficient, which is between that of a quartz crystal and that of lithium tantalate crystal. LGSO is mainly applied in fabrication of SAW (surface acoustic wave), BAW (bulk acoustic wave) devices and sensors (pressure sensor, acceleration sensor. etc.).

A list of the main applications of LGSO (LGS) include:

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

Diameter: 10 - 60 mm, or can be customized

Thickness: 0.25-0.5 mm, or can be customized

Total Thickness Variation (TTV) for a 2" Wafer: < 10um

First Reference Flat: 15.0 mm

Second Reference Flat: 8.0 mm

Surface Roughness (Polished): Ra ≤ 1 nm

Surface Polish Choices: SSP or DSP.

Orientations: Euler angles (0°,138.5°,26.7°) or (0°,22°,90°), or Z-cut, or following customer specifications. Definition of Euler angles (0,138.5,26.6): 42.5 degree rotated Y-cut with reference flat perpendicular to 26.6 degree rotated X axis

Lead time: 6-8 weeks

Table 1 Dielectric, piezoelectric, elastic stiffness constants and their first order temperature coefficients of Langasite crystal

Constant

Relative

Dielectric Constant

Piezoelectric Constant

(pC/N)

Elastic Stiffness (1011 Pa)

ε11

ε33

d11

d14

c11

c12

c13

c14

C33

C44

Value

18.96

50.19

5.66

-5.48

1.898

1.058

1.022

0.144

2.626

0.535

First Order Temp. Coef.

10-6 K-1

150

-760

329

-342

-66

204

-75

-335

-94

-63


Table 2 Comparative properties of piezoelectric crystals

Properties \ Crystal

Quartz

SiO2

Langasite

La3Ga5SiO14

Lithium Tetraborate

Li2B4O7

Lithium Tantalate

LiTaO3

Electromechanical Coupling Factor K, %(BAW)

7.0

15.8

24.0

47.0

Frequency Spacing, %

0.25

0.90

4.00

7.00

Q-Factor Q, ~103

100

50

10

2

Temperature Frequency Coefficient

TFC, ~10-6/C

0.5

1.6

6.0

4.0


Table 3 SAW properties of Langasite and Quartz

Properties (Crystal)

Quartz (SiO2)

Langasite (La3Ga5SiO14)

Density, g/cm3

2.65

5.746

SAW Velocity Vef, m/s

(0°, 132.75°, 0°)

3157

(0°, 138.5°, 26.7°)

2723

Electromechanical coupling factor K2emc, %(SAW)

0.14

0.36

Second order temp. coef.

ñ2, ~10-8/up>2

-3.2

-6.8

Temp. Coef. TTO

25

23

Dielectric Constant

4.92

27

Power flow angle F, °

0

0.5