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Home > Wafers and Substrates > Optical Grade LiNbO3, LiTaO3 Crystal Wafers > Langasite(LGS) Crystals and Wafers

Langasite (LGS) Crystals and Wafers

  • Optimized for surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices
  • High thermal stability with temperature up to 900℃
  • High electro-mechanical coupling factor (15.8%) 
  • Diameters of wafers: ɸ6-76.2mm
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LGS Crystals Blanks or Blocks:

X Direction 5~40mm Y Direction 5~40mm
Z Direction ~80mm Direction Precision ±20’

 

Langasite Slices:

Diameter 5~14mm Frequency 2.7~21MHz
Direction Precision ±20’ Surface Roughness(Lapped) Ra=0.3~0.5μm

 

Sensor, SAW Wafers:

Diameter 6~76.2mm Thickness 0.13~0.5mm
Reference Flat 2~15mm Surface Roughness (CMP single or double sides) Ra≤1nm
Orientation Following customer specifications
 

 

Table 1. Basic Properties of Langasite

Constant Relative Dielectric Constant Piezoelectric Constant (pC/N) Elastic Stiffness (1011Pa)
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 Parameters of Piezoelectric Crystals

Crystals Quartz SiO2 Langasite La3Ga5SiO14 Lithium tetraborate Li2B4O7 Lithium Tantalite LiTa3
Electromechanical Coupling Factor K%(BAW) 7.0 15.8 24.0 47.0
Frequency Spacing Δf, % 0.25 0.90 4.00 7.00
Q-Factor Q, x103 100 50 10 2
Temperature Frequency Coefficient TFC, x10-6/°C 0.5 1.6 6.0 4.0


Table 3. SAW properties of Langasite and Quartz

Crystals Quartz(SiO2) Langasite(La3Ga5SiO14)
Density (g/cm3) 2.65 5.746
SAW Velocity Vef (m/s) (0º,132.75 º,0 º)3157 (0º,140 º,25 º)2756
K2emc,%(SAW) 0.14 0.36
Second order temp.coef.  α2(x10-8/°C2) -3.2 -6.8
Temp. Coef. TTO(°C) 25 23
Dielectric Constant (ε) 4.92 27
Power flow angle Ф, º 0 0.5

Langasite crystal (La3Ga5SiO14, LGS), also called Lanthanum gallium silicate, belonging to the space group P321, point group 32, is a novel piezoelectric material with great potential for the fabrication of surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices. 

The LGS crystal has a higher electromechanical coupling factor (15.8%) than that of a quartz crystal, and the value indicates the effectiveness with which a piezoelectric material converts electrical energies into mechanical energies. It is also worth noting that the propagation velocities of a surface acoustic wave in LGS crystal is much lower, this value determines the filter size. When manufacturing quartz and LGS filters operating at the same center frequency, the geometrical dimensions of LGS filters can be made smaller, which conforms with the trend of the dense integration of modern electronics and saves production cost. In addition, The devices made of langasite crystal could be used at high temperatures up to 900℃ because of its high thermal stability. 

Hangzhou Shalom EO offers the LGS crystals blanks, polished substrates, and wafers upon customers' request.