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Langasite(LGS) Crystals and Wafers

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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
 

 

Basic Properties:

Langasite crystal possesses some great properties, such as higher electromechanical coupling factor than quartz, no phase transition from room temperature to melt point. Some properties of langasite crystal are shown in Table 1.

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

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 properties of piezoelectric crystals

Properties 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

 

With the rapid development of the communication technology, the new generation communication system enables people not only to talk, but also to transmit image, data and video. Langasite crystal possesses high SAW properties compared with quartz.which make it to be the most competitive material in this field. SAW properties of langasite and quartz are listed in the Table 3.

Table 3 SAW properties of langasite and Quartz

Properties 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), belonging to the space group P321, point group 32, has been reported to be promising new piezoelectric materials for fabrication of surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices. The devices made of langasite crystal could be used at a high temperature up to 900℃ because of its high thermal stability. Hangzhou Shalom EO offers the LGS crystals blanks, polished substrates and wafers upon customer's request.