Langatate La3Ga5.5Ta0.5O14
Lanthanum gallium tantalate (langatate — LGT) crystals have certain advantages compared to traditional piezoelectric materials (piezoceramics and quartz) used in sensors measuring physical values.
LGT has no:
- phase transitions up to the melting temperature 1450 °C;
- pyroelectric effect;
- hysteresis.
However the material demonstrates:
- high electromechanical coupling factor Kemc (more than twice as much as quartz);
- steady-state value of piezoelectric constant d11 in a temperature range up to 600 °C (less than 5% change up to 450 °C);
- high electrical resistivity (about 108 Ohm·m @ 540 °C).
The key physical properties of langatate (LGT) and traditional materials are compared in a table below:
| Properties | Unit | NAVY Symbol | Langatate | Quartz | APC-850 N-2 | APC-856 |
|---|---|---|---|---|---|---|
| Relative dielectric constant | 1 | K=εT33/ε0 | 80.3 | 4.6 | 1750 | 4100 |
| Curie temperature | °C | Tc | - | 570 | 360 | 150 |
| Piezoelectric charge constant | 10-12 C/N or m/Vz | -d11 | 6.5 | 2.3 | d33=400 | d33=620 |
| d14 | 4.7 | 0.9 | d15=590 | d15=710 | ||
| Piezoelectric voltage constant | 10-3 Vm/N or m2/C | -g11 | 38 | 58 | g33=26 | g33=18.5 |
| g14 | 27.7 | 18 | g15=36 | g15=25 | ||
| Young's modulus | 1010 N/m2 | YE11 | 11 | 7.8 | 6.3 | 5.8 |
| YE33 | 19 | 10.4 | 5.4 | 4.5 | ||
| Frequency constants L = longitudinal mode T = thickness mode |
Hz-m or m/s | NL | 2870 | - | 1500 | - |
| NT | 1320 | 1666 | 2032 | 1980 | ||
| Elastic compliance | 10-12 m2/N | SE11 | 9.0 | 12.8 | 15.3 | 15.0 |
| SE33 | 5.2 | 9.6 | 17.3 | 17.0 | ||
| Density | g/cm3 | ρ | 6.13 | 2.65 | 7.7 | 7.5 |
| Q-value | 1 | Qm | 50000 | 106 | 80 | 72 |
Shapes, geometries, surface finish, metallization
- We can provide lapped/polished, unplated/plated langatate sensor blanks of various shapes and geometries (circular/rectangular/disks) (external diameter from 8 mm, internal diameter from 3 mm, thickness from 0.5 mm).
- Sensing piezoelectric elements can have the grinding or polished surface, spraying electrodes from different metals is possible (Cr, Au).
Application
- Langatate elements can be used in pressure and vibration sensors operating at temperatures up to 600 °C. Sensors capable of withstanding 900 °C are currently under development. We supply our products to the US, European and Japanese companies.
Langatate samples for tests and investigations are provided on request. Technical information is also available.
