Setup for measurements of thermoelectric properties under pressure up to 30 GPa at room temperature (with synthetic diamond anvils)

Details of experiments with using of this apparatus:

• smooth generation of applied force (quasi-hydrostatic pressure) and automatic recording of the electrical and mechanical parameters of the sample
• measurement of thermoelectric power in two regimes:
  • at a fixed pressure and simultaneous changing of temperature gradient
  • at a fixed temperature gradient and gradual changing of applied pressure
• measurements performed at a microscopic samples having a discoid form with a diameter of about 200 microns and thick of about 30 microns
• Chamber with the modified Bridgman anvils from synthetic diamonds with working diameters of ~ 600 microns are used to generate pressure up to 30 GPa
• as a gasket and a pressure-transmitting medium is a container made of limestone (soft mineral based on CaCO₃)
• error in determining of values of thermoelectric power at high pressures, does not exceed 5%
• pressure values are evaluated on the calibration curve based on well-known and clearly observable transitions in crystals under pressure with an accuracy of about 10%

The sample in the high-pressure chamber:

1. Sample
2. Gasket from lithographic stone serving as the pressure transmitting medium
3. The insertions of synthetic diamonds (anvils)
4. Supporting matrixes form hard alloys

Annular thickening in the gasket 2 produces back pressure P_s (up to 10 GPa) at the edges of the anvils. High hydrostatic pressure P generated in the central part of the chamber.

Photo of anvils with a diamond handpiece: 1 - hard-alloyed base 2 - diamond handpiece

Device for measurements of thermoelectric properties under pressure up to 10 GPa at room temperature (chamber with hard-alloyed anvils)

Details of experiments with using of this apparatus:

• smooth generation of applied force (quasi-hydrostatic pressure) and automatic recording of the electrical and mechanical parameters of the sample
• measurement of thermoelectric power in two regimes:
  • at a fixed pressure and simultaneous changing of temperature gradient
  • at a fixed temperature gradient and gradual changing of applied pressure
• measurements performed at a microscopic samples having a discoid form with a diameter of about 200 microns and thick of about 30 microns
• Toroidal-type chamber with a hemispherical concave anvils with a working diameter of 1 mm made of solid carbide-tungsten alloy used to generate pressure up to 10 GPa
• as a gasket and a pressure-transmitting medium is a container made of limestone (soft mineral based on CaCO₃)
• error in determining of values of thermoelectric power at high pressures, does not exceed 5%
• pressure values are evaluated on the calibration curve based on well-known and clearly observable transitions under pressure with an accuracy of about 10%

The sample in the high-pressure chamber:

1. Sample
2. Gasket from lithographic stone serving as the pressure transmitting medium
3. The insertions from solid carbide-tungsten alloy (anvils)
4. Supporting matrixes form hard alloys

Annular thickening in the gasket 2 produces back pressure P_s (up to 10 GPa) at the edges of the anvils. High quasihydrostatic pressure P generated in the central part of the chamber.