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Physical Measurements Service
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TTO (Thermal Transport Option)
The TTO system provides thermal conductivity by measuring the temperature drop along the sample as a known amount of heat passes through the sample.
Also, TTO measures the thermoelectric Seebeck effect as an electrical voltage drop that accompanies the temperature drop across certain materials. The system can also measure electrical resistivity.
All three measurement types are essential in order to assess the so-called “thermoelectric figure of merit”, which is the quantity of main interest in thermoelectric materials. Opción TTO (Medidas de Transporte térmico)
  • Temperature range 1.9 K a 400 K *
  • Magnetic Field Range: 0 a ± 9 T, ± 14 T **
  • Seebeck voltage range: 1 µV a 5 106 µV (5V)
  • Electrical resistance rangea 0.5 µΩ a 0.5 MΩ
  • Recommended sample geometrys ***
    • Needle: 10x1x1 mm³ (k = 10-150 W/mK)
    • Brick: 8x2x2 mm³ (k = 2-30 W/mK)
    • Pellet: 3x5x5 mm³ (k = 0.1-1.5 W/mK, lead disc diameter 6.3 mm)
  • Two contacts
    Suitable for samples with low thermal conductivity:
    Opción TTO (dos contactos -1) Opción TTO (dos contactos -2)
  • Four contacts
    Suitable for samples with large thermal conductivity:
    Opción TTO (cuatro contactos)
  • Measurement modes
    • Continuous measurement mode
      Measurements are taken continually (steady state is not required) and the software is adjusting parameters (such as heater power and period) to optimize the measurements. This mode is amenable to slow sweeps of system variables such as temperature or magnetic field, and it is often the fastest mode.
    • Single measurement mode
      It requires that the system reach a steady state in both the heater “off” and “on” states, which also implies that temperature or field slewing is unavailable. No curve fitting calculations are required in this mode so interpretation of the raw data is more straightforward. The user should specify the measurement parameters (such as heater power and period).
    * At T> 300K radiation losses should be considered
  **H> 0.1 T only for temperatures T > 20 K
*** Sample geometry is limited by the available space on the sample holder and sample conductivity