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Physical Measurements Service
Facilities
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HC option (Heat capacity measurements, He-4 or He-3)
A partir del ajuste de la evolución de la temperatura T(t) el sistema obtiene el valor de la capacidad calorífica.
Permite incorporar la opción He-3.
This option measures the heat capacity at constant pressure (CP). Basically, a known amount of heat is applied at constant power for a fixed time, in order to produce a specified temperature increment, and then this heating period is followed by a cooling period of the same duration (semiadiabatic relaxation method).
The fit of the temperature time dependence T(t) provides CP.
The heat capacity option is compatible with the He-3 system.
Puck estándar
Standard Puck
  • Temperature Range: 1.9 K at 400 K.
  • Magnetic field range: 0 a ± 9 T, ± 14 T. *
Puck He-3
Standard Puck
  • Temperature Range: 350 mK at 350 K.
  • Magnetic field range: 0 a ± 9 T, ± 14 T. **
  • Samples:
    Powder, film, pellet.
    It is recommended to use samples with relatively flat geometry. Samples with low thermal conductivity should be as thin as possible to minimize the time it takes for the sample to reach internal thermal equilibrium. Maximum horizontal dimension (platform sample holder limited) is 3 mm. Samples weighting approximately 1 to 200 mg. Proper thermal contact between the sample and platform requires grease to attach the sample to the platform.
  • Measurements:
    The heat capacity is measured under High-Vacuum conditions (0.9 mTorr) ensuring that the paths by which heat escapes the sample platform are just the platform wires, whose thermal conductivity is known (calibrated).
    Since high vacuum reduces the thermal contact with the PPMS system the reference temperature is now read from an additional thermometer located in the sample holder. In standard heat capacity measurements it is located buried in the standard puck. In He-3 heat capacity measurements the thermometer, which is actually the He-3 option thermometer, is in contact with the sample holder.
    * The magnetic field is applied perpendicular to standard puck sample platform. A vertical puck adapter is available to place the sample puck in the parallel orientation.
  ** He-3 option allows sample puck orientation either parallel or perpendicular to the magnetic field applied.