Variable Field Translation Balance (VFTB)
(GFZ)
Close-up of sample holder
sketch of important VFTB elements
Example of magneto-granulometric results
Example of thermomagnetic and hysteresis data

Analytical performance:

Measurement of thermomagnetic curves (saturation magnetization vs. temperature), hysteresis curves, back field curves, and fully automatic acquisition of isothermal remnant magnetization (IRM) curves.

Applications:

  • Rock magnetic investigation
  • magnetomineralogy, determination of : Curie-Temperature
  • magnetogranulometry, determination of : saturation magnetization - Ms
  • saturation remanence - Msr
  • coercive force - Bc
  • coercive force of remanence - Bcr
  • coercivity spektrum

Sample types:

Powder = dried sediments / crushed hard rocks; about 0.2 cm3.

Further details:

The VFTB is based on a conventional horizontal 'Curie-balance', equipped with an electromagnet, a cylindrical water-cooled oven, a thermocouple, and a sample holder of about 0.2 cm3. The sample holder is connected to a pick-up coil and hanging on thin wires allowing for a horizontal movement. But, in contrast to the classical Curie-balance, the electromagnet has flat poles and the sample is sited within the area of homogenous magnetic field between the poles. In addition to this, a coil quadruple is arranged arround the measuring volume producing a small alternating magnetic gradient field that forces the sample to oscillate horizontally within the homogenous static field of the electromagnet. The strength of the static field that induces the magnetic moment in the sample is measured with a Hall probe. The operating frequency of the gradient coils is 2.4 Hz, which is equal to the resonance frequency of the sample holder assemblage.