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About IIG Observatory Instruments and Facilities

MMTD Thermal Demagnetizer

Instrument Details
Name: MMTD-80 Thermal Demagnetizer
Made: Magnetic Measurements

Maximum temperature : 800 °C
Temperature resolution : 1°
Temperature repeatability : 1°
Temperature accuracy : < 3°
Temperature gradient within furnace : < 10°
TRM dc field : up to > 0.1 mT
Titanium sample boats : 45 cm long

Rock specimens are heated to higher temperatures and cooled to room temperature in a (mumetal shielded) zero magnetic field chamber. If the temperature of a rock specimen raised above the Curie point, NRM of magnetic particles will be ‘unblocked’, while cooling in a zero magnetic field will result in random orientation of particles and therefore no contribution to the NRM of the rock. Step wise increment of the temperature to maximum of 800°C would reveal the assemblages of magnetic components and their behavior. This instrument has a provision of using inert gas during heating to prevent oxidation of magnetic minerals due to raise in the temperature.

This instrument is used in palaeomagnetic investigations to demagnetize (Magnetic cleaning technique) the rock specimens and thus to remove the unwanted viscous and/or secondary components to obtain ChRM directions; also used in curie temperature studies to discriminate the magnetic minerals on the basis of their curie temperature.

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