Temperature detection method based on the magnetoimpedance effect in soft magnetic nanocrystalline alloys

GÓMEZ-POLO, C.; SOCOLOVSKY, L. M.; KNOBEL, M.; VÁZQUEZ, M.

SENSOR LETTERS

AMER SCIENTIFIC PUBLISHERS

Año: 2007 vol. 5 p. 1 - 4

1546-198X

The temperature dependence of the ac electrical impedance is analysed in a soft magnetic Fe based nanocrystalline wire. An amorphous Fe73
5Si13
5B9Cu1Nb3 wire (diameter 20 m) was annealed in vacuum at 550 Cdur ing 30 min, leading to a nanocrystalline structure. The magnetoimpedance characterisation indicates the occurrence of a sharp decrease in the electrical impedance around the Curie temperature, TCa, of the residual amorphous phase (340 C). The thermal dependence of the electrical impedance, ZT , is analysed and estimated taking into account the temperature dependence of the magnetic permeability. The basic characteristics of ZT  correlated to its potential application as temperature detectors are analysed. The results indicate that the sensor span (measuring temperature range) can be suitably controlled through the main parameter that controls the magnetization process of the samples around TCa, i.e., the mean circumferential magnetic field acting on the sample (amplitude of the exciting electrical current).