| Autor: |
Kettler, W. H., Wernhardt, R., Rosenberg, M. |
| Předmět: |
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| Zdroj: |
Review of Scientific Instruments; Dec1986, Vol. 57 Issue 12, p3053, 6p |
| Abstrakt: |
A new differential ac technique is described for rapid and continuous measurement of thermoelectric power of thin metallic ribbons over a wide temperature range. Sinusoidal heating of one thermocouple junction by means of a small resistive heater results in a measuring principle which eliminates spurious thermoelectric voltages in the lead wires and favorably benefits from ac signal processing. The resultant equilibrium temperature of the heated junction contains a constant term depending on thermal parameters of the system, and an oscillating term with a frequency-dependent amplitude. By choosing a suitable sample configuration no corrections are required for the thermal response of the system. By careful shielding of the measuring circuits and using modern lock-in amplifiers noise voltages can be reduced to less than 1 nV for measuring frequencies below 10 Hz. Measurements accurate to 1% are possible, using temperature differences smaller than 10 mK. The effectiveness of this technique is demonstrated by comparing our measurement of the thermoelectric power of an amorphous Fe[sub 80]B[sub 20] alloy with measurements using conventional techniques and by studying the thermopower of an amorphous Fe[sub 90]Zr[sub 10] alloy in the vicinity of its second-order magnetic phase transition. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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