High Pressure: Effect on Dysprosium.
The electrical resistance of dysprosium was studied in the temperature-pressure range 77 degrees to 200 degrees K and 15 to 120 kb. The variations of the Néel transition with pressure was found to good accuracy, the value of dT(N)/dP being-0.62+/-0.4 deg/kb. From this result, second-order thermodynamic equations yield values of -64 x 10-6 ( degrees C)(-1) and 4.0 x 10(-14) cm(2)/dyne for the changes in the coefficient of linear expansion and the compressibility, respectively, at the 1-atm Néel point. The Néel transition disappears at 45 to 55 kb, and no magnetic transitions are seen at higher pressures in the temperature range indicated. The other boundaries in the region investigated have been determined but are very uncertain. The cause of the cusp in the isothermal compressions is not clear from the available data. Above the Néel boundary, the pressure dependence of the cusp with respect to temperature, dP/dT, is very small and may even be zero. Below the Néel temperature, dP/dT is uncertain. From isothermal measurements, the value is -1, while from the isobaric measurements a value of -0.25 is obtained.
Souers
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Jura
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