|Serway, Raymond A., Beichner, Robert J., & Jewett Jr., John W. Physics for Scientists and Engineers with Modern Physics. Fifth Edition. Orlando: Saunders College Publishing, 2000: 963.||Table 30.3: Curie Temperatures for Several Ferromagnetic Substances
|Jössang, P. & Jössang, A. C.S.M. Pouillet, member of the French Academy of Sciences, discovered the "Curie" point in… 1832. Science Tribune, January 1997.||"Pouillet had found magnetic limits of quite the right order for iron (TC = 770°C), nickel (TC = 358°C) and cobalt (TC = 1130°C) even though one did not know how to measure high temperatures at the time."||631 K|
|Ferromagnetic Curie Temperatures. Hyperphysics. Georgia State University.||
|Effects of Composition, Processing and Structure on Properties of Nickel and Nickel Alloys. Key-to-metals.||"It is ferromagnetic, with a Curie temperature of 358°C (676°F) and good electrical (25% IACS) and thermal conductivity (82.9 W/m K, or 48 Btu/ft h °F)."||631.15 K|
The Curie temperature is named after the famous researcher, Pierre Curie, whom in 1895 discovered that there exists a critical temperature at which certain materials (such as nickel, iron, cobalt, gadolinium and others) lose their ferromagnetic properties. Their strong spontaneous magnetization (ferromagnetism) disappears due to thermal fluctuations within the external magnetic field.
Ferromagnetic substances will tend to stay magnetized to some extent after being subjected to an external magnetic field when it is below its Curie temperature. The tendency for this to happen is called magnetic hysteresis. (The word hysteresis literally means "lagging behind.") The process mainly depends on the history of the substance and the strength of the applied field. A hysteresis loop forms around the substance, where its shape and size is determined by the aforementioned factors. A very narrow hysteresis loop and small remaining magnetization, as a "soft" ferromagnetic nickel material may have, can be easily demagnetized by being carried through a series of hysteresis loops, thereby decreasing the applied external magnetic field.
At temperatures below the Curie point, the dipoles are partially aligned within the ferromagnetic material, enabling it to develop a magnetic field of its own. However, when the temperature reaches or exceeds the magnets' specified temperature, the thermal change causes the electrons within the substance to be excited so that the dipoles can no longer align, the net magnetization to become zero, and the substance to be purely paramagnetic (weaker than ferromagnets).
The Curie temperature of nickel is known to be either 627 K or 631 K.
Stephanie Ma -- 2005
|Serway, Raymond A., and Robert J. Beichner. Physics: For Scientists and Engineers with Modern Physics (5th Edition). Saunders College Publishing. New York, 2000: 936.||"Table 30.3: Curie Temperatures for Several Ferromagnetic Substances: Substance: Nickel,
Tcurie (K): 631"
|Effects of Composition, Processing and Structure on Properties of Nickel and Nickel and Alloys. Keys-to-metals. 2004.||"It is ferromagnetic, with a Curie temperature of 358°C (676°F)."||358 °C|
|Jössang, P., and A. Jössang. C.S.M. Pouillet, member of the French Academy of Sciences, discovered the "Curie" point in… 1832. Science Tribune. January 1997.||"The magnetic limit he determined experimentally for Nickel was 350°C approx. compared to the 340°C approx. later found by Curie."||~350 °C|
|Nickel-Properties, Fabrication and Applications of Commercially Pure Nickel. Azom.com.||"Table 1. Properties of Nickel 200, the commercially pure grade (99.6% Ni): Curie Temperature - 360°C"||360 °C|
The Curie temperature or Curie point is a temperature at which a material loses its magnetic characteristics such as an ability to attract other magnets. The Curie temperature was named after the French scientist Pierre Curie who supposedly discovered it. However, it was believed that another French physicist C.S.M. Pouillet has discovered it 60 years before Pierre Curie. Instead of Curie temperature, he called it the "magnetic limit".
When the temperature is below the Curie temperature, the magnetic poles of the electrons will align themselves and point in the same direction. Ferromagnetic materials include iron, nickel, cobalt, and gadolinium. These ferromagnetic metals tend to stay magnetized even after the external magnetic field was removed. Ferromagnetism is caused by the spinning of the electrons and the interaction with the adjacent electrons known as exchange coupling. When the temperature is above the Curie temperature, the material is paramagnetic. In the absence of an external magnetic field, the magnetic dipoles will align in a random fashion and tend to move freely. The magnetic field of the material will disappear.
Nickel is use in chemical processing and electronics. It's use mainly in forms of alloys such as stainless steal and other corrosion-resistant alloys. Nickel metal has high Curie temperature with good thermal and high electrical conductivity. It also has a low hardness and good ductility. Therefore, it is easy to shape nickel into various forms.
Julie Tan -- 2005