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Topic: Curie point


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  Curie point - Wikipedia, the free encyclopedia
The Curie point is a term in physics and materials science, named after Pierre Curie (1859-1906), and refers to a characteristic property of a ferromagnetic material.
At temperatures below the Curie point, an applied magnetic field has a paramagnetic effect on the magnetization, but the combination of paramagnetism with ferromagnetism leads to the magnetization following a hysteresis curve with the applied field strength.
The destruction of magnetization at the Curie temperature is a second-order phase transition and a critical point where the magnetic susceptibility is theoretically infinite.
en.wikipedia.org /wiki/Curie_point   (359 words)

  
 Ferromagnetism - Wikipedia, the free encyclopedia
The melting point, or more precisely the glass transition temperature, is only 714 K for the alloy versus a melting point of 1811 K for pure iron.
As the temperature increases, thermal oscillation, or entropy, competes with the ferromagnetic tendency for dipoles to align.
The Curie temperature itself is a critical point, where the magnetic susceptibility is theoretically infinite and, although there is no net magnetization, domain-like spin correlations fluctuate at all lengthscales.
en.wikipedia.org /wiki/Ferromagnetism   (1271 words)

  
 World Almanac for Kids
CURIE, Marie (1867–1934) and Pierre (1859–1906), French physicists and Nobel laureates, who were wife and husband; together, they discovered the chemical elements radium and polonium.
Curie thus began studying uranium radiations, and, using piezoelectric techniques devised by her husband, carefully measured the radiations in pitchblende, an ore containing uranium.
Pierre Curie ended his own work on magnetism to join his wife’s research, and in 1898 the Curies announced their discovery of two new elements: polonium (named by Marie in honor of Poland) and radium.
www.worldalmanacforkids.com /explore/inventions/curie_marie.html   (546 words)

  
 Phase transition - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-11-06)
The transition between the ferromagnetic and paramagnetic phases of magnetic materials at the Curie point.
Near the critical point, the fluid is sufficiently hot and compressed that the distinction between the liquid and gaseous phases is almost non-existent.
It was pointed out by Landau that, given any state of a system, one may unequivocally say whether or not it possesses a given symmetry.
www.sciencedaily.com /encyclopedia/phase_transition   (2103 words)

  
 Curie Temperature of Iron
The Curie temperature of iron is 1043 K. Even sources copyrighted before the year 1984 had the Curie temperature of iron to be the same number as more current sources.
When the temperature of iron is at the Curie temperature or higher, then the iron becomes paramagnetic and when the temperature of iron is below the Curie temperature, then it is ferromagnetic.
The Curie temperature of iron is about 1043 K. At temperatures below the Curie point, the magnetic moments are completely aligned within magnetic domains in ferromagnetic materials.
hypertextbook.com /facts/2002/FeliciaLau.shtml   (596 words)

  
 Exhibit Cross Reference - Curie Point
In this exhibit a large magnet attracts a U-shaped piece of metal which is attached to the end of a pendulum.
A current is passed through the metal, heating it until its curie point is reached.
The visitor is allowed to keep the heating on or off with buttons on the exhibit and also is able to feel the magnetic force diminish as the curie point is reached by feeling the pull on a string tied to the pendulum.
www.exploratorium.edu /xref/exhibits/curie_point.html   (105 words)

  
 MSN Encarta - Pierre Curie
Pierre Curie also worked on important topics in the structure of crystals and helped discover the piezoelectric effect in crystals—a property of producing electrical voltages when they are compressed.
Pierre Curie was born in Paris and educated at home by his parents.
In 1880 Pierre and his brother Jacques Curie discovered that some crystals developed positive electrical charges at one end and negative electrical charges at the other when the crystals were compressed.
encarta.msn.com /encyclopedia_761555255/Curie_Pierre.html   (402 words)

  
 Pierre Curie - Biography
Curie's studies of radioactive substances were made together with his wife, whom he married in 1895.
Pierre Curie's work is recorded in numerous publications in the Comptes Rendus de l'Académie des Sciences, the Journal de Physique and the Annales de Physique et Chimie.
Curie was awarded the Davy Medal of the Royal Society of London in 1903 (jointly with his wife) and in 1905 he was elected to the Academy of Sciences.
nobelprize.org /physics/laureates/1903/pierre-curie-bio.html   (536 words)

  
 Exploratorium: Science Snacks: Curie Point
A piece of iron will ordinarily be attracted to a magnet, but when you heat the iron to a high enough temperature (called the Curie point), it loses its ability to be magnetized.
The iron wire is made of atoms that act like tiny magnets, each one having a north and south pole of its own.
This iron is at a temperature above the Curie point and therefore can't be magnetized.
www.exploratorium.edu /snacks/curie_point.html   (512 words)

  
 PIRA 5G50.00 TEMPERATURE AND MAGNETISM
Monel metals have curie points between 25 C and 100 C depending on the alloy.
A gadolinium strip forming the rim of a plexiglass wheel is heated and cooled on opposite sides of a magnetic field, and a weight is lifted by the resulting rotation.
Use the Curie point engine as a simple demonstration of the Carnot principle.
www.wesleyan.edu /physics/demos/pirabib/5eandm/5G50.html   (568 words)

  
 [No title]
] Feed to a point where current is a maximum, as at the center of a half-wave antenna.
] A trochoid in which the distance from the center of the rolling circle to the point describing the curve is less than the radius of the rolling circle.
] The reciprocal of the radius of the circle which most nearly approximates a curve at a given point; the rate of change of the unit tangent vector to a curve with respect to arc length of the curve.
www.accessscience.com /Dictionary/C/C62/DictC62.html   (2594 words)

  
 Pierre Curie
The Curie brothers had found that when pressure is applied to certain crystals, they generate electrical voltage.
After their discovery of polonium and radium, the Curies decided on a division of labor: he concentrated on investigating the properties of radium, while she did chemical experiments with a view to preparing pure compounds.
Marie Curie never forgave France for what she considered its rude treatment of her husband--the failure to give him either the honors or the laboratory facilities he merited.
www.aip.org /history/curie/pierre_text.htm   (690 words)

  
 Applications of Ferroelectric Ceramic Materials
On decreasing the temperature through the Curie point, a ferroelectric crystal undergoes a phase transition from a non-ferroelectric phase to a ferroelectric phase.
The substitution of Pb for Ba raises the Curie point.
This is because of the formation of multiple domains in a single grain, the motion of whose walls increases the dielectric constant at the Curie point.
www.rci.rutgers.edu /~ecerg/projects/ferroelectric.html   (10045 words)

  
 The change in size of a ferromagnetic at the Curie point
The changes of size of iron and nickel at their Curie points are too great to be explained by purely magnetic forces.
On Heisenberg's theory of ferromagnetism, magnetization is accompanied by a change in the strength of binding between atoms, and the resulting changes of size of crystals of iron and nickel at their Curie points are of the same order of magnitude as those observed.
A consideration of the specific heat discontinuity at the Curie point shows, however, that the theory is far from satisfactory.
stacks.iop.org /0959-5309/42/390   (295 words)

  
 Circuit Cellar - Digital Library - EQ Answer
In the Weller system, the back part of the tip is made of a ferrite material that has a Curie point of approximately 600°, 700°, or 800°F as indicated by a "6," "7," or "8," respectively, stamped on the end.
When the tip gets to its Curie point, it no longer attracts the magnet, which is released, and the switch turns off.
When the plating reaches its Curie point, the induced current flows through the copper core instead and, because its resistivity is much lower, the heating is much less.
www.circuitcellar.com /library/eq/160/3.htm   (285 words)

  
 Pierre Curie
He was also, with collaborators, the first to report the decay of radioactive materials and the skin burns that radioactive substances can inflict.
Reflecting on her first meeting with Pierre Curie, Marie Curie recalled being “struck by the open expression of his face and by the slight suggestion of detachment in his whole attitude.”
The Curies in their laboratory at the School for Industrial Physics and Chemistry.
www.aip.org /history/curie/pierre.htm   (752 words)

  
 Re: Curie point engine vs Carnot efficiency
http://www.exploratorium.edu/snacks/curie_point.html For that demonstration of the curie point, if I chose the metal object to be the control mass, electrical energy is used to heat the control mass, so that it cannot be said that energy is transferred to the control mass as heat.
From the illustrations in the above web reference, it also appears any work produced is due to the potential energy provided to the control mass as a starting condition, rather than a cyclic release of work more common in a heat engine.
In summary, Carnot efficiency does not apply to the demonstration of the Curie point because the later is not a heat engine.
www.madsci.org /posts/archives/2003-05/1053350779.Ph.r.html   (207 words)

  
 Infolytica » Gallery » Induction heating past the Curie point   (Site not responding. Last check: 2007-11-06)
Eddy current losses in the workpiece raise its temperature past the Curie point, which in turn affects the distribution of the eddy currents.
Without a fully coupled solver and temperature dependent material properties the change in the eddy current distribution as the temperature changes would not be modeled correctly.
The temperature at the base of the workpiece eventually increases beyond the Curie point, which impacts the magnetic properties.
www.infolytica.com /en/coolstuff/ex0052   (346 words)

  
 AUTO CURIE POINT PYROLYZER WITH SAMPLER   (Site not responding. Last check: 2007-11-06)
The Model JPS-330 Curie Point Pyrolyzer with sampler represents the state-of-the-art in automated pyrolysis GC system for the analysis of polymers and other nonvolatiles by GC.
The heart of the system is in the PYROFOIL in which the sample is heated and pyrolyzed.
Twenty different PYROFOILs, a series of ferromagnetic alloys, are available with the system with temperature range from 160 C to 1040 C. Since each ferromagnetic alloy has a precise Curie Point temperature the results obtained with the system is always reproducible.
www.labinternet.com /p040_033.htm   (160 words)

  
 MSN Encarta - Search Results - Curie point
MSN Encarta - Search Results - Curie point
Curie, Pierre (1859-1906), French physicist and Nobel laureate, best known for the work on radioactivity that he did with his wife, Marie Curie.
Curie, Marie (1867-1934), Polish-born French chemist and physicist who twice won the Nobel Prize and is best known for her investigations of...
ca.encarta.msn.com /Curie+point.html   (116 words)

  
 Curie Point   (Site not responding. Last check: 2007-11-06)
Canadian quarters (which have some iron in them) are picked up by a magnet, and heated by a torch.
As each quarter heats up to its curie point, it falls off the magnet into a container of water below.
After the quarter enters the water which cools it down, it can be picked up again with the magnet.
physics.ucsd.edu /was-sdphul/labs/demos/modern/curie.html   (77 words)

  
 Demonstrations
Heat the junction of the magnet and the rod with the Bunsen burner and observe the loss of magnetic attraction due to heat (Curie Point).
George Barnes, "Demonstrating the Curie Point in Nickel", TPT, Vol.
Smith, "An AC Bridge Method for the Measurement of Curie Points", AJP, Vol.
faraday.physics.uiowa.edu /em/5G50.10.htm   (352 words)

  
 The Collection and Detection of Accelarant Vapors Using Porous Polymers and Curie Point Pyrolysis Wires Coated with ...
The sampling of organic vapors from arson residues using different types of adsorbants is studied.
Sampling tubes packed with porous polymers (Porapak Q and Tenax GC) as well as Curie point pyrolysis wires coated with finely divided or granular active carbon are used.
Author Andrasko J Title The Collection and Detection of Accelarant Vapors Using Porous Polymers and Curie Point Pyrolysis Wires Coated with Active Carbon Symposium, Committee on
www.astm.org /JOURNALS/FORENSIC/PAGES/313.htm   (204 words)

  
 5g50.15.HTML   (Site not responding. Last check: 2007-11-06)
PURPOSE: To show the Curie point of nickel.
DESCRIPTION: A Canadian nickel has the ferromagnetic element nickel as a major part of its composition, and is strongly attracted to a magnet, as shown in the photograph.
When heated above its Curie temperature by the gas torch, it loses its fe rromagnetism and falls away from the magnet to the table.
www.phy.mtu.edu /LECDEMO/websit/5g50.15.htm   (70 words)

  
 A radio-frequency method for determining Curie point temperatures   (Site not responding. Last check: 2007-11-06)
A radio-frequency method for determining Curie point temperatures
A radio-frequency method utilizing the fact that rapid changes in permeability occur at the Curie point is described.
The circuit used is essentially a temperature-compensated marginal oscillator.
stacks.iop.org /0022-3735/1/1136   (203 words)

  
 Scitoys Message Board: Curie point and magnet (wheel)
Scitoys Message Board: Curie point and magnet (wheel)
The temperature has to be about 180°-200°, so the Curie point of your magnet is too high for me. Have you an idea of what material I have to use?
Only registered users and moderators may post messages here.
www.scitoys.com /board/messages/1/194.html?1077025011   (100 words)

  
 The Collection and Detection of Accelarant Vapors Using Porous Polymers and Curie Point Pyrolysis Wires Coated with ...   (Site not responding. Last check: 2007-11-06)
The Collection and Detection of Accelarant Vapors Using Porous Polymers and Curie Point Pyrolysis Wires Coated with Active Carbon.
Keywords: accelerants, activated charcoal, arson, Curie point pyrolysis, fire accelerants, fire residues, forensic science, porous polymers, thermal desorption, vapor analysis, vapors
Abstract: The sampling of organic vapors from arson residues using different types of adsorbants is studied.
journalsip.astm.org /jofs/PAGES/238.htm   (148 words)

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