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Topic: Curie temperature

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  Curie point - Wikipedia, the free encyclopedia
As the temperature is increased from below the Curie point, thermal fluctuations increasingly destroy this alignment, until the net magnetization becomes zero at and above the Curie point.
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.
In analogy to ferromagnetic materials, the Curie temperature is also used in piezoelectric materials to describe the temperature above which the material loses its spontaneous polarization and piezoelectric characteristics.
en.wikipedia.org /wiki/Curie_temperature   (348 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.
As the temperature is increased, thermal fluctuations abruptly destroy this alignment until the net magnetization becomes zero at and above the Curie point.
hypertextbook.com /facts/2002/FeliciaLau.shtml   (594 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)

 Pierre and Marie Curie
Pierre and Marie Curie are best known for their pioneering work in the study of radioactivity, which led to their discovery in 1898 of the elements radium and polonium.
In 1903, Marie Curie obtained her doctorate for a thesis on radioactive substances, and with her husband and Henri Becquerel she won the Nobel Prize for physics for the joint discovery of radioactivity.
The work of Marie and Pierre Curie, which by its nature dealt with changes in the atomic nucleus, led the way toward the modern understanding of the atom as an entity that can be split to release enormous energy.
chemistry.mtu.edu /~pcharles/SCIHISTORY/Marie_Curie.html   (750 words)

 Positive temperature coefficient thermistor device - Patent 5425099   (Site not responding. Last check: 2007-10-03)
The positive temperature coefficient thermistor element according to claim 1, wherein a temperature difference is created between a surface and the center of the ceramic body when a predetermined voltage is applied between said electrodes, thereby separating said ceramic body into layers.
The positive temperature coefficient thermistor element according to claim 4, wherein a temperature difference is created between a surface and the center of the ceramic body when a predetermined voltage is applied between the electrodes, thereby separating said ceramic body into layers.
A temperature at which the terminal for telegraph and telephone systems is used, that is, a temperature at which the use must be ensured is generally in the range of -10.degree.
www.freepatentsonline.com /5425099.html   (3466 words)

 Magneto Thermodynamics, Part 3
Therefore, the temperature of the un-paired electron spin population is infinite (2.1.4), and obviously no longer in thermal equilibrium with the bulk population (heat flows from spin population into bulk population).
During this decline in temperature, the un-paired electron spin population momentarily dips below the Curie transition temperature (3.1.3), thereby causing a momentary rise in total magnetic flux as ferromagnetic spin coupling forces contribute to overall un-paired electron spin alignment.
The purpose of this step is to force the temperature of the un-paired electron spin population to fall below the Curie transition temperature (3.1.3, 3.1.5, 3.2.2), and thereby cause the magnetic susceptibility of the core to become infinite (onset of ferromagnetic behavior).
www.geocities.com /electrogravitics/mt3.html   (1982 words)

 Limitations - Morgan Electro Ceramics Piezoelectric Tutorial
As the operating temperature increases, piezoelectric performance of a material decreases, until complete and permanent depolarization occurs at the material's Curie temperature.
At elevated temperatures, the ageing process accelerates, piezoelectric performance decreases and the maximum safe stress level is reduced.
Temperature limited transducers are dependent on the efficiency of the heat removal from the ceramic.
www.morganelectroceramics.com /tutorials/piezoguide11.html   (892 words)

 Magnetotransport in doped manganate perovskites
A larger pseudoperovskite cell size seems to correlate with a lower Curie temperature, and a lower Curie temperature leads to a higher resistivity peak, which is accompanied by a larger magnetoresistance effect.
Near the Curie temperature, the phase transition could be driven by the application of a relatively small magnetic field.
Curiously, they reported that higher substrate temperature resulted in polycrystalline films, which was not a commonly seen phenomenon.
www.research.ibm.com /journal/rd/421/sun.html   (4882 words)

 BioMagnetic Research and Technology | Full text | Physically synthesized Ni-Cu nanoparticles for magnetic hyperthermia
In this study the desired range of Curie temperatures was obtained by combination of melting and ball milling of nickel-copper alloy.
The use of materials with Curie temperature in the range of 41–46°C is desired to provide a safeguard against overheating of normal cells, due to the decrease of magnetic coupling in the paramagnetic regime (above Tc).
The liquid temperature of the alloy is 1365 °C [4] – a higher temperature was used in order to avoid inaccuracies due to differences between actual and set temperature.
www.biomagres.com /content/2/1/4   (2104 words)

 [No title]
Temperature is a number that is related to the average kinetic energy of the molecules of a substance.
If temperature is measured in Kelvin degrees, then this number is directly proportional to the average kinetic energy of the molecules.
The Curie temperature of iron is about 1043 K. The Curie temperature gives an idea of the amount of energy takes to break up the long-range ordering in the material.
www.lycos.com /info/temperature--energy.html   (434 words)

 pierre Curie   (Site not responding. Last check: 2007-10-03)
Educated by his father, a doctor, Curie developed a passion for mathematics at the age of 14 and showed a particular aptitude for spatial geometry, which was later to help him in his work on crystallography.
Curie's studies of radioactive substances were made together with his wife, whom he married in 1895.
In 1903 Pierre Curie was also awarded the Davy Medal of the Royal Society of London and appointed professor of physics at the University of Parisin 1904, and in 1905 he was elected to the French Academy of Sciences.
www.ob-ultrasound.net /curie.html   (711 words)

 PASPS III Conference: Poster Session
The Curie temperature in dilute magnetic semiconductors with hole-mediated ferromagnetism critically depends on the density of free holes [Dietl et al., Phys.
The Curie temperature, determined from magnetotransport measurements, increases drastically both with rising growth temperature and with decreasing V/III flux ratio.
In general, both the Curie temperature and the vertical gradient in hole concentration are further enhancend by postgrowth annealing.
www.sainc.com /pasps3/agendaposterView.asp?paperID=44   (407 words)

 Cobalt palladium seeds for thermal treatment of tumors - Patent 5429583   (Site not responding. Last check: 2007-10-03)
The injectable ferromagnetic thermoseed as in claim 4 wherein said predetermined radius lies in the range of from 0.2 mm to 2.0 mm and said predetermined length is in a range of from 5 mm to 50 mm.
Another object of the invention is to provide a thermoseed formed from a ferromagnetic alloy that exhibits an increasing magnetization with temperature characteristic until its Curie point temperature is approached as the thermoseed is inductively heated upon exposure to an oscillating magnetic field.
The composition of the CoPd ferromagnetic alloys for inducting hyperthermia use is determined by the Curie temperature transition of the alloy.
www.freepatentsonline.com /5429583.html   (4748 words)

 [No title]
This temperature is reached at about 20 km depth in the Earth, whereas at the outer boundary of the Core (about 2900 km depth) the temperature is about 20000C.
This is well above the Curie temperature, so although the core is largely iron, that iron is no longer ferromagnetic, and the Earth's core cannot be a permanent magnet.
Nickel is a ferromagnetic material with a Curie temperature of 3580C, which is easily achieved by heating with a torch or Bunsen burner.
www.geol.binghamton.edu /faculty/barker/demos/demo13.txt   (343 words)

 Curie — Infoplease.com
Pierre Curie's early work dealt with crystallography and with the effects of temperature on magnetism; he discovered (1883) and, with his brother Jacques Curie, investigated piezoelectricity (a form of electric polarity) in crystals.
In 1895 she married Pierre Curie and engaged in independent research in his laboratory at the municipal school of physics and chemistry where Pierre was director of laboratories (from 1882) and professor (from 1895).
She was made director of the laboratory of radioactivity at the Curie Institute of Radium, established jointly by the Univ. of Paris and the Pasteur Institute, for research on radioactivity and for radium therapy.
www.infoplease.com /ce6/people/A0814297.html   (673 words)

 Curie Temperature of Gadolinium
The Curie temperature is the point at which certain metals loses the behavior of ferromagnetism, when metals stay magnified after being exposed to a magnetic field.
Unlike the other more common ferromagnetic metals, which have a curie temperature of well over five hundred Kelvin, Gadolinium's Curie temperature is around room temperature at 293 Kelvin.
Besides being superconductivity at extremely low temperatures and is strongly magnetic at room temperature, Gadolinium is the only metal outside the fourth period metals that shows signs of ferromagnetic properties.
hypertextbook.com /facts/2004/AndrewLee.shtml   (329 words)

 Dexter Magnetic Technologies
The Curie temperature refers to the transition temperature above which ferromagnetic materials lose their useful magnetic properties.
Ferrite materials are actually ferrimagnetic materials [a similar but distinctly different type of magnetic material], and thus this transition temperature in ferrite cores is more correctly referred to as the Néel temperature.
When the Néel temperature is surpassed the core is rendered useless in the circuit.
www.dextermag.com /Soft-Magnetics-FAQs.aspx   (449 words)

 Positive Temperature Co-Efficient of Resistivity (PTCR) Materials - An Overview
Positive temperature co-efficient of resistivity or PTCR materials area family of semiconductors which exhibit special properties in relation to electrical conductivity.
PTCR materials behaviour is characterised by a slow increase in resistivity up to a certain temperature, which is dependent on the actual material.
When operated in the region of the Curie temperature, the PTCR will maintain an almost static temperature despite large variations in ambient temperature and voltage.
www.azom.com /details.asp?ArticleID=82   (595 words)

 Classes of Magnetic Materials
The Curie temperature is also an intrinsic property and is a diagnostic parameter that can be used for mineral identification.
In addition to the Curie temperature and saturation magnetization, ferromagnets can retain a memory of an applied field once it is removed.
It exhibits all the hallmarks of ferromagnetic behavior- spontaneous magnetization, Curie temperatures, hysteresis, and remanence.
www.geo.umn.edu /orgs/irm/hg2m/hg2m_b/hg2m_b.html   (1459 words)

Monel metals have curie points between 25 C and 100 C depending on the alloy.
The temperature of a piece of gadolinium is measured with a thermocouple while it is between the poles of an electromagnet.
A room temperature magnet is suspended 2 cm above a liquid helium cooled (5l/hr) lead plate in a supercooled container.
www.wesleyan.edu /physics/demos/pirabib/5eandm/5G50.html   (568 words)

 Low Temperatures Changing Magnetic Properties
The term "Curie Temperature" is the temperature above which a magnetic material looses its magnetic properties, or conversely, below which it has magnetic properties.
There are no common metals that have a curie temperature below about room temperature, and only one (Gadolinium) whose curie temperature is that low; it becomes magnetic below 293°K (20°C), that is, at room temperature and below.
Other materials (called paramagnets) have electrons that are randomly organized, say at room temperature, but that become organized if the temperature is reduced so that the atoms are not bounced around too much.
www.newton.dep.anl.gov /askasci/mats05/mats05064.htm   (334 words)

 Curie Temperature
Brief: All ferromagnets have a maximum temperature where the ferromagnetic property disappears as a result of thermal agitation.
Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism.
All of these alignment effects only occur at temperatures below a certain critical temperature, called the Curie temperature (for ferromagnets and ferrimagnets) or the Néel temperature (for antiferromagnets).
www.grantchronicles.com /brief.htm   (268 words)

 Section 3A
It was apparent that, while the characteristic shape of each curve is retained as the magnet's temperature varies, the curve's position relative to each axis changes.
Whatever flux density we expected the magnet to provide at room temperature, this will be different at any other temperature, directly affecting the performance of the device in which the magnet is installed.
From the Curie Temperatures of the constituent elements, it is clear that cobalt-based alloys should have better temperature stability than iron-based alloys, and indeed the Table above confirms this.
www.magnetweb.com /Sect3A.htm   (798 words)

 Putting Some Spin On It
Although the bonding energy of a copper-zinc alloy could be calculated from first principles, no one could calculate the Curie temperature of iron.
The Ames team found a way to include temperature in the equations, making it possible to calculate the magnetic structure of a material as it is heated or cooled as well as at the surreal temperature of absolute zero.
Stocks says they "got a good shot at the Curie temperature, which was a sign that they were getting there," but the simulation broke down when they were trying to calculate the magnetic susceptibility of iron above the Curie temperature.
www.external.ameslab.gov /news/Inquiry/spring96/spin.html   (1776 words)

 [No title]
July 3, 1934, spent many impoverished years as a teacher and governess before she joined her sister Bronia in Paris in order to study mathematics and physics at the Sorbonne, earning degrees in both subjects in 1893 and 1894.
Since 1882, Pierre had headed the laboratory at the Ecole de Physique et de Chimie Industrielle in Paris, and it was here that both Marie and Pierre continued to work after their marriage.
She thus became the first female lecturer at the Sorbonne, and in 1908 she was appointed professor.
www.phy.hr /~dpaar/fizicari/xcurie.html   (745 words)

 [No title]
] The electric or magnetic susceptibility at some temperature times the difference of the temperature and the Curie temperature, which is a constant at temperatures above the Curie temperature according to the Curie-Weiss law.
] The temperature marking the transition between ferromagnetism and paramagnetism, or between the ferroelectric phase and paraelectric phase.
] That temperature at which a resin or adhesive is subjected to curing.
www.accessscience.com /Dictionary/C/C62/DictC62.html   (1677 words)

 Curie temperature scale concept from the Astronomy knowledge base   (Site not responding. Last check: 2007-10-03)
Curie temperature scale concept from the Astronomy knowledge base
has definition This is sometimes used for indicating temperature in the vicinity of absolute zero.
It is based on Curie's law, which states that the susceptibility of a paramagnetic material is approximately proportional to its absolute temperature.
www.site.uottawa.ca:4321 /astronomy/Curietemperaturescale.html   (106 words)

 Temperature effects on magnets
The Curie Temperature, Tc is the temperature at which the magnet will be completely demagnetized.
The maximum operating temperature of a particular magnet is NOT only a function of the material, but also a function of design.
Generally, the higher the Br, the lower the Hci and therefore, the lower the ability of the magnet to withstand adverse temperatures.
www.mceproducts.com /knowledge-base/article/article-dtl.asp?id=23   (659 words)

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