# Talk:Curie temperature

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## Marie Curie?

is this named after Marie Curie?

Curie temperature is named after Pierre Curie, Marie's husband, Jan 8, 2003
Also confirmed by Encyclopdia Britannica andy 19:15, 14 Sep 2004 (UTC)

## Curie Points

What are the transition curves of different ferrous materials?

why steel losses its ferromagnetic properties at curie temperature

So increasing the temperature causes material to lose it's magnetism. In case of Neo dymium magnets, can this magnetic field be regained by electromagnetism? (eg by putting the magnet in another stronger magnetic field?)

Neodymium is ferromagnetic and loses it's spontaneous magnetism above the Curie Temperature when it becomes paramagnetic. Therefore placing it in an applied magnetic field will realign it's magnetic moments resulting in magnetism. However removing the applied field the magnetic moments will become disordered again and will lose it's magnetism.ACGrain (talk) 15:03, 5 February 2013 (UTC)

## Temperature and Curie

If a magnet loses it's magnetic field due to heat, then there must be a temperature where the magnet works at it's best, as well as information on how a magnet interacts in near to 0 Kelvin (absolute zero or -274°C). Can someone extend on this?

New section on Approaching Absolute Zero added which I hope has answered your query. ACGrain (talk) 17:15, 4 February 2013 (UTC)

## Curie point depends on temperature

The Curie point is dependent on pressure and is hard to predict for very high pressures. In particular, it is not possible to say for sure whether the core of the Earth is above the Curie point even though it is very hot. There is a little bit of information on this in the book "The Magnetic Field of the Earth" by Ronald T. Merrill. —Preceding unsigned comment added by 206.174.6.108 (talk) 22:07, 11 December 2007 (UTC)

## Couple of points

I think it is worth saying that the loss of ferromagnetism at and above the curie point is reversible - i.e. normal magnetic properties are recovered when the temperature is reduced.

Also the meaning of this this sentence is obscure - it has already been said that a material loses its ferromgnetic properties above the curie point, so how can non-existent ferromagnetism combine with paramagnetism ? ....

'At temperatures above 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. '

Andrew Smith —Preceding unsigned comment added by 82.32.50.77 (talk) 11:32, 16 June 2009 (UTC)

I agree that that it would be useful to mention that this is a reversible phenomenon. I originally came to this page with that exact question, and had to spend some time trolling the net elsewhere to find an answer. I will edit the article to include this bit of info; however, I don't have a solid source to use for citation purposes. If you have one, please add it! Monolith2 (talk) 17:25, 15 February 2010 (UTC)

## Effect on heat capacity

There is a distinct peak in specific heat around the Curie temperature as energy is absorbed (or released) in destroying (or creating) the magnetic domains on heating (cooling). [ http://www.springerlink.com/content/n87733048p152x72/ ] This peak in heat capacity produces a corresponding dip in thermal diffusivity at the Curie temperature. Other properties are less-affected. This is worth noting. StainlessSteelDoctor (talk) 16:39, 4 July 2009 (UTC)

I appreciate your caution in changing the encyclopedia, but I'm guessing you know about that info better than anyone else, so my advice to you would be to be bold and change the article yourself. Awickert (talk) 16:55, 4 July 2009 (UTC)

## The description reads like its describing ferroelectric not piezo

It may be the case that the curie temperature defines the temperature at which above it won't be piezo electric, but piezo electrics aren't spontaneously polarized to start with as is described. The symmetry requirements for ferroelectrics are a subset of piezos which are switchable and polar (piezos need only be non centrosymmetric). To stop being piezo electric it would have to lose this. PZT is definately piezo electric, but to have a 'displaced central cation' and therefore spontaneous polarisation, it would have to be ferroelectric (and therefore, in general, have even less symmetry). At best it is a bad example, then.131.111.243.37 (talk) 08:28, 31 May 2010 (UTC)

## Curie temperature of iron

This article says that the Curie temperature of iron is 768 degrees C., But Britannica and a bunch of other sources say it's 770 degrees C.

References:

http://hypertextbook.com/facts/2002/FeliciaLau.shtml

http://www.britannica.com/EBchecked/topic/146902/Curie-point

Guy Macon 09:55, 15 July 2010 (UTC)

Buschow, K. H. J.Encyclopedia of materials : science and technology,Elsvier, 2001 ISBN 0-08-043152-6 page 5021 table 1 says 1043 K, which is 770 C. --Wtshymanski (talk) 13:23, 15 July 2010 (UTC)

## Tc or TC?

Is the correct abbreviation Tc (upper-case T, subscript-lower-case c) or TC (upper-case T, subscript-upper-case C)? — Preceding unsigned comment added by Guymacon (talkcontribs) 01:46, 31 December 2010 (UTC)

I'm not aware of a standard for this, and I've seen both choices in refereed publications. Uppercase makes sense to me because it stands for the name "Curie". But that is just my opinion. RockMagnetist (talk) 22:31, 31 December 2010 (UTC)

## Suggestions

I'm a student and for my project I am working on improving this Wikipedia page. I would very much like to interact with other people working on this page and also find out what suggestions and ideas that would contribute towards this. I have currently added a paramagnetic properties section which I hope has made things clearer and will be putting up a ferromagnetic properties sections shortly. I will also be looking through previous ideas on the talk page and hope to contribute answers to these questions in the near future. ACGrain (talk) 20:13, 26 January 2013 (UTC)

Welcome to Wikipedia, ACGrain! I see you caught on to the technical side of citations quickly. It's good, also, that you are adding the citations as you write. I do have one suggestion - there is a lot of material that is only marginally relevant to the Curie temperature and is covered in existing Wikipedia articles. Some examples are magnetic moment, ferromagnetism, ferrimagnetism, paramagnetism, and spontaneous magnetization. I suggest that before you add any more material, think about what concepts are really needed to explain Curie temperature phenomena; and try finding wikilinks for the technical concepts in your text. See Wikipedia:Manual of Style/Linking. RockMagnetist (talk) 00:44, 6 February 2013 (UTC)
You make an excellent point, I realise I was perhaps drifting off topic and going into detail that wasn't necessary. I have rewritten parts to link it back to the Curie Temperature and keep it to point with a basic understanding and wikilinks. I hope this reads better and is now relevant? Thank you also for the tips on the code, as you noticed with the citations I was getting a bit muddled before! ACGrain (talk) 22:12, 6 February 2013 (UTC)
The good quality of this page is quite obvious! Overall it is a very informative and explanatory article regarding this very important topic. However, there are some improvements that could be made. I think it could be better to keep a "progressive form" of the article. For example, the first paragraph (above the table of contents) should just be about a first clear meaning of the Curie temperature. This can help anyone who is just curious about the topic and looking for a quick brief explanation! Also, I can see that "magnetic moment" is mentioned before it is explained. A more reader-friendly form of this could be the opposite(but maybe this is not too important!). In addition, I suggest slightly larger images of magnetic orderings. Philipposc (talk) 23:47, 8 February 2013 (UTC)

## The Curie Temperature of Gadolinium (Gd)

There appears to be a lot of debate over the Curie Temperatures for Gadolinium

The following are references for 289K (16°C)

Wilson, [by] M.N. Rudden [and] J. (1971). A simplified approach to solid state physics (1st ed. ed.). London: Butterworths. p. 128. ISBN 0408700033.

Cusack, N (1958). The Electrical and Magnetic Properties of Solids. Norwich: Jarard and Sons LTD. p. 320.

The following is a reference for 292K (19°C)

Jullien, André Guinier ; Rémi (1989). The solid state from superconductors to superalloys ([Pbk. ed. ed.). Oxford: Oxford Univ. Press. p. 155. ISBN 0198555547.

A more recent journal states it as 290.6±0.2K

Zverev, V.I.; Gimaev, R.R.; Tishin, A.M.; Mudryk, Ya.; Gschneidner, K.A.; Pecharsky, V.K. (1 October 2011). "The role of demagnetization factor in determining the ‘true’ value of the Curie temperature". Journal of Magnetism and Magnetic Materials 323 (20): 2453–2457. doi:10.1016/j.jmmm.2011.05.012. Retrieved 09/02/2103. Check date values in: `|accessdate=` (help)

The article below discusses the evidence of metastability near it's Curie Temperature. Gadolinium appears to have a complex system with an unstable magnetic structure which can therefore have different points where the phase transition occurs.

Seyoum, Hailemichael M.; Ghahremani, Mohammadreza; ElBidweihy, Hatem; Bennett, Lawrence H.; Della Torre, Edward (1 January 2012). "Evidence of metastability near the Curie temperature of polycrystalline gadolinium". Journal of Applied Physics 112 (11): 113913. doi:10.1063/1.4767908. Retrieved 09/02/2103. Check date values in: `|accessdate=` (help)

Are there any other thoughts on this matter? ACGrain (talk) 15:28, 9 February 2013 (UTC)

Hi, I've always been fascinated with curie points, in particular the magnetism behavior right around the curie point. Does the change happen suddenly or does it ease in over a range of temperatures? I've had scientist (I'm a software developer) say it's quite immediate at the curie point and others not sure. What I really wish we had was a graph showing temperature on the X axis and magnetic permiability (or some good measure of whatever it is that changes at the curie point) on the Y axis. Makes sense? Thank you! — Preceding unsigned comment added by 69.233.52.38 (talk) 23:32, 12 March 2013 (UTC)

## citations and understanding

I have recently added a large amount of content and tried to develop the article so it is of a good understandable level. I also believe the article now has a good level of citations to back up what is written. I would like to know what peoples thoughts are in removing the two boxes at the top of the wiki page? Or if not what is still missing that can fulfil these criteria? ACGrain (talk) 19:23, 24 February 2013 (UTC)

I think the lead is far too technical for a general purpose encyclopedia and needs to be taken down to a hgihg-schoool level of comprehension. --Wtshymanski (talk) 21:43, 28 February 2013 (UTC)
Removing the Refimprove tag was a no-brainer. RockMagnetist (talk) 21:49, 28 February 2013 (UTC)
I've rewritten the lead of the introduction to try and achieve this. What are your thoughts? How does the rest of the article compare on understanding levels? ACGrain (talk) 21:49, 1 March 2013 (UTC)

## Applications

I think piezoelectric materials or superconductivity could be mentioned here. Piezoelectric materials are mentioned in another section and therefore a small expansion of the applications of these materials (since they are in a way connected to the curie temperature) would be useful. For instance, a piezoelectric material is the "quartz" we find in watch circuits. Also, in radios, piezoelectric devices can be used in tuners, where the correct strain in the crystal will amplify only the desired frequency. Some powerful superconducting electromagnets can be used in maglev trains, or in Magnetic Resonance Imaging (MRI) and Nuclear magnetic resonance (NMR) machines.Philipposc (talk) 00:06, 9 February 2013 (UTC)

I do agree that piezoelectric should be added in some form to the applications but I am unsure about superconductivity, from what I understand the transition temperature for superconductors is different from the Curie Temperature? Or have I misunderstood? ACGrain (talk) 16:51, 10 March 2013 (UTC)

## Reverted restructuring that recommended focus on ferroelectrics

This is to describe the reversion I did earlier today. Sorry, I was unable to elaborate in the "Edit Summary" because I accidentally clicked save before doing so. The reverted changes suggested that the terms "Curie point" or "Curie temperature" be exclusive to ferroelectrics. Also, it was argued that the magnetic transition be referred to as the "Néel point". However, I'm not sure these changes represent historical developments or standard usage as suggested by the previous editor. While searching through different references, I found that the term "Néel point" is used for anti-ferromagnetic materials and not necessarily magnetic materials in general. In my experience, Curie temperature can be used for either magnetic or electric phase transitions.

Perhaps a few references could be provided verifying that the reverted edits concerning ferroelectrics should be kept? For now though, I think we should maintain the common usage for Curie temperature as a general term that is primarily associated with magnetic transitions. Rahsecond (talk) 08:18, 15 August 2013 (UTC)

You were right to revert. The additions amounted to an unsourced essay that dismissed the most common uses of the term as "misuse". If some material scientists prefer a different terminology, their view should be added for balance, but only if sources are provided. RockMagnetist (talk) 21:53, 15 August 2013 (UTC)