Sciencemadness Discussion Board - NdFeB

NdFeB

IrC - 18-4-2010 at 15:53

After searching this site to the end and google for days I finally am desperate enough to ask. Does anyone have a link or a pic to the precise structure of Nd2Fe7B or in some places I read Nd2Fe14B? Thousands of hits to sellers which after searching their sites you learn nothing worthwhile, and links to pay for PDF sites such as Science Direct and IOP. Why is it so hard to find for free specific structure and chemistry related information of this super magnet material. I would really appreciate it if anyone has some decent info I could use. I want to see exactly how the atoms of these three elements are arranged, hopefully with atom spacing data and the difference between the Fe7 and Fe14 materials. I cannot believe it is simply a homogeneous mixture as this would not account for the anisotropy of the field alignment among other factors. I get the impression this is the case from the way it is made (mixing the powders and heating) along with the seeming lack of relevant data on any kind of crystal structure.

Slight clarification other than some references in the pay for PDF sites to face centered cubic structure which without paying for and reading the documents I can only assume it does form specific crystal structures (especially with the knowledge of the magnetic anisotropy). I want to understand the relation in alignment between the Fe and Nd as well as how does the non magnetic boron figure in. I also consider the fact that under 400 degrees it loses it magnetic properties, again implying structure. Does the Fe atoms act to allow the Nd to "broadcast" the field out of the crystal lattice, and what role does boron play. I just cannot find a really good description of how this super-magnet material functions.

Anyone out here able to help? If so thanks in advance.

sparkgap - 18-4-2010 at 17:16

Hey,

I can't find any freely-available stuff with lattice pictures either, so you might want to give a list of the articles you want in the References subforum, and I'll see what I can turn up. This and this looked the most interesting to me with a cursory search.

sparky (^_^)

IrC - 18-4-2010 at 17:57

Thanks, those look closer than what I have been going through so far. Right now I am trying to search the patent office but they have the worst search engine. Google is not much better. I remember one time mentioning here I firmly believed pay sites came up first in google and IIRC John or maybe it was Polverone did not agree. That was 5 years or so ago. I think I am correct even if google would not admit to it but I have found going to the last pages in a search and working in reverse finds more free interesting stuff, in this case page 69 of the hits (25/page) yet so far nada. I think this subject is held with a great deal of secrecy or am I just imagining things. Anyway I'll see what links I can find but the very brief descriptions, even on the links you mention, do not indicate if what I am looking for is in there. If I come up with something I will ask you to see what you can see. I do not know why it is but I always pick the interests which seem the most difficult to find. What started me on it is I have so many pounds of Lanthanides I needed something new to try, being bored with glow powders and so on. Actually it was an article I read about China getting ready to start cutting the US off in these materials due to the decreasing supply of Nd mostly due to electric cars and their increasing need. So I figure there must be other super magnet materials and even if Nd is coming up short this does not mean I cannot make a killing creating the next super magnet using a different rare earth. Just because China is running low on Nd does not mean they would not provide large amounts of a different element than Nd. The hard part in playing with this subject I thought was finding ways to make powders from my incredibly hard metals but I am slowly learning the real hard part is coming up with the science itself.

I have looked at 164 patents so far, is all you get using NdFeB as keywords. Virtually every one is about something to use the magnets for not how to make them. Less than 10 are novel compositions where they list the whole periodic table trying to preclude others from patents, yet they are nearly the same and not one has a clue about lattice structure. This is one damn hard bit of info to find! Below a few interesting patents, a few of them only related to uses for, not making, NdFeB.

7,531,050
7,507,302
7,505,243
7,488,395
7,488,394
7,488,393
7,559,996
7,547,346
7,547,365
7,569,114
7,571,757

[Edited on 4-19-2010 by IrC]

not_important - 18-4-2010 at 22:42

Quote: Originally posted by IrC

... Actually it was an article I read about China getting ready to start cutting the US off in these materials due to the decreasing supply of Nd mostly due to electric cars and their increasing need. So I figure there must be other super magnet materials and even if Nd is coming up short this does not mean I cannot make a killing creating the next super magnet using a different rare earth. Just because China is running low on Nd does not mean they would not provide large amounts of a different element than Nd. The hard part in playing with this subject I thought was finding ways to make powders from my incredibly hard metals but I am slowly learning the real hard part is coming up with the science itself...

China is not running short of neodymium. There is a likely shortage of dysprosium, used as a modifier to NdFeB magnets.

But the real excitement on this is due to China restricting exports of rare earth oxides and metals. The Chinese government has produced a number of papers indicating they intend to become the dominant player in REE and other rare technologically significant elements as part of their mercantilist neo-Confucianism outlook.

Part of the problem is that China produces at least 95% of the world output of REE, and their ore deposits are much larger than anywhere else. The U.S. reserves are around 1/4 to 1/3 the size of China's.

On top of that many of the Chinese deposits are unusually rich in the heavy REE - from terbium to lutetium. These are present in much lower percentages in most other REE deposits.

Plenty of people have been looking for replacements:

http://www.gao.gov/htext/d10617r.html

http://www.technewsdaily.com/scientists-race-to-engineer-a-n...

http://www.technewsdaily.com/us-military-supply-of-rare-eart...

IrC - 18-4-2010 at 23:26

What I meant was the US will be running low from China reducing or halting shipments. From one of your links "China has warned that its own industrial demands could compel it to stop exporting rare earths within the next five or 10 years." says the same thing. Since I am sure green nuts will block us from mining vast amounts of our own just as they have for 50 years forced us to send our money to the middle east for oil, we really will be running low. I spent years prospecting around the Mt-Id border and I can see it now. They will claim mining rare earths there will trigger the super volcano in W. Yellowstone or some such dip-shit thing like that.

Anyway, it would seem here is a project we can really discover something new as well as profit, inventing the next generation of super magnets. Still, I cannot believe no one on earth has published crystallographic data on NdFeB as I need some or other starting point. I simply cannot find any decent science online for this subject. I have spent so many hours searching I am going to go whacko. I knew I should have built a cabin up there in the 70's when I was looking for U and Au. No that would not work I cannot be one of those no electricity hide from the world waiting for the end crackpots I must have my internet and Direct TV. Hey wait, I can do it with todays technology.

If anyone is considering opening a Taco Bell up there in the wilderness let me know. A guy has got to have his limitations.

sparkgap - 19-4-2010 at 00:32

After taking this search a bit more seriously I turned up these two. If you think these (as well as the ones I previously linked to) have what you need I'll put them up.

sparky (~_~)

P.S. I also do the "searching backwards" thing, except that I use Google Scholar.

IrC - 19-4-2010 at 01:31

Please do so this is exactly what I am looking for. Can tell more from the first "these" link in it's preview. Was hoping Miller indices would show up somewhere and it looks like you found it.

One thing I am curious about is Fe7 and more often Fe14 being indicated. I wonder if Fe14 is really two cells linked sharing one common Nd. Having never seen the structure but thinking about what it might look like, I picture a ring of face centered Fe atoms with Nd centered at each end. Maybe wild guesswork but for some reason I picture the Fe ring acting like a "duct" for the fields from the Nd atoms. Of course the B gets in the way of my imaginary pic unless it is trapped in the center of the lattice. I get stuck on the thought of the reason Boron aids the picture, some kind of diamagnetic effect which shifts the F electrons in the Nd atoms to "align" and "duct" their field through the Fe ring which atoms of course add to the field as the iron core in an electromagnet does. Possibly the diamagnetism of the Boron causes the high coercivity giving rise to the extreme ability to resist demagnetization. The only other picture in my mind is two face centered rings of 4 Fe atoms, missing one which is replaced by one B atom again with Nd at the ends. So a long chain of these cells would create a very large field.

These flights of fancy are what happens when no data is around to look at.

[Edited on 4-19-2010 by IrC]

JohnWW - 19-4-2010 at 03:54

I am very sure that there must be better ferromagnetic rare-earth metals than Nd that can be separated by ion-exchange chromatography, and used as permanent magnets, at least alloyed with Fe, Co, and/or Ni; plus a small amount of a strongly diamagnetic element like B or Al that serves to magnetically "harden" the alloy by increasing its coercivity and retentivity (as in AlNiCo and NdFeB magnets). In fact, the best rare-earth metals for the purpose would be those around the middle of the rare-earth series, with close to the maximum number of 7 unpaired 4f electrons and one unpaired 5d electron possessed by Gd.

Rare-earth metals, along with Th and U, are found mostly in pegmatites, the macro-crystalline form of Precambrian granite which forms the oldest basement rocks of continental land masses, which were the last part of the original granitic masses to cool and solidify. Apparently the rare-earth metals (and Th and U) were about the last metals, as silicates, to crystallize out from molten granite. However, except in areas of severe erosion, particularly by glaciation, pegmatites are at a considerable depth beneath overburdens of ordinary granite and/or much later sedimentary (or metamorphic) rocks. Besides an area in China, such areas where pegmatites have been exposed by erosion (particularly glaciation) include parts of Norway, Sweden, Greenland, Canada, Russia, South Africa, and Australia, so it is most unlikely that China could possibly have any monopoly on rare-earth metals.

The metals around the middle of the actinide series, with up to 7 unpaired 5f electrons (for example Pu, which is very strongly ferromagnetic, as well as having a maximum oxidation state of 8 with all its 5f electrons able to take part in chemical bonding), could potentially be used in permanent magnets, but their radioactivity and especially high chemical toxicity limits this. The most accessible such ferromagnetic actinide metal would be uranium as depleted U-238 and a half-life of 4.5 x 10^9 years, so use in permanent magnetic alloys (perhaps in alloys with Fe, Co, or Ni, and a small amount of B or Al) could well be a way of using up the huge stockpiles of depleted U-238 that have accumulated for decades as the byproduct of extraction of fissile U-235 as the "enriched uranium" used in bombs and the fuel rods of nuclear power plants. (The only other uses for the stuff are as pottery glazes as the oxides, analytical chemical reagents mostly as uranyl salts, extra-dense keels for yachts where Pb is not dense enough, and extra-heavy and hard-tipped bullets and explosive shells as used in Iraq).

[Edited on 19-4-10 by JohnWW]

chief - 19-4-2010 at 04:07

I have at hands the ICSD, with all the structure ...
==> but currently no software to calculate the cells from that data ...

So I could in the moment only give you the crystallographic base-data, no interatomic distances or binding-angles ...

Maybe its usefule this way:

[Edited on 19-4-2010 by chief]

Attachment: ndfb.txt (4kB)
This file has been downloaded 854 times

IrC - 19-4-2010 at 04:15

Still it is a starting point. I love a good mystery.

sparkgap - 19-4-2010 at 04:17

These ORTEPs sure look interesting...

sparky (^_^)

chief - 19-4-2010 at 04:30

see the above post for the basic data on the known Nd-Fe-B-compounds ..., uploaded a file ...

IrC - 19-4-2010 at 09:25

Thanks everyone some good information. I knew the diamagnetism of the Boron was involved in the high coercivity and further thought indicates why in my mind. Assuming the Fe rings not only aid the field but also "shield the Nd from external fields" which would reduce an outside fields ability to shift the orientation of the Nd atoms. I can also picture a diamagnetic defect in the ring (B) which would serve to deflect external fields further away from the lattice. Together this would answer both the high coercivity and remanence. A high BHmax along with a high Tc it seems to me could be explained by a strongly bound ring structure acting as a shield to the Nd atoms from external forces combined with the Fe ring adding to the field. I start thinking about the possibility of say Gd2 - 2(Unn (odd n)) - Bi. However it may be a new set of numbers is needed for a ring structure along this line. Still, something to think about.

One other thought while sitting here looking at my floating graphite. Almost identical to this wiki pic except no hole in mine and silver (color) plated magnets.

190px-Diamagnetic_graphite_levitation.jpg - 15kB

190px-Diamagnetic_graphite_levitation.jpg - 15kB

What about replacing the Boron with pyrolytic graphite? I cannot get this much levitation with Boron or Bismuth so obviously the diamagnetism is much greater. Not too much of a stretch thinking about my blocks of copper graphite alloy. Except of course for the alteration of this property of carbon. Still I wonder is there a way to use carbon with the right crystal structure in the next super magnet?

[Edited on 4-19-2010 by IrC]

not_important - 20-4-2010 at 09:32

Pyrolytic carbon's properties are a bulk effect, the multiple interconnected graphene planes being essential. The NdFeB phases structure depends on getting atoms into certain places to obtain certain structures that bear very little resemblance to graphene.

Pyrolytic carbon gives more levitation than bismuth because it is much less dense, around 2,2 vs 9,78. It is anisotropic so its diamagnetism varies with the axis it is measured on.

While you're busy replacing neodymium with other lanthinoids, you may want to consider the relative occurrence of them. Replacing Nd with Tm is likely not a winning choice.

Ln price abundance chart.gif - 13kB

Chart in log(ppm in crust) so values below zero mean less than 1 ppm
laabund.gif - 3kB

IrC - 20-4-2010 at 12:18

Yeah I figured that about the carbon but still somewhere out there is the next magical brew. I have many pounds of most of the RE's, especially La. I imagine I will concentrate on La as it is so much cheaper than most of them. By the way thanks kmno4 for the PDF. 128 K of solid gold I tell you. I use google too much, I really need to look into other search methods. I swear google is turning into a pay per view (meaning you pay they let others view yours first) no doubt related to not serving up over 1000 hits even when they say there were a million or so. I can only assume the other 999,999 hits were what you were really looking for but no profit in it for google or something like that.

I was thinking the boron could be in the middle, and with a triangular structure being the strongest geometric shape it makes sense from the high coercivity (Hci), and high Curie temperature (Tc) standpoint. I am glad I started this thread you people have really helped a great deal. Backspacing kmno4's link to the magnets Dir contains a bunch of useful files. I would like to get better at searching, like how did kmno4 find the link to begin with, I never ran across it searching google for keywords like NdFeB crystal structure and so forth. I miss the days when multiple engines were around such as Northern Lights among others, the NL engine back in the late 90's always gave me more useful hits when looking for scientific subjects than google did. Not to mention I believe google has gone the wrong way, less science and more buy it here crap than ever.

Anyway, thanks for the help people, off to really study the PDF I just received, like I said bar none so far the best structure information I have yet encountered.

One last minute thought: http://fffff.at/dr-google/ , kmno4 I looked into this Dr Google you mentioned but I find a medical diagnosis type of engine. Is there a "science" one? I guess I am asking how did you find the file you gave using this? From the usefulness of the PDF I think I should be using your method of searching. Or does the medical one also search for non medical subjects?

[Edited on 4-20-2010 by IrC]

chief - 20-4-2010 at 13:24

As far as I heard at university the magnetism comes from unpaired spins ... of Iron ...
==> The rest of the structure just holds the Iron in place ...

kmno4 - 20-4-2010 at 14:02

Nevermind (Dr) Google.
Something more about "these" materials and other (M2Fe14C) can be found in "Handbook of Magnetic Materials" (search Gigapedia etc.) especially in volume 4.
ps.
Volume 4 of this "Handbook" -->Download

IrC - 20-4-2010 at 17:17

Quote: Originally posted by chief

As far as I heard at university the magnetism comes from unpaired spins ... of Iron ...
==> The rest of the structure just holds the Iron in place ...

You will never reach 1.4 Tesla with Iron alone. It is the F and D electrons in Nd which make Iron Neodymium Boride such a powerful magnetic material. You must not consider unpaired electrons as the only factor. Where they are in the orbitals and the number also comes into play. Going by the number of unpaired electrons would make one wonder why Bi is not ferromagnetic in properties, in actuality it is a diamagnet, or it repels magnetic fields. I know, I once made a notebook with each element in the table, and showed the entire electron structure complete rather than shorthand referencing the next noble gas below it so I could just look at the whole structure for each element. I kept seeing unpaired electrons and could not understand why so many were not magnetic. Later on after gaining more knowledge I came to the understanding that diamagnetism was also the result of unpaired electrons the difference being where they were in the orbital structure as opposed to other elements which had the same number or fewer electrons (speaking of unpaired) which did show magnetic properties.

kmno4 thanks again, good information. Studying the structure I find that like snowflakes there really is art in nature, amazing to see. I find that my thought of using La has another advantage besides being more prevalent than Nd.

However it is something I do not quite understand. It seems that making a structure comprised of rare earths and transition metals has a problem related to where the RE is in the series. Possibly someone could clarify why this is. Is it related to the Lanthanide contraction or is it some type of quantum effect. Going down in the series towards La gives a stronger magnet yet you would think the number of unpaired electrons would be more important say Gd being better than La. What happens is above Sm the magnetic moments begin to couple anti parallel to the TM (transition metal) moments, reducing the field. As we go towards the lighter RE's at Sm and "lighter", the moments begin to couple in parallel increasing the magnetic field. This would seem to rule out everything above Sm if a very strong magnet is the goal. This is bad luck I would like to see the maximum number of unpaired electrons in the quest for a new material. Anyway really I just wonder if anyone can explain why this is.

[Edited on 4-21-2010 by IrC]

chief - 21-4-2010 at 08:38

But 1.4 Tesla is not beyond the magneztizability of "magnetic" steel-alloys (with silicon, eg.) ..., as they are found in transformers etc. ...; in those also just the iron plays the magnetic role, while the other elements are there to make a ordering of enough iron-spins possible ...

So the iron might well count alone for most of the magnetic field ...
==> Boron, I guess, ist there for it's chemic versatility: Whoever heared anything about the chemistry of boron and saw the zoo of possible structures knows what I mean ...

Some samarium-compounds were in developement for deep-temperature-applications, like in spaceflight ...
==> Nd is maybe just the cheapest of the usable rare-earths ...

[Edited on 21-4-2010 by chief]

IrC - 21-4-2010 at 10:18

"Some samarium-compounds were in developement for deep-temperature-applications, like in spaceflight"

And no Iron is in this magnet.

On the other point you made: What I meant was permanent magnet from Iron alone with such a strong field, not what can we do like aid Iron with a coil with current flowing through it. Iron is the bulk of metal in Nd2Fe14B. Nearly as strong is Sm2Co5, which has no Iron. You had stated all other elements merely held the composition together and I was pointing out if this were true then why did we not have 14,000 Gauss "permanent" magnets prior to the 20th century.

Structure as you say is important as seen from the bulk of the mixtures so far tried going from not much of a magnet to a great one merely by altering the way treatment such as sintering is done. From this yes structure is important. I guess the point I mean is there are things going on which are vitally important related to the actual function an "impurity" in the lattice performs, much more than mere structure. Coercivity is increased by Boron in the structure not just because the Boron wants to be in a certain place in the lattice (but this is critical also), the diamagnetic properties of the Boron are paramount. It sounded like you were saying "all other elements only function to create a specific lattice structure and only Iron gives the magnetic properties". I could be wrong but this is how I read it. In any case the only point I was getting at is the magnetic moments or diamagnetic properties are critical when considering all the other elements in the structure besides Fe.

I believe (but I could be wrong) the resistance to opposing fields weakening the magnet happens something like this. Imagine a tapered object stuck into a say foam ring. As you go further you expand the ring until you break it. Call an external opposing field this tapered object. If you had something pushing against this tapered object you would be making it harder for the tapered object to expand the ring thereby making it harder to wreck the ring structure. I know we are dealing with triangular and hexagonal structures but the foam ring being spread apart seems like an easy way to visualize what I am getting at. If the diamagnetic properties of Boron push back against this field and are orientated in such a position and direction as to make it harder for an external field to disassociate the lattice structure (or realign the moments of the wanted field producing elements) then it would take a greater opposing force from outside to weaken the magnet. I probably just did the worst description of how I see it ever written yet hopefully my point that much more is being done by the non Fe elements than merely "holding the structure together" is coherent.

[Edited on 4-21-2010 by IrC]

chief - 21-4-2010 at 13:55

With iron in the coil the "amplification"-effect comes from the ordering of the spins ; only that it looses this ordering as soon as the coil is switched off ...
The NdFeB-Material just puts some sort of energy-barrier in front of any magnetization/demagnetization ... : Harder to magnetize, harder to de-magnetize ... : Once the spins are ordered they stay in place ..., until enough activation-energy is applied to overcome the ordering, either thermally or by a different magnetization ...

The samarium-compounds I was talking about were similar to the NdF2B-stuff, only with partially (or fully, can't remember exactly) substituting SM for Nd ...

ICSD lists only the following 2 compounds: B4 Fe1 Sm1 , B60 Fe60 Sm17
with the parameters ....
+--------+---------------+----------+-----------+-----------+-----------+-----------+-----------+
| sgr | sum_form | a_len | b_len | c_len | alpha | beta | gamma |
+--------+---------------+----------+-----------+-----------+-----------+-----------+-----------+
| PBAM | B4 Fe1 Sm1 | 5.958000 | 11.530000 | 3.465000 | 90.000000 | 90.000000 | 90.000000 |
| P42/NZ | B60 Fe60 Sm17 | 7.098000 | 7.098000 | 58.690000 | 90.000000 | 90.000000 | 90.000000 |
+--------+---------------+----------+-----------+-----------+-----------+-----------+-----------+

Maybe this wasn't followed: I read it in the 1990s, the database is maybe 3 or 4 years old ...

Anyhow the following compounds, without Iron, are listed:
+---------+----------------------------------------+
| sgr | sum_form |
+---------+----------------------------------------+
| PBAM | B4 Fe1 Sm1 |
| P121/N1 | B5 Co1 O10 Sm1 |
| P63/MMC | B1 O3 Sm1 |
| P1 | B1 O3 Sm1 |
| P4-21C | B40 Co40 Sm11 |
| C1M1 | B6 Ca8 O20 Sm2 |
| PBAM | B4 Mn1 Sm1 |
| P31 | B6 Ge2 O34 Sm14 |
| P42/NZ | B60 Fe60 Sm17 |
| P4/MBM | B4 Sm1 |
| P121/N1 | B5 Cd1 O10 Sm1 |
| P1- | B1 O3 Sm1 |
| PM3-M | B5.76 Sm1 |
| C1M1 | B3 Ca4 O10 Sm1 |
| PM3-M | B5.82 Sm1 |
| PM3-M | B5.49 Sm1 |
| PM3-M | B5.49 Sm1 |
| PM3-M | B5.49 Sm1 |
| P6/MMM | B3 Co7 Sm2 |
| I4/MMM | C1 B2 Ni2 Sm1 |
| P6/MMM | B3 Co7 Sm2 |
| PM3-M | B6 Sm0.99 |
| P6/MMM | B2 Co3 Sm1 |
| P6/MMM | B2 Co3 Sm1 |
| PM3-M | B1 Pd3 Sm1 |
| PM3-M | B1 Rh3 Sm1 |
| P6/MMM | B2 Rh3 Sm1 |
| P6/MMM | B2 Ru3 Sm1 |
| P6/MMM | B2 Sm1 |
| P4/NMMZ | B10 Co29 Si4 Sm3 |
| P6- | B1 Ba4 N26 O1 Si12 Sm7 |
| P31 | B6 Eu3.33 Gd3.63 Ge2 Nd3.33 O34 Sm3.71 |
| I12/C1 | B3 O6 Sm1 |
| P4/MBM | B16 Si3.64 Sm10 |
| P121/N1 | B1 O17 P2 Sm7 |
| PM3-M | B0.8 Rh3 Sm1 |
| P63/MMC | B1 O3 Sm1 |
| I4/MMM | C1 B2 Rh2 Sm1 |
| PBCA | B1 O10 Si2 Sm3 |
+---------+----------------------------------------+

They contain Co and other well known stuff instead of the Fe ... ; can you identify the magnetic ones ?

[Edited on 21-4-2010 by chief]

IrC - 21-4-2010 at 14:48

Your first line is merely simple high school physics, "everyone" knows that. So not sure what you are really saying other than repeating that Nd adds no moment to the field. I do not agree. Nd's contribution to the field is no less than 1.4 uB and likely more but it takes time to study the documents so far provided in this thread by others. You question at the end: are you asking me or someone to study and work out in theory each structure to predict it's magnetic properties? I have to wonder how many man years of time in the laboratory were expended coming up with the list you provide. So again unsure of your point.

JohnWW - 21-4-2010 at 15:58

I would say that few, if any, of those compositions listed above by Chief could possibly be usefully ferromagnetic - they nearly all contain too high concentrations of diamagnetic and strongly electronegative elements - although most of them would be at least paramagnetic.

A drawback of lanthanide-based magnets is that they have too low a Curie temperature - the transition point from ferromagnetism to paramagnetism - for many uses in which they are liable to be exposed to significant heating. Those of Co, Ni, and especially Fe, and their alloys, are much higher. I am not sure about the actinide ferromagnetic metals, around the middle of the series; but I am sure that their Curie points are also much higher than those of (the middle part of) the lanthanides, and comparable to that of Fe, Ni, and Co and their ferromagnetic alloys, because their 5f electrons can participate in metallic conduction and chemical bonding to at least an extent similar to 3d electrons.

That being the case, I would very much like to see data on the magnetic properties of ferromagnetic alloys of actinide metals, especially of depleted U-238 and of Pu-244 (which has a half-life of 82 million years, making it radiologically fairly safe but of course extremely chemically toxic, and traces of it occur naturally in U ores), perhaps in combination with Fe and B or Al.

I am rather surprised at Irc's statement that La makes good ferromagnetic alloys, because in the ground state it has no 4f electrons and only one 5d electron. It just might be that, in combination with Fe, 3d and 4s electrons (of which there are a total of 8) from Fe enter the seven vacant 4f orbitals in La atoms.

I happen to posses a ferromagnetic alloy, in the form of a lamp standard, that contains no Fe, Co, Ni, or lanthanide metals. It appears to be made of a ferromagnetic brassy-appearing Cu-Mn alloy, a composition range of which appears to have this property, in spite of Cu being only paramagnetic and Mn being antiferromagnetic (unpaired 3d electron spins aligned parallel but in opposing directions). Apparently the excess numbers of 3d electrons in the Cu are shared with the Mn atoms, enabling ferromagnetic alignment of electron spins comparable to Fe and Co and Ni.

BTW, I also wonder if any of the six platinum-group metals, or any of their alloys, are usefully ferromagnetic, although of course they are much too valuable to be used for magnets to any significant extent. It is likely because their unpaired 4d and 5d electrons can participate in metallic conduction and chemical bonding more extensively than 3d electrons.

[Edited on 22-4-10 by JohnWW]

IrC - 21-4-2010 at 17:18

Actually I did not think I stated La would be good, rather I hoped it would. Since I have a bunch of it, (and it is a cheaper substitute for Nd), and from reading around page 142 or thereabouts of the link http://exchange.chemport.ru/index.php?mode=download&way=... given by kmno4 where the magnetic contribution increased going down the series starting at Sm and going to La, even finding Ce is a good choice from the data. Another reason I have hopes for La, is the work in the text where they found using raw Misch metal in it's typically produced proportions of RE's works better than Ce alone, and we know there is much La in Misch metal. Were are not talking about that lighter flint Ce-Fe stuff, rather the normal multi RE form. They also go into great depth on your Actinide question, and yes somewhere in there I read casually but have yet to study intently they mentioned using Platinum in one of the experiments performed with fairly good results. Cannot quote the page on that one, maybe later after I have had time to really study it. Right now I am just on a quest to find a good composition as I am sure a lot of others are also doing out there.

franklyn - 21-4-2010 at 20:11

Heeeere I come to save the daaaay

Permanent Magnets
http://cas.web.cern.ch/cas/Belgium-2009/Lectures/PDFs/Bahrdt...

Magnetic Bulk Materials
http://magnet.atp.tuwien.ac.at/download/fidler_euro.pdf

Nanocrystalline Hard Magnetic Alloys
http://www.biblioteca.org.ar/libros/90057.pdf

Magnetic and Superconducting Materials
www.msm.cam.ac.uk/Teaching/PtIII/M13/M13H.pdf

Nanocomposite Magnets Master Thesis
http://www.physics.gla.ac.uk/~dtngo/Thesis/NDThe_Master_Thes...

Magnetic Properties & Origins Defined
http://www.freewebs.com/schandnithphys/Magnetic.pdf

Multiferroic Crystals & Thin Films
http://upload.wikimedia.org/wikipedia/commons/0/07/Multiferr...

_____________________

I'm curious what keywords do not produce the desired result since
that cannot then be properly termed a search. Try _
- NdFeB "unit cell"
- Magnequench "unit cell"

Below are resources from my own archived material.

Attachment: SD 9-85 Scanned 21-Apr.pdf (617kB)
This file has been downloaded 713 times

Attachment: PS 2-85 Scanned 21-Apr.pdf (568kB)
This file has been downloaded 882 times NdFeB unit cell .jpg - 86kB

IrC - 21-4-2010 at 21:59

Thank you franklyn. I love this place! Best science on the planet. Mostly I have been using ones such as "NdFeB structure" and variations, without and with quotes. But I am not very good at searching. I am very good at understanding things once I find them to study. My schooling was 40 to 50 years ago, we did not have the information overload like today. How I would love to have had the access you people have today to information while all my brain cells still worked. I have been trying to catch up for over a decade ever since so much good scientific information has become so easily available. Trust me in the 60's had you been looking for rare earth super magnets and theory 101 you would have had a long search, like 40 years or so. Back then a simple patent search would have cost thousands, or would have required a 1500 mile trip to the patent office, and a few grand spending months in a motel carefully going through records by hand, and then God help you if you had to copy very much to take home. Hopefully you will never even know what a lithograph was. By the 70's Royal copiers with CDS drums were coming into play more and more but cost per copy was high. Se and Te drums came out later, better but still slow and costly per sheet. Today you can sit in your underwear watching the Simpsons and saving a terrabyte of patents and other papers such as what you just posted to DVD's. Another thing is it will take a while studying all these information sources thus far gleaned from this thread just to get better at knowing what to look for in a more focused manner.

However that is the point. To stop learning and discovering is to die or fade away.

chief - 22-4-2010 at 09:23

The point is, thats it's not simple enough to just make it possible arguing with f- and d-shells or maybe the diamagnetics of boron ...
==> If it were _that_ simple, then it wouldn't be a problem to make materials with almost _any_ reasonable properties ...

Whoever knows about the reasons of strong magnetism may prove it by finding some new material with according properties ...

... but I bet: Most here would have trouble making the existing compounds, even though these might be good busines on ebay ... and quite legal ...

12AX7 - 22-4-2010 at 09:57

Cobalt platinum:
http://www.platinummetalsreview.com/pdf/pmr-v1-i3-084-086.pd...
This table claims it has 3 times the energy of barium ferrite, which I believe is still used today for cheap ceramic magnets. If the units are actually MGOe (it says 10^-6, not 10^6?), then NdFeB is about 7 times stronger.

I don't see how you can justify diamagnetism as an active effect. It must be conjugated something silly in order to be more than ppm, in which case there should also be "ferrodiamagnetic" materials which exhibit macroscopic diamagnetism in the same way that ferromagnetic materials can be conjugated to produce macroscopic ferromagnets.

Tim

IrC - 22-4-2010 at 10:29

"The point is, thats it's not simple enough to just make it possible arguing with f- and d-shells or maybe the diamagnetics of boron ."

My idea or approach is find the best compositions from all the theory I can find and learn. Study how similar mixtures are processed. Try it with my stuff. I can kiln 2000 C but it's hell on the coils and I lose some often. Pain in the ass to recoil and paint with ITC-213 and 100 so I prefer not so hot. I have equipment to pulse fields (quarter squisher tech). But I need to obtain high temp vessels with gas tight abilities, as well as inert gasses. Problem is any techniques requiring steady multi Tesla fields for long cooling is financially out of my reach at the moment. In any case my point was you could try infinity but trying the most likely candidates first seems more logical.

So far my ceramic mad sci has been running a quartz tube through my furnace, and running H2 (produced locally on the fly with calcium hydride, water, and vapor dryers) through it with my latest mix ideas. I sent some to Fleaker and I keep forgetting he asked for more once, or maybe it was just commenting on them. For health reasons it's been nearly 5 years since I could play mad scientist too much, and over that time I got bored with superconductors and glow powder. So many selling these (produced in large Chinese plants) on Ebay just not a money maker for the lone small outfit. I did accumulate stuff to start building a tube furnace but will be a while. Been looking for something fun that I do not have to produce, just invent, which would help fund even more mad sci. New magnets looks good and looks fun. Without fun whats the point I ask. Just wish I had JohnWW's knowledge of orbital mechanics that would help, as I mentioned best to start with the most logical and likely prospects first rather than spend eternity trying everything on the planet.

"I don't see how you can justify diamagnetism as an active effect. It must be conjugated something silly in order to be more than ppm, in which case there should also be "ferrodiamagnetic" materials which exhibit macroscopic diamagnetism in the same way that ferromagnetic materials can be conjugated to produce macroscopic ferromagnets."

I think it is involved with increasing the ability to resist demagnetization. I am no expert, but with all the information posted thus far it helps, only takes time to study.

[Edited on 4-22-2010 by IrC]

chief - 23-4-2010 at 05:09

Most commercial Nd2Fe14B-magnets are compressed from the elements, as powder-mixture, in tablet-presses, and then sintered at 1200 Celsius ...
==> Magnetization is done with "magnetizers", mechaniclly stable setups where capacitor-discharges give the magnetic fields ...

So it might be possible for the amateur to make this stuff and sell it, as long as he uses a composition, where the patent-rights have run out, or maybe some somewhat different composition ...

A tablet-press for maybe 2-cm-magnets would need to have maybe 10 tons of force ...

Thats basically the equipment for manufacturing these: Raw-materials as element-powders, tablet-press, quartz-vessels for the sintering, a bottle of argon for inert atmosphere ..., and a magnetizer.
==> In case something goes wrong a x-ray-diffraction unit, for analyzing the phases, would b the best bet; some debye-scherrer camera could be made and would be the most simple thing for the purpose ...

I was once into making these, but had then other priorities ...

The most dangerous part would be the press: The piston and cylinder my break, which means bullet-fast steel flying around ...

[Edited on 23-4-2010 by chief]

JohnWW - 23-4-2010 at 06:56

Further to my speculation above about actinide-based (as distinct from lanthanide) rare-earth magnets, using especially depleted U-238 (of which there are huge stockpiles, as a byproduct of "enrichment" to obtain U-235, in the U$A and Russia, sitting around awaiting some use) and Pu-244, which are the longest-lived isotopes of the most suitable metals:

It is to be observed that U is the electronic homolog of Nd, both having one unpaired 5d or 6d electron and three unpaired 4f or 5f electrons; although in U the 5f electrons are much less strongly held than the 4f electrons in Nd, and unlike the latter can participate readily in electrical conduction and covalent chemical bonding (with the +6 oxidation state being most common for U, resulting in chemical similarities to Cr, Mo, and W instead). So, I wonder if anyone has thought of trying an alloy composition of U2Fe14B for permanent magnet properties, or, in view of the larger atomic radius of U compared to Nd, with the B replaced with Al to produce U2Fe14Al.

Also, Nd and U have four vacant 4f or 5f orbitals, of the seven 4f or 5f that each have, with the result that they have four less than the maximum possible numbers of unpaired f electrons that Gd and Cm (the latter being however too short-lived and radioactive to be suitable) have. So, I wonder also if compositions like Gd2Fe14B, which would have the same crystal structure as NdFe14B, have been tried, although Gd is much less abundant than Nd.

Again, noting that Mn, in the ground metallic state, has the maximum possible number of five unpaired 3d electrons (although pure Mn is antiferromagnetic, not ferromagnetic), with Fe having one more electron than this, both also having two paired 4s electrons, while Nd has a deficiency of four 4f electrons that could be unpaired if they were present, I wonder if alloys of Nd (or even Pr or Ce, which are more abundant, or Th-232 which is the longest-lived of all natural actinide isotopes, with fewer 4f or 5f electrons) with Co, Ni, and Cu (instead of Fe), which have paired surpluses of 3d electrons beyond the maximum unpaired number that Mn and Fe have, have been tried, in suitable molar proportions although having regard to the possible viable crystal structures. This would assume that in the alloys the surplus 3d electrons, and the 4s electrons, can enter the vacant lanthanide or actinide 4f or 5f orbitals, with a larger proportion of the alloying 3d-transition metal being usable with Pr or Ce or Th.

[Edited on 23-4-10 by JohnWW]

IrC - 23-4-2010 at 09:18

Actually chief I was more into coming up with something new, yet trying old to verify the process. No way to compete with the big factories. I mentioned the quarter squisher tech stuff I have, and figure a 20 ton bottle jack works as a press starting place. Yet still looking for a sleeve (say a cylinder of quartz several inches thick) which I could wrap stainless tubing around it for the pulse coil, and in effect building a tube furnace around this. I want to try using the heat, pressure, and pulsed field all at once. With the option to continue the pulses while it was cooling. Two 2 inch tow balls make a good electrode, with a needle at the end of a 10 KV strobe trigger transformer circuit to ionize the gap thereby firing the pulse I have already perfected. This portion of the idea works very well.

Along John's lines I actually already did acquire the Uranium, and all the other elements he mentioned (as well as many more). Thinking vacuum may be cheaper to implement rather than inert gas, but have not decided on this idea.

12AX7 - 23-4-2010 at 10:25

Would you like an induction heater? Sounds like the perfect item for sintering.

Tim

IrC - 23-4-2010 at 10:42

You know Tim that is a very good idea. No idea why I had not even been thinking along those lines other than selective brain fading, i.e. some of my neurons fire and some do not yet they can never decide which ones will be which type. I remember reading some of your stuff on this subject a few years ago and was very impressed with your work.

Edit to add however I wonder. Would the fields from induction heating interfere with the magnetic alignment going on. Novel to think about is some way to use the induction fields tailored to aid the process. Or am I just wishfully imagining things. Got to go find Tim's page and study more. Fortunately he always has that link on the bottom.

http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat8.h...

Need to study this page again yet an AC field would seem to act to degauss so I need to wonder about using rapid high power DC pulses orientated correctly to both heat and not demagnetize at the same time. Or is that even possible I wonder. Seems an AC field would be needed for induction heating.

[Edited on 4-23-2010 by IrC]

Polverone - 23-4-2010 at 10:55

This press release is fairly fluffy, as press releases usually are, but it may give you some names of institutions and people to search for if you want to keep abreast of academic efforts to find a new generation of permanent magnets.

12AX7 - 23-4-2010 at 13:05

The magnetic field is approximately B = mu_0*N*I/R, or around 25mT for a 2" coil, 5 turns, 200A. Nowhere near the 1T+ needed to magnetize. This means ferrite pole pieces are an excellent choice if you need to concentrate the heating, and also that very little heating will occur by hysteresis loss, only eddy currents. (Which has a downside: powdered metals may have very high bulk resistivity, heating slowly unless you use a very high frequency.)

FYI, I'd be cautious using your quarter shrinker around the same device... it's not designed to handle kA scale induced currents!

Tim

IrC - 23-4-2010 at 13:58

Food for thought. I think I need to look into induction heating at a high enough frequency and low enough field intensity where the heating field would not interfere with magnetic alignment. I know what you are saying about high pulsed fields, I assume you were talking about inducing Tesla type voltages back into the heating coil. Much to optimize in such designs. Blocking the lower frequency components of a high pulsed field from creating back EMF in the heating coils would be hard but higher frequency components could be limited with chokes from the feed into the heating coil. However this would still leave a Tesla effect back EMF across the turns of the heating coil. Already bored myself to death blowing apart coils (and other things) on purpose, certainly not something I want to do by accident.

chief - 24-4-2010 at 01:04

@IrC: Quartz-tubing as well as glassware can be obtained; prices for raw tubing are around 20 $/Meter (or was it per kg ?)

As for "coming up with something new": Those materials-systems surely have be searched by hundereds of diplomands and doctorants ...; that;s what always happens when noone has a better idea ...
==> lot's of professors on the world, who just can assign such searching as a task to their students ...

===================

Where the magnetism comes from: As the formula says it's NdFe14B, so it's 14 times more Iron than Neodymium ...
==> Thereby most of the field still comes from the iron ...

, the other elements just permit the existencence and stability of the ordering of the iron-spins ... ; I bet that this would be the most fertile soil for planting any theories onto ...

===================

Also I wouldn't go for the induction-heating: Any laboratory-furnace that can reach the 1200 Cels will do ...
==> ... also much better controllable, not so easy to overheat anything ...

As long as the material would be pressed as tablets only a Argon-Bottle would be needed; not even any quartz necessary ...

Main busines would be to obtain/get the Elements as powders ... for a rasonable price ...

[Edited on 24-4-2010 by chief]

watson.fawkes - 24-4-2010 at 06:32

Quote: Originally posted by IrC

I think I need to look into induction heating at a high enough frequency and low enough field intensity where the heating field would not interfere with magnetic alignment.

This sounds like needless worrying. You'll generally be sintering at a temperature above the Curie point, where the magnetic domains are in a "liquid" phase (as opposed to the "solid" phase below it) and will move around freely, following your driving field.

chief - 24-4-2010 at 07:59

Just thought it might help:

All the known compounds with the p42/mnm-symmetry:

Attachment: p42_mnm.txt (16kB)
This file has been downloaded 983 times

IrC - 24-4-2010 at 13:53

Actually Watson from experience building electrets I find having the field on before the point of becoming a solid (or in the case here of making magnets, a crystal structure) and letting the material continue in the field as it cools works best. It would seem to me keeping the field on through the whole process of cooling past the Curie temperature would help moments prefer a certain orientation aas they settle into a lattice structure. Then using the quarter squisher pulse of extremely strong field would then cause the structure to be aligned in the optimum orientation.

Of course it seems trying to use induction heating would create engineering problems. My original thought was only having one coil, the pulse coil, and building a kiln around this structure. My thought about an extremely thick walled quartz tube was aimed at keeping the material under mechanical pressure through the heating and cooling cycle. Simply making the material the same way it is now being done would seem to me to be creating what we already have, rather than coming up with new and stronger (in field strength) magnet materials.

[Edited on 4-24-2010 by IrC]

franklyn - 24-4-2010 at 15:14

As with a simple iron bar , heating the material to the curie temperature and
allowing it to cool within an externally applied magnetic field will polarize the
remanent field of the magnet itself. This is usually done cold by a powerfully
pulsed electromagnet. Magnet alloys are either cast as the AlNiCO or sintered
powder such as the common Ferrite. There is an optimal minimal magnetic
domain size that may contain anywhere from a few tens of thousands to
several million atoms. Since this is a crystal of ordered unit cells mechanical
powdering of the melt produces the right size. The directions or axis of a
magnetic domain which can become permanently polarized , called anisotropic,
determines the resistance to demagnetization. NdFeB powdered domains have
a single anisotropic orientation making them extremely resistant to nucleation
( when adjacent domains form a closed magnetic loop which does not exhibit
a magnetic field externally ). This property is exploited by first orienting the
loose individual crystal domains directionally with an applied magnetic field
and mild vibrating agitation. The bulk material is isostatically pressed in this
state to retain the crystal bias and sintered to weld the powder grains together
to keep the magnetic anisotropy. The same method is used having the powder
mixed within a plastic binder , easier to process but with reduced properties.
Magnetization is also done cold although the highest performing grades can
actually be heated up to their curie points of 80 ºC. Lower performing grades
have higher curie points over 100 ºC. up to about 150 ºC. for lowest grades.
Grade is just the product of the remanent field called B and the coercive H
field that would be applied externally of opposite polarity needed to reduce
the remanent field to zero. Very commonly availble NdFeB magnets can be
had at anything above 35N (BH) up to 42N. The highest commercially available
is 55N , but this has a disturbingly low curie point of around 55ºC.

So what determines grades you may ask. The single domain crystal will be
mechanically wedged into a space with adjacent crystals. The internal unit
cells of a crystal grain are not necessarily oriented with the external contours
of the grain , so the intrinsic anisotropic direction of the crystal will only
approximately line up with the direction of the bulk magnet. This will
adversely affect the overall properties of the magnet since nucleation will
result more easily. The higher curie points of the lower grades indicates that
most crystal domains retain the desired magnetized direction. As those that
are more marginal are aligned their contribution to the magnet is seen. These
marginally oriented crystals also are the first to nucleate at lower temperature
and adversely affect the magnets overall performance. A high grade ~ 50N if
warmed to its curie temperature will degrade into a lower grade having a
somewhat higher curie temperature.
Grades you see are largely the result of handling and processing rather than
the theoretical properties of the material itself.
Directional casting as is done for aircraft engine parts will produce a single
large crystal of an alloy. Trouble is that the constituent elements of many
magnetic materials are not miscible so do not form a solution. The best that
can be done is to produce a heterogeneous blend of the elements. Rapidly
quenching an agitated melt ( before the composition can separate ) is the
method employed for the production of powders.
More common magnetic alloys that have multiple anisotropic magnetic
directions , when cast as a large crystal , nucleation occurs at a runaway
rate much as dominoes falling. Aggregation of individual domain crystals
mitigates this occurence; which explains the optimal size paradigm.

.

12AX7 - 24-4-2010 at 18:00

IrC, do you typically charge your quarter shrinker to the point where the coil is destroyed? If the coil survives, it may be effective to switch between power sources, thus disconnecting the induction heater when the pulse is required. You'll have to make your own switch I'm afraid, which could be a few slabs of copper and a lever with latching action. Pull the big Frankenstein-esque lever *CLUNK*, then fire away.

Tim

IrC - 24-4-2010 at 20:00

I have but only when that is what I wanted to do. If one terminal of the induction heating can be grounded then the switch is simple. Ground, through coil to tow hitch ball. Open circuit to pulser. So connecting to the coil is simple, low current path needing to carry only the induction heating current. A side connection to ball - coil junction. I will go look at some of your circuitry to see.

Elec_IndSG3524.gif - 6kB

If this earlier work of yours is still similar to your current design the bottom is grounded so this idea would work fine. However in a newer one you have R601 and "inverter control" outputs between the bottom of the work coil and ground complicating things. However DPDT switching would still work keeping your "tank coil" on the heater supply side of the circuit. That should work except it would require the pulser to not be ground referenced on the cap bank side. I doubt circulating currents from a say 1 KW heating source would be greater than a couple hundred amperes as far as considering the switch ratings. Something surplus or maybe building one does not seem a difficult problem.

Elec_Induction5.gif - 5kB

I did not see the rest of the circuit to study where you go from "- + inverter current". Hard to figure the ground reference issue unless I can see the whole circuit. Maybe you have that on there somewhere, your site is way beyond where it was last time I looked, much more to search through.

Oh yeah I forgot. Images copyright 12AX7 and borrowed from his site.

[Edited on 4-25-2010 by IrC]

12AX7 - 24-4-2010 at 20:25

That circuit comes from page 6 I believe, so you'll find the control circuit and what it does with inverter current (if anything) there.

I don't think I was using current at the time, actually, so you'll probably have a hard time figuring that one out.

Here's a representative drawing of the current "state of the art":

Power comes in, is rectified and filtered, and the inverter is coupled to the output transformer. The secondary winding is copper tubing like so, so the output network is completely isolated (I should probably add some small capacitors to it, just to keep RFI down).

Just because a quarter shrinker is a big mess of crap when it fires, I'd like to see some filtering between them, since even with the isolated output, there will be a lot of noise carried on that connection. You could make a common-mode filter choke using a stack of toroids just large enough to pass the copper tubes through. Should be able to find 3/4-1" i.d. ferrites on eBay or surplus sites for under a buck each, and heck, 10 would be fine (a stack of about 5", roughly).

It would also be nice to have a provision to short out the induction heater (at the disconnect switch), to prevent induced voltage. Induced noise would be either from capacitance of the switch, or if it's not wide enough, a spark could jump, something that obviously should be avoided.

I can make a diagram for this. This fits in the realm of EMC (electromagnetic compliance), a rather extreme case you'll admit (I can't imagine how a quarter shrinker could possibly pass any organization's emissions tests

), a subject which I myself am gathering knowledge on but am still quite green about. EMC is about dealing with the parasitic squigglies of real components, so it's voodoo magic getting real devices to pass. The standards of which I am considering here aren't likely to pass any organization's standards, anyway, but considering the magnitude of voltage and current nearby, I'd like to make sure this thing doesn't get shocked just from the fields.

Tim

watson.fawkes - 27-4-2010 at 06:04

Quote: Originally posted by IrC

Actually Watson from experience building electrets I find having the field on before the point of becoming a solid (or in the case here of making magnets, a crystal structure) and letting the material continue in the field as it cools works best. It would seem to me keeping the field on through the whole process of cooling past the Curie temperature would help moments prefer a certain orientation aas they settle into a lattice structure. Then using the quarter squisher pulse of extremely strong field would then cause the structure to be aligned in the optimum orientation.

We're talking about several different field configurations here. All I was saying is that in the heating phase, presumably the first phase, you don't have to worry about overall magnetic field alignment in the ceramic, exactly because (as you point out) its macroscopic magnetic field alignment locks in as it cools, which is some later phase. All this means that induction heating can work just fine for you if what you're using it for is to get to sintering temperatures.

I should also point out that you don't need an external magnetic field that's as strong as the field locked into the final material. The purpose of the external field is to align magnetic domains to some common external reference so that as they lock in they will all be pointing in the same direction. The magnetic domains are what's called a "spin glass". If you're trying to get maximum alignment in the glass, what you need is not big pulses but rather an annealing process. You're annealing magnetic alignment rather than the crystal structure, in this case. One form of annealing is to hold the material just barely below the Curie point. This gives some amount of spin mobility, not enough to destabilize the long-range order, but enough for the last recalcitrant domains to find their way into the overall alignment.

I should make sure I understand what you're doing, I realize. Perhaps you mean you want to use high-power pulse energy to drive densification of the ceramic. If so, you'll be sintering above the Curie point, so the magnetic domain alignment won't be relevant. If this is the case, Barsoum's book Fundamentals of Ceramics was where I really learned about the physics of sintering. I will highly recommend if you're planning some lab work in this area.

IrC - 27-4-2010 at 15:32

Good advice, right now I am doing a lot of study and thinking of design ideas, including Tim's concerns. Searching for the book online, may have to just buy a copy. I am looking at the design where I could use a single coil for both heating and magnetic pulsing, would be simpler to build. I can see how to build a switch to take care of the things Tim mentioned. Does not look to difficult. So much good information has been provided by members so far I am going to spend a while carefully studying all of it before I say too much more, helps if I ask better questions and this is best done with a good handle on the subject. Which also eliminates asking too many uninformed questions.

Below is a long list of relevant patents.

Attachment: ndfeb.doc (36kB)
This file has been downloaded 510 times

[Edited on 4-28-2010 by IrC]

quantumcorespacealchemyst - 1-1-2015 at 03:25

what about running a direct current of high amps throught the material to melt it and then switch the input of the electrodes to the aligning field current/pulses from there untill after it solidifies?

the uranium bond in valence 3 state, any good info on this?