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Alternate Perceptions Magazine, November 2019


The World's Strongest Permanent Magnet (Neodymium-Iron-Boron): A Chemical Perspective.

by: Brett I. Cohen, Ph.D.
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With the recent trade wars between China and The United States of America, there has been increasing interest in rare-earth metals and how China trade could affect the economy of the United States, if the trade of these rare-earth metals between China and The United States of America are halted.  As of 2017, China produced approximately 80% of the world's rare-earth elements supply, found mainly in Inner Mongolia (Hammond, 2009).  Other countries that produce rare-earth metals are India and South Africa, but their productions are much smaller and dwarfed by the scale of Chinese production.  It is important to note, that alternative sources for rare-earth metals are underway today in Australia, Brazil, Canada, South Africa, Greenland, and The United States of America.

Rare-earth elements are a set of seventeen chemical elements found on the periodic table (see Figure 1).  They comprise fifteen lanthanides metals, as well as scandium (Sc) and yttrium (Y).  Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits (when mined) as the lanthanide metals and exhibit similar chemical properties.  The 17 rare-earth elements are: cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).

Abundance {in parts per million (ppm)} and some industrial applications for the seventeen rare-earth metals are: Scandium {22 ppm} (aerospace components and lamps), Yttrium (33 ppm} (lasers, high-temperature superconductors, microwave filters, and energy-efficient light bulbs), Lanthanum {39 ppm} (camera lenses and battery-electrodes), Cerium {66.5 ppm} (polishing powder, yellow colors in glass and ceramics and catalyst for self-cleaning ovens), Praseodymium {9.2 ppm} (rare-earth magnets  and lasers),  Neodymium {41.5 ppm} (rare-earth magnets (see below), lasers, and violet colors in glass and ceramics), Promethium {1 X 10-15 ppm} (nuclear batteries and luminous paint), Samarium {7.05 ppm} (rare-earth magnets, lasers, and control rods of nuclear reactors), Europium {2 ppm} (lasers, lamps, and NMR relaxation agent), Gadolinium {6.2 ppm} (lasers, X-ray tubes, MRI contrast agent, and NMR relaxation agent), Terbium {1.2 ppm} (lasers, lamps and stabilizer of fuel cells), Dysprosium {5.2 ppm}(additive in neodymium based magnets, lasers, and hard disk drives), Holmium {1.3 ppm}(lasers), Erbium {3.5 ppm}  (Infrared lasers and fiber-optic technology), Thulium {0.52 ppm} (Portable X-ray machines,  lamps, and lasers), Ytterbium {3.2 ppm} (Infrared lasers, chemical reducing agent, nuclear medicine, and monitoring earthquakes), and Lutetium {0.8 ppm} (positron emission tomography – PET scan detectors, high-refractive-index glass, catalyst used in refineries, and LED light bulb) (Hammond, 2009).  It is interesting to note, that the element neodymium (41.5 ppm) is the second most abundant in the earth's crust as compared to the other rare-earth metals.  The most abundant rare-earth metal is Cerium (66.5 ppm).  Interestingly, in my laboratory research, I have added lanthanide series metals such as lanthanum and cerium, to dental composite polymer cements for tooth restoration materials (see U.S. Patent No. 5,204,398 to Cohen, 1993).

Rare-earth magnets are strong permanent magnets made from alloys of rare-earth elements.  A magnet is a material or object that produces a magnetic field.  This magnetic field is invisible but is responsible for the most notable property of a magnet, in which a force that pulls on other ferromagnetic materials, such as iron, attracts or repels other magnets.  A permanent magnet (through synthetic processing) is an object made from a material that is magnetized and creates its own persistent magnetic field.  Rare-Earth magnets were developed in the 1970's and 1980's and are the strongest type of permanent magnets on Planet Earth (Cullity and Graham, 2008).  These magnets produce significantly stronger magnetic fields than other magnet types such as ferrite (a ceramic material made by mixing and firing large proportions of iron(III) oxide (Fe2O3, rust) blended with small proportions of one or more additional metallic elements, such as barium, manganese, nickel, and zinc) and alnico (a family of iron alloys which in addition to iron are composed primarily of aluminum, nickel and cobalt) magnets.  The magnetic field typically produced by rare-earth magnets {such as, neodymium-iron-boron with the chemical formula (Nd2Fe14B)} can exceed 1.4 teslas {tesla (symbol T) is a derived unit of the magnetic induction (also, magnetic flux density)}, whereas ferrite (ceramic magnets) or alnico magnets typically exhibit fields of  approximately 0.5 to 1 tesla (Cullity and Graham, 2008).  Magnetic induction is also defined as the process by which an object or material is magnetized by an external magnetic field.

There are two types of rare-earth magnets; neodymium {neodymium-iron-boron (Nd2Fe14B), also known as NIB} and samarium–cobalt {with the chemical formula (SmCo5)}.  Rare-earth magnets are extremely brittle and also vulnerable to corrosion, so they are usually plated or coated to protect them from breaking, chipping, or crumbling into powder.  Use of protective surface treatments such as gold, nickel, zinc, and tin plating and epoxy-resin coating can also provide corrosion protection for these rare-earth magnets.  Neodymium-iron-boron or NIB magnets exceeding 1.4 T {unit of the magnetic induction (also, magnetic flux density)} are the world's strongest permanent magnet on Planet Earth as compared to samarium-cobalt and samarium alloy magnets with approximately 1 T.  Samarium-cobalt and samarium alloy magnets have the distinction of being the second strongest permanent magnet on Planet Earth.

This article will detail chemically how and why neodymium-iron-boron (Nd2Fe14B) magnets represent the world's strongest permanent magnet on Planet Earth.



Neodymium-Iron-Boron Magnets and their Extreme Strength

Neodymium (from the Greek "neos", meaning new, and "didymos", meaning twin) is a chemical element (see Figure 1) with the chemical symbol of Nd and atomic number (the number of protons in the nucleus of an atom) of 60.  Neodymium belongs to the lanthanide series and is a rare-earth element.  Neodymium is a hard, slightly malleable silvery metal, that quickly tarnishes in air and moisture.  Although neodymium is classed as a rare-earth element, it is fairly common and no rarer than cobalt, nickel, or copper, and is widely distributed in the Earth's crust (see above).

Invented in the 1980's, neodymium-iron-boron magnets are the strongest and most affordable type of rare-earth magnet.  For nearly 40 years of research utilizing other lanthanide elements and other elements on the periodic table, no other permanent magnet has the magnetic strength of that found for neodymium-iron-boron magnets.  These magnets are made of an alloy of neodymium, iron, and boron (Nd2Fe14B) where 2 atoms of neodymium, with 14 atoms of iron and one atom of boron are sintered together chemically.  Neodymium magnets are used in numerous applications requiring strong (compact permanent magnets), which include; electric motors for cordless tools, hard disk drives, and jewelry clasps. These magnets have the highest magnetic field strength (see above) and have a higher coercivity (which makes them magnetically stable) compared to other permanent and synthetic magnets.  Coercivity is the resistance of a magnetic material to changes in magnetization, which is equivalent to the field intensity necessary to demagnetize the fully magnetized material.

The rare-earth (lanthanide) elements such as neodymium (see above and Figure 1) are metals that are ferromagnetic (in which the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets), in that like iron they can be magnetized to become permanent magnets.  The greater strength of neodymium-iron-boron (Nd2Fe14B) magnets as compared to other magnets is mostly due to two factors. 

First, the crystalline structure of neodymium-iron-boron (Nd2Fe14B) has a very high magnetic anisotropy.  In condensed matter physics, magnetic anisotropy describes how an object's magnetic properties can be different depending on direction.  In the simplest case, there is no preferential direction for an object's magnetic moment. The magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field.  Therefore, neodymium-iron-boron (Nd2Fe14B) magnets will respond to an applied magnetic field in the same way, regardless of which direction the field is applied. This is known as magnetic isotropy.  Therefore, the crystal structure of neodymium-iron-boron (Nd2Fe14B) preferentially magnetizes along a specific crystal axis (is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material) but is very difficult to magnetize in other directions.  Like other magnets, neodymium-iron-boron (Nd2Fe14B) magnets are composed of microcrystalline grains, which are aligned in a powerful magnetic field during the sintered manufacturing process, so their magnetic axes all point in the same direction. Therefore, resistance of the crystal lattice to turning its direction of magnetization gives neodymium-iron-boron (Nd2Fe14B) magnets a very high magnetic coercivity or resistance to being demagnetized.

The second factor for neodymium-iron-boron (Nd2Fe14B) magnets high strength are that the 2 atoms of neodymium, with 14 atoms of iron and one atom of boron can have high magnetic moments.  As mentioned earlier, the magnetic moment is the magnetic strength and orientation of a magnet or other object that produces a magnetic field. This is because the orbital electron structure of these atoms contain many unpaired electrons as compared to other elements, in which almost all of the electrons exist in pairs with opposite spins and as a result these other element atoms result in magnetic fields which cancel out and have no magnetism.  This is a stark contract for neodymium-iron-boron (Nd2Fe14B) magnets as compared to other permanent magnets.

  It is also important to note, that a lanthanide metal such as neodymium results is an incomplete filling of the f orbital shell, which contain 4 unpaired electrons.  In chemistry, an electron shell, or a principal energy level, may be thought of as an orbit followed by electrons around an atom's nucleus.  This is similar to the metaphor of the planets (representing the electrons) orbiting around the sun (representing the atomic nucleus where the protons and neutrons exist) in our solar system. The closest electron shell to the nucleus is called the “1st shell”, followed by the “2nd shell”, then the “3rd shell” and so on.  Each numbered shell is farther and farther from the nucleus.  Each electron shell is composed of one or more subshells, which are themselves composed of atomic orbitals.  For example, the “1st shell” has one subshell, called 1s; the “2nd shell” has two subshells, called 2s and 2p; the “3rd shell” has three subshells, called 3s, 3p, and 3d; the “4th shell” has four subshells, called 4s, 4p, 4d and 4f, etc.  Maximum electron placement in each subshell is as follows: s subshell 2 electrons with one orbital, p subshell 6 electrons with 3 orbitals, d subshell 10 electrons with 5 orbitals, f subshell 14 electrons with 7 orbitals.  For further description and details concerning the placement of electrons in orbital subshells please refer to my August 2017 Phenomena Magazine article entitled, "Debunked:  The Mystery of the Dogon and Chemistry" (Cohen, 2017).  

Therefore, these 4 unpaired electrons for each of the neodymium atoms in a neodymium-iron-boron (Nd2Fe14B) magnet in the f orbital subshell align so that they spin in the same direction, which generates a strong magnetic field.  This gives neodymium-iron-boron (Nd2Fe14B) magnets high remanence.  Remanence or remanent magnetization is the magnetization left behind in a ferromagnetic material (such as iron) after an external magnetic field is removed.  Neodymium-iron-boron (Nd2Fe14B) magnets have the potential for storing large amounts of magnetic energy and the magnetic energy production of neodymium-iron-boron (Nd2Fe14B) magnets is approximately 18 times greater than "ordinary" magnets by volume (Cullity and Graham, 2008). This, therefore, allows rare-earth magnets like neodymium-iron-boron (Nd2Fe14B) to be smaller than other magnets with higher and stronger field strengths.

In conclusion, this article illustrates the strength of neodymium-iron-boron (Nd2Fe14B) permanent magnets and why this lanthanide metal type of magnet is the world's strongest.  Neodymium-iron-boron (Nd2Fe14B) magnets are composed of microcrystalline grains, which are aligned in a powerful magnetic field during the sintered manufacturing process, so their magnetic axes all point in the same direction. Therefore, resistance of the crystal lattice to turning its direction of magnetization gives neodymium-iron-boron (Nd2Fe14B) magnets a very high magnetic coercivity or resistance to being demagnetized.  Also, the orbital electron structure of the atoms found for neodymium-iron-boron (Nd2Fe14B) contains many unpaired electrons as compared to other elements.  This is a huge difference for neodymium-iron-boron (Nd2Fe14B) magnets as compared to other magnets.  Therefore, the 4 unpaired electrons for each of the neodymium atoms for a neodymium-iron-boron (Nd2Fe14B) magnet in the f orbital subshell align so that they spin in the same direction, which generates a strong magnetic field and also provides for strong magnetism.  With magnets providing the basis for cutting edge technology, further research and development using rare-earth metals is clearly warranted.  This makes the current trade issues with China regarding these rare-earth elements of paramount importance.



REFERENCES

Cohen, Brett I.  Composite dental cement composition containing a lathanide series compound. U.S. Patent No. 5,204,398, issue date: April 20, 1993.
Cohen, Brett I.  Debunked: The Mystery of the Dogon and Chemistry.  Phenomena Magazine 2017; Vol. 100: 40-43.
Cullity, B. D.; Graham, C. D. (2008). Introduction to Magnetic Materials. Wiley-IEEE. 
Hammond, C.R. "Section 4; The Elements". In David R. Lide (ed.). CRC Handbook of Chemistry and Physics. (Internet Version 2009) (89th ed.). Boca Raton, FL: CRC Press/Taylor and Francis.

Figure Legend



Figure 1.  Rare-Earth Metals on Periodic Table.


About the Author:

Dr Brett I. Cohen holds a PhD in inorganic and bioinorganic chemistry from the State University of New York at Albany. He received his PhD in November 1987 for his thesis entitled “Chemical Model Systems for Dioxygen-Activating Copper Proteins” and was a postdoctoral fellow at Rutgers University in 1988–1989. His research at Rutgers was in the area of peptide synthesis utilising transition metal chemistry.  After his postdoctoral fellowship, from 1989 to 2003 Dr Cohen was one of the owners of a dental company (manufacturer of dental composites and dental materials) where he was Chief Executive Officer and Vice President of Dental Research. 

 Dr Cohen has been awarded 16 US patents and has had over 100 papers published in peer-reviewed journals (such as Journal of the American Chemical Society, Inorganic Chemistry, Journal of Dental Research, Journal of Prosthetic Dentistry, Journal of Endodontics and Autism, etc.). These papers cover a variety of areas such as inorganic and bioinorganic chemistry, biomedicine, autism, physical chemistry, dentistry and more... 

In the Alternative Arena Dr Cohen has published articles for Nexus Magazine, Phenomena Magazine, The Skeptic (Australia), Alternate Perceptions Magazine (AP Magazine), Heartfulness Magazine, Living Paranormal Magazine (LPM), Interalia Magazine, and Argunners Magazine, etc.  These articles cover a variety of topics such as UFO's, Crop Circles, Ancient Mysteries {for example; Queen's Chambers Chemistry in The Great Pyramid at Giza, Roman Flexible glass (Vitrum Flexile), Secret Chemistry of Damascus Steel, Chemistry of the Iron Pillar of Delhi, Neanderthal chemical Tar (glue) adhesives for halt (spear) weapons, Chemistry for the Sulfuric Acid Lake of Kawah Ijen at Java (Indonesia), and "Greek Fire", etc.}, Alternative History (for example, Secret Chemistry of "Aero" Airship Flight in the mid 1850's,  Prussian Blue staining the walls of German World War II concentration camps, and Early use of Chemical Warfare during the Persian-Roman War, etc.),  Mythology {Cryptozoology} (Chemical mechanism of fire-breathing dragons), Spirituality (Non-dualism), Alternative Health (Autism and links to Epigenetics and Non-dualism and Autism, etc.) and more...

Dr Cohen's article Non-dualism (or Non-Duality) and Autism was published in Alternate Perceptions Magazine (AP Magazine), issue 230; May 2017.

Dr Cohen's article The Secrets of Damascus Steel Revealed: A Chemical Perspective was published in Alternate Perceptions Magazine (AP) Magazine, issue 231; June 2017.

Dr Cohen's article The Creation Story: A Journey From Paradise to Duality and a Possible Return Home was published in Alternate Perceptions Magazine (AP Magazine), issue 232; July 2017.

Dr Cohen's article The Strangest Solid on Earth, Lighter than Air: A Chemical Perspective was published in Alternate Perceptions Magazine (AP Magazine), issue 257; August 2019.

Dr. Cohen can be reached via email at This email address is being protected from spambots. You need JavaScript enabled to view it.

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