Diamagnetic, Paramagnetic, and Ferromagnetic Materials
When a material is placed within a magnetic field, the magnetic forces of the material's electrons will be affected. This effect is known as Faraday's Law of Magnetic Induction. However, materials can react quite differently to the presence of an external magnetic field. This reaction is dependent on a number of factors, such as the atomic and molecular structure of the material, and the net magnetic field associated with the atoms. The magnetic moments associated with atoms have three origins. These are the electron motion, the change in motion caused by an external magnetic field, and the spin of the electrons.
Diamagnetic materials have a weak, negative susceptibility to magnetic fields. Diamagnetic materials are slightly repelled by a magnetic field and the material does not retain the magnetic properties when the external field is removed. In diamagnetic materials all the electron are paired so there is no permanent net magnetic moment per atom. Diamagnetic properties arise from the realignment of the electron paths under the influence of an external magnetic field. Most elements in the periodic table, including copper, silver, and gold, are diamagnetic.
Paramagnetic materials have a small, positive susceptibility to magnetic fields. These materials are slightly attracted by a magnetic field and the material does not retain the magnetic properties when the external field is removed. Paramagnetic properties are due to the presence of some unpaired electrons, and from the realignment of the electron paths caused by the external magnetic field. Paramagnetic materials include magnesium, molybdenum, lithium, and tantalum.
Ferromagnetic materials have a large, positive susceptibility to an external magnetic field. They exhibit a strong attraction to magnetic fields and are able to retain their magnetic properties after the external field has been removed. Ferromagnetic materials have some unpaired electrons so their atoms have a net magnetic moment. They get their strong magnetic properties due to the presence of magnetic domains. In these domains, large numbers of atom's moments (1012 to 1015) are aligned parallel so that the magnetic force within the domain is strong. When a ferromagnetic material is in the unmagnitized state, the domains are nearly randomly organized and the net magnetic field for the part as a whole is zero. When a magnetizing force is applied, the domains become aligned to produce a strong magnetic field within the part. Iron, nickel, and cobalt are examples of ferromagnetic materials. Components with these materials are commonly inspected using the magnetic particle method.
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Substance | Formula | Mass Susceptibility |
(10-6 c.g.s. units) | ||
Aluminum | Al | + 16.5 |
Aluminum oxide | Al2O3 | -37.0 |
Antimony | Sb | -99.0 |
Antimony oxide | Sb2O3 | -69.4 |
Barium | Ba | +20.6 |
Barium oxide | BaO | -29.1 |
Beryllium | Be | -9.0 |
Beryllium oxide | BeO | -11.9 |
Bismuth | Bi | -280.1 |
Bismuth oxide | BiO | -110.0 |
Boric acid | H3BO3 | -34.1 |
Boron | B | -6.7 |
Boron oxide | B2O3 | -39.0 |
Cadmium | Cd | -19.8 |
Cadmium oxide | CdO | -30.0 |
Cadmium sulfide | CdS | -50.0 |
Calcium | Ca | +40.0 |
Calcium carbonate | CaCO3 | -38.2 |
Calcium oxide | CaO | -15.0 |
Carbon, diamond | C | -5.9 |
Carbon, graphite | C | -6.0 |
Cerium (alpha) | Ce | +5,160.0 |
Cerium oxide | CeO2 | +26.0 |
Cesium | Cs | +29.0 |
Cesium oxide | CsO2 | +1,534.0 |
Chromium | Cr | +180.0 |
Chromium oxide | Cr2O3 | +1,960.0 |
Cobalt | Co | ferro |
Cobalt oxide | CoO | +4,900.0 |
Copper | Cu | -5.46 |
Copper oxide | CuO | +259.6 |
Dysprosium | Dy | +103,500.0 |
Dysprosium oxide | Dy2O3 | +89,600.0 |
Erbium | Er | +44,300.0 |
Erbium oxide | Er2O3 | +73,920.0 |
Europium | Eu | +34,000.0 |
Europium oxide | Eu2O3 | +10,100.0 |
Gadolinium | Gd | +755,000.0 |
Gadolinium oxide | Gd2O3 | +53,200.0 |
Gallium | Ga | -21.6 |
Gallium oxide | Ga2O | -34.0 |
Germanium | Ge | -76.84 |
Germanium oxide | GeO | -28.8 |
Germanium sulfide | GeS | -40.9 |
Gold | Au | -28.0 |
Hafnium | Hf | ~75.0- 104.0 |
Hafnium oxide | HfO2 | -23.0 |
Holmium oxide | Ho2O3 | +88,100.0 |
Indium | In | -64.0 |
Indium oxide | In2O | -47.0 |
Indium sulfide | InS | -28.0 |
Iridium | Ir | +32.1 |
Iridium oxide | IrO2 | +224.0 |
Iron | Fe | ferro |
Iron oxide | FeO | +7,200.0 |
Iron oxide (red) | Fe2O3 | +3,586.0 |
Iron sulfide | FeS | +1,074.0 |
Lanthanum | La | +118.0 |
Lanthanum oxide | La2O3 | -78.0 |
Lanthanum sulfide | La2S3 | -100.0 |
Lead | Pb | -23.0 |
Lead oxide | PbO | -42.0 |
Lead sulfide | PbS | -84.0 |
Lithium | Li | +14.2 |
Magnesium | Mg | >0.0 |
Magnesium oxide | MgO | -10.2 |
Manganese (alpha) | Mn | +529.0 |
Manganese (beta) | Mn | +483.0 |
Mercury (liquid) | Hg | -33.4 |
Mercury (solid) | Hg | -24.1 |
Molybdenum | Mo | -96.5 |
Molybdenum oxide | MoO2 | +41.0 |
Molybdenum sulfide | MoS3 | -63.0 |
Neodymium | Nd | +5,628.0 |
Neodymium oxide | Nd2O3 | +10,200.0 |
Neodymium sulfide | Nd2S3 | +5,550.0 |
Nickel | Ni | ferro |
Nickel oxide | NiO | +6,60.0 |
Nickel sulfide | NiS | +190.0 |
Niobium | Nb | +195.0 |
Niobium oxide | Nb2O5 | -10.0 |
Nitric acid | HNO3 | -19.9 |
Nitrogen oxide (solid) | NO | +19.8 |
Osmium | Os | +9.9 |
Palladium | Pd | +567.4 |
Phosphorus, black | P | -26.6 |
Phosphorus, red | P | -20.8 |
Platinum | Pt | +201.9 |
Platinum oxide | Pt2O3 | -37.70 |
Potassium | K | +20.8 |
Potassium oxide | KO2 | +3,230.0 |
Potassium sulfide | K2S | -60.0 |
Praseodymium | Pr | +5,010.0 |
Praseodymium oxide | PrO2 | +1,930.0 |
Praseodymium sulfide | Pr2S3 | +10,770.0 |
Rhenium | Re | +67.6 |
Rhenium oxide | ReO2 | +44.0 |
Rhodium | Rh | +111.0- +123.0 |
Rhodium oxide | Rh2O3 | +104.0 |
Rubidium | Rb | +17.0 |
Rubidium oxide | RbO2 | +1,527.0 |
Rubidium sulfide | Rb2S2 | -90.0 |
Ruthenium | Ru | +43.2 |
Ruthenium oxide | RuO2 | +162.0 |
Samarium | Sm | +1,860.0- +2,230.0 |
Samarium oxide | Sm2O3 | +1,988.0 |
Samarium sulfide | Sm2S3 | +3,300.0 |
Scandium | Sc | +315.0 |
Selenium | Se | -25.0 |
Selenium oxide | SeO2 | -27.2 |
Silicon | Si | -3.9 |
Silicon carbide | SiC | -12.8 |
Silicon oxide | SiO2 | -29.6 |
Silver | Ag | -19.5 |
Silver oxide | AgO | -19.6 |
Sodium | Na | +16.0 |
Sodium oxide | Na2O | -19.8 |
Sodium sulfide | Na2S | -39.0 |
Strontium | Sr | +92.0 |
Strontium oxide | SrO | -35.0 |
Sulfur (alpha) | S | -15.5 |
Sulfur (beta) | S | -14.9 |
Tantalum | Ta | +124.0- +154.0 |
Tantalum oxide | Ta2O5 | -32.0 |
Technetium | Tc | +250.0- +290.0 |
Technetium oxide | Tc2O7 | -40.0 |
Tellurium | Te | -106.0 |
Terbium | Tb | +146,000.0 |
Terbium oxide | Tb2O3 | +78,340.0 |
Thallium (alpha) | Tl | -50.9 |
Thallium (beta) | Tl | -32.3 |
Thallium oxide | Tl2O3 | +76.0 |
Thallium sulfide | Tl2S | -88.8 |
Thorium | Th | +132.0 |
Thorium oxide | ThO2 | -16.0 |
Thulium | Tm | +25,500.0 |
Thulium oxide | Tm2O3 | +51,444.0 |
Tin (gray) | Sn | -37.0 |
Tin oxide | SnO | -19.0 |
Tin oxide | SnO2 | -41.0 |
Titanium | Ti | +150.0- 153.0 |
Titanium carbide | TiC | +8.0 |
Titanium oxide | TiO2 | +5.9 |
Tungsten | W | +59.0 |
Tungsten carbide | WC | +10.0 |
Tungsten oxide | WO2 | +57.0 |
Vanadium | V | +255.0 |
Vanadium oxide | V2O3 | +1,976.0 |
Water | H20 | -7.2×10-7 emu |
Ytterbium | Yb | +249.0 |
Yttrium | Y | +2.43 |
Yttrium oxide | Y2O3 | +44.4 |
Zinc | Zn | -11.4 |
Zinc oxide | ZnO | -46.0 |
Zinc sulfide | ZnS | -25.0 |
Zirconium | Zr | +119.0- 122.0 |
Zirconium carbide | ZrC | -26.0 |
Zirconium oxide | ZrO2 | -13.8 |
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