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Magnetic Susceptibilities of

Paramagnetic and Diamagnetic

Materials at 20C

Material

m=Km-1

(x 10-5)

Paramagnetic

Iron oxide (FeO) 720

Iron amoniumalum

66

Uranium 40

Platinum 26

Tungsten 6.8Cesium 5.1

Aluminum 2.2

Lithium 1.4

Magnesium 1.2

Sodium 0.72

Oxygen gas 0.19

Diamagnetic

Ammonia -.26

Bismuth -16.6

Mercury -2.9

Silver -2.6

Carbon (diamond) -2.1

Carbon (graphite) -1.6

Lead -1.8

Sodium chloride -1.4

Copper -1.0

Water -0.91

Paramagnetism Diamagnetism

Here the quantity Km is called the relative

permeability, a quantity which measures theratio of the internal magnetization to theapplied magnetic field. If the material doesnot respond to the magnetic field bymagnetizing, then the field in the materialwill be just the applied field and the relativepermeability Km =1. A positive relative

permeability greater than 1 implies that thematerial magnetizes in response to theapplied magnetic field. The quantity m is

called magnetic susceptibility, and it is justthe permeability minus 1. The magneticsusceptibility is then zero if the materialdoes not respond with any magnetization.So both quantities give the sameinformation, and both are dimensionlessquantities.

For ordinary solids and liquids at roomtemperature, the relative permeability Km is

typically in the range 1.00001 to 1.003. Werecognize this weak magnetic character ofcommon materials by the saying "they arenot magnetic", which recognizes their greatcontrast to the magnetic response offerromagnetic materials. More precisely,they are either paramagnetic ordiamagnetic, but that represents a verysmall magnetic response compared toferromagnets.

The gases N2 and H2 are weakly

diamagnetic with susceptabilities -0.0005 x

10-5 for N2 and -0.00021 x 10-5 for H2.

That is in contrast to the large paramagneticsusceptability of O2 in the table.

Index

Tables

ReferenceYoungSection

29-8

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Magnetic Properties of

Ferromagnetic Materials

Material TreatmentInitial

RelativePermeability

MaximumRelative

Permeability

CoerciveForce

(oersteds)

RemanentFlux

Density(gauss)

Iron, 99.8%pure

Annealed 150 5000 1.0 13,000

Iron, 99.95%pure

Annealedin

hydrogen10,000 200,000 0.05 13,000

78 Permalloy Annealed,quenched

8,000 100,000 .05 7,000

Superpermalloy

Annealedin

hydrogen,controlledcooling

100,000 1,000,000 0.002 7,000

Cobalt, 99%pure

Annealed 70 250 10 5,000

Nickel, 99%pure

Annealed 110 600 0.7 4,000

Steel, 0.9% C Quenched 50 100 70 10,300

Steel, 30% Co Quenched ... ... 240 9,500

Alnico 5Cooled inmagnetic

field4 ... 575 12,500

Silmanal Baked ... ... 6,000 550

Iron, finepowder Pressed ... ... 470 6,000

In this table the remanent flux density is the retained magnetic field B, and theSI unit for B is the Tesla (T). 1 Tesla = 10,000 gauss. The "coercive force" isthe applied reverse magnetic field strength H required to force the net magneticfield back to zero after magnetization. The SI unit for H is A/m, and 1 A/m =0.01257 oersteds.

Discussion of relative permeability

Coercivity and Remanence

Index

Tables

Reference

Brown

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