05. bahan magnetik

BAHAN MAGNETIK

Klasifikasi bahan magnetik

1. Diamagnetik

2. Paramagnetik

3. Ferro-, ferri-, antiferromagnetik

Berdasarkan responnya terhadap medan

magnetik, bahan magnetik dikelompokkan dalam

tiga kelompok utama

Diamagnetik (1)

Suseptibilitas

magnetik kecil dan

negatif

H M

Diamagnetik (2)

Suseptibilitas magnetik

tidak bergantung

pada temperatur

Quartz (SiO2) - (13-17) x 10-6

Calcite (CaCO3) - (8-39) x 10-6

Graphite (C) - (80-200) x 10-6

Halite (NaCl) - (10-16) x 10-6

Sphalerite (ZnS) - (0.77-19) x 10-6

Contoh mineral diamagnetik

(SI) Mineral

Data from Hunt et al (1995)

H = 0, M = 0 H > 0, M > 0

H

Paramagnetik (1)

Suseptibilitas magnetik kecil dan positif

Paramagnetik (2)

Suseptibilitas magnetik bergantung pada temperatur

Hukum Curie-Weiss

Contoh mineral paramagnetik

Olivine (Fe,Mg)2SiO4 1.6 10-3

Montmorillonite (clay) 0.34 10-3

Siderite (FeCO3) 1.3-11.0 10-3

Serpentinite 3.1-75.0 10-3

(Mg3Si2O5(OH)4)

Chromite (FeCr2O4) 3-120 10-3

Data from Hunt et al (1995)

(SI) Mineral

Mineral ferromagnetik : FeO-TiO2-Fe2O3

Diagram Ternary

Suseptibilitas magnetik bernilai positif dan besar

Magnetic ordering

M 0

H = 0

Ferromagnetik (1)

Unsur ferromagnetik :

Iron (Fe)

Nickel (Ni)

Cobalt (Co)

Gadolinium (Gd)

Antiferromagnetik dan

non-perfect antiferromagnetik

M = 0

Unsur antiferromagnetik :

Chromium (Cr)

Manganese (Mn)

Antiferromagnetik Non- perpect antiferromagnetik

(spin-canted antiferromagnetik)

M

Contoh: Hematite (Fe2O3)

M Contoh: Magnetite (Fe3O4)

Ferrimagnetik

Kurva histeresis

M = Ms

M =

Msr

M = 0

Summary

Ferromagnetism Antiferromagnetism

Non-perfect

Antiferromagnetism Ferrimagnetism

important for rock and

paleomagnetism

Diamagnetism

Paramagnetism

Bahan magnetik berdasarkan ukuran

SPM (superparamagnetik)

SD (single domain)

PSD (pseudo-single domain)

MD (multidomain)

Magnetic domain (1)

dua domain single domain closure domain empat domain

Domain adalah daerah pada bahan magnetik

yang mempunyai spinning electron bebas.

Tanda panah menunjukkan

dipol magnetik.

Dalam masing-masing domain,

semua dipol sejajar,

sedangkan arah dipol antara

satu domain dengan yang

lainnya bervariasi.

Magnetic domain (2)

Domain wall

Domain wall merupakan

daerah transisi antar

domain di mana

magnetisasi mempunyai

arah yang berbeda.

Iron single crystal

photomicrographs

Domain magnetik berubah

bentuk ketika bahan

magnetik dikenakan pada

medan magnetik

c18f1

3

Konfigurasi domain

pada beberapa

tahap magnetisasi

Magnetite

Chemical

Formula: Fe++Fe+++2O4

Composition: Molecular Weight = 231.54 gm

Iron 72.36 % Fe 31.03 % FeO / 68

.97 % Fe2O3

Oxygen 27.64 % O

Empirical

Formula: Fe3+2Fe

2+O4

Environment: Common accessory mineral in igneous and

metamorphic rocks. Can be biogenically

produced by a wide variety of organisms.

Locality: Many localities and environments world

wide.

Name Origin: Named for Magnes, a Geek shepherd,

who discovered the mineral on Mt, Ida, He

noted that the nails of his shoe and the iron

ferrule of his staff clung to a rock.

Sifat Fisis Magnetite

Cleavage: None

Color: Grayish black, Iron black.

Density: 5.1 - 5.2, Average = 5.15

Habit: Crystalline - Fine - Occurs as well-formed fine sized

crystals.

Habit: Massive - Granular - Common texture observed in granite

and other igneous rock.

Habit: Massive - Uniformly indistinguishable crystals forming

large masses.

Hardness: 5.5-6 - Knife Blade-Orthoclase

Luminescence: Non-fluorescent.

Luster: Metallic

Magnetism: Naturally strong

Streak: black

Hematite

Chemical

Formula: Fe2O3


Iron 69.94 % Fe 100.00 % Fe2O3

Oxygen 30.06 % O

Empirical

Formula: Fe3+2O3

Environment: Magmatic, hydrothermal, metamorphic and

sedimentary.

Locality: Matto Grosso, Brazil. Mesabi iron ore range,

Minnesota, USA. Link to MinDat.org Location

Data.

Name Origin: From the Greek, haimatites, "bloodlike'" in

allusion to vivid red color of the powder.

Sifat Fisis Hematite

Cleavage: None

Color: Reddish gray, Black, Blackish red.

Density: 5.3

Fracture: Conchoidal - Fractures developed in brittle materials

characterized by smoothly curving surfaces, (e.g. quartz).

Habit: Blocky - Crystal shape tends to be equant (e.g.

feldspars).

Habit: Earthy - Dull, clay-like texture with no visible crystalline

affinities, (e.g. howlite).

Habit: Tabular - Form dimensions are thin in one direction.

Hardness: 6.5 - Pyrite


Luster: Metallic

Magnetism: Magnetic after heating

Streak: reddish brown

Maghemite

Chemical

Formula: gamma-Fe+++2O3


Iron 69.94 % Fe 100.00 % Fe2O3

Oxygen 30.06 % O

Empirical

Formula: Fe3+2O3

Environment: Formed by weathering or low-

temperature oxidation of spinels

containing ferrous iron, commonly

magnetite or titanian magnetite.

Widespread yellow pigment in sediments.

Name

Origin:

From MAGnetite and HEMatite, in allusion

to the mineral's magnetism and

composition.

Sifat Fisis Maghemite

Cleavage: None

Color: Dark brown.

Density: 4.9

Fracture: Sub Conchoidal - Fractures developed in brittle materials

characterized by semi-curving surfaces.

Habit: Massive - Granular - Common texture observed in

granite and other igneous rock.

Habit: Massive - Uniformly indistinguishable crystals forming

large masses.

Hardness: 6 - Orthoclase

Luster: Metallic

Magnetism: Strongly magnetic

Streak: brown

Goethite

Chemical

Formula: Fe+++O(OH)


Iron 62.85 % Fe 89.86 % Fe2O3

Hydrogen 1.13 % H 10.14 % H2O

Oxygen 36.01 % O

Empirical

Formula: Fe3+O(OH)

Environment: Common in iron ore deposits.

Name Origin: Named after the German poet, J. W.

Goethe (1749-1832)

Sifat Fisis Goethite

Cleavage: {010} Perfect, {100} Distinct

Color: Brown, Reddish brown, Yellowish brown, Brownish yellow,

Ocher yellow.

Density: 3.3 - 4.3, Average = 3.8

Fracture: Hackly - Jagged, torn surfaces, (e.g. fractured metals).

Habit: Acicular - Occurs as needle-like crystals.

Habit: Radial - Crystals radiate from a center without producing

stellar forms (e.g. stibnite)

Habit: Reniform - "Kidney like" in shape (e.g.. hematite).

Hardness: 5-5.5 - Apatite-Knife Blade


Luster: Adamantine - Silky

Streak: yellowish brown

Citra SEM mineral magnetik (1)

Huliselan et al., 2010

R-9998 MO-4228



M Brown

KS

KP


Fly ash

Magiera et al., 2011

05. bahan magnetik

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