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bahan magnetik
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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
Composition: Molecular Weight = 159.69 gm
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
Luminescence: Non-fluorescent.
Luster: Metallic
Magnetism: Magnetic after heating
Streak: reddish brown
Maghemite
Chemical
Formula: gamma-Fe+++2O3
Composition: Molecular Weight = 159.69 gm
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)
Composition: Molecular Weight = 88.85 gm
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
Luminescence: Non-fluorescent.
Luster: Adamantine - Silky
Streak: yellowish brown
Citra SEM mineral magnetik (1)
Huliselan et al., 2010
R-9998 MO-4228
Citra SEM mineral magnetik (2)
Citra SEM mineral magnetik (3)
M Brown
KS
KP
Citra SEM mineral magnetik (4)
Fly ash
Magiera et al., 2011