On Inhomogeneities in the Magnetization of Ferromagnetic Materials

Bitter, Francis

doi:10.1103/physrev.38.1903

Cited by 315 publications

(94 citation statements)

References 2 publications

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“…Monoclinic and hexagonal pyrrhotites were distinguished by applying a thin layer of ferrofluid, which is attracted by the magnetic grains in the samples (Bitter, 1931). The ferrofluid method reveals inhomogeneities in magnetic particles such as those caused by the exsolution of lamellae or shows domain structures in magnetic pyrrhotite grains.…”

Section: Methodsmentioning

confidence: 99%

“…According to Bin and Pauthenet (1963), crystal anisotropy is high. Soffel (1977Soffel ( ,1981 investigated the domain structure of natural fine-grained pyrrhotite in a diabase using the Bitter pattern technique (Bitter, 1931). Extrapolation of the empirical relationship between grain size and the number of domains yields a value of 1.6 µm for the critical single-domain to two-domain transition.…”

Section: Introductionmentioning

confidence: 99%

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Rock Magnetic Properties of Hydrothermally Formed Iron Sulfides from Middle Valley, Juan de Fuca Ridge

Körner¹

1994

Proceedings of the Ocean Drilling Program, 139 Scientific Results

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Hydrothermally formed sulfide samples recovered from the Juan de Fuca Ridge during Ocean Drilling Program Leg 139 were investigated to determine the carrier of remanent magnetization and to study rock magnetic properties. The samples were examined by isothermal remanent magnetization acquisition, alternating field demagnetization, back field measurements, thermomagnetic and hysteresis measurements, X-ray diffraction, and ore microscopy. Grain sizes for magnetite and pyrrhotite particles were estimated from hysteresis parameters on samples containing only one magnetic phase. Magnetomineralogical analyses made on whole-rock samples show that massive sulfides recovered from Holes 856G and 856H are composed predominantly of pyrite, pyrrhotite, magnetite, and minor amounts of sphalerite and chalcopyrite. Magnetite together with two types of pyrrhotite determines the magnetic properties of these rock samples. The first type of pyrrhotite is ferrimagnetic up to 320°C. X-ray diffraction data are in good agreement with those for monoclinic pyrrhotite. The second type of pyrrhotite is antiferromagnetic at room temperature and ferrimagnetic between 200°C and 270°C. X-ray diffraction data show typical peaks for hexagonal pyrrhotite. Thermomagnetic analyses indicate that samples from Hole 856G contain mainly magnetite, whereas parameters from Hole 856H were also influenced by pyrrhotite. Pyrrhotite and magnetite were distinguished by the large J rs /J s and the small B cr /B c ratios for pyrrhotite compared with those for magnetite, and through direct methods such as ore microscopy and X-ray diffraction.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rock Magnetic Properties of Hydrothermally Formed Iron Sulfides from Middle Valley, Juan de Fuca Ridge

Körner¹

1994

Proceedings of the Ocean Drilling Program, 139 Scientific Results

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“…Экспериментальное доказательство существования доменов и вы-яснение их роли в намагничении ферромагнетиков было проведено в класси-ческих экспериментах Баркгаузена 6 , Биттера 7 , Акулова и Дехтяря 8 , Сикстуса и Тонкса 9 . Детальное исследование доменов и ДГ долгое время сдерживалось отсутствием качественных магнитоупорядоченных кристаллов (в дальнейшем -магнетиков) и сложностью доменной структуры массивных образцов.…”

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Dynamics of domain walls in weak ferromagnets

Baryakhtar¹,

Иванов²,

Chetkin³

1985

Uspekhi Fizicheskikh Nauk

116

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“…Numerous references exist reporting the experimental observation of domain structure and behaviour by using a variety of techniques. Examples of different techniques can be found in Bitter (1931), Parpia, Tanner and Lord (1983), and Hetherington, Jakubovics, Szpunar and Tanner (1987). Excellent treatments of the whole subject of ferromagnetic domains are given by Kittel (1949) and Craik and Tebble (1965).…”

Section: Magnetic Domainsmentioning

confidence: 99%

The physical properties of magnetic inks

1993

NDT & E International

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. {Philip Larkin, Nursery Tale) IV AbstractThe magnetic particle inspection (MPI) method is a widely used non destructive testing (NDT) technique for ferrous structures. Magnetic inks used in MPI are suspensions of fine ferro/ferrimagnetic particles which, when applied to a magnetized test specimen, deUneate surface flaws. This work is an investigation of some of the properties of magnetic ink systems and some aspects of their interaction with defect leakage flux. Reviews of magnetism, the MPI method and leakage flux at defects are given. The construction, characterization and automation of a 1.2 T electromagnet vibrating sample magnetometer, used for magnetic measurements on the inks, is described. The instrument has a resolution of better than 10"'^ JT~^ A 20 model of indication formation in MPI, based upon the simulation of many particles in the neighbourhood of a defect, is presented. Results of the role of several of the model parameters are given. Results indicate that carrier coefficients of viscosity at the lower end of the range investigated (r/ = 0.3 mPas) are optimum. The size and contrast of an indication increases with defect size. The contrast and rate of formation of contrast increase with defect aspect ratio. The effect of the contrast paint layer thickness indicates that the recommendation of the British Standard, BS 5044 (1973), is qualitatively correct. Experimental observations of particles in field gradients reveals a discrepancy between theoretical and observed behaviour which is attributed, in particular, to unobservable voids in the particles. Detailed characterization of the particles shows them to be aggregates of 20 -200 nm crystallites which are probably single domain particles. The morphology of larger aggregates is related to measurements of the low field susceptibility Evidence from intensive magnetic measurements supports the relationship between magnetic properties and aggregate characteristics. A 'Int' magnetic viscosity effect is reported. At 77 K, the coeflScient of magnetic viscosity has a maximum near the coercivity field. A cknowledgementsIt is my privilege to acknowledge the assistance and support given to me by many people during the course of this work.

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On Inhomogeneities in the Magnetization of Ferromagnetic Materials

Cited by 315 publications

References 2 publications

Rock Magnetic Properties of Hydrothermally Formed Iron Sulfides from Middle Valley, Juan de Fuca Ridge

Rock Magnetic Properties of Hydrothermally Formed Iron Sulfides from Middle Valley, Juan de Fuca Ridge

Dynamics of domain walls in weak ferromagnets

The physical properties of magnetic inks

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