Characterisation of magnetic pigment dispersions using pulsed magnetic fields

Hancock, Chris; Greaves, S.J.; O’Grady, K.; Williams, Robert G.; Owens, A.R.

doi:10.1109/20.539255

Cited by 6 publications

(2 citation statements)

References 6 publications

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“…Measurements have also been carried out using the PFM with the results presented in form of isothermal magnetization (IRM) curves [37,38], which have previously been used by Mayo et al [35,36] as a tool to assess the quality of MP dispersions using a VSM and a 50 Hz B-H loop tracer. The conclusion from this work was that it is possible to monitor the reduction in aggregate size with milling time and this can be used to estimate the dispersion quality.…”

Section: Resultsmentioning

confidence: 99%

“…The conclusion from this work was that it is possible to monitor the reduction in aggregate size with milling time and this can be used to estimate the dispersion quality. Recent work has been carried out using the PFM to measure the IRM curves for γ -Fe 2 O 3 and CrO 2 dispersions and comparisons were made with VSM measurements [29,37]. Other published work using the instrument includes measurements on waterand organic-based dispersions of γ -Fe 2 O 3 where the PFM measurements were compared with those made at low temperature using a VSM [38].…”

Section: Resultsmentioning

confidence: 99%

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A pulsed field magnetometer for analysing the properties of magnetic pigment dispersions used in particulate recording media

Hancock

Owens

Williams

1998

Meas. Sci. Technol.

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We have designed and developed a pulsed field magnetometer to measure the dynamic properties of magnetic dispersions commonly used in recording media. The instrument produces well defined single-shot field pulses of variable amplitude from 10 Oe to 1270 Oe, adjustable in steps of 10 Oe. Pulse widths of between and can be selected with a resolution of . The rise and fall times of the pulses are between and and are symmetrical throughout the range of field amplitudes and pulse widths. Results obtained from the instrument indicate that it is possible to distinguish between inherent particle switching and physical particle rotation, which is not possible when using conventional AC and DC magnetometers. It has also been found that the instrument may be used in on-line measurements to access the quality of magnetic pigment dispersions used for magnetic tape manufacture.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A pulsed field magnetometer for analysing the properties of magnetic pigment dispersions used in particulate recording media

Hancock

Owens

Williams

1998

Meas. Sci. Technol.

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The characterisation of magnetic pigment dispersions using pulsed magnetic fields

Blackwell

O’Grady

Nelson

et al. 2003

Journal of Magnetism and Magnetic Materials

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Cluster demagnetizing effects in particulate dispersions

Blackwell

O’Grady

Verdes

et al. 2002

Journal of Applied Physics

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We describe a study of a dispersion of metal pigments. We have used a high field pulsed magnetometer to examine the acquisition of remanence and have observed anomalous behavior as a function of both the magnitude of the pulsed field and its duration. The remanence increases monotonically until a critical field or a critical time is reached and then suddenly decreases at a highly reproducible value of field, and then subsequently increases when a larger pulsed field is applied. At very high fields a second drop in remanence is observed. By comparison with a computer simulation we infer that this behavior may arise due to strong demagnetising dipolar interactions in aggregates of a certain critical size.

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Characterisation of magnetic pigment dispersions using pulsed magnetic fields

Cited by 6 publications

References 6 publications

A pulsed field magnetometer for analysing the properties of magnetic pigment dispersions used in particulate recording media

A pulsed field magnetometer for analysing the properties of magnetic pigment dispersions used in particulate recording media

The characterisation of magnetic pigment dispersions using pulsed magnetic fields

Cluster demagnetizing effects in particulate dispersions

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