New acoustic detection technique for a magnetocaloric effect

Otowski, W.; Glorieux, Christ; Hofman, R; Thoen, Jan

doi:10.1016/0040-6031(93)80416-8

Cited by 16 publications

(10 citation statements)

References 11 publications

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“…An example of the latter is to measure the temperature through acoustic detection of the temperature change. Otowski et al developed an experimental setup where a sample is placed in a small, gas tight cell and subjected to a periodically changing magnetic field 138. This field consists of a base field and a harmonic amplitude variation, much smaller than the base field.…”

Section: Characterization Methodsmentioning

confidence: 99%

“…Such a thermoacoustic setup has been used to measure the adiabatic temperature change for various forms of Gd. [138][139][140] Christensen et al describe an alternative indirect approach where an IR camera is used to detect the temperature of a Gd plate which is quickly removed from the gap of a Halbach cylinder. [ 141 ] This allows the adiabatic temperature change to be spatially resolved across the sample.…”

Section: Magnetization Measurementsmentioning

confidence: 99%

“…Otowski et al developed an experimental setup where a sample is placed in a small, gas tight cell and subjected to a periodically changing magnetic fi eld. [ 138 ] This fi eld consists of a base fi eld and a harmonic amplitude variation, much smaller than the base fi eld. The frequencies of the modulation are of the order of 1-10 Hz.…”

Section: Magnetization Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Materials Challenges for High Performance Magnetocaloric Refrigeration Devices

Smith

Bahl

Bjørk

et al. 2012

Advanced Energy Materials

504

262

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Magnetocaloric materials with a Curie temperature near room temperature have attracted significant interest for some time due to their possible application for high‐efficiency refrigeration devices. This review focuses on a number of key issues of relevance for the characterization, performance and implementation of such materials in actual devices. The phenomenology and fundamental thermodynamics of magnetocaloric materials is discussed, as well as the hysteresis behavior often found in first‐order materials. A number of theoretical and experimental approaches and their implications are reviewed. The question of how to evaluate the suitability of a given material for use in a magnetocaloric device is covered in some detail, including a critical assessment of a number of common performance metrics. Of particular interest is which non‐magnetocaloric properties need to be considered in this connection. An overview of several important materials classes is given before considering the performance of materials in actual devices. Finally, an outlook on further developments is presented.

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Section: Characterization Methodsmentioning

confidence: 99%

Section: Magnetization Measurementsmentioning

confidence: 99%

Section: Magnetization Measurementsmentioning

confidence: 99%

See 1 more Smart Citation

Materials Challenges for High Performance Magnetocaloric Refrigeration Devices

Smith

Bahl

Bjørk

et al. 2012

Advanced Energy Materials

504

262

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“…Furthermore, a noncontact technique is even more important for this purpose. The acoustic detection of the MCE accomplishes these desirable characteristics and it was first proposed by Otowski et al 6 in 1993. It is similar to the photoacoustic technique, with the thermal wave being generated by the adiabatic application of a modulated magnetic field superimposed to a static one.…”

Section: Introductionmentioning

confidence: 99%

Acoustic detection of the magnetocaloric effect: Application to Gd andGd5.09Ge2.03Si1.88

et al. 2009

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In this paper we present a simple method for the determination of the total magnetocaloric effect based on the acoustic detection of the adiabatic temperature rise caused by the application of an ac magnetic field of small amplitude. The continuous scanning of a superimposed dc magnetic field allows, by numerical integration, the determination of large temperature variations caused by magnetic field steps from zero to tens of kOe. Absolute values of temperature rise are easily acquired after the calibration of the microphone signal using an appropriate reference sample. Once the calibration is done, no further information about the sample's thermal properties is necessary since the measured signal is directly proportional to the temperature variation. Measurements were made in Gd and Gd 5.09 Ge 2.03 Si 1.88 samples in the temperature range from 240 to 320 K. The technique shows to be suitable for the investigation of materials undergoing both purely magnetic phase transitions, as in the case of Gd, and magnetic-crystallographic first-order ones, as observed for Gd 5.09 Ge 2.03 Si 1.88 . Besides the ability to determine the temperature variation due to a large magnetic field step through the continuous scanning of the magnetic field, the technique is also very suitable for measuring the magnetocaloric effect under very small magnetic field steps since it has sensitivity below millikelvin. Moreover, it is able to detect temperature variations in very small amount of sample, leading to its potential application in magnetocaloric thin films.

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“…Photoacoustic-like detection schemes have been demonstrated to give a temperature resolution of the order of 5 lK and were used to study, e.g., bulk samples of Gd (Ref. 4) and Gd-Ge-Si. 5 Only recently, the first claim of a magnetocaloric measurement on a 3 lm thick Gd thin film was made using acoustic detection.…”

Section: @T @Hmentioning

confidence: 99%

Temperature dependent low-field measurements of the magnetocaloric ΔT with sub-mK resolution in small volume and thin film samples

Döntgen

Rudolph

Gottschall

et al. 2015

Applied Physics Letters

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We present temperature dependent ΔT measurements of the magnetocaloric effect in a thin film sample of Gd, employing magnetomodulation and detection of thermal radiation. A bulk sample of the metamagnetic material LaFe11.05Co0.91Si1.04 shows a strong broadening of the ΔT peak for increasing field amplitudes between 4 and 45 mT. Bulk Gd in comparison shows only a weak broadening. All investigated samples exhibit a clear quadratic dependence of ΔT on the external field Hext at the ΔT peak maximum, contrary to earlier predictions. An analytic expression is derived that interpolates between the Hext2-behavior at low and the well-known Hext2/3-behavior at high fields.

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New acoustic detection technique for a magnetocaloric effect

Cited by 16 publications

References 11 publications

Materials Challenges for High Performance Magnetocaloric Refrigeration Devices

Materials Challenges for High Performance Magnetocaloric Refrigeration Devices

Acoustic detection of the magnetocaloric effect: Application to Gd andGd5.09Ge2.03Si1.88

Temperature dependent low-field measurements of the magnetocaloric ΔT with sub-mK resolution in small volume and thin film samples

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