A miniature capacitance dilatometer for thermal expansion and magnetostriction

Abstract

A very small capacitive sensor for measuring thermal expansion and magnetostriction of small and irregular shaped samples has been developed. A capacitive method with tilted plates is used. The tilted plate capacitance formula is used for the calculation of the capacitor gap, the calibration is performed by measuring the signal of a standard material. The active length of the sample can be less than 1 mm. The absolute resolution is about 1 Å. All mechanical connections of the dilatometer are carried out by tiny CuBe springs, enabling the small force on the sample to be adjusted ͑50-500 mN͒ and no additional sample fixing is necessary. The cell has been tested in the temperature range 0.3-200 K and in static magnetic fields up to 15 T. The zero signal of the dilatometer has been determined by measuring a silver sample. The correct operation and reproducibility has been verified by measuring the thermal expansion of Cu. The thermal expansion and magnetostriction of a DyCu 2 single crystal has been determined. The advantage of this method compared to specific heat measurements is that a large temperature range can be covered with one equipment. This high static and dynamic range of sample length, temperature, and magnetic field suggests a number of possible applications, like the investigation of crystal field effects on the magnetoelastic properties of single crystals or structural phase transitions.

Doping effects on trimerization and magnetoelectric coupling of single crystal multiferroic (Y,Lu)MnO3

“…In our final calibration test, we achieved a resolution of 1.7 Å at 4 K, similar to that reported in Ref. 27. The thermal expansion coefficients measurement was performed by a three-terminal method from 10 to 300 K with a capacitance bridge (2500A, Andeen Hagering) by putting the whole set-up inside a commercial cryostat (PPMS9, Quantum Design).…”

“…A major differences between our design and that of Ref. 27 are the facts that our capacitance cell was made of oxygen-free high conductivity (OFHC) copper instead of silver used in Ref. 27 and also was machined to be all-in-one type capacitance cell and electrical shield ring for samples.…”

“…27 are the facts that our capacitance cell was made of oxygen-free high conductivity (OFHC) copper instead of silver used in Ref. 27 and also was machined to be all-in-one type capacitance cell and electrical shield ring for samples. In our final calibration test, we achieved a resolution of 1.7 Å at 4 K, similar to that reported in Ref.…”

Versatile and compact capacitive dilatometer

“…Researchers considering a capacitive dilatometer design should consult the papers by Pott and Schefzyk [3], Swenson [4], and Rotter et al [5] for recent discussions of the history and capabilities of this approach to dilatometry and for details of capacitive dilatometer design (both in the papers themselves and the extensive references therein). The principle difference between our design and those described in the references above is in the open architecture of the sample mounting arrangement which permits a wide range of sample shapes and sizes as well as the ability to observe and (to a limited degree) adjust the orientation of the sample in the dilatometer.…”

Construção de um transdutor quase-estatíco de tensão mecânica em propriedades magnéticas, aplicado a Liga (Fe0,8Al0,2)98.B2

“…STT CTT tensões é essencial para determinar o real potencial dos materiais estudados na fabricação de sensores e consequentemente, possibilita o estudo e construção de dispositivos sensoriais no futuro [5] .…”