Three Terminal Capacitive Dilatometer
We designed Three Terminal Capacitance Dilalatometer (h=32mm, w=21mm) for low temperature thermal expansion measurements. Our data includes the measurement of themperature dependant capaitance and the conversion of capacitance to equivalent length change of the sample. The Dilatometer is tested by measuring the samples with known thermal expansion and compared with reported literature. The fractional length change data measured using our modified Dilatometer is in good agreement with reported one. Moreover, our design eliminate the use of kapton foil in the cell that contributes non-linearly to the thermal expansion and also does not require the use of an adhesive like Stycast which tends to crack after thermal cycling resulting in an electrical short between the capacitor plates and the cell body. We have used Alumina washers for providing insulation between the plates and the cell body.
Steps to reproduce
For reproducing data, we firstly designed Three Terminal Capacitance Dilatometer. The Dilatometer with sample installed is then mounted inside the cryostate to achieved liquid nitrogen temperature. We, then measured temperature dependent capacitance using Capacitance Bridge by varying the temperature at 0.5k/min interval using Temperature Contoller. Once, measured data obtained, the temperature depandent capacitance is then converted into the equivalent length change of sample using appoprite mathematical expressions. To test the Dilatometer, we calculated the fractional length chage of the sample and compared the fractional length change copper (as the Dilatometer is made of Copper) available in the literature.Further, we used Originlab software for data anlysis.