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.