Introduction:

Dielectric or electrical insulating material are understood as the material in which electrostic field can persist for long times. Layers of such substance are commonly inserted into capacitors to improve their perfomance, and the term dielectric refers specifically to this application.

An electric field polarizes the molecules of dielectric producing concentrations of charge on its surface that create an electric field opposed (antiparallel) to that of capacitor. This reduces the electric potential. Considered in reverse, this means that, with a dielectric, a given electric potential causes the capacitor to accumulate a larger charge.

Description of the experimental set-up

Probes Arrangement

It has two individually spring loaded probes. The probes arrangement is mounted in a suitable stand, which also holds the sample plate. To ensure the correct measurement of sample temperature, the RTD is embedded in the sample plate just below the sample. This stand also serves as the lid of temperature controlled oven. Proper leads are provided for connection to Capacitance Meter and Temperature Controller.

Sample

Barium Titanate (BaTiO3)

Oven

This is a high quality temperature controlled oven. The oven has been designed for fast heating and cooling rates, which enhances the effectiveness of the controller.

Main Units

The Set-up consists of two units housed in the same cabinet.

a) Oven Controller

Platinum RTD (A class) has been used for sensing the temperature.Feedback circuit ensures offset and linearity trimming and a fast accurate control of the oven temperature.

Specifications of the Oven

Temperature Range Ambient to 473K

Oven Specially designed for Dielectric measurement

a) Digital Capacitance Meter

This a compact direct reading instrument for the measurement of capacitance of the sample.

Specifications of the Oven

Range  50-6000pf

Resolution 1pf

Display 3½ digit, 7 segment LED with autopolarity and decimal indication