I am familiar with the TSD testing of polymers only, but I assume that the principle is the same for any material. We used disc-like samples of about 4 cm diameter with evaporated electrodes, using gurad ring. Sample thickness was about 1 mm, the voltage was in the order of 1 kV and we used programmed heating and cooling, the current was detected by a picoammeter, lograithmic amplifier can also be used. the question is whether you can prepare such samples from your ceramic samples.