Low temperature Seebeck coefficient measurement: Possible sources of uncertainty and spurious emf

In the present work we have addressed the possible sources of uncertainty and spurious emf in the low temperature Seebeck coefficient measurement (dc method) from 77 to 300 K in an apparatus based on copper block sandwich type design using a YBCO high temperature superconducting sample. Two identical differential copper-constantan thermocouples were used under different conditions for gradient measurement. Similarly, two identical pairs of signal leads (Copper) were used to measure the signal across the sample. A systematic comparison has been made by comparing the values of gradient and signal measured across the thermocouples and signal leads, which were connected/mounted under different methods and techniques. Besides, measurements were performed under different methods like slow cool down, cool down in an exchange gas atmosphere, natural warm-up, steady state cool down etc and a comparison has been made.