Dear Anuradha,

the bandstructure of a material changes under hydrostatic pressure. As a consequence, the Fermi level shifts. This can effect the change from p-type to n-type. Therefore the sign of the Seebeck coefficient changes too. The sign of the Seebeck coefficient depends on the conduction type (and at low carrier concentrations on the ratio of the mobilities of holes and electrons).

With Regard

R. Mitdank

Check if there is any phase change (change in the lattice structure). Apparently the bond lengths of cation-cation, anion-cation, and anion-anion could be different under hydrostatic pressure as compared to that of ambient conditions. The cations could be displaced from its equilibrium position creating vacancies. This will alter the orbitals overlapping, and therefore results in different electronic structure of the material.

Dear Anuradha,

the bandstructure of a material changes under hydrostatic pressure. As a consequence, the Fermi level shifts. This can effect the change from p-type to n-type. Therefore the sign of the Seebeck coefficient changes too. The sign of the Seebeck coefficient depends on the conduction type (and at low carrier concentrations on the ratio of the mobilities of holes and electrons).

With Regard

R. Mitdank

thank you Krishnan Raja and Rüdiger Mitdank sir for your reply.

I agree with the Dr. Rudiger Mitdank explanation.