A composite high-pressure cell with sintered diamond insets for study of thermoelectric and thermomagnetic properties in a range up to 30 GPa: Application to Pr and PbTe

A composite high-pressure cell with the sintered diamond insets is reported to be an effective tool for investigation of transport properties of solids under pressure as high as ∼30 GPa. The temperature distribution inside the cell was calculated. Using this cell, the pressure-driven phase transitions in praseodymium (Pr) have been studied by the thermopower technique (Seebeck effect). The results have shown that a scenario of the phase transitions in Pr (existence of the monoclinic C2/m phase) crucially depends on defects and distortions in a crystal lattice. So, the monoclinic phase was noticeable only for the first pressurization cycle. A technique of measurement of the longitudinal and the transverse thermomagnetic Nernst–Ettingshausen (N–E) effects (magnetothermopower) under high P is explained. With an example of lead telluride (PbTe), it is demonstrated that magnetic field can significantly improve the thermoelectric efficiency under pressure. The merits of the cell developed are discussed concerning basic research and technologies.