Speaker
Description
Severe plastic deformation processes are an excellent way to attain grain refinements and introduce dislocations in the material without compromising on the dimensions of the sample and high-pressure torsion (HPT) is a prime example of a severe plastic deformation process. In this work, HPT processing is employed to introduce a dense network of dislocation structures in BiCuSeO and subsequently using hot-pressing (HP) as a recovery sintering mechanism to minimize crack and fracture in the ceramic thereby increasing the mechanical integrity while retaining the effects of the HPT. This methodology was represented as HPT-HP process. The effect of pressure and strain from the HPT-HP processing results in a reduction in the bandgap of the material BiCuSeO from 0.83 eV (HP) to 0.74 eV (HPT-HP1). The best HPT-HP condition was then taken forward for Pb-substitution to achieve a similar effect. The shear deformation from the HPT creates increased levels of dislocation density of about 5.02 x 10^(16) m^(-2) in HPT-HP Bi0.94Pb0.06Cu0.97SeO sample. These dislocations along with their corresponding lattice strains reduce the lattice part of thermal conductivity to a low 0.36 W/mK at 823 K while simultaneously having the reduced bandgap effect and positively observing 145.5 S/cm electrical conductivity in the HPT-HP Bi0.94Pb0.06Cu0.97SeO sample, resulting in a zT of 1.11.
| Professional Status of the Speaker | Doctoral or Master Student |
|---|---|
| Invitation letter for visa | Yes |
| Interest in submitting a paper in a special issue of | No interest |
