Viscoelastic Properties and Nanoscale Structures of Composite Oligopeptide-Polysaccharide Hydrogels
Laura L. Hyland, Marc B. Taraban, Yue Feng, Boualem Hammouda, Y. Bruce Yu
The main goal of thermoelectrics research is to optimize the charge and entropy flow separately in order to improve thermoelectric efficiency. Heavily doped semiconductors are good candidates for thermoelectric materials, due to low thermal conductivity from electrons, and good electrical conductivity when doped with carriers. The key task is to find ways to lower thermal conductivity from phonons (lattice thermal conductivity), which is the majority contribution to the thermal conductivity, without degrading electrical conductivity. It has been shown that nanostructures significantly reduce lattice thermal conductivity due to the increase in phonon scattering at interfaces. However, scattering at interfaces can also lower electrical conductivity. Therefore, it is important to study the network of nanoscale microstructures to find the optimal conditions for low thermal conductivity and high electrical conductivity. Here we report on small angle neutron scattering studies on network of microstructures in bulk (Bi,Sb)2Te3 synthesized by the Melt-Spin (MS) method and the Spark-Plasma-Sintering (SPS) process. We find that bulk (Bi,Sb)2Te3 samples with high ZT have lamellar microstructure with thickness of a few nm and smooth interfaces. Compared with physical property measurements, we find that nanoscale microstructures and rough interfaces generated by the MS method are responsible for the reduction of both lattice thermal conductivity and electrical conductivity. We also find that the smoother the interface and the higher the density of nanoscale microstructures both achieved by SPS process, the better the electrical conductivity. Our new finding is that networking of nanoscale microstructures plays a big role in the improvement of electrical conductivity with little change in lattice thermal conductivity.
, Taraban, M.
, Feng, Y.
, Hammouda, B.
and Yu, Y.
Viscoelastic Properties and Nanoscale Structures of Composite Oligopeptide-Polysaccharide Hydrogels, Biopolymers, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=909479
(Accessed December 2, 2023)