Engineering of thermal conductivity in functional materials using chemical doping and nanoparticle additives

The intrinsic ability of solid materials to conduct heat is called thermal conductivity (and here is denoted by the symbol κ). It is essential to control the thermal conductivity in functional materials wherever heat transfer plays a key role, such as in thermoelectric devices, "thermal interface" materials for heat management in electronics, biomedical implants and personal protective equipment. Techniques are needed to tailor the thermal conductivity for specific applications. For example, thermoelectric devices require lower thermal conductivity to maximise their efficiency. Such devices offer a way to capture approximately 60-70% of the energy that is converted into unused heat as a secondary by-product of many technological and industrial processes. Consequently, methods to control thermal conductivity are important to improve thermo-electronic devices' efficiency. This thesis focuses on controlling thermal conductivity using chemical doping methods, including embedding a secondary phase of nanoparticles into a primary phase to form a so-called nanocomposite. In this thesis, the laser flash analysis technique was applied as the principal method to understand the thermal transport behaviour among the fabricated materials.