Grain boundary and defects assisted thermal conductivity of nano-crystalline Gd2Ti2O7 Pyrochlore

TL;DR

This study investigates how grain boundaries, porosity, and structural defects influence the thermal conductivity of nanocrystalline Gd2Ti2O7 pyrochlore, revealing mechanisms that reduce heat transfer for potential thermal barrier applications.

Contribution

It provides a detailed analysis of the effects of microstructural features on thermal conductivity in nanocrystalline Gd2Ti2O7, highlighting boundary and defect scattering mechanisms.

Findings

Thermal conductivity decreases with smaller grain size due to phonon-pore scattering.

Boundary scattering dominates thermal transmission at higher temperatures.

Measured thermal conductivities meet requirements for thermal barrier coatings.

Abstract

The thermal conductivity study on the pyrochlore structured ceramics is important for utilization of these materials as an inert matrix fuel, electrolytes for oxide fuel cell and thermal barrier coating. The impact of porosity, structural defects and boundary scattering on thermal properties of the nanocrystalline Gd2Ti2O7 fabricated by spark plasma sintering followed by high energy ball milling has been investigated. The thermal conductivity has been measured in the temperature range from room temperature to 900 C using laser flash apparatus (LFA), and results were discussed by including several phenomena contributing to the thermal transmission in nc-pyrochlore in support of the scattering mechanism. A systematic decrease in thermal conductivity with reducing grain size can be understood by the phonon-pore scattering phenomenon. Furthermore, dominate of the boundary scattering on the thermal transmission with the increasing temperature is also observed. The experimentally determined values of thermal conductivity are compatible with the thermal insulation requirements for thermal barrier coating (TBC) applications