Extremely low thermal conductivity of β -Ga2O3with porous structure

Abstract

Due to the ultrawide bandgap (4.9 eV), high carrier mobility (300 cm 2 V - 1 s - 1), and high thermal stability, β - Ga 2 O 3 can be a potential candidate for high-temperature thermoelectric materials. However, the intrinsically high thermal conductivity may hinder its application for thermoelectric conversion. In this work, porous β - Ga 2 O 3 was prepared by the solvothermal method together with spark plasma sintering technology. Positron lifetime measurement and N 2 adsorption confirm the introduction of pores by adding sucrose in the sample preparation. The sucrose-derived β - Ga 2 O 3 sintered at a relatively low temperature of 600 °C remains highly porous, which results in an extremely low thermal conductivity of 0.45 W m - 1 K - 1 at room temperature, and it further decreases to 0.29 W m - 1 K - 1 at 600 °C. This is the lowest thermal conductivity for β - Ga 2 O 3 reported so far. Our work provides an avenue to reduce the thermal conductivity for β - Ga 2 O 3 and is believed to be widely applicable to many other thermoelectric materials.