Thermal conductivity of β-SiAlONs prepared by a combination of combustion synthesis and spark plasma sintering

• We measured the thermal conductivity of CS-SPSed β-SiAlON for the first time.
• The highest thermal conductivity of 9.45 W m−1 K−1 was obtained when z = 1 at room temperature.
• Both thermal diffusivity and thermal conductivity decreased with an increase in the z value.
• In the β-Si6−zAlzOzN8−z system, the defects cause phonon scattering, accordingly reduce the thermal conductivity.

β-Si6−zAlzOzN8−zs (z = 1–3) have been synthesized by combustion synthesis (CS) and the as-received powders were densified by spark plasma sintering (SPS). The thermal properties of the dense β-SiAlONs have been investigated by the laser-flash method from room temperature to a high temperature of 800 °C. The highest thermal conductivity of 9.45 W m−1 K−1 was obtained when z = 1 at room temperature. Both thermal diffusivity and thermal conductivity decreased with an increase in the z value. In the β-Si6−zAlzOzN8−z, with z value increasing, more Si4+ and N3− ions get replaced by Al3+ and O2− ions, thereby more lattice defects are formed. These defects cause phonon scattering, accordingly reduce the thermal conductivity.