Radiation-induced thermal conductivity degradation in LiAlO₂ and LiAl₅O₈ investigated by molecular dynamics

Radiation damage in lithium ceramic materials can severely degrade thermal transport properties, limiting their performance in nuclear environments such as tritium-producing burnable absorber rods (TPBARs). This study compares the intrinsic thermal conductivity degradation in single crystals of LiAlO₂ and LiAl₅O₈ due to radiation-induced point defects. LiAlO₂ shows a significant drop in thermal conductivity of up to 75% under increasing defect concentration and temperature, while LiAl₅O₈ retains over 50% of its thermal conductivity, even at high defect levels and elevated temperatures. The greater resilience of LiAl₅O₈ is attributed to its structural resilience, which suppresses defect generation and preserves phonon transport. Partial phonon density of states analysis reveals that Li and Al vacancies strongly suppress vibrational modes in LiAlO₂, while LiAl₅O₈ shows minimal change, supporting its superior radiation tolerance. These results suggest LiAl₅O₈ to be a more durable candidate for high-temperature radiation environments.