Liquid-phase driven growth of ultralong, flexible AlN whiskers

Abstract

Heat dissipation ceramic materials, with high thermal conductivity and temperature resistance, are vital for vast domains such as electronic packaging, aerospace, and the automotive industry. However, the polycrystalline or amorphous structures and discrete particles of ceramic materials degrade their thermal performance, limiting their effectiveness in advanced heat dissipation applications. Here, a liquid-phase driven growth strategy is employed to construct monocrystalline AlN whiskers with a defect-free hexagonal wurtzite structure, achieving remarkable thermal conductivity and flexibility. Specifically, by generating Fe alloy droplets at the tip of the whiskers, the whiskers are induced to grow fixedly along the [001] direction. The directional growth significantly enhances the length and flexibility of AlN whiskers. At a stable temperature and pressure, the liquid phase effectively balances the local supersaturation, resulting in a smooth and defect-free surface for the grown whiskers. This study elucidates a novel and effective strategy for developing ultralong and flexible monocrystalline AlN whiskers.