Synthesis of AlB12 and YB66 Nanoparticles by RF Thermal Plasmas

Boron-rich compounds of AlB12 and YB66 nanoparticles were synthesized in radio frequency (RF) thermal plasmas. Yttrium tetraboride or aluminium powders with 10 μm in diameter and boron powder with 45 μm in diameter were evaporated in the high temperature region of the thermal plasma, and then metal boride nanoparticles were formed in the tail region of the plasma with rapid quenching. Boron-rich compounds were identified by X-ray diffractometry in the product. Polyhedral shaped nanoparticles about 20 nm in size were measured in Al-B system by transmission electron microscopy, while YB66 particles about 50 nm in size were cubic in morphology. The composition of raw powder and the input power of RF thermal plasma were controlled to enhance the content of boron-rich metal borides in as-prepared nanoparticles. Since boron has very high melting point and evaporation temperature, high boron content in the raw powder and high input plasma power were preferable to synthesize AlB12 and YB66 nanoparticles.