Size Measurement and Classification of Ultrafine Refractory Metal Particles Produced by Laser Irradiation

Refractory metal ultrafine particles were synthesized by the irradiation of two synchronized-pulse Nd: YAG lasers on a refractory metal substrate in a low pressure inert gas atmosphere. A size distribution of the refractory metal ultrafine particles was measured by a low pressure differential mobility analyzer (LP-DMA) developed by ourselves for each pressure condition. The experimental results showed the peak of the size distribution was shifted from the several nm to the tens of nm level with increasing the pressure. The ultrafine particles of a 10 nm-size (σg=1.12) were precisely classified by the LP-DMA. We could control the shape of the particles from agglomeration condition to spherical one by using an electric furnace. In conclusion, the size classification of narrow distribution and the shape of the generated ultrafine particles could be well controlled.