Refinement of β-Si₃N₄ Single Crystal Grown from Silicon Melt

Abstract

Silicon powder in a reaction-sintered silicon nitride crucible was heated at 1600°C in a nitrogen atomosphere. Clustered β-Si₃N₄ single crystals were obtained in residual silicon metal after cooling. The silicon residuals were dissolved by chemical purification using a mixture of aqueous HF and HNO₃, and subsequently treated and with H₂SO₄. Scanning electron microscopy observation showed that large β-Si₃N₄ crystals without Si residuals could be successfully separated by this process.