Abstract
We synthesized AlN using aluminium chloride hexahydrate and urea as the starting materials. By directly introducing aluminium chloride into melted urea at 135°C, a urea-precursor was formed under non-aqueous conditions with no γ-Al2O3 observed in any calcination steps. As a result, well-crystalline AlN powder was obtained by the pyrolysis of urea-precursor above 900°C under a stream of N2 gas for 1hour. In this process the urea-precursor decomposed below 400°C, and an AlN skeleton with a layer structure formed above 800°C. The total yield of AlN powder based on the Al atom was only 80% due to production of volatile Al(NH3)6AlH4Cl2 as a by-product. The AlN powder was characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy (SEM). Morphological observation of the AlN powder by mean of SEM revealed large particles of about 30-μm diameter, which consisted of ultrafine particles of less than 1-μm diameter.
Original language | English |
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Pages (from-to) | 53-58 |
Number of pages | 6 |
Journal | Key Engineering Materials |
Volume | 159-160 |
Publication status | Published - 1999 Jan 1 |
Keywords
- AlN Powder
- AlN Skeleton
- Ultrafine Particles
- Urea-Precursor
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering