Effect of Na2CO3 on hexagonal boron nitride prepared from urea and boric acid |
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Authors: | Hasan Erdem Ç amurlu |
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Affiliation: | Akdeniz University, Mechanical Engineering Department, 07058 Antalya, Turkey |
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Abstract: | Formation of hexagonal boron nitride (hBN) from a precursor obtained by the reaction of urea and boric acid was studied in nitrogen, ammonia and argon atmospheres in 700-1200 °C temperature range. Effect of sodium carbonate (Na2CO3) addition on this process was investigated. Reaction products were subjected to X-ray diffraction, particle size distribution, gravimetric and Fourier transformed infrared spectroscopy analyses. Particle size and crystallite thickness of the formed hBN were seen to increase from about 60 nm and 5 nm at 700 °C to 230 nm and 19 nm at 1200 °C, respectively in NH3 atmosphere with Na2CO3 addition. Highest conversion of boron in the precursor into hBN was achieved as 73.6% when Na2CO3 added precursor was reacted at 1200 °C in NH3. hBN powder with high yield and relatively large particle size was obtained at low temperature such as 1200 °C with Na2CO3 addition. Role of Na2CO3 addition was suggested to be formation of a sodium borate melt from which hBN crystallized via the reaction of borate and nitrogen ions in the melt. Obtained hBN has the potential for utilization as a clean starting material for synthesis of B or N containing compounds. |
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Keywords: | A. Grain growth A. Powders: chemical preparation D. Nitrides D. Hexagonal boron nitride |
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