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Molten salt synthesis of highly ordered and nanostructured hexagonal boron nitride
摘要： Hexagonal boron nitride (h-BN) is a well-known ceramic that has wide application areas ranging from electronics to metallurgy. However, highly ordered h-BN is conventionally synthesized at high temperatures above 1800 °C. In this work, we investigated the formation of BN from boric acid (H3BO3)-ammonium chloride (NH4Cl) mixture in the sodium chloride (NaCl)-potassium chloride (KCl) eutectic salt. We report the synthesis of highly ordered and nanostructured h-BN at 1000 °C using molten salt synthesis. The effect of starting composition, synthesis temperature, and dwell time on BN formation and its structural ordering were systematically investigated. It is concluded that the molten salt plays important roles in the formation of BN and its structural ordering, which is achieved by i) decomposing the boron (B)-nitrogen (N) bearing reactants that lead to the formation of BN layers, and ii) increasing the mobility of BN layers formed. Furthermore, we propose a possible reaction mechanism that governs the BN formation from the reactant mixture in molten salts and explain the observations based on thermodynamic and kinetic considerations.
关键词： Molten salt synthesis,NaCl-KCl eutectic salt,Boron nitride,Structural ordering,High-resolution transmission electron microscopy
更新于2025-11-21 11:01:37
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Nondestructive nanofabrication on monocrystalline silicon via site-controlled formation and removal of oxide mask
摘要： A nondestructively patterned silicon substrate serves as an ideal support for forming high-quality optical structures or devices. A new approach was proposed for fabricating site-controlled structures without destruction on a monocrystalline silicon surface via local anodic oxidation (LAO) and two-step postetching. The nondestruction was demonstrated by conductivity detection with conductive atomic force microscopy (AFM), and an almost perfect crystal lattice was observed from the fabricated hillock by high-resolution transmission electron microscopy (HRTEM). By programming AFM tip traces for LAO processing, site-controlled nondestructive patterns with di?erent layouts can be produced. This approach provides a new route for realizing nondestructive optical substrates.
关键词： conductive atomic force microscopy,high-resolution transmission electron microscopy,local anodic oxidation,nondestructive nanofabrication,monocrystalline silicon
更新于2025-11-14 17:04:02