文献类型：期刊文献

英文题名：Synthesis of high-purity α-Si3N4 nanopowders and their morphological evolution process using chloride as additives

作者：Wang, Yan[1];Zhang, Jingmei[1];Wang, Deqiang[1];Wang, Zeyu[1];Wang, Hao[1];Gu, Jinlou[1]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai 200237, Peoples R China

年份：2025

卷号：51

期号：22

起止页码：36095

外文期刊名：CERAMICS INTERNATIONAL

收录：;EI(收录号：20252218502594);WOS:【SCI-EXPANDED(收录号:WOS:001560539800044)】；

语种：英文

外文关键词：Spherical nanopowders; Sol-gel processes; Phase transformation; Grain growth; Morphology control

摘要：Near-spherical alpha-Si3N4 nanopowders are considered as favorable raw materials for the preparation of highperformance Si3N4 ceramics. However, the synthesis of alpha-Si3N4 nanopowders faces challenges such as low alpha-phase content, uncontrollable particle morphology, and complex preparation processes. To achieve the objective of synthesizing Si3N4 nanopowders with well-defined morphology and high alpha-phase content through an efficient and cost-effective approach. This work demonstrated the synthesis of high-alpha-phase Si3N4 nanopowders (98 wt% alpha-phase content at 1475 degrees C) through a carbothermal reduction and nitridation using tetraethyl orthosilicate and glucose precursors with dual additives (MgCl2/YCl3). The resultant near-spherical nanopowders exhibited a uniform nanoscale morphology (mean diameter: 35 nm) while maintaining exceptional phase purity. This study demonstrated that in situ-generated oxides from halide compounds form eutectic liquid phases with SiO2, which promoted both Si3N4 synthesis and phase transformation. The viscosity differential within these liquid phases further caused the divergent catalytic efficacy of different additives. The study further revealed that the morphological evolution of near-spherical alpha-Si3N4 nanopowders into hexagonal prism crystals was primarily governed by the reaction temperature. This study synthesized high-purity near-spherical alpha-Si3N4 nanopowders through an efficient and straightforward method, while systematically elucidating the morphological evolution mechanism of the nanopowders. The as-prepared Si3N4 nanopowders demonstrated promising potential for application as a raw powder material in high-performance Si3N4 ceramics.