Abstract Silicon nitride (Si3N4) particles with different morphologies have been used in many fields. In this work, α-Si3N4 whiskers and granular particles with high-phase purity were successfully tailored by the controllable crystallisation process of amorphous Si3N4 powders under different N2 pressure. Impressively, α-Si3N4 whiskers were prepared by simply heat treating amorphous Si3N4 powders at 1550 °C for 2 h under the low N2 pressure of 0.2 MPa, whereas equiaxed α-Si3N4 particles with uniform size of ~280 nm were obtained under an elevated N2 pressure of 2.0 MPa. With the evaluated N2 pressures and temperatures, large scale α-Si3N4 whiskers or equiaxed α-Si3N4 particles could be produced. The growth mechanisms of the α-Si3N4 particles with distinct morphologies were rationally proposed, and these consist of two main growth processes. First, amorphous Si3N4 powders decomposed into Si(g) and N2(g) under high-temperature treatment. Subsequently, N2(g) dominated the recombination of the evaporated chemical with the Si3N4 molecule. The initial N2 concentration, which plays a key role in tailoring the shape and size of products, was controlled by the N2 pressure.

中文翻译：

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从无定形 Si3N4 粉末合成 α-Si3N4 晶须或等轴颗粒

摘要 具有不同形貌的氮化硅 (Si3N4) 颗粒已被用于许多领域。在这项工作中，通过在不同 N2 压力下无定形 Si3N4 粉末的可控结晶过程，成功地定制了具有高相纯度的 α-Si3N4 晶须和颗粒。令人印象深刻的是，α-Si3N4 晶须是通过在 0.2 MPa 的低 N2 压力下，在 1550 °C 下简单地热处理非晶 Si3N4 粉末 2 小时来制备的，而在升高的 N2 压力下，获得了尺寸均匀约 280 nm 的等轴 α-Si3N4 颗粒。压力为 2.0 兆帕。通过评估的 N2 压力和温度，可以产生大规模的 α-Si3N4 晶须或等轴 α-Si3N4 颗粒。合理地提出了具有不同形态的 α-Si3N4 颗粒的生长机制，它们包括两个主要的生长过程。第一的，无定形 Si3N4 粉末在高温处理下分解为 Si(g) 和 N2(g)。随后，N2(g) 主导了蒸发的化学物质与 Si3N4 分子的复合。初始 N2 浓度在定制产品的形状和尺寸方面起着关键作用，它由 N2 压力控制。