We compare Bi2Te3 powders prepared by conventional ball milling to powders milled in supercritical carbon dioxide (scCO2). We demonstrate that scCO2 milling overcomes size-reduction limitations reported for conventional milling. XRD and TEM reveal nanograins with smaller average sizes (<10 nm) and narrower grain size distributions in the scCO2 milled case. scCO2 milling also preserves the crystallinity and shows less oxidation than conventional milling. This is the first report of Bi2Te3 with a sub-10 nm grain size whilst conserving high quality crystallinity, made using a top-down approach. Our study offers a route for developing unprecedentedly fine bulk nanostructured Bi2Te3-based thermoelectric materials.

中文翻译：

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使用超临界二氧化碳球磨机生产亚 10 nm Bi ₂ Te ₃晶粒的自上而下方法

我们将通过传统球磨制备的 Bi2Te3 粉末与在超临界二氧化碳 (scCO2) 中研磨的粉末进行比较。我们证明 scCO2 研磨克服了传统研磨报告的尺寸减小限制。XRD 和 TEM 揭示了在 scCO2 研磨情况下具有更小平均尺寸 (<10 nm) 和更窄粒度分布的纳米颗粒。scCO2 研磨还保持结晶度，并且比传统研磨显示更少的氧化。这是 Bi2Te3 的第一份报告，具有亚 10 nm 的晶粒尺寸，同时保持高质量的结晶度，使用自上而下的方法制作。我们的研究为开发前所未有的精细块状纳米结构 Bi2Te3 基热电材料提供了一条途径。