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<p>This study investigates the surface modification of Y<sub>2</sub>O<sub>3</sub> using NH<sub>4</sub>F salt solutions with concentrations ranging from 10 to 80&#xa0;wt%, with the goal of exploring the formation and properties of the modified surface layer. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed before and after heat treatment for all concentration levels. The results revealed that the formation of ammonium yttrium fluoride phases, such as NH<sub>4</sub>Y<sub>2</sub>F<sub>7</sub> and (NH<sub>4</sub>)<sub>3</sub>Y<sub>2</sub>F<sub>9</sub>, was dependent on the NH<sub>4</sub>F concentration. At concentrations exceeding 60&#xa0;wt%, the (NH<sub>4</sub>)<sub>3</sub>Y<sub>2</sub>F<sub>9</sub> phase became dominant, and the surface modification layer thickness reached a plateau, indicating saturation of the reaction. Following heat treatment at 500&#xa0;°C, both NH<sub>4</sub>Y<sub>2</sub>F<sub>7</sub> and (NH<sub>4</sub>)<sub>3</sub>Y<sub>2</sub>F<sub>9</sub> phases were transformed into yttrium oxyfluoride (YOF), as confirmed by XRD analysis. SEM revealed microstructural changes on the surface, varying with the NH<sub>4</sub>F concentration. Additionally, samples modified at 10&#xa0;wt% were subjected to transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) for further characterization. TEM analysis identified a well-defined fluorinated layer approximately 1.05&#xa0;μm thick, while XPS confirmed the successful formation of Y–F bonds and a shift in binding energies. These findings demonstrate that the concentration of NH<sub>4</sub>F plays a critical role in determining the phase composition and structural characteristics of the modified surface layer, offering valuable insights for the development of fluorine-based, plasma-resistant materials.</p>

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Microstructure and TEM/XPS characterization of YOF layers on Y2O3 substrates modified via NH4F salt solution treatment

  • 期刊论文

  • 发表日期：

    2025年2月4日

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  • Hwan-Yoon Jang,
  • Eui Keun Park,
  • Kati Raju,
  • Hyun-Kwuon Lee

摘要

This study investigates the surface modification of Y2O3 using NH4F salt solutions with concentrations ranging from 10 to 80 wt%, with the goal of exploring the formation and properties of the modified surface layer. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed before and after heat treatment for all concentration levels. The results revealed that the formation of ammonium yttrium fluoride phases, such as NH4Y2F7 and (NH4)3Y2F9, was dependent on the NH4F concentration. At concentrations exceeding 60 wt%, the (NH4)3Y2F9 phase became dominant, and the surface modification layer thickness reached a plateau, indicating saturation of the reaction. Following heat treatment at 500 °C, both NH4Y2F7 and (NH4)3Y2F9 phases were transformed into yttrium oxyfluoride (YOF), as confirmed by XRD analysis. SEM revealed microstructural changes on the surface, varying with the NH4F concentration. Additionally, samples modified at 10 wt% were subjected to transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) for further characterization. TEM analysis identified a well-defined fluorinated layer approximately 1.05 μm thick, while XPS confirmed the successful formation of Y–F bonds and a shift in binding energies. These findings demonstrate that the concentration of NH4F plays a critical role in determining the phase composition and structural characteristics of the modified surface layer, offering valuable insights for the development of fluorine-based, plasma-resistant materials.