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<p>This study explores the impact of different sources of pure α-Al₂O₃ powder and sintering temperatures on the microstructure, densification, and dielectric properties of Al₂O₃ ceramics within the terahertz (THz) frequency range. In this regard, two commercially available α-Al₂O₃ powders, Almatis and Alfa Aesar, are sintered at temperatures of 1500&#xa0;°C, 1550&#xa0;°C, and 1600&#xa0;°C. The microstructural analysis indicates that samples derived from Almatis have finer grain sizes of 1.6 ± 0.1&#xa0;μm at 1500&#xa0;°C due to the presence of sintering aids that inhibit the grain growth. In contrast, Alfa Aesar samples exhibit larger grains up to 3.8 ± 0.4&#xa0;μm at 1600&#xa0;°C. As the sintering temperature increases, the relative density improves, reaching a peak of 97.6 ± 2.1% for Almatis samples sintered at 1600&#xa0;°C. The examination of dielectric properties presents that Almatis powder used ceramics consistently have lower absorption coefficients and loss tangents when compared to the Alfa Aesar samples. This difference is attributed to reduced porosity and optimized grain morphology in the Almatis ceramics. On the other hand, Alfa Aesar samples demonstrate higher permittivity, up to 10.11 at 1550&#xa0;°C, but experience increased dielectric losses. The variations in sintering temperatures significantly impact the dielectric stability, with Almatis samples showing minimal fluctuations in the refractive index. The obtained results highlight the essential role of powder source selection and sintering conditions in optimizing Al₂O₃ ceramics for high-performance THz applications, especially for next-generation 6G communication systems requiring low-loss substrates.</p>

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Impact of pure α-Al2O3 powder sources and sintering temperature on the behaviour of Al2O3 ceramics in Terahertz band

  • 期刊论文

  • 发表日期：

    2025年11月18日

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  • Kagan Murat Purlu,
  • Sekip Dalgac,
  • Elif Isik,
  • Betul Kafkaslioglu Yildiz,
  • Kholoud Elmabruk

摘要

This study explores the impact of different sources of pure α-Al₂O₃ powder and sintering temperatures on the microstructure, densification, and dielectric properties of Al₂O₃ ceramics within the terahertz (THz) frequency range. In this regard, two commercially available α-Al₂O₃ powders, Almatis and Alfa Aesar, are sintered at temperatures of 1500 °C, 1550 °C, and 1600 °C. The microstructural analysis indicates that samples derived from Almatis have finer grain sizes of 1.6 ± 0.1 μm at 1500 °C due to the presence of sintering aids that inhibit the grain growth. In contrast, Alfa Aesar samples exhibit larger grains up to 3.8 ± 0.4 μm at 1600 °C. As the sintering temperature increases, the relative density improves, reaching a peak of 97.6 ± 2.1% for Almatis samples sintered at 1600 °C. The examination of dielectric properties presents that Almatis powder used ceramics consistently have lower absorption coefficients and loss tangents when compared to the Alfa Aesar samples. This difference is attributed to reduced porosity and optimized grain morphology in the Almatis ceramics. On the other hand, Alfa Aesar samples demonstrate higher permittivity, up to 10.11 at 1550 °C, but experience increased dielectric losses. The variations in sintering temperatures significantly impact the dielectric stability, with Almatis samples showing minimal fluctuations in the refractive index. The obtained results highlight the essential role of powder source selection and sintering conditions in optimizing Al₂O₃ ceramics for high-performance THz applications, especially for next-generation 6G communication systems requiring low-loss substrates.