Densely sintered alumina is produced with a 5 wt% addition of a CuO‐TiO₂‐Nb₂O₅‐Ag₂O sintering aid under a firing temperature of only 835°C with a prolonged holding time of 96 hours. The sintered material exhibits a thermal conductivity of 20 W/mK, which is significantly greater than that of conventional low‐temperature co‐fired ceramic (LTCC) materials (~2‐7 W/mK). Additionally, suitable dielectric characteristics are observed, such as a relative dielectric constant ε_r of 11.3, quality factor–resonant frequency product Q × f of 4700 GHz, and temperature coefficient of resonant frequency τ_f of −87 ppm/K. The low‐temperature densification is revealed to occur mainly in the solid state, before liquid phase formation. Lattice constant measurements, transmission electron microscopy, and energy dispersive spectroscopy reveal an increase in unit cell volume upon densification and the incorporation of Cu²⁺ and Ti⁴⁺ ions into the alumina lattice, which promotes densification. The diffusion speeds of Cu²⁺ and Ti⁴⁺ ions are indirectly affected by Nb and Ag atoms by lowering the additive melting temperature. Therefore, sintering additives with low melting points and elements that incorporate into the lattice of the base material are effective for low‐temperature sintering of aluminum‐based oxides.

中文翻译：

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具有优异导热性的低温共烧氧化铝的烧结机理

在仅835°C的烧成温度下，经添加5 wt％的CuO-TiO ₂ -Nb ₂ O ₅ -Ag ₂ O烧结助剂即可生产致密烧结氧化铝，可长时间保持96小时。烧结材料的导热系数为20 W / mK，大大高于传统的低温共烧陶瓷（LTCC）材料的导热系数（〜2-7 W / mK）。此外，适当的介电特性被观察到，例如相对介电常数ε _{- [R} 11.3，品质因数谐振频率产物Q  ×  ˚F 4700千兆赫，及谐振频率的温度系数τ _˚F为-87 ppm / K。发现低温致密化主要发生在液相形成之前的固态。晶格常数测量，透射电子显微镜和能量色散光谱显示，致密化以及将Cu ²⁺和Ti ⁴⁺离子掺入到氧化铝晶格中会增加晶胞的体积，从而促进致密化。通过降低添加剂的熔化温度，Nb和Ag原子间接影响Cu ²⁺和Ti ⁴⁺离子的扩散速度。因此，具有低熔点的烧结添加剂和掺入基础材料晶格中的元素对于铝基氧化物的低温烧结是有效的。