Improvement of the dielectric properties of rutile-doped Al2O3 ceramics by annealing treatment

Microwave Dielectric Properties of Sintered Alumina Using Nano‐Scaled Powders of α Alumina and TiO2

“…In addition, a closer ratio between powder particle size and sintered grain size (pps:sgs) is important for obtaining finer‐grained microstructures and higher relative density 17 . In comparison with the result (pps:sgs∼1:10) reported by Miyauchi et al , 10 a closer ratio (pps:sgs∼1:4) was obtained in this work, implying a higher density, which would be beneficial to a reduction in the dielectric loss.…”

“…In addition, the density also increased with increasing TiO 2 content below 1350°C due to a high density of TiO 2 . In comparison with the densities reported by Miyauchi et al 10 higher values were obtained in this paper, indicating that the use of nano‐scaled powders as starting materials did lead to specimens with a higher density.…”

“…Figure 5 shows the SEM micrographs of the specimens using nano α‐Al 2 O 3 ceramics with TiO 2 sintered at 1400 o C for 4 h. The result indicated that the addition of TiO 2 helped to promote the grain growth. Moreover, smaller grain sizes were obtained in comparison with that reported by Miyauchi et al 10 This observation was attributed to the green compact associated with a fine particle; also, the uniform size distribution tended to prolong the intermediate stage of sintering, which resulted in an effective inhibition of grain growth 16 . In addition, a closer ratio between powder particle size and sintered grain size (pps:sgs) is important for obtaining finer‐grained microstructures and higher relative density 17 .…”

“…For practical applications, it is required to have a τ f value as close to 0 as possible. Shifting of the τ f value can be achieved by post‐annealing treatment due to the decomposition of the Al 2 TiO 5 phase 9–10 . It also possesses a Q × f value of 148 000 GHz at 1350°C.…”

Preparation and Microwave Dielectric Properties of TiO2-Doped YAG Ceramics

“…Low permittivity and high-Q dielectric ceramics have been attracted much attention as the advanced substrate materials in microwave integrated circuits (MIC) [1], and Al 2 O 3 [2,3], Mg 2 SiO 4 [4], and Zn 2 SiO 4 [5][6][7][8] ceramics have been investigated as potential candidate materials.…”