The microwave dielectric characteristics of glass-doped Al/sub 2/O/sub 3/-TiO/sub 2/ ceramics

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

“…ceramics have a high Qf of 48,000 GHz, ε r of 100, and a positive large τ f of +450 ppm/ • C. 8 Tzou et al Reported that Al 2 O 3 -TiO 2 ceramics containing glass additives achieved a τ f ∼ 0 ppm/ • C by adjusting both sintering temperature and TiO 2 content. 9 However, dense ceramics were not obtained at a low sintering temperature (1300 • C). They also found that the formation of Al 2 TiO 5 caused a decrease in Qf and τ f when the sample was sintered at high temperature.…”

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

“…The Q Â f value of nano a-Al 2 O 3 ceramics with 0.5 wt% nano TiO 2 is higher than that without addition. 8 In order to lower the sintering temperature and achieve a zero t f value for alumina ceramics, Tzou et al 13 added MgO-CaO-Al 2 O 3 -SiO 2 (MCAS) glass additions as a sintering aid to alumina ceramics. MCAS glass additions lowered the sintering temperature, but also led to a considerable decrease in the Q Â f value.…”

“…MCAS glass additions lowered the sintering temperature, but also led to a considerable decrease in the Q Â f value. 13 Moreover, Miyauchi et al 10 utilized an annealing method to adjust the t f value of 0.9Al 2 O 3 -0.1TiO 2 . In comparison, the nano a-Al 2 O 3 ceramics with 8 wt% TiO 2 additions not only has lowest sintering temperature but also possesses a low dielectric loss and a near-zero t f value, which makes it very promising for commercial applications.…”

“…Therefore, TiO 2 (e r 5 100, Q Â fB50 000 GHz, t f 5 450 ppm/1C) 11 has often been utilized in controlling microwave dielectric properties and the sintering behavior. 12,13 In this paper, nano TiO 2 powder was used as a sintering aid and t f compensator, and was added to nano a-Al 2 O 3 powder as starting materials to further lower the sintering temperature and to improve the microwave dielectric properties of the specimens. The dielectric properties at microwave frequencies of the sintered ceramics were characterized and discussed in terms of the densification and the second phase (Al 2 TiO 5 ) of the specimens.…”

High Q dielectric resonator material with low dielectric constant for millimeter-wave applications

“…1,2 Tzou et al reported that Al 2 O 3 TiO 2 ceramics achieved τ f = 0 ppm/ • Cby lowering the sintering temperature with a low melting point glass. 2 However, the Q × f values of these ceramics were relatively low (about 10,000 GHz) and dense ceramics was not * Corresponding author. obtained at a low sintering temperature of 1300 • C. In this study, the addition of MnO was attempted to synthesize the Al 2 O 3 TiO 2 mixed ceramics without the formation of Al 2 TiO 5 phase.…”