Effects of TiO2 on sinterability and dielectric properties of high-Q forsterite ceramics

Tsunooka, Tsutomu; Androu, M.; Higashida, Yutaka; Sugiura, Hirotsugu; Ohsato, Hitoshi

doi:10.1016/s0955-2219(03)00177-8

Cited by 206 publications

(113 citation statements)

References 2 publications

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“…The density of sintered pure MgAl 2 O 4 was measured to be 3.48 g/cm 3 which is about 97% of its theoretical density [16](3.58 g/cm 3 ). It has been reported [17] that the densification behaviour of TiO 2 is hindered due to the anatase to rutile phase transition consequent to the reduction of Ti 4+ to Ti 3+ .…”

Section: Resultsmentioning

confidence: 85%

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

et al. 2005

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Section: Resultsmentioning

confidence: 85%

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

et al. 2005

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“…7 [22]. Other properties are also excellent: Q · f = 85000 GHz, and ε r = 11 when sintered at 1200 • C. Fig.…”

Section: Adjustment τ F To Zero On Forsteritementioning

confidence: 85%

“…Other properties are also excellent: Q · f = 85000 GHz, and ε r = 11 when sintered at 1200 • C. Fig. 7 shows the relationship between (a) apparent density, (b) quality factor, (c) dielectric constant and (d) τ f of the Mg 2 SiO 4 ceramics added with TiO 2 and sintered at 1200 • C and 1400 • C for 2h as a function of TiO 2 content [22]. In the case of sintered at 1200 • C, the τ f of Mg 2 SiO 4 ceramics added with TiO 2 increased linearly with increasing TiO 2 addition, the τ f changed from negative to positive values between 20 and 25wt% addition of TiO 2 .…”

Section: Adjustment τ F To Zero On Forsteritementioning

confidence: 99%

Forsterite ceramics for millimeterwave dielectrics

et al. 2006

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The wireless communications have been tremendously developed in the recent ubiquitous age. The utilizable frequency region has been expanded to millimeterwaves because of shortage of conventional frequency regions. For the ultra high frequencies of millimeterwaves, dielectrics with ultra high quality factor Q and low dielectric constant ε r are desired. Low ε r is necessary to short the delay time of signals and to make devices small in size. Silicates for candidate of millimeterwave materials have low dielectric constant, because of silica-oxygen tetrahedra composed of half covalent bonds. Forsterite (Mg 2 SiO 4 ) as such kind of silicates has high Q · f of 270000 GHz and low ε r of 6.8. The temperature coefficient of resonant frequency τ f was improved by adding rutile TiO 2 with high τ f of plus 450 ppm/ • C. In this paper, these results for forsterite are summarized.Keywords Microwave and millimeterwave dielectric ceramics . Silicate . Forsterite

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“…Rutile TiO 2 shows a large positive value of τ f =450 ppm/°C. Consequently, the composite ceramics showed τ f of 3.95 ppm/°C by appending 25 wt% TiO 2 [3,4]. Unfortunately, the secondary phases of MgSiO 3 , MgTi 2 O 5 and MgTiO 3 affect the microwave dielectric properties in the resultant composite ceramics.…”

Section: Introductionmentioning

confidence: 99%

Mg2SiO4–TiO2 composite ceramics prepared using a liquid phase deposition process

et al. 2007

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Forsterite (Mg 2 SiO 4 ) indicates a high quality factor (Q·f) of 270,000 GHz and a low dielectric constant ɛ r of 6.8, which are applicable for microwave and millimeterwave dielectric devices. However, a large negative temperature coefficient of resonant frequency (τ f ) of −73 ppm/°C hinders stability. Actually, Mg 2 SiO 4 -TiO 2 composite ceramics prepared by ordinary solid state reaction showed improved τ f to 0 ppm/°C. However, Q·f of the composite ceramics decreased because other phases such as MgTi 2 O 5 , MgTiO 3 and MgSiO 3 were created in the reaction between TiO 2 and Mg 2 SiO 4 during sintering. This study uses a different process to prepare the Mg 2 SiO 4 -TiO 2 composite ceramics to prevent the production of the secondary phase. Porous Mg 2 SiO 4 ceramics were prepared by sintering Mg 2 SiO 4 with pore-forming agents. Then, TiO 2 was inserted into the pores using liquid phase deposition (LPD). Deposited TiO 2 in the pores was anatase form. The increase of the inserted anatase TiO 2 amount contributed to improvement of τ f .

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Effects of TiO2 on sinterability and dielectric properties of high-Q forsterite ceramics

Cited by 206 publications

References 2 publications

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

(1-x)MgAl2O4-xTiO2 dielectrics for microwave and millimeter wave applications

Forsterite ceramics for millimeterwave dielectrics

Mg2SiO4–TiO2 composite ceramics prepared using a liquid phase deposition process

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