Crystal structure of corundum type Mg4(Nb2–xTax)O9 microwave dielectric ceramics with low dielectric loss

Ogawa, Hirotaka; Kan, Akinori; Ishihara, Soichi; Higashida, Yutaka

doi:10.1016/s0955-2219(03)00167-5

Cited by 134 publications

(65 citation statements)

References 11 publications

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“…Impurities and defects in crystals degrade the Q by formation of dipoles. Long sintering time also improves Q value as shown for the case of green phase reported by Ogawa et al [15]. This is because prolonged heating improves the crystallinity of the compound without local dipole moments.…”

Section: Introductionsupporting

confidence: 52%

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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Section: Introductionsupporting

confidence: 52%

Forsterite ceramics for millimeterwave dielectrics

et al. 2006

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“…As x>1.2, ρ r decreased abruptly to 0.57 for x=1. 6. This demonstrated that Sb 5+ substitutions for Nb 5+ is effective in reducing the sintering temperature of Mg 4 (Nb 2−x Sb x )O 9 for 0.4≤x≤1, but suppressed the densification process as the compositions x>1.2.…”

Section: Resultsmentioning

confidence: 90%

“…Among which, α-A1 2 O 3 ceramics with corundum structure has a very high Q value (Qf∼300,000 GHz) and low dielectric constant (ɛ∼10), widely used as substrate and IC packaging materials. Very recently, it was found that Mg 4 Nb 2 O 9 (MN) ceramics exhibited a very high Qf value comparable to Al 2 O 3 [6]. By a substitution of Ta 5+ for Nb 5+ , the Qf value of Mg 4 Nb 2 O 9 could be further improved [6].…”

Section: Introductionmentioning

confidence: 99%

“…Very recently, it was found that Mg 4 Nb 2 O 9 (MN) ceramics exhibited a very high Qf value comparable to Al 2 O 3 [6]. By a substitution of Ta 5+ for Nb 5+ , the Qf value of Mg 4 Nb 2 O 9 could be further improved [6]. Thus, Mg 4 Nb 2 O 9 is a suitable material for microwave applications, such as substrates and resonators at high frequency.…”

Section: Introductionmentioning

confidence: 99%

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The sintering behavior and microwave dielectric properties of Mg4(Nb,Sb)2O9 ceramics

Liu

Yao

et al. 2007

J Electroceram

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“…13)16) (Kan et al reported that a dielectric constant of 11.6 and a Q©f of 160,256 GHz were obtained for Mg 4 (Nb 2¹x V x )O 9 at x = 0.0625 sintered at 1025°C.) Among those solid solutions, an extremely high Q © f (³350,000 GHz) could be achieved from specimens using Mg 4 (Nb 2¹x Ta x ) 2 O 9 .…”

Section: Introductionmentioning

confidence: 99%

Dielectric properties and crystal structure of Mg4Ta2O9 ceramics with Mg2+ substituted by Co2+

Wang

Huang

et al. 2014

J. Ceram. Soc. Japan

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Dielectric properties of (Mg (1¹x) Co x ) 4 Ta 2 O 9 (x = 0.01 to 0.09) prepared by solid state reaction were investigated. The maximum properties of the (Mg (1¹x) Co x ) 4 Ta 2 O 9 (x = 0.05) system were namely, an obtained ¾ r value of 12.27, a Q©f value of 440,000 GHz, and a¸f value of ¹59 ppm/°C sintered at 1325°C. The theoretical polarizability of (Mg (1¹x) Co x ) 4 Ta 2 O 9 increased with Co substitution, x. (Mg (1¹x) Co x ) 4 Ta 2 O 9 with Mg 2+ substituted by and Co 2+ not only improved the microwave dielectric properties, but also decreased sintering temperature. From the calculation of the covalency of cationoxygen bonds, it is found that the covalency of the CoO bond is lower than that of the MgO bond and the difference in the covalency between these cationoxygen bonds influences the temperature dependence of dielectric constant on the compounds. From our experiment, the best microwave dielectric property happens in (Mg 0.95 Co 0.05 ) 4 Ta 2 O 9 sintered at 1325°C for 4 h, and it's Q©f is 440,000 GHz with¸f = 59.5 ppm/°C.

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Crystal structure of corundum type Mg4(Nb2–xTax)O9 microwave dielectric ceramics with low dielectric loss

Cited by 134 publications

References 11 publications

Forsterite ceramics for millimeterwave dielectrics

Forsterite ceramics for millimeterwave dielectrics

The sintering behavior and microwave dielectric properties of Mg4(Nb,Sb)2O9 ceramics

Dielectric properties and crystal structure of Mg<sub>4</sub>Ta<sub>2</sub>O<sub>9</sub> ceramics with Mg<sup>2+</sup> substituted by Co<sup>2+</sup>

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