B2O3-modified fused silica microwave dielectric materials with ultra-low dielectric constant

Li, Lei; Liu, Cong Hui; Zhu, Jun; Chen, Xiang Ming

doi:10.1016/j.jeurceramsoc.2014.12.016

Cited by 56 publications

(21 citation statements)

References 32 publications

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“…The permittivity of a solid can be predicted by the Clausius‐Mossotti relation

\frac{ε_{r} - 1}{ε_{r} + 2} = \frac{4 π}{3} n α,

where n is the number of molecules per unit volume, and α is the molecular polarizability, which can be calculated from the constituting ionic polarizabilities. The small and highly charged cations such as B 3+ , Si 4+ , and Al 3+ possess low ionic polarizabilities, so the relatively low permittivity is expected in the ceramics consisting of these cations . Especially, B 3+ has the lowest ionic polarizability of only 0.05 Å 3 .…”

Section: Introductionmentioning

confidence: 99%

“…The small and highly charged cations such as B 3+ , Si 4+ , and Al 3+ possess low ionic polarizabilities, so the relatively low permittivity is expected in the ceramics consisting of these cations. [8][9][10][11][12][13][14][15] Especially, B 3+ has the lowest ionic polarizability of only 0.05 Å 3 . 8 Therefore, the borates are important low-permittivity microwave dielectric ceramics.…”

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confidence: 99%

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Cold sintering and microwave dielectric properties of dense HBO₂‐II ceramics

Hong

Yan

et al. 2019

J Am Ceram Soc

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HBO2‐II ceramics were prepared by cold sintering with 10wt% dehydrated ethanol as the transient liquid phase. When the processing temperature is 30°C, the relative density of the mechanically robust HBO2‐II ceramics increases from 77.5% to 84.5% with increasing the uniaxial pressure from 200 to 500 MPa. It changes less than 0.2% for higher pressure up to 700 MPa. Under a constant uniaxial pressure of 500 MPa, the relative density further increases to 94.7% for the processing temperature of 120°C. HBO2‐I is observed as the secondary phase when the processing temperature is 150°C. In comparison, the compacts prepared in the absence of ethanol are fragile, and the relative densities are 78.5%‐84.5% for the processing temperatures of 30‐120°C and uniaxial pressure of 500 MPa. It is indicated that ethanol promotes the densification significantly through the dissolution‐precipitation mechanism. The permittivity increases with increasing the processing temperature, while the Qf value decreases. The optimal properties with the relative density of 94.7%, εr = 4.21, Qf = 47 500 GHz, and τf = −70.0 ppm/°C were obtained in the single‐phase HBO2‐II ceramics cold sintered at 120°C under 500 MPa for 10 minutes. The relative density and Qf value are significantly higher than those of the HBO2‐II ceramic prepared by sintering the H3BO3 compact at 180°C for 2 hours (70.3% and 32 700 GHz, respectively). The results indicate that the nonaqueous solvent can also be used as the transient liquid phase for cold sintering, so that more materials that are unstable or insoluble in water can be densified by this method.

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“…The permittivity of a solid can be predicted by the Clausius‐Mossotti relation

\frac{ε_{r} - 1}{ε_{r} + 2} = \frac{4 π}{3} n α,

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Cold sintering and microwave dielectric properties of dense HBO₂‐II ceramics

Hong

Yan

et al. 2019

J Am Ceram Soc

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“…Thus, the mass transport is greatly accelerated through the dissolution-precipitation mechanism activated by the liquid phase, so that the sintering temperature can be lowered significantly. [23][24][25][26][27] In the present paper, therefore, we prepared the B 2 O 3 bulk by the melting method, and investigated the microwave dielectric properties. 9,10 The low-temperature sintering of microwave dielectric ceramics is also very important, especially considering their integration with microwave circuits, which promotes the rapid development of low-temperature cofired ceramics (LTCC).…”

Section: Introductionmentioning

confidence: 99%

Preparation and microwave dielectric properties of B₂O₃ bulk

Hong

Yan

et al. 2019

Int J Applied Ceramic Tech

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The transparent B2O3 bulks were prepared by quenching B2O3 melt or cooling it down to room temperature with the rate of 0.1‐1°C/min. The quenched sample exhibited the dense microstructure, while the pores were observed for low cooling rates, and this is consistent with the slight decrease in density and permittivity (εr) with decreasing the cooling rate. Both the amorphous and cubic phases of B2O3 were indicated by XRD, and the content of the cubic phase increased with the decrease in cooling rate, which was responsible for the decreasing Qf value with the lower cooling rate. The temperature coefficient of resonant frequency (τf) was insensitive to the cooling rate, and the microwave dielectric properties with εr = 3.86‐3.97, Qf = 3,200‐5,300 GHz and τf = −48.9 to −42.8 ppm/°C were obtained in the B2O3 bulks. The reported microwave dielectric properties of B2O3 bulk are helpful to estimate the effects of the residual B2O3 on the properties of the microwave dielectric ceramics with B2O3 and H3BO3 as the sintering aid.

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“…Although several conventional ultra‐low loss complex perovskite systems have been developed, such as Ba(Mg 1/3 Ta 2/3 )O 3 (BMT) and Ba(Zn 1/3 Ta 2/3 )O 3 (BZT), high sintering temperature (≥1400°C) and expensive raw materials limit their wide range of applications in microwaves. As a consequence, the search for novel low cost, moderate sintering temperature and high Q microwave dielectrics remain to be actively explored …”

Section: Introductionmentioning

confidence: 99%

“…As a consequence, the search for novel low cost, moderate sintering temperature and high Q microwave dielectrics remain to be actively explored. 8,9 Recently, rock-salt type lithium based compounds such as Li 2 NbO 6 have gained considerable attention in materials research due to their relatively low sintering temperature and abundant raw materials. [10][11][12] Among these outstanding materials, lithium metatitanate (Li 2 TiO 3 ) which is a unique microwave dielectric material with a rare positive temperature coefficient of resonant frequency, demonstrates superior microwave dielectric properties (e r~2 2, Q 9 f~50 000 GHz, and s f~+ 20.3 ppm/°C) and has been considered as a promising candidate for microwave applications in the last few years.…”

Section: Introductionmentioning

confidence: 99%

High‐Q microwave ceramics of Li₂TiO₃ co‐doped with magnesium and niobium

et al. 2018

J Am Ceram Soc

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In order to solve the problems of acceptor/donor individual doping in Li2TiO3 system and clarify the superiority mechanism of co‐doping for improving the Q value, Mg + Nb co‐doped Li2TiO3 have been designed and sintered at a medium temperature of 1260°C. The effects of each Mg/Nb ion on structure, morphology, grain‐boundary resistance and microwave dielectric properties are investigated. The substitution of (Mg1/3Nb2/3)4+ inhibits not only the diffusion of Li+ and reduction in Ti4+, but also the formation of microcracks in ceramics, which promotes the enhancement of Q value. The experiments reveal that Q × f value of Li2TiO3 ceramics co‐doped with magnesium and niobium is 113 774 GHz (at 8.573 GHz), which is increased by 113% compared with the pure Li2TiO3 ceramics. And the co‐doped ceramics have an appropriate dielectric constant of 19.01 and a near‐zero resonance frequency temperature coefficient of 13.38 ppm/°C. These results offer a scientific basis for co‐doping in Li2TiO3 system, and the outstanding performance of (Mg + Nb) co‐doped ceramics provides a solid foundation for widespread applications of microwave substrates, resonators, filters and patch antennas in modern wireless communication equipments.

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B2O3-modified fused silica microwave dielectric materials with ultra-low dielectric constant

Cited by 56 publications

References 32 publications

Cold sintering and microwave dielectric properties of dense HBO₂‐II ceramics

Cold sintering and microwave dielectric properties of dense HBO₂‐II ceramics

Preparation and microwave dielectric properties of B₂O₃ bulk

High‐Q microwave ceramics of Li₂TiO₃ co‐doped with magnesium and niobium

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B2O3-modified fused silica microwave dielectric materials with ultra-low dielectric constant

Cited by 56 publications

References 32 publications

Cold sintering and microwave dielectric properties of dense HBO2‐II ceramics

Cold sintering and microwave dielectric properties of dense HBO2‐II ceramics

Preparation and microwave dielectric properties of B2O3 bulk

High‐Q microwave ceramics of Li2TiO3 co‐doped with magnesium and niobium

Contact Info

Product

Resources

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Cold sintering and microwave dielectric properties of dense HBO₂‐II ceramics

Cold sintering and microwave dielectric properties of dense HBO₂‐II ceramics

Preparation and microwave dielectric properties of B₂O₃ bulk

High‐Q microwave ceramics of Li₂TiO₃ co‐doped with magnesium and niobium