Microwave dielectric properties of Al2O3 ceramics co-doped with MgO and Nb2O5

Zhang, Kang; Yuan, Lü; Fu, Yen−Pei; Yuan, Chao; Li, Wei

doi:10.1007/s10854-015-3248-0

Cited by 7 publications

(2 citation statements)

References 24 publications

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“…Therefore, the presence of the secondary phase always affects the dielectric loss, and the Q × f value usually remains relatively low, at less than approximately 40,000 GHz [6,7]. Another example is alumina (Al 2 O 3 ) ceramics with a dielectric constant of 10, exhibiting exceptionally low dielectric loss and a Q × f value that can exceed 300,000 GHz [8,9]. However, a prolonged high-temperature sintering is necessary to obtain dense ceramics [10,11].…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Microwave Dielectric Property of xMgO-SiO2 (x = 1~2) System for 5G Applications

Wang,

Li,

Zhu

et al. 2023

Crystals

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Mg2SiO4 and MgSiO3 ceramics with superior microwave dielectric properties are considered to be promising candidates for 5G applications. However, a slight deviation from the stoichiometric Mg/Si ratio will significantly influence their microwave dielectric properties, which will hinder their practical applications. In this work, the xMgO-SiO2 (x = 1~2) ceramics were synthesized by a solid-state reaction method. The influence of the Mg/Si ratio x on the crystalline phase, microstructure, and microwave dielectric properties was investigated through X-ray diffraction (XRD), a scanning electron microscope (SEM), and the resonant cavity method. The XRD patterns revealed the coexistence of Mg2SiO4 and MgSiO3 within the x range of 1~2, which was further demonstrated by the energy-dispersive X-ray spectra. The SEM images show a typical polycrystalline morphology of ceramics with an inhomogeneous grain size distribution. It is found that the microwave dielectric properties fluctuate at both sides of the x range while those remain relatively stable with minor changes at the intermediate components, indicating an obvious low composition dependence helpful for practical applications. Further, a demonstrator of a microstrip patch antenna for 5G applications using the 1.5MgO-SiO2 ceramic was designed and fabricated, and a return loss of −16.2 dB was demonstrated, which demonstrated the potential applications.

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Section: Introductionmentioning

confidence: 99%

Crystal Structure and Microwave Dielectric Property of xMgO-SiO2 (x = 1~2) System for 5G Applications

Wang,

Li,

Zhu

et al. 2023

Crystals

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“…Microwave dielectric materials conquer today's wireless communication industry by providing a wide variety of applications such as broadcasting satellites, cellular phone, global positioning systems etc. [1]. New microwave substrate materials with low relative permittivity and high performance are desired for high speed communication devices [2].…”

Section: Introductionmentioning

confidence: 99%

Microwave dielectric properties of mineral sillimanite obtained by conventional and cold sintering process

Induja

Sebastian

2017

Journal of the European Ceramic Society

100

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The sillimanite (Al2SiO5) mineral has been sintered by conventional ceramic route and by cold sintering methods. The mineral has very poor sinterability and transformed to mullite on sintering above 1525°C.The dielectric properties of sillimanite mineral (Al2SiO5) are investigated at radio and microwave frequency ranges. The mineral sintered at 1525°C has low εr of 4.71 and tanδ of 0.002 at 1 MHz and at microwave frequency εr = 4.43, Qu× f = 41,800 GHz with τf = −17 ppm/°C. The sintering aid used for cold sintering Al2SiO5 is sodium chloride (NaCl). The Al2SiO5NaCl composite was cold sintered at 120°C. XRD analysis of the composite revealed that there is no additional phase apart from Al2SiO5 and NaCl. The densification of the Al2SiO5NaCl composite was confirmed by using microstructure analysis. The Al2SiO5NaCl composite has εr of 5.37 and tanδ of 0.005 at 1 MHz whereas at microwave frequency it has εr = 4.52, Qu× f = 22,350 GHz with τf = −24 ppm/°C. The cold sintered NaCl has εr = 5.2, Qu× f = 12,000 GHz with τf = −36 ppm/°C. Recently Kahari et al. reported [15,16] a novel method toprepare Li2MoO4 ceramics at room temperature by moistening the water soluble Li2MoO4 powder using deionized water and pressing the sample at about 130 MPa. The samples were then dried at room temperature or at 120°C. There was no appreciable difference in the sintered density of the samples dried at room temperature, dried at 120°C or sintered at 540°C. The amount of water in the pressed samples was about 2-3 wt% before drying or sintering. It is believed that the densification of the samples occurred during pressing. X-ray diffraction study showed that the crystal structure remains the same and water did not react to form any hydrates. The room temperature dried samples showed a Qu × f value slightly less than that prepared by conventional sintering method and is attributed to the presence of small amount of residual water. It was found [16] that ceramic powder particle size has great influence on preparation; densification and dielectric properties. Larger particles are

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Other Important Materials

Sebastian

Pullar

2017

Microwave Materials and Applications 2V Set

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Microwave dielectric properties of Al2O3 ceramics co-doped with MgO and Nb2O5

Cited by 7 publications

References 24 publications

Crystal Structure and Microwave Dielectric Property of xMgO-SiO2 (x = 1~2) System for 5G Applications

Crystal Structure and Microwave Dielectric Property of xMgO-SiO2 (x = 1~2) System for 5G Applications

Microwave dielectric properties of mineral sillimanite obtained by conventional and cold sintering process

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