Stabilization and tunable microwave dielectric properties of the rutile polymorph in α-PbO2-type GaTaO4-based ceramics

Pan, Zhengwei; Yu, Xiaodi; Wang, Quanchao; Cao, Jiang; Pan, Fengjuan; Liang, Chaolun; Lu, Fengqi; Kuang, Xiaojun; Su, Congxue; Wang, Jing; Fang, Liang

doi:10.1039/c4tc00295d

Cited by 10 publications

(11 citation statements)

References 31 publications

(46 reference statements)

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“…The relative permittivity and bulk density gradually increased with a slight drop after 1500°C, while the quality factor reached a maximum of 42 060 ± 310 GHz at 1450°C. It has been confirmed that interdependent factors involving intrinsic and extrinsic parts have varying degrees of influence on microwave dielectric properties . Porosity, impurities, defects, site/charge order, etc., are usually considered as extrinsic factors that cannot be entirely excluded in the processing of the solid‐state reaction method.…”

Section: Resultsmentioning

confidence: 93%

“…It has been confirmed that interdependent factors involving intrinsic and extrinsic parts have varying degrees of influence on microwave dielectric properties. 8,47 Porosity, impurities, defects, site/charge order, etc., are usually considered as extrinsic factors that cannot be entirely excluded in the processing of the solid-state reaction method. The intrinsic contribution to relative permittivity is predominantly related to dielectric polarization, including ionic, dipolar, and electronic factors.…”

Section: Microwave Dielectric Properties and Chemical Bond Charactementioning

confidence: 99%

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Vibrational spectroscopic and crystal chemical analyses of double perovskite Y₂MgTiO₆ microwave dielectric ceramics

et al. 2019

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Structure‐property relationships of Y2MgTiO6, a type of double perovskite materials, were investigated systematically. Rietveld refinement of XRD patterns confirmed that Y2MgTiO6 belongs to the P21/c space group and has a structure analogous to that of monoclinic Dy2MgTiO6. In accordance with the observed number of vibrational bands and group theoretical predictions, O and Y ions at the 4e site dominated the Raman peaks. The IR reflectivity spectrum indicated that the major contributions to the relative permittivity and intrinsic loss were modes lower than 500 cm−1. The measured relative permittivity closely approached the calculated values determined according to P‐V‐L theory, the Clausius‐Mossotti equation and IR fitted results. The larger bond energy for Mg–O bonds than for Ti–O bonds corresponds to a more stable octahedron of [MgO6], as verified by the octahedral distortion. Satisfactory microwave dielectric properties of Y2MgTiO6 ceramics were as follows: εr = 20.4 ± 0.8, Q × f = 42 060 ± 310 GHz, τf = −52 ± 3 ppm/°C, sintered at 1450°C.

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Section: Resultsmentioning

confidence: 93%

Section: Microwave Dielectric Properties and Chemical Bond Charactementioning

confidence: 99%

Vibrational spectroscopic and crystal chemical analyses of double perovskite Y₂MgTiO₆ microwave dielectric ceramics

et al. 2019

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“…Although the -PbO2 phase retards the oxygen-loss rate of the oxides, Fe1-/3Nb1+/3O4 (=0 and 0.045) samples are theoretically unstable under the reducing under 5% H2 at 700 . The low-temperature cation ordering in a wolframite can be attributed to the charge imbalance between the Fe 3+ and Nb 5+ cation, and thus the addition of TiO2 on both layer decreases the charge imbalance amongst the cation planes and the cation ordering [50]. Tena et al [51] and Balzer et al [44] studied the phase transition of FeNbO4-TiO2 solid solution and found similar results.…”

Section: Solid Solution Between Fe0985nb1015o4 and Tio2mentioning

confidence: 83%

An FeNbO4-based oxide anode for a solid oxide fuel cell (SOFC)

Liu

Xie

Irvine

et al. 2020

Electrochimica Acta

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The advantage of n-type semiconductor for an anode of solid oxide fuel cells (SOFCs) lies in its higher electronic conductivity in reducing atmosphere than in air. In this study, n-type FeNbO4-based oxides that can be reduced at temperatures below 700 o C for a conductivity above 1 S cm -1 are explored as anode materials for a ceria-based SOFC utilizing liquefied-petroleum-gas (LPG) fuel apart from pure H2. Fe0.8Nb1.2O4 with 20 at.% Fe deficiency was founded in the sample sintered at 1250 o C. The structure stability of FeNbO4 under reducing atmosphere can be improved by its solid solution with a lessreducible TiO2 that also stabilizes the high-temperature -PbO2 type structure with mixed Fe 3+ and Nb 5+ cation. In particular, a full cell employing Ti0.36(Fe0.985Nb1.015)0.84O4, a stable and electrically conductive (1 S cm -1 ) oxide in 5% H2, as anode shows a powder density of 180 mW cm -2 at 700 o C if 0.5 wt.% Pd is impregnated to increase the electrocatalysis and the electric loss is mostly from the electrolyte. The oxide anode showed a degradation (20% during the 5 to 26 hours aging) and the carbon deposition is slight after 5-hour operation under an LPG fuel.[1] and are not restrained by efficiency limitations applicable to heat engines (i.e. the Carnot cycle). The potential widespread use of SOFCs also depends on the availability of fuel[2]. Comparing to the low-temperature proton-exchange-membrane fuel cell (PEMFC), the advantage of an all-ceramic SOFC device could be the ability to use carbonaceous fuel, i.e. carbon monoxide, methane et al., other than pure H2 fuel[3-6]. The fuel versatility of an SOFC increases the fuel availability since the infrastructure for carbonaceous fuel is mature, which will facilitate the commercialization of this technique and reduce the additional cost on H2 storage and transport[2]. The conventional nickelbased anode catalyzing the oxidation of the H2 fuel on GDC electrolyte is Ni(O)-GDC cermet and a high performance (e.g. 2 W cm 2 at 550 o C)[7] has been achieved via the optimization of the cathode materials and the thinning of the electrolyte[8]. However, the carbon deposition or coking process of the Ni under a carbonaceous fuel would prohibit the long-term operation for continuous power supply[9] and thus novel oxide perovskites, such as (La, Sr)(Cr, Mn)O3, Sr2MoMO6 (M=Mg, Cr or Mn) and (La, Sr)TiO3, has been developed for the operation under hydrocarbon fuels[10-20].Generally, both nand p-type semiconducting oxides can be used as the anode materials in an SOFC. La0.75Sr0.25Cr0.5Mn0.5O3 is a paradigmatic p-type semiconducting oxide showing a decreased conductivity under reducing atmosphere of fuel than in air, while (La, Sr)TiO3 is an n-type semiconductor showing superior stability and conductivity if is fully reduced[21] at elevated temperatures [22] (above 750 o C under H2). However, an SOFC under the intense in-situ reduction at elevated temperature for anodes can possibly induce the reduction of the GDC electrolyte, causing the increase of electronic conduction and i...

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“…CaTiO 3 , which belongs to a representative perovskite family, possesses good physical-chemical resistance and stability even in some corrosive environments [10][11][12]. Thus lanthanide ions like Sm, Eu or Pr doped CaTiO 3 phosphors have been rapidly developed because of their chemical stability and environmental friendship [13,14].…”

Section: Introductionmentioning

confidence: 99%

Enhanced fluorescence and heat dissipation of calcium titanate red phosphor based on silver coating

Chen

Qin

Zhang

et al. 2015

Journal of Colloid and Interface Science

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Stabilization and tunable microwave dielectric properties of the rutile polymorph in α-PbO2-type GaTaO4-based ceramics

Cited by 10 publications

References 31 publications

Vibrational spectroscopic and crystal chemical analyses of double perovskite Y₂MgTiO₆ microwave dielectric ceramics

Vibrational spectroscopic and crystal chemical analyses of double perovskite Y₂MgTiO₆ microwave dielectric ceramics

An FeNbO4-based oxide anode for a solid oxide fuel cell (SOFC)

Enhanced fluorescence and heat dissipation of calcium titanate red phosphor based on silver coating

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Stabilization and tunable microwave dielectric properties of the rutile polymorph in α-PbO2-type GaTaO4-based ceramics

Cited by 10 publications

References 31 publications

Vibrational spectroscopic and crystal chemical analyses of double perovskite Y2MgTiO6 microwave dielectric ceramics

Vibrational spectroscopic and crystal chemical analyses of double perovskite Y2MgTiO6 microwave dielectric ceramics

An FeNbO4-based oxide anode for a solid oxide fuel cell (SOFC)

Enhanced fluorescence and heat dissipation of calcium titanate red phosphor based on silver coating

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Product

Resources

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Vibrational spectroscopic and crystal chemical analyses of double perovskite Y₂MgTiO₆ microwave dielectric ceramics

Vibrational spectroscopic and crystal chemical analyses of double perovskite Y₂MgTiO₆ microwave dielectric ceramics