Temperature–stable dielectrics based on Cu–doped Bi2Mg2/3Nb4/3O7 pyrochlore ceramics for LTCC

Guo, Qianyu; Li, Lingxia; Yu, Shihui; Sun, Zheng; Zheng, Haoran; Li, Jiangteng; Luo, Weijia

doi:10.1016/j.ceramint.2017.09.177

Cited by 42 publications

(11 citation statements)

References 31 publications

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“…Compounds with pyrochlore structure can exhibit magnetic, piezoelectric, and electro-optical properties; they are known as superconductors, multiferroics, photocatalysts, and dielectrics. − Pyrochlore-based materials are used in solid-state devices as thermistors, thick-film resistors, and communication elements and are used as components of ceramic forms for radioactive waste. Bismuth-based pyrochlores, due to their excellent dielectric properties, low sintering temperature, chemical inertness with respect to Ag-electrodes, and composition-adjustable temperature coefficient of capacitance, prove to be extremely promising materials for manufacturing multilayered ceramic capacitors and electronic devices for the microwave range. − Two interpenetrating weakly interacting sublattices of A 2 O and B 2 O 6 are distinguished in the cubic structure of pyrochlore A 2 B 2 O 7 ( Fd 3̅ m ). , The B 2 O 6 basic structure octahedrons arranged around the diamond grid points form a vertex-linked tetrahedral framework. The framework of regular octahedrons contains extensive voids with two or more large cations A and one additional atom O′ for each formulaic unit (BO 3 ) 2 of the framework.…”

Section: Introductionmentioning

confidence: 99%

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi₂NiTa₂O₉ Pyrochlore

et al. 2021

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A phase-pure nickel bismuth tantalate with pyrochlore structure was synthesized by a solid-phase synthesis method for the first time. The crystal structure of pyrochlore (refined formula Bi 1.58 Ni 0.60 Ta 1.40 O 7 , sp. gr. Fd-3m, a = 10.5343 Å, Z = 8) was clarified by the Rietveld method on the basis of X-ray powder diffraction (XRD) data. The crystallite size determined by the Scherrer method is ∼46 nm. The sample has an atypical pink-purple color. The electronic state of the atoms was investigated by XPS. According to XPS analysis, bismuth atoms have an effective charge of +3; nickel atoms, +(2 + δ); tantalum ions, +(5 − δ). The thermal expansion coefficient of the cell is calculated from high-temperature X-ray measurements in the range of 30−1200 °C. The thermal expansion coefficient (TEC) increases monotonically from 3.79 × 10 −6 °C−1 (30 °C) to 8.32 × 10 −6 °C−1 (990 °C). Above 1080 °C, the TEC decreases due to the thermal dissociation of pyrochlore with new NiTa 2 O 6 phase formation. Ni-doped bismuth tantalate refers to dielectrics and exhibits a moderately high dielectric constant, ∼32, and low dielectric losses, ∼2 × 10 −3 at 1 MHz and ∼30 °C. Above 300 °C, the dielectric losses and dielectric permittivity increase in the low-frequency region due to the activation of oxygen anions. It is found that the electrical characteristics of the sample are significantly affected by the ambient air humidity. An equivalent scheme which satisfactorily describes the electrical properties of the sample has been proposed.

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Section: Introductionmentioning

confidence: 99%

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi₂NiTa₂O₉ Pyrochlore

et al. 2021

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“…The BO 6 octahedron is correlated with the different A-site cations environment, thus closely affecting the temperature independence of dielectric constant. 32 The dielectric constant of Ni-BMN pyrochlores decreased with increasing temperature from 25 to 200 °C at 1 MHz is shown in Figure 6(b). However, the dielectric loss also decreased greatly after Ni-doping.…”

Section: Resultsmentioning

confidence: 98%

“…However, the BO 6 oxygen octahedron rarely deviates as for the skeleton structure. The BO 6 octahedron is correlated with the different A-site cations environment, thus closely affecting the temperature independence of dielectric constant …”

Section: Resultsmentioning

confidence: 99%

Disordered Structures and Dielectric Properties of Ni-Doped Bismuth Magnesium Niobate Pyrochlores

et al. 2021

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Bismuth based cubic pyrochlores are attractive candidates for microwave agile devices. The structure dependence of dielectric properties of Bi1.5Mg1–x Ni x Nb1.5O7 (Ni-BMN, x = 0.0–0.5) ceramics are discussed systematically. All the Ni-BMN pyrochlores show a cubic pyrochlore structure with a preferential (222)-orientation. However, Ni2+ ions entering would reduce the symmetry of cubic pyrochlore structure, which may increase the disorder degree of cubic pyrochlore structure. The detailed status of A2O and BO6 networks in Ni-BMN are revealed by structure analysis. The dielectric constant of Ni-BMN pyrochlores show slightly decrease from 168 to 148 with increasing Ni-doping content due to the lower polarizability of Ni2+. However, Ni-doping can effectively decrease the dielectric loss of Ni-BMN pyrochlores from 0.00072 to 0.00039. Moreover, Ni-doping improves the temperature stability of Ni-BMN pyrochlores, which is attributed to the altered O–Ni-O chain.

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“…In order to increase the propagation velocity and inhibit signal damping, dielectric materials should possess high quality factor and permittivity . For practical engineering applications, the temperature coefficient of resonance frequency must be close to zero to guarantee the stability of performance . However, many types of dielectric ceramics do not possess these properties.…”

Section: Introductionmentioning

confidence: 99%

“…[5][6][7][8] For practical engineering applications, the temperature coefficient of resonance frequency must be close to zero to guarantee the stability of performance. 9,10 However, many types of dielectric ceramics do not possess these properties. Instead, materials with high dielectric loss or large temperature coefficients of resonance frequency are quite common.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure and enhanced microwave dielectric properties of Ta⁵⁺ substituted Li₃Mg₂NbO₆ ceramics

et al. 2019

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Composition and structure play dominant roles in realizing the microwave dielectric properties that are necessary for the ever‐increasing demands of the Internet of Things and related communication technologies. In the present study, the substitution of Ta5+ in Li3Mg2Nb1−xTaxO6 ceramics and its effect on the structural characteristics and microwave dielectric performances is systematically studied. All the substituted compositions were determined to be pure phase orthorhombic Li3Mg2NbO6 structure of space group Fddd. Furthermore, a NbO6 octahedral distortion, Nb‐O bond valence, packing fraction and polarizability were calculated to explore the structure‐property‐performance paradigm in the context of microwave dielectric performance. Scanning electron microscopy revealed homogeneous microstructures, with the introduction of Ta5+ promoting grain growth. Raman spectra indicated that the variation of the band (blue shift and red shift) at 771 cm−1 was highly correlated with the variation in unit cell volume. The polarizability significantly impacted ɛr values. The Q × f values were strongly influenced by the packing fraction and grain size. The changes in the NbO6 octahedral distortion and Nb–O bond valence impacted the τf values. The Li3Mg2Nb0.98Ta0.02O6 composition displayed the most dramatic improvements in microwave dielectric properties: εr = 15.58, Q × f = 113 000 GHz and τf = −4.5 ppm/°C, providing a potential candidate for next generation microwave and millimeter‐wave applications.

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Temperature–stable dielectrics based on Cu–doped Bi2Mg2/3Nb4/3O7 pyrochlore ceramics for LTCC

Cited by 42 publications

References 31 publications

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi₂NiTa₂O₉ Pyrochlore

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi₂NiTa₂O₉ Pyrochlore

Disordered Structures and Dielectric Properties of Ni-Doped Bismuth Magnesium Niobate Pyrochlores

Crystal structure and enhanced microwave dielectric properties of Ta⁵⁺ substituted Li₃Mg₂NbO₆ ceramics

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Temperature–stable dielectrics based on Cu–doped Bi2Mg2/3Nb4/3O7 pyrochlore ceramics for LTCC

Cited by 42 publications

References 31 publications

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi2NiTa2O9 Pyrochlore

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi2NiTa2O9 Pyrochlore

Disordered Structures and Dielectric Properties of Ni-Doped Bismuth Magnesium Niobate Pyrochlores

Crystal structure and enhanced microwave dielectric properties of Ta5+ substituted Li3Mg2NbO6 ceramics

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Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi₂NiTa₂O₉ Pyrochlore

Thermal Expansion, XPS Spectra, and Structural and Electrical Properties of a New Bi₂NiTa₂O₉ Pyrochlore

Crystal structure and enhanced microwave dielectric properties of Ta⁵⁺ substituted Li₃Mg₂NbO₆ ceramics