JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Sijie Wang,Weishuang Fang,Daofu Wu,Kuiyi Meng,Ying Tang,Junfeng Yang,Mingjian Ding,Huixing Lin,Liang Fang
K20 microwave dielectric ceramics SrLnAlO 4 (Ln = Eu, Gd, and Ho) were prepared at 1440–1520 °C. SrEuAlO 4 and SrGdAlO 4 crystallized into tetragonal K 2 NiF 4 -type structures. While SrHoAlO 4 was a mixture (SrHo 2 Al 2 O 7 , Ho 2 O 3 , and Sr 3 HoAl 2 O 7.5 ) due to the too-small radius of Ho 3+ to bond in [HoO 9 ] dodecahedron . SrEuAlO 4 and SrGdAlO 4 exhibited near-zero τ f values of +1.7 and +4.3 ppm/°C and low ε r (19.37 and 19.14) along with contrasting Q × f values (70,030 and 5560 GHz). Compared with the modified molecular polarizability ( α Corr ) based on the bond valence deviation, the α obs values of SrEuAlO 4 and SrGdAlO 4 are much higher, indicating that their dielectric polarizabilities were underestimated, and this phenomenon was mainly influenced by rattling cations, which also causes their τ f with near-zero values. Due to the magnetic subsystem adversely affecting microwave dielectric losses , the worsened Q × f value of SrGdAlO 4 compared to that of SrEuAlO 4 is due to the high magnetic moment of Gd 3+ (7.94 μ B ).
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
Materials
·
2019
·Vol. 12
·期 5
·803
·
IF 2.972
Lei Tian,Jing Nan,He Wang,Chunying Shen
Perovskite ceramics are a common microwave dielectric material, but the development and application of this material has been limited by the high, positive resonance frequency temperature coefficient and sintering temperature. Therefore, adjusting the temperature coefficient of the resonance frequency and reducing the sintering temperature have become important research directions. In this work, 0.95(Ca0.88Sr0.12)TiO3–0.05(Bi0.5Na0.5)TiO3ceramics (referred to as 0.95CST-0.05BNT) were prepared by standard solid-state reaction and microwave sintering. Microwave sintering greatly shortened the sintering period and holding time. Moreover, the 0.95CST–0.05BNT ceramics showed more uniform grain size distribution, and microwave sintering reduced energy consumption in the experiment. Therefore, the temperature coefficient of the resonance frequency of MWS ceramics was reduced by 119 × 10−6/℃. All of the ceramics, which were sintered at 1300 °C for 40 minutes, showed optimal microwave dielectric properties:εr= 187.6,Q×f= 8958 GHz, andτf= +520 × 10−6/°C.Keywords:dielectric properties;microwave sintering;temperature coefficient;ceramics
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2022
·Vol. 33
·期 15
·11625-11631
·
IF 2.779
Xing Zhuo,Weng Juhai,Ma Chi
A series of Ga 3+ -doped Zn 2 GeO 4 willemite ceramics, in a general formula Zn 2+0.5 x Ge 1− x Ga x O 4 (0.1 ≤ x ≤ 0.4), were prepared and the influence of Ga 3+ doping on the phase composition, structure, microstructure, and microwave dielectric properties were studied. XRD, SEM, and Raman analysis evidence that by moderate gallium substitution in the nominal Zn 2 GeO 4 , the unfavorable ZnO phase was suppressed, while a low-loss ZnGa 2 O 4 phase was induced. With increasing doping content, the ZnGa 2 O 4 phase increases in phase percentage and becomes dominant (~ 69%) after x = 0.3. Due to the mixture rule, both relative permittivity and quality factor were improved, which is related to the superior dielectric properties of ZnGa 2 O 4 compared to Zn 2 GeO 4 . The microwave dielectric properties show a remarkable dependence on the composition. Sintered at 1230 °C, a combination of dielectric performances with ε r ~ 9.4, Q × f ~ 97,000 GHz, and τ f ~ − 30.7 ppm/°C was accessed in the x = 0.4 composition.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2023
·Vol. 224
·期 19
·2300078
·
IF 2.5
Yifei Wu,Kun Wu,Fei Xiao,Wenjie Diao,Daguang He,Hui Yang,Jun Shi
High thermal conductivity polymeric dielectrics with advanced dielectric properties are urgently demanded in various applications. In this study, a series of thermoplastic polyesters containing different content of fluorine and mesogenic unit in main chains are synthesized utilizing polycondensation. The preferred orientation of liquid crystal can effectively inhibit phonon scattering, and the introduction of fluorine can reduce the polarizability of the polymer and increase the free volume. By introducing the biphenyl mesogenic unit and fluorine into the main chain, its thermal conductivity has been increased to 0.425 Wm −1 k −1 from 0.183 Wm −1 k −1 (the polymer without liquid crystal element), which is 132% higher than that of the liquid crystal polymer without fluorine. In addition, the dielectric constant of polyester decreased to 2.97, and the dielectric loss drops to 8.74 × 10 −4 . The influence mechanism of two ways on its thermal and dielectric properties is explored. Good thermal conductivity and excellent dielectric properties make potential in the thermal management system and flexible electronics.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Weichao Wang,Gu Liu,Liuying Wang,Chaoqun Ge,Long Wang,Bin Wang,Jie Huang
The advancement of absorption materials and coating preparation technology is crucial to address the challenges posed by electromagnetic interference and pollution in high-temperature extreme environments. Here, by using a granulation and plasma spraying strategy, we successfully fabricated a series of La 0.8 Sr 0.2 MnO 3 /Al 2 O 3 –13%TiO 2 (LSMO/AT13) high-temperature microwave absorption coatings that have excellent dielectric properties and extremely thermal stability. The results showed that the LSMO/AT13 coatings exhibited remarkable oxidation resistance , withstanding high-temperature aerobic environments of up to 1000 °C. Based on the temperature-dependent permittivity of the coatings, the establishment process of polarization and the transformation of loss mechanism were observed and explained. With the increase of temperature, the main dielectric loss mechanism of the coatings transitions from polarization loss to conductive loss. Thanks to the coordinated effects of impedance and loss, the coatings are capable of effectively absorbing microwave over a wide temperature range. When the LSMO content was 30 wt% and the thickness was 1.9 mm, the effective bandwidth ranged from 1.7 GHz to 2.4 GHz at temperatures below 773 K. This study demonstrates the promising application of LSMO/AT13 microwave absorption coatings for ultra-high temperature environment, and provides a reference for the design and optimization of high-temperature microwave absorption coatings.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2021
·
IF 2.993
Jinxiang Guo,Zhaofei Tong,Qihua Liang,Fangyu Gan,Lepeng Wei,Qingrong Yao,Jianqiu Deng,Zhao Lu,Huaiying Zhou
Bi 1-x Pr x FeO 3 material with perovskite structure was prepared using organic tartaric acid-assisted sol–gel self-propagating combustion method to obtain high-efficiency microwave absorption materials. The influence of the introduction of Pr on dielectric properties and permeability was further studied. After 15% Pr introduced, the lowest reflection absorption loss reaches –32.34 dB, but the absorption bandwidth is only 2.25 GHz. When Pr is 5%, the lowest reflection absorption loss value of −27.31 dB is obtained, and the effective bandwidth which below −10 dB is 3.41 GHz. The structural changes in the process of Pr replacing Bi were analyzed to explore the properties of BPFO perovskite. The influence of strong interaction force, residual magnetization, and natural resonance of ceramic nanoparticles on microwave absorption performance was explored. This work supplies a reliable candidate material for making up electromagnetic attenuation ceramic materials with excellent properties.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 12
·1-16
·
IF 2.8
Wang Fenglin,Mao Haijun,Chen Xingyu,Li Wei,Liu Zhuofeng,Zhang Weijun,Bai Shuxin
In this work, A -site Nd doped BaTiO 3 ceramics in the form of Ba 1− x Nd 2 x /3 TiO 3 with a wide substitution level range of x = 0–0.2 have been prepared via solid-state reaction method. Powder X-ray diffraction results reveal that Nd is completely incorporated into the BaTiO 3 lattice in all specimens. Further analyses based on Rietveld refinement suggest that tetragonal and pseudo-cubic phases coexist in Ba 1− x Nd 2 x /3 TiO 3 ceramics with x ≤ 0.06, and the amount of tetragonal phase is raised with the increase of x value. When x value is larger than 0.08, only pseudo-cubic is observed. The generated \(V^{\prime\prime}_{{{\text{Ba}}}}\) , \({\text{Nd}}_{{{\text{Ba}}}}^{\cdot }\) and \(V_{{\text{O}}}^{{\cdot \cdot }}\) defects, which are identified by X-ray photoelectron spectra, make the grain size displays a tendency of decrease first mainly due to the pining effect, and then increase ascribed to the accelerate of mass diffuse. By introducing such wide range of substitution level, Ba 1− x Nd 2 x /3 TiO 3 ceramics with colossal dielectric constant ( x = 0.08), temperature-stable dielectric properties ( x = 0.15), especially relaxor behavior ( x = 0.20) noticed for the first time, are, respectively, received, which is closely related to the variation of phases and defects induced by the addition of Nd. This study may provide a special idea to modify BaTiO 3 to satisfy diversified applications by single element with a wide doping range, and could lay the foundation of future works focusing on the various potential applications of Ba 1− x Nd 2 x /3 TiO 3 ceramics.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Wei Wan,Meizhen Tao,Hailin Cao,Yuqing Zhao,Junrong Luo,Jian Yang,Tai Qiu
Exploring flexible dielectrics with high dielectric constant and low loss is pertinent for many applications in electronic devices. In the present work, a non-ferroelectric polymer, polyvinyl alcohol (PVA), was used to fabricate homogeneous dielectric composite films with a relatively high dielectric constant and a low dielectric loss by using 2D nano sheets (Ti 3 C 2 T x MXene) as the filler. To limit dielectric loss, SiO 2 was coated onto the surface of MXene to provide interfacial barrier effect and suppress dielectric loss. MXene@SiO 2 /PVA composite films showed lower dielectric losses at low frequencies (from 20 Hz to ~ 10 kHz) compared with MXene/PVA composite films. MXene@SiO 2 /PVA composite films with 2.5 wt% MXene loading and 5 wt% (with respect to MXene content) SiO 2 coating had a dielectric constant of 27.2 (a 292.5% rise compared to neat PVA film) and a dielectric loss of only 0.057 (a 259.6% reduction compared to MXene/PVA composite film) at 100 Hz and room temperature (RT). In addition, this SiO 2 -coated composite film had stable dielectric properties (dielectric constant and loss change from 27.2 to 29.3 and 0.057 to 0.104, respectively) in the temperature range of RT to 60 °C. This work provides a promising way to fabricate PVA-based dielectric composites with excellent dielectric properties for practical applications in electronics.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2020
·Vol. 12
·期 3
·574
·
IF 3.426
Zhicai Zhu,Liqin Yao,Qilong Zhang,Hui Yang
In this paper, homogeneous polystyrene (PS) microspheres with controllable sizes of 40 nm, 80 nm, and 120 nm were synthesized by controlling the temperature of solvothermal method. In order to explore the effect of PS microspheres on dielectric-hydrophobic properties of the composite films, the composite films containing polystyrene, Polydimethylsiloxane, and P(VDF-TrFE) with high dielectric and hydrophobicity were successfully prepared by a simple and feasible solution blending method. The dielectric constant and hydrophobicity of composite films were boosted by increasing the mass fraction of PS content and decreasing the size of PS due to the enhanced interfacial polarization and the uniform surface micro bulge structure. Meanwhile, the composite films maintain a low loss tangent. Typically, the dielectric constant with 5 wt.% 40 nm PS reached to 29 at 100Hz, which is 4 times that of PDMS/P(VDF-TrFE) (mass ratio: 2/3). Otherwise, the largest the contact angle of 126° in the same composition was remarkably larger than the pure PDMS/P(VDF-TrFE) (110°). These improved properties have more potential applications in the electric wetting devices.Keywords:dielectric properties;hydrophobicity;micro bulge structure;interfacial polarization
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Xiaoyu Li,Naichao Chen,Jin Cheng,Xianqiang Chen,Biao Guo,Fei Jin,Hong Wang
The Li 2 MoO 4 -MoO 3 ceramic system can be densely sintered at ultralow temperatures (< 500 °C). However, the phase composition of the Li 2 MoO 4 -MoO 3 system at a molar ratio of 1:1 has always been controversial. In this study, the traditional solid-state method was used to synthesize Li 4 Mo 5 O 17 (400 °C, 10 h) and Li 2 Mo 2 O 7 (350–400 °C, 4 h). Li 2 Mo 2 O 7 is an intermediate phase that can be converted to Li 4 Mo 5 O 17 at higher temperatures. The Li 4 Mo 5 O 17 ceramic could be sintered and densified at only 490 °C in air, exhibiting a relative density of 95.6% and excellent dielectric properties , including ε ′= 12.79 and tan δ = 0.0004 at 1 GHz. Such an ultralow sintering temperature and dielectric loss indicate that the Li 4 Mo 5 O 17 ceramic is a good candidate for high-frequency capacitance applications.
研究领域:
材料科学
·
电子材料
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2015
·
IF 3.569
Biao Zhang,Feng Ye,Ye Gao,Qiang Liu,ShiChao Liu,Limeng Liu
Bisphenol-A cyanate ester resin (BADCy)/Ni 0.5 Ti 0.5 NbO 4 composites with novel structure, within which Ni 0.5 Ti 0.5 NbO 4 and BADCy are continuous directional distribution and parallel to the electric field direction (marked as composite-directional), were designed and fabricated using freeze casting combined with vacuum assisted infiltration process. Dielectric properties as well as the moisture absorption of the composites were studied. Theoretical models used to predict the dielectric properties of the composites were established. Results show that the novel structure can significantly improve the dielectric constant while decrease dielectric loss compare with traditional structure in which Ni 0.5 Ti 0.5 NbO 4 filler is homogeneously distributed (the composite marked as composite-homogeneous). Dielectric constant of composite-directional is as high as 19.93 while dielectric loss is only 4.07 × 10 −3 (at 7319 MHz) when Ni 0.5 Ti 0.5 NbO 4 content is 43.79 vol%. Furthermore, the dielectric constant of both composite-directional and composite-homogeneous can be predicted using Rother-Lichtenecker model when the fitting parameters ( n ) are −0.5188 and −0.1499, respectively. Distribution state of Ni 0.5 Ti 0.5 NbO 4 is the main reason for the difference of fitting parameters. Due to the excellent properties of composite-directional, this kind of composites can be used as printed circuit board (PCB) materials.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2015
·
IF 2.999
Biao Zhang,Feng Ye,Shichao Liu,Haoqian Zhang,Qiang Liu,Ye Gao,Jie Ma
In this study, we developed a new route to fabricate polymer/ceramic composites. This method mainly involves tape casting and vacuum assist infiltration (called TC-VI). Composites, using Bisphenol-A cyanate ester resin (BADCy) as matrix and mixed dielectric ceramic powders (1− x ) Ni 0.5 Ti 0.5 NbO 4 + x ZnNb 2 O 6 ( x = 0–100 vol. %) as fillers, were prepared successfully by this route. Dielectric properties and thermal conductivity of the composites were tested. Furthermore, the migration of silver (Ag) electrodes in the composites was investigated. Results show that the composites exhibit excellent dielectric properties. Dielectric constant of the composites can be adjusted continuously from 13.49 to 22.46 (at 9045 MHz). Dielectric loss is lower than 3.68 × 10 −3 (at 7320 MHz). The addition of ceramic fillers can significantly enhance the thermal conductivity of BADCy resin. Moreover, no obvious Ag element migration can be detected in the composites. Due to the good performances of the composites, this method could be widely used in the fabrication of multilayer devices.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）