CERAMICS INTERNATIONAL
·
2024
·Vol. 51
·期 6
·6968-6975
·
IF 5.1
Xinrong Yang,Deqin Chen,Guobin Zhu,Siyu Xiong,Xiaowei Zhu,Laijun Liu,Chunchun Li
The impact of configurational entropy on the microwave dielectric properties of LnNbO 4 fergusonite was investigated by designing a series of high-entropy counterparts, including (La, Nd, Sm, Ho, Yb, Y)NbO 4 (6RNO), (La, Nd, Sm, Eu, Ho, Yb, Y)NbO 4 (7RNO), (La, Nd, Sm, Eu, Gd, Ho, Yb, Y)NbO 4 (8RNO), and (La, Nd, Sm, Eu, Gd, Ho, Tm, Yb, Lu, Y)NbO 4 (10RNO). Simply prepared by the solid-state route, a pure phase with a monoclinic fergusonite structure of space group C /2 c was obtained. By comparing the microstructural evolution and lattice vibration modes, an analysis was conducted on the variations in microwave dielectric performances. It was confirmed that the permittivity ( ε r ) is primarily influenced by relative density, while the quality factor ( Q × f ) exhibits a strong correlation with packing fraction and lattice vibrations. The resonant frequency temperature coefficient (τ f ) is significantly associated with bond valence. The optimal microwave dielectric properties were achieved in 7RNO ceramics at a temperature of 1270 °C, resulting in a relative density of 95.43 %. The microwave dielectric properties were measured as ε r = 18.62, Q × f = 35200 GHz, τ f = −23.28 ppm/°C. The present study expands the application of entropy engineering to achieve ultrahigh configurational entropy in microwave dielectric ceramics . These findings demonstrate that optimizing the configuration entropy is an effective approach for manipulating the dielectric properties, thereby providing valuable insights for material component design.
研究领域:
材料科学
·
无机非金属材料
·
功能陶瓷
·
介电材料
·
固态化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2015
·
IF 2.999
Ying Lei,Yu Li,Lin Xu,Junyou Yang,Rundong Wan,Hongming Long
Nano-structured Half-Heusler TiNiSn thermoelectric bulk was prepared by microwave-assisted rapid solid-state synthesis and sintering. The mixture of powders of Ti, Ni, Sn was cold pressed before being heated by microwave irradiation. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz tube resulting in near single phase compounds in 4 min 20 s. The synthesized sample was milled for 30 min in an agate mortar and cold pressed for the following sintering. An 86% density of TiNiSn thermoelectric bulk contains ∼100 nm pore and nanocrystal was sintered in 20 min. For TiNiSn bulk, low thermal conductivity of 2–3 W/m·K at temperatures in the range of the room temperature to 773 K. The ZT values of around 0.3 are found, with the microwave-prepared sample displaying noticeable superior properties over conventionally prepared half-Heuslers due to inclusion of nanopore and In-situ nanocrystal.
研究领域:
材料科学
·
无机非金属材料
·
功能材料
·
固态化学
·
纳米材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2018
·Vol. 44
·期 9
·10420-10425
·
IF 3.057
Yurun Feng,Xue Guo,Hongyu Gong,Yujun Zhang,Yu Liu,Xiao Lin,Junjie Mao
PDCs-SiCN(Fe) ceramics were successfully fabricated with different content of ferric acetylacetonate (FA) by polymer-derived method. The effects of FA on the phase composition, microstructure, resistivity, dielectric properties , magnetic properties and microwave absorption properties of PDCs-SiCN(Fe) ceramics in the range of 2–18 GHz were investigated. The samples presented amorphous structure with a few crystalline phases of α-Fe and free carbon in the gaps, which were expected to be good soft magnetic materials . The average real permittivity and imaginary permittivity of PDCs-SiCN(Fe) ceramics with 50 wt% FA was about 14.1 and 5.3 respectively. Furthermore, the PDCs-SiCN(Fe) ceramics with 50 wt% FA addition content showed the broad absorption bandwidth in the 5.1–8.4 GHz with RL ≤ −10 dB (> 90% absorption) at 4 mm.
研究领域:
材料科学
·
功能陶瓷
·
电磁特性
·
吸波材料
·
复合材料
✓ 已验证
DOI
高影响因子
POWDER TECHNOLOGY
·
2018
·
IF 3.23
Hongjing Wu,Shaohua Qu,Kejun Lin,Yuchang Qing,Liuding Wang,Yuancheng Fan,Quanhong Fu,Fuli Zhang
It has been rarely reported that the microwave absorption materials can exhibit excellent low-frequency EM wave absorbing properties. In this paper, we synthesized steady short carbon fibers (SCFs)@TiO 2 composites by using simple one-pot hydrothermal process. The conductive short carbon fibers could be separated by TiO 2 nanoparticles from each other and reduced the conductivity of composite materials as a whole, meeting the requirements of impedance matching . With the introduction of SCFs content, SCFs@TiO 2 composites showed improved tan δ E values at low frequencies, implying the enhanced microwave attenuation ability at low and medium frequency. We unexpectedly found that the SCFs@TiO 2 composites exhibited very strong absorbing peaks ( i.e. , −46.3 dB) at low frequencies with relatively thin matching thickness. Interestingly, when the thickness of the SCFs@TiO 2 composite was only 1.0 mm, the absorbing bandwidth with a RL value less than −10 dB was over 14.3–16.7 GHz ( i.e. , absorbing frequency bandwidth is 2.4 GHz).
研究领域:
材料科学
·
电磁功能材料
·
纳米复合材料
·
微波吸收材料
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yilin Huang,Wenjian Wang,Xingwang Hou,Ke Ran,Dongxu He,Shuai Wang,Yuan Fang,Rui Zhao,Weidong Xue
With the development of technology, microwave absorption technology shows its important position. In this work, A simple salt-template method was used to prepare copper phthalocyanine as N-doped graphene intercalated with CuO (CuO/NC). And a method to controllably regulate the dielectric constant by varying the ratio of salt templates and sintering temperature was proposed. When the treatment temperature is 900 °C and the ratio of salt template to raw material is 100:1, The minimum reflection loss (RL min ) of CuO/NC composite can reach −42.05 dB and the effective absorption bandwidth can reach 6.88 GHz with a thickness of 2.1 mm and a raw material filling of only 2 %, covering the entire Ku band. And the superior performance of the material was confirmed by simulation of the monostatic radar cross section. This research provides a new research direction for the synthesis of lightweight broadband microwave absorbing materials.
研究领域:
材料科学
·
纳米科技
·
电磁功能材料
·
复合材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·Vol. 43
·期 17
·15551-15555
·
IF 2.986
Youzhi Wang,Xue Guo,Yurun Feng,Xiao Lin,Hongyu Gong
Ferreous polymer-derived SiCN ceramics (PDCs-SiCN(Fe)) were successfully synthesized by precursor conversion method. The phase composition and microstructure of the obtained products were investigated by XRD , SEM and TEM . The result indicated a mainly amorphous structure with a few α-Fe,and graphite phases in the gaps. The conductivity, electromagnetic parameters and wave absorbing properties of the prepared ceramics were studied at the frequency band from 2 to 18 GHz. The reflectance of PDCs-SiCN(Fe) was about −10 dB (> 90% absorption) in the range of 4–16 GHz with 25 wt% nano-Fe 2 O 3 addition at the thickness 8 mm. The maximum value of dielectric and magnetic loss angle tangent was about 1.5, indicating PDCs-SiCN(Fe) ceramics possessed good absorption performance .
研究领域:
材料科学
·
陶瓷学
·
电磁学
·
功能材料
·
复合材料
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2019
·
IF 2.961
Ziqi Zhu,Pei Yang,Minzhi Chen,Tao Zhang,Yizhong Cao,Wei Zhang,Xiaoyan Zhou,Weimin Chen
Carbon dots (CDs) have sparked tremendous attention owing to their unique properties and great potential in various fields. Herein, novel amphiphilic CDs (ACDs) were synthesized solvothermally by microwave heating a mixture of xylose and ethylenediamine in N, N-dimethylacetamide. The xylose-derived ACDs were monodisperse nanoparticles with an average diameter of about 1.81 nm, and exhibited excitation-dependent emission behavior in both aqueous and several common organic solvents . Furthermore, the synthesized ACDs can be uniformly dispersed into polyvinyl alcohol (PVA) solution to fabricate transparent luminescent composites, the as-prepared PVA/ACDs composites not only exhibited excellent fluorescence with excitation-dependent emission performance, but also achieved water-induced shape memory behavior. The intrinsic reason and pH sensitivity of shape recovery were investigated, the results confirmed that a faster shape recovery can be obtained in water at pH 4 within 180 s. Further investigation illustrated that the sensitivity of additional hydrogen bonding between PVA and ACDs to the water molecular was highly related to the shape recovery of the luminescent composite. The green synthesis route for xylan-derived ACDs and fabrication of smart luminescent composite will open many possibilities for the valuable application of low-cost biomass.
研究领域:
纳米材料学
·
高分子科学
·
生物医学工程
·
功能材料
·
绿色化学
·
智能材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·Vol. 48
·期 6
·8579-8588
·
IF 4.527
Sunyi Shen,Shaolei Song,Jinming Wang,Rong Li,Xingchao Li,Qiang Zhen
Microstructure control and multiple compounding methods in the synthesis stage can enhance microwave absorption performance of microwave absorbents. In this work, we successfully synthesized binary TiB 2 –SiC (TsBC) powders with hexagonal sheet (TiB 2 ) and particle (SiC) interlocking structures by sol-gel carbothermal reduction method. We investigated the effect of raw material ratio and synthesis temperature on the synthesized powders and evaluated the microwave absorption properties of the synthesized TsBC powders. It was found that the TsBC absorber exhibited excellent microwave adsorption properties with the minimum Reflection Loss ( R L ) reached −21.8 dB at 17.4 GHz corresponding to the thickness of 4 mm. This excellent performance was attributed to the interfacial polarization between TiB 2 –SiC interfaces and the multiple reflections between the sheet-particle interlocking structures.
研究领域:
材料科学
·
功能材料
·
复合材料
·
电磁学
·
无机非金属材料
✓ 已验证
DOI
高影响因子
BIOMASS & BIOENERGY
·
2022
·
IF 5.774
Jie Zhang,Danyang Cao,Shanshan Wang,Xin Feng,Jiahua Zhu,Xiaohua Lu,Liwen Mu
In this study, heteroelement-rich groups (N and B elements, tris (2-hydrazinylethyl) borate) were successfully synthesised on lignin by microwave amination. The reaction between lignin and heteroelement-rich groups was confirmed using several characterization techniques, including fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, and X-ray photoelectron spectroscopy (XPS). A lignin model compound (2-phenoxyacetophenone (L-M)) was used to study the bond-breaking mechanism of lignin depolymerization , and the amine group, which acted as a nucleophile , attacked the C–C bond to form an amide bond with the lignin. As an effective additive, modified lignin can increase the viscosity of poly (ethylene glycol) 200 (PEG200), reducing the wear volume and friction coefficient in the friction test. Theoretical calculations showed that the polarity of the modified lignin increased, which allowed the modified lignin to form a strong physical adsorption on the metal surface. In addition, the reciprocal hydrogen bonding between the modified lignin and PEG200 contributes synergistically to the enhanced lubrication film strength , and thus, the better tribological properties of these new lubricants.
研究领域:
高分子化学
·
材料科学
·
绿色化学
·
表面工程
·
能源材料
·
可持续技术
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2018
·Vol. 44
·期 17
·21000-21003
·
IF 3.057
Jie Zhang,Zhenxing Yue,Yu Luo,Longtu Li
A cofired trilayer ceramic architecture showing as MgTiO 3 /TiO 2 /MgTiO 3 was designed to realize temperature-stable and ultrahigh- Q microwave dielectrics in the typical MgTiO 3 -TiO 2 system. The effects of TiO 2 content on the microwave dielectric properties of cofired trilayer ceramics were studied. Through the design of cofired trilayer architecture, the chemical reactions between MgTiO 3 and TiO 2 were limited within a narrow region of MgTiO 3 /TiO 2 interfaces (~ 15 µm in width), which could be beneficial for optimizing the microwave dielectric properties. Excellent characteristics of ε r ~ 18.38, Q×f value ~ 169,900 GHz and τ f ~ − 1 ppm/°C were gained for the MgTiO 3 /TiO 2 /MgTiO 3 ceramic architectures stacked with 1.63 vol% TiO 2 . The current work could serve as new strategies to develop high-performance dielectric resonators and multilayers for 5G wireless communication applications.
研究领域:
材料科学
·
无机非金属材料
·
电子陶瓷
·
微波介质材料
·
功能陶瓷
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 64
·40650-40657
·
IF 3.108
Wei Chen,Qingyun Liu,Xixi Zhu,Min Fu
Strontium ferrites/graphene (SrFe12O19/G) composites were synthesized by a facile one-step surfactant assisted hydrothermal method. The structure, magnetic properties and electromagnetic parameters of the as-prepared composites were evaluated. Uniform SrFe12O19 nanoparticles with a diameter of 60–70 nm were well distributed on the graphene. The formation of SrFe12O19 nanoparticles and the reduction of graphene oxide were accomplished simultaneously. The re-stacking of graphene sheets and the aggregation of SrFe12O19 nanoparticles were inhibited. The as-obtained composites exhibited better absorbing properties than the pristine SrFe12O19 particles due to the synergistic effect of SrFe12O19 and graphene. The minimum reflection loss (RL) of SrFe12O19/G composites with the thickness of 3 mm reached −34.8 dB at 13.6 GHz, and the effective absorption bandwidth (RL < −10 dB) was 5.7 GHz. However, the minimum RL of the SrFe12O19 particles only reached −13.5 dB, and the effective absorption bandwidth was 4.6 GHz. A possible mechanism for the enhanced absorbing performance was proposed.
研究领域:
材料科学
·
纳米材料
·
电磁学
·
功能材料
·
复合材料
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2024
·Vol. 53
·期 10
·6553-6562
·
IF 2.2
Zhang Yu,Ma Jianli,Chen Chen,She Yubin
In this work, non-stoichiometric Li 2(1+ x ) Mg 3 Ti 4 O 12 (L x MTO, x = 0.00–0.05) ceramics with excess lithium were prepared through a simple reaction sintering route to suppress lithium volatilization. According to the characterization of the phase composition and microscopic morphology of the pellets, single-phase L x MTO ceramics with a good microstructure were obtained. Excess lithium effectively inhibited the volatilization and optimized the morphology of the ceramics. A trend in relative density with an initial increase followed by a steep decrease was a predominant observation with the change in dielectric properties. The permittivity of the samples was dominated by the relative density and distortion of the [TiO 6 ] octahedron structure caused by Li + . The dielectric loss primarily originated from the refraction loss and scattering generated by pores, and the grain boundaries also contributed to the loss in the quality factor. Ultimately, at 1220°C, the Li 2.08 Mg 3 Ti 4 O 12 ceramics exhibited excellent microwave dielectric properties: ε r = 17.83, Q × f = 69,823 GHz and τ f = −18.19 ppm/°C.
研究领域:
材料科学
·
无机非金属材料
·
介电材料
·
陶瓷学
·
固态化学
·
电子材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）