Journal of Materiomics
·
2020
·
IF 5.797
Gang Liu,Jia Dong,Leiyang Zhang,Yan Yan,Ruiyi Jing,Li Jin
In the present work, the nature of phase evolution of (1− x )(Na 0.5 Bi 0.5 )TiO 3 - x SrTiO 3 (NBT- x ST) solid solutions with x of 0–0.6 is revealed by characterizing the dielectric and ferroelectric properties. Two unique dielectric anomalies associated with high-temperature nanoregions (PNRs) in the ergodic relaxor (ER) state and low-temperature PNRs in the nonergodic relaxor (NR) state are identified. Characteristic temperatures, including T B , T RT∗ , T m , T d and T T ∗ , are determined in fresh and poled states on the basis of the characteristics of the evolution of these two dielectric anomalies. The whole evolution of the transition from the NR state to the ER state is reflected by the temperature-dependent polarization versus electric field ( P - E ) hysteresis loops, i.e., from the square loops, via the double-like loops, to the slim loops. The characteristic temperatures, including T P-N , T N-R and T R-dis , are determined by the characteristics of the evolution of P - E loops. Accordingly, a phase diagram of NBT- x ST was constructed according to these characteristic temperatures. Most importantly, the relationship between polarization responses and heterogeneous polar phase coexistence has been established and a schematic diagram is given. This work will help to understand the phase evolution and its impact on the macroscopic properties of NBT and the associated NBT-based solid solutions.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Zhenyu Xu,Han Liu,Weiping Zhou,Wanchun Yu,Guoqiang Xiao,Di Lu,Fei Gao,Zhenzhi Cheng,Guangsheng Luo
In this study, the impact of Gd 3+ doping on the structural, magnetic and dielectric properties of BaSrCo 2 (Fe 1- x Gd x ) 11 AlO 22 ( x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) ferrite ceramics synthesized by the conventional solid-state reaction method are investigated. XRD results reveal that all the samples crystallize in the R 3 ‾ m space group. With the increase of Gd content, the formation of M-type phase is effectively inhibited due to Gd 3+ ions may change the activation energy of nucleation of the grains and the formation energy of hexaferrite. SEM analysis confirms the presence of hexagonal grains in samples with homogeneous elements distribution. The XPS results verify the coexistence of ferric and ferrous ions in the ceramics. The magnetization and coercivity are suppressed by Gd 3+ substitution. The permeability increases firstly and then decreases with the substitution of Gd ions. While the dielectric constant increases with the substitution of Gd. The real and imaginary parts of the dielectric constant in the frequency range of 2–18 GHz change slightly with doping amounts variation, and all the samples exhibit prominent peaks at about 14 GHz due to natural resonance.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOM
·
2024
·
IF 2.1
Saleem Muhammad Farooq,Ashraf Ghulam Abbas,Javid Muhammad,Haleem Yasir A.,Haidry Azhar Ali,Farooq Sajid,Lei Ma,Bilal Muhammad,Habib Muhammad,Akhtar Muhammad Saeed,Khan Rashid,Wang Tianwu
Understanding the dielectric properties of materials in the THz frequency range is crucial for the advancement of THz devices. Despite their significance, the dielectric characteristics of zirconium carbide (ZrC) within this frequency range remain underexplored, in particular the impact of surface carbon and oxide layers typically found on carbide particles. While traditional studies mainly focus on particle size, this study emphasizes the pivotal role of particle morphology in determining dielectric properties. Milling was employed to increase the surface exposure of ZrC particles, which were initially covered with layers of carbon and oxides. The dielectric parameters, derived from experimental THz time-domain spectroscopy (THz-TDS) data, indicated that increased milling led to improved energy storage capabilities. This enhancement is attributed to increased electronic polarizability and charge disorder-induced ionic polarization due to the increased surface exposure. Furthermore, the dielectric properties displayed reduced dispersion after further milling attributed to the uniform particle sizes and shapes achieved through this process. Our findings underscore the critical influence of surface carbon and oxide layers on the dielectric properties of ZrC and similar carbide particles—an aspect often overlooked in studies that focus solely on particle size and shape, ignoring the distinct dielectric contributions of each surface layer.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 50
·31654-31662
·
IF 3.108
Jun Wang,Xilin Wang,Youwei Yao,Juyi Guo,Xiaogang Ouyang,Zhidong Jia
The application of polymer composites with electric field dependent nonlinear conductive and dielectric characteristics for high voltage equipment is an effective method to control electric field stress and disperse space charges. In this study, core-satellite CaCu3Ti4O12@ZnO fillers were synthesized and doped into silicone rubber composites, and compared to a mixture of CaCu3Ti4O12 and ZnO with the same filler concentration. The composites exhibited both nonlinear conductive and nonlinear dielectric properties with nanoparticle fillers for the first time. Both the nonlinear conductive coefficient and dielectric coefficient increased with filler concentration. The classical current-path model was utilized to explain the nonlinear conductive properties, while the interface-barrier-layer-capacitor model and double-depletion-layer model were introduced to explain the nonlinear dielectric properties, which would broaden the thinking for the fabrication of nonlinear composites.
研究领域:
材料科学
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 59
·37194-37204
·
IF 3.361
Muqun Wang,Yuxuan Qin,Wei Gao,Shaofeng Liang
With the rapid increase of intelligent communication equipment, electromagnetic pollution is becoming more and more serious, and the research and application of high-performance electromagnetic shielding materials have attracted great attention from the academic and engineering circles. Traditional metal-based electromagnetic shielding materials have high reflection loss, high density, and are difficult to process. Polymer-based materials with carbon materials as fillers have the advantages of flexibility, light weight, corrosion resistance and low processing costs. They have become the most important materials in the field of electromagnetic shielding in recent years. However, the conductivity of conductive polymer materials is not high. Therefore, improving the electromagnetic shielding performance and the proportion of absorption loss under low density conditions have become key issues for polymer-based electromagnetic shielding materials. MWCNT/MCHMs/WPU composites were prepared by a solution mixing method, with 20 wt%, 40 wt%, 60 wt% MWCNTs and 40 wt% MWCNT/10 wt% MCHMs as fillers. By comparing the effects of different MWCNT content and MCHMs on the dielectric properties, electromagnetic shielding properties and mechanical properties of the MWCNT/MCHMs/WPU composites, the relationship between the structure and properties of the composites has been explored. The 0.6 mm WPU/60 wt% MWCNT composite has an electrical conductivity of 95.4 S m−1 and an electromagnetic shielding effectiveness of 40 dB in the X band. Adding 10 wt% MCHMs to the WPU/40 wt% MWCNT composite material can significantly improve the composite. The δ of the material increased from 51.2 S m−1 to 55.4 S m−1, and the SE increased from 30 dB to 33 dB. The research results show that the increase in MWCNT content and MCHMs is beneficial to improving the electrical conductivity and electromagnetic shielding performance of the composite materials.
研究领域:
材料科学
·
电磁学
·
聚合物科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Geng Wang,Qiuyun Fu,Longhui Zha,Ming Hu,Jin Huang,Zhiping Zheng,Wei Luo
A series of high-k Ba 4 Nd 28/3 Ti 18- y Ga 4 y /3 O 54 (0≤ y ≤2, BNTG) ceramics with temperature stable and ultra-low dielectric loss were synthesized via the conventional solid-state reaction. The main phase of all BNTG ceramics demonstrated an orthorhombic tungsten-bronze structure, but the impurity phase (gallium-rich phase) was found in BNTG ( y = 2) ceramic. Partial substitution of Ga 3+ for Ti 4+ in B-site was a valid method to improve the temperature stability and dielectric loss of BNTG ceramics. The variation of ε r values of BNTG ceramics was dominated by the ionic polarizability. The ultra-low dielectric loss (ultra-high Q × f values) was associated with grain size, suppression of Ti 3+ and impurity phase. The decrease of TCF values was highly dependent on the tilting of Ti-O octahedra and impurity phase. Finally, outstanding combination dielectric characteristics were achieved for BNTG microwave ceramics at y = 1.5 ( ε r = 72.8, Q × f = 14,600 GHz, TCF=+4.1 ppm/°C) and at y = 2 ( ε r = 70.3, Q × f = 15,500 GHz, TCF=+3.9 ppm/°C).
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
CARBON
·
2019
·
IF 7.466
Hailong Xu,Xiaowei Yin,Xiaomeng Fan,Zhiming Tang,Zexin Hou,Minghang Li,Xinliang Li,Litong Zhang,Laifei Cheng
Designing pure carbonaceous microwave absorbers with strong absorption capability and broad effective absorption bandwidth (EAB) is still a challenge for efficient microwave absorption. Here, a kind of bimetallic metal-organic frameworks derived porous amorphous carbon particle with hollow graphene spheres confined in it (HGS@PAC), was prepared by the controlled annealing process . The thickness of hollow graphene spheres could be tuned from 9 graphene layers to 24 graphene layers by adjusting the annealing time, and thereby tuning their dielectric properties . The minimum RC of the optimized HGS@PAC reaches −56 dB at 3.5 GHz with a thickness of 6.75 mm, indicating its strong microwave absorption performance . In addition, the widest EAB reaches 5.6 GHz (12.4–18 GHz) with a thickness of only 1.85 mm. It is important to highlight that the EAB can cover the whole measured bandwidth (2–18 GHz) with the sample thickness ranging from 1.85 mm to 10 mm. The enhanced microwave attenuation ability can be ascribed to the enhanced interfacial polarization , dipole polarization, and conductive loss, resulting from the designed unique architectures.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Yuxin Fu,Yugang Huang,Runsheng Huang,Haojie Zhang,Rui Zhan,Jianwen Yang
To reduce the limitations of traditional polyimides (PIs), such as poor processability, limited flexibility, and low solubility, a series of siloxane-modified photosensitive PIs (PSPIs, designated as D1∼D6) were designed and synthesized. The cured films of these PSPIs were prepared by UV irradiation. In comparison to conventional PIs, the cured films exhibited good heat tolerance, enhanced flexibility, and a lower glass transition temperature. Some films demonstrated very good mechanical properties, low dielectric characteristics, and excellent hydrophobicity, with a maximum tensile strain of 66%, a low dielectric constant as low as 2.7, a high surface contact angle of 113°, and a minimal moisture absorption as low as 0.02%. These cured films hold great potential for applications in packaging and solder mask protection for high-frequency, high-speed printed circuit boards (PCBs).
研究领域:
材料科学
·
高分子化学
·
电子工程
✓ 已验证
DOI
高影响因子
ORGANIC ELECTRONICS
·
2023
·
IF 3.2
Farooq Aslam,Guanghao Qu,Yang Feng,Shengtao Li
It is well known that the interfacial region between the polymeric matrix and nanofiller plays a very important role in tailoring the electrical insulation properties of nanocomposite. In this study two type of polyhedral-oligomeric-silsesquioxane (POSS) are doped into epoxy (EP) to investigate the tailoring of interfacial traps that can limit the mobility of charge carriers and enhance the breakdown strength . Incorporating acryloxypropyl POSS (AP-POSS) to EP matrix improves the breakdown strength than that of pristine EP and octaphenyl POSS (OP-POSS). The molecular simulation and experiments identifies that the compatibility between EP/POSS and trap depth is dependent on the interfacial interaction energy and crosslinking density. The side groups of AP-POSS has large number of localized energy states and higher electron affinity ( E A ) that can tailor deeper traps and restrain the mobility of electrons in EP/AP-POSS. The interfacial compatibility of POSS side groups with EP tune the interfacial traps and dielectric characteristics.
研究领域:
材料科学
·
电气工程
·
纳米技术
✓ 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）