JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
C.F. Xing,J. Bao,Y.F. Sun,J.J. Sun,H.T. Wu
A novel Ba 2 BiSbO 6 microwave dielectric ceramic was prepared via the traditional solid-state method, and the microwave dielectric properties of Ba 2 BiSbO 6 were investigated for the first time. The analysis of X-ray diffraction patterns indicated that the pure monoclinic Ba 2 BiSbO 6 phase could be formed in the temperature range of 950–1150 °C. Rietveld refinement results further confirmed that Ba 2 BiSbO 6 belonged to a monoclinic system with space group I2/m (12). Dense and homogeneous microstructures of Ba 2 BiSbO 6 ceramics sintered at 1100–1150 °C could be revealed from the scanning electric microscope. The bond ionicity, lattice energy and coefficient of the thermal expansion were initially calculated based on the complex chemical bond theory. The complex dielectric constant and loss were gained from the fitting data of far infrared spectra, which were in good agreement with the measured values. The optimum microwave dielectric properties of ε r = 26.61, Q · f = 13,764 GHz (at 5.95 GHz) and τ f = −26.6 ppm/°C were achieved in Ba 2 BiSbO 6 ceramic sintered at 1100 °C.
研究领域:
材料科学
·
陶瓷工程
·
电子材料
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2016
·Vol. 45
·期 10
·5133-5139
·
IF 1.491
Ullah Atta,Liu Hanxing,Hao Hua,Iqbal Javed,Yao Zhonghua,Cao Minghe,Xu Qi
The ceramics were prepared using the solid-state reaction method and their phase, microstructure and microwave dielectric properties were investigated. A single-phase clinoenstatite system with monoclinic structure (space group P2 1 /c) was confirmed through x-ray diffraction (XRD) analysis for the compositions with x ≤ 0.1. The compositions with x ≥ 0.15 contain SiO 2 and (Mg 1− x
Ni
x
) 2 SiO 4 phases only as confirmed from the XRD data of their sintered samples. The unit cell volume was decreased while the theoretical density was increased with increase in x from 0 to 0.1. A decrease in dielectric constant ( ε
r ) while an increase in unloaded quality factor multiplying the resonant frequency ( Q
u
f
o ) and temperature coefficient of resonant frequency ( τ
f ) was observed with increase in Ni content from 0 to x = 0.1. In the present study, ε
r ∼ 6.10, Q
u
f
o ∼ 118,702 GHz and τ
f ∼ −10 ppm/°C was achieved for the composition with x = 0.1 sintered at 1425°C for 9 h. The material is a good candidate for millimeter wave applications.
研究领域:
材料科学
·
陶瓷学
·
物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 20
·8491-8501
·
IF 3.553
Zhang Yun,Ding Shihua,Li Chao,Song Tianxiu,Zhang Yingchun
A new type of ceramic, namely MnZrTa 2 O 8 , was synthesized after sintering at high temperature in this work. The possible dielectric loss mechanism was discussed by Raman spectroscopy and chemical bond theory. X-ray diffraction indicated that MnZrTa 2 O 8 formed through a reaction between ZrO 2 and intermediate MnTa 2 O 6 . After sintering at 1350 °C, a monoclinic structure with cell parameters a = 4.8370(3) Å, b = 5.7163(1) Å, c = 5.1398(5) Å, β = 91.7219° was gained for ceramic. Among all bonds, Ta–O with the greatest bond ionicity and lattice energy was the dominant factor that influenced the microwave dielectric properties. The temperature coefficient of the resonant frequency τ f changed from − 50.55 to − 41.21 ppm/ °C, which was related to the lattice energy. The effect of porosity on dielectric loss was also checked and found to be significant. MnZrTa 2 O 8 ceramic exhibited relative permittivity ε r ~ 23.0 and enhanced quality factor Q × f ~48103 GHz (at 8.97 GHz), which provided a promising candidate for electric components.
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 30
·16919-16928
·
IF 3.049
Wenzhi Li,Mingxue Su,Tao Yang,Tingwei Zhang,Qiaozhi Ma,Song Li,Qifu Huang
Liquid fuel intermediates can be produced via aldol condensation reactions through furan aldehydes and ketones driven from biomass. It was found that cerous phosphate (CP) with two different crystal structures (hexagonal and monoclinic structure), which was tailored by different hydrothermal temperature (120 °C for the hexagonal structure and 180 °C for the monoclinic structure) and calcination temperature (900 °C for the monoclinic structure) as a solid acid catalyst, exhibit high catalytic performance in aldol condensation between furfural and acetone. The CP with hexagonal structure gave 89.1% conversion of furfural with 42% yield of 4-(2-furyl)-3-buten-2-one (FAc) and 17.5% of yield of 1,5-di-2-furanyl-1,4-pentadien-3-one (F2Ac), much higher than CP with monoclinic structure. However, both furfural conversion and aldol product yield increased from 82.3% to 96% and from 50.5% to 68.4%, respectively, for CP with the monoclinic structure after calcination owing to the higher amount of acid of catalyst after calcination but decreased continuously for CP with hexagonal structure after calcination because of its rapidly reduced BET surface area and total pore volume. The results indicated that calcination affects significantly the physical–chemical properties of CP catalysts, which influence subsequently the catalytic performance in the aldol condensation reaction. Recycling experiments showed that the catalytic performance after five number runs for CP with monoclinic structure after calcination was acceptable but was not ideal for CP with hexagonal structure owing to its poor hydrothermal stability.
研究领域:
催化化学
·
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2024
·Vol. 14
·期 21
·14716-14721
·
IF 3.9
Xiang-Yu Niu,Xin-Yi Dou,Cheng-Yu Fu,Yi-Chun Xu,Xu-Yong Feng
Halide solid-state electrolytes (SSEs) are considered promising candidates for practical applications in all-solid-state batteries (ASSBs), due to their outstanding high voltage stability and compatibility with electrode materials. However, Na+ halide SSEs suffer from low ionic conductivity and high activation energy, which limit their applications in sodium all-solid-state batteries. Here, sodium yttrium bromide solid-state electrolytes (Na3YBr6) with a low activation energy of 0.15 eV is prepared via solid state reaction. Structure characterization using X-ray diffraction reveals a monoclinic structure (P21/c) of Na3YBr6. First principle calculations reveal that the low migration activation energy comes from the larger size and vibration of Br− anions, both of which expand the Na+ ion migration channel and reduce its activation energy. The electrochemical window of Na3YBr6 is determined to be 1.43 to 3.35 V vs. Na/Na+, which is slightly narrower than chlorides. This work indicates bromides are a good catholyte candidate for sodium all solid-state batteries, due to their low ion migration activation energy and relatively high oxidation stability.
研究领域:
材料科学
·
电池技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Electronic Materials
·
2022
·
IF 4.494
Jing Li,Yinlu Gao,Xinglai Zhang,Lixin Chen,Yonghui Ma,Liu Yang,Qing Liu,Xue Jiang,Baodan Liu
The phase transformation threshold and mechanism of layered GaTe1–xSex crystals have been controversial for a long time. Herein, we demonstrate that an extremely low Se content of 20% can induce the phase transformation of GaTe1–xSex from monoclinic structure to hexagonal structure. Theoretical and experimental studies reveal that the introducing of Se dopants effectively stabilizes the host lattice of metastable h-GaTe and thus induces the transformation of GaTe1–xSex from monoclinic to hexagonal lattice in the low Se doping range. The obtained GaTe1–xSex crystals also display tunable band gaps from 1.65 to 1. 85 eV and near band edge emission from 755 to 675 nm with increasing Se content from x = 0 to x = 0.44. More importantly, in comparison with GaTe and GaSe, layered GaTe1–xSex nanosheets exhibit p-type conductivity, higher carrier concentration, excellent photoresponse, and air stability. The fabricated GaTe1–xSex nanosheet photodetectors also show outstanding performance in the UV and visible range including a high responsivity of 91.3 A/W, an excellent EQE of 3.16 × 104%, and a specific detectivity of 5.05 × 109 Jones.
研究领域:
材料科学
·
光电子学
·
纳米技术
·
半导体物理
✓ 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）