JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2017
·
IF 3.454
Atta Ullah,Hanxing Liu,Hua Hao,Javed Iqbal,Zhonghua Yao,Minghe Cao
(1- x )Mg 0.90 Ni 0.1 SiO 3 - x TiO 2 ( x = 0, 0.01, 0.03, 0.05) ceramics were successfully formed by the conventional solid-state methods and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), and their microstructure and microwave dielectric properties systematically investigated. It was observed that when TiO 2 content increased from 0 to 5 wt%, the Q u f o of the sample decreased from 118,702 GHz to 101,307 GHz and increases the τ f value from −10 ppm/°C to +3.14 ppm/°C accompanied by a notable lowering in the sintering temperature (125 °C). A good combination of microwave dielectric properties (ε r ∼ 8.29, Q u f o ∼ 101,307 GHz and τ f ∼ −2.98 ppm/°C) were achieved for Mg 0.90 Ni 0.1 SiO 3 containing 3 wt% of TiO 2 sintered at 1300 °C for 9 h which make this material of possible interest for millimeter wave applications.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
Crystals
·
2023
·Vol. 13
·期 6
·955
·
IF 2.7
Qi Su,Jingjing Qu,Fei Liu,Changlai Yuan,Xiao Liu,Mingwei Su,Liufang Meng,Guohua Chen
Ti4+-ion-doped (n+ 1)SrO −nCeO2(n= 2) ceramic systems were prepared with the conventional solid-state reaction method, and the effects of the phase structures and compositions, sintering behaviors, microstructures and microwave dielectric properties of these ceramic systems were investigated in detail as a function of TiO2content. The analytical results of the XRD patterns show that the pure (n+ 1)SrO −nCeO2(n= 2) system is a composite-phase ceramic system with coexisting SrCeO3and Sr2CeO4phases (represented as a SrCeO3+ Sr2CeO4system), which belong to the orthogonal structures of the Pmcn (62) and Pbam (55) space groups, respectively. For thexTiO2-(1 − x) (SrCeO3+ Sr2CeO4) (x= 0.1–0.4) ceramic samples, the secondary phase Sr2TiO4can also be detected within the range of the investigated components. Meanwhile, the Raman spectroscopy, SEM-EDS, and HRTEM (SAED) analysis results also verified the correctness and consistency of the phase structures and compositions for all the given specimens. In addition, complex impedance spectroscopy was used to detect the conductive behavior of these compound ceramic systems, and the calculation results show that the appropriate addition of Ti4+-ions can make the SrCeO3+ Sr2CeO4system have better thermal stability. The composition ofx= 0.2 multiphase structural ceramic sample sintered at 1330 °C for 4 h has a near zero τfvalue of ~−4.6 ppm/°C, a moderateεrof ~40.3 and a higherQ×f~44,020 GHz (at 6.56 GHz). The relatively superior-performing ceramics developed in this work are expected to provide a promising microwave dielectric material for communication components.Keywords:phase structures and compositions;SrCeO3+ Sr2CeO4system;TiO2addition;microwave dielectric properties
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
Advanced Energy Materials
·
2022
·Vol. 12
·期 9
·2103607
·
IF 29.698
Zhonghui Gao,Jiayi Yang,Guanchen Li,Thimo Ferber,Junrun Feng,Yuyu Li,Haoyu Fu,Wolfram Jaegermann,Charles W. Monroe,Yunhui Huang
Solid-state sodium–metal batteries will not achieve reasonable power density without electrolytes that solve the dendrite (filamentation) problem. Metal-filament formation during plating at ceramic/metal interfaces can cause electrical failure by internal short-circuit or mechanical failure by electrolyte fracture. Herein, an Na 3 Zr 2 Si 2 PO 12 (NZSP) sodium-ion-conducting NASICON electrolyte in which TiO 2 is incorporated as an additive is presented, leading to a two-phase composite NZSP(TiO 2 ) with improved density, Young's modulus, hardness, grain structure, and bulk permittivity. These features of NZSP(TiO 2 ) suppress dendrite growth along grain boundaries, microcracks, and micropores. As well as demonstrating ultralow ceramic/Na kinetic resistance with electrochemical measurements, X-ray photoelectron spectroscopy is performed to probe interfacial reaction mechanisms. The TiO 2 phase forms within grain boundaries and along NZSP surfaces. This modifies the two-phase material's microstructure and improves its electrochemical performance, while also increasing the critical current density for dendrite formation. Design guidelines are discussed to mitigate microscopic defects and dendrites in two-phase ceramic electrolytes.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Huidong Gu,Chang Feng,Hai-ou Zhu,Haikui Zhu,Xifeng Ding,Lixi Wang,Guohui Zhou,Meng Wang,Shiwo Ta,Qitu Zhang
Li 3 PO 4 ceramic is a promising microwave ceramic material with low dielectric constant. The effect of Li nonstoichiometry on phase compositions, microstructures, and microwave dielectric characteristics of Li 3 PO 4 ceramics, on the other hand, has been examined infrequently. Therefore, in the first part of this study, the stoichiometry and Li nonstoichiometry compositions based on Li 3+x PO 4 (x = 0, 0.03, 0.06, 0.09, 0.12 and 0.15) were prepared by conventional solid-phase method. The results show that a few nonstoichiometric lithium ions enter the lattice of Li 3+x PO 4 . Compared with the chemical content of Li 3 PO 4 , the sintering characteristics, relative dielectric constants and quality factors of Li 3+x PO 4 ceramics can be improved by slightly excessive Li ions, while the properties of Li 3 PO 4 ceramics can be deteriorated by excessive Li ions. Li 3.12 PO 4 ceramics sintered at 975 °C for 2 h have good dielectric properties ( ε r = 5.89, Q×f = 44,000 GHz, τ f = −206 ppm/ ° C). In order to improve its large negative temperature coefficient of resonant frequency, in the following study, rutile nano TiO 2 particles were added as τ f compensator. Adding TiO 2 powders not only effectively improve the temperature stabilities of the multiphase ceramics, but also make the grain growth more uniform. With the increase of TiO 2 content from 0.40 to 0.60, τ f increases from −73.5 ppm/ ° C to +42.3 ppm/ ° C. The best dielectric property of 0.45Li 3.12 PO 4 -0.55TiO 2 composite ceramic is ε r = 13.29, Q×f = 40,700 GHz, τ f = +8.8 ppm/ ° C.
研究领域:
材料科学
·
电子材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Zhiyu Ma,Weijia Guo,Zhenxing Yue
TiO 2 -added Ba 4 (Sm 0.65 Nd 0.35 ) 9.33 Ti 17.75 Al 0.33 O 54 (BSNTA) ceramics were fabricated with a solid-state reaction method. Slight TiO 2 addition increased the dielectric constant ( ε r ) of BSNTA ceramics and brought about a near-zero temperature coefficient of resonant frequency ( τ f ). Sintering in oxygen increased the density of TiO 2 -added BSNTA ceramics and surprisingly concurrently improved the ε r and Q × f value. Thermally stimulated depolarization current (TSDC) measurements indicated that TiO 2 addition introduced oxygen vacancies ( V O .. ) and Ti Ti ' − V O .. defect dipoles and that an oxygen-sufficient sintering atmosphere decreased the concentration of these defects and thus increased Q × f values. From the viewpoint of defect behaviors, this observation offered original insight into the mechanism by which the sintering atmosphere had impacts on the Q × f value of titanate ceramics. Satisfying dielectric properties ( ε r = 79.5, Q × f = 14,840 GHz, τ f = 0 ppm/°C) were attained in oxygen-sintered BSNTA-0.6%TiO 2 ceramics that might be suitable for the manufacture of miniature microwave devices such as filters and antennas.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Jiefei Ding,Xin Ding,Xinxiu Wang,Guanglong Li,Xianglong Meng,Yong Zhang,Ruirun Chen
The application of Mg-based hydrides in portable and stationary energy storage is primarily hindered by sluggish sorption kinetics and unfavorable cycle stability. Herein, an attempt is made to enhance the hydrogen storage properties of MgSc alloy by the addition of TiO 2 nanoparticles to regulate multivalent‑oxygen vacancy. The formation of Sc 2 O 3 and MgTi 2 O 4 phases during heat treatment act as active sites, facilitating hydrogen absorption in the initial stages. Notably, MgSc-TiO 2 demonstrates a rapid rate of de/hydrogenation. The absorption capacity in the first cycle is 6.5 wt%, and releases 6.3 wt% H 2 within just 5 min. TiO 2 doping significantly improves the kinetics and cycling stability of the hydrogen absorption and desorption reaction, achieving a reversible capacity of 6.14 wt% at 320 °C. After 10 cycles, the capacity remains 6.32 wt% without visible decay. The improvement is attributed to the solid solution effect of Sc, the multivalent of Ti, the acceleration of electron transfer by oxygen vacancies and the alleviation of volume expansion stress by MgTi 2 O 4 . Ti hydrides participate in the de/hydrogenation reaction. Additionally, multivalent Ti contributes to electron transfer between Mg 2+ and H − , thereby weakening the stability of Mg H bond. Oxygen vacancies enhance the absorption of hydrogen and accelerate H atoms diffusion.
研究领域:
材料科学
·
能量存储
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纳米技术
·
储氢合金
·
物理化学
✓ 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）