JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 21
·1-13
·
IF 2.8
Su Congxue,Tao Wenlong,Chen Lianchun,Che Haiyan,Wang Ruijuan,Fan Jun,Qin Xingliu,Chen Zhilin,Fang Liang
Orthorhombic olivine-structured LiTmRO 4 (R = Si, Ge) ceramics were synthesized using a solid-state reaction. Promising microwave dielectric properties of ε r = 8.18, τ f = 13.7 ppm/°C and a high-quality factor ( Q × f ) of 24,274 GHz for LiTmSiO 4 were obtained at 1130 °C, and ε r = 8.67, τ f = − 24.4 ppm/°C and Q × f = 19,231 GHz for LiTmGeO 4 were achieved at 1090 °C. According to the bond valence results, Tm 3+ and Ge 4+ presented a compressed state, but Li + exhibited a strong rattling state in LiTmGeO 4 , which led to a higher ε r than ε theo . The integrated effect of the rattling cations (Li + and Si 4+ ) and a compressed cation (Tm 3+ ) in LiTmSiO 4 resulted in a smaller positive deviation ∆ ε r . The larger packing fraction of LiTmSiO 4 contributed to a higher Q × f than that of LiTmGeO 4 . The R–O bond in both ceramics played a leading role in influencing Q × f according to the Phillips–Van Vechten–Levine chemical bond theory.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Kui Liu,Huaiwu Zhang,Cheng Liu,Jie Li,Liang Shi,Xueying Wang,Dainan Zhang
Novel (Mg 0.2 Ni 0.2 Zn 0.2 Co 0.2 Mn 0.2 ) 2 SiO 4 (A5SO) high-entropy microwave dielectric ceramics with olivine structure were prepared in the sintering temperature range of 1100 °C–1300 °C via the solid-phase reaction route. The crystal structure was confirmed by XRD , Raman, and Rietveld refinement . Optimal microwave dielectric properties ( ε r = 8.02, tan δ = 0.00051 at 14.5 GHz, and τ f = −38.2 ppm/°C) were obtained at the sintering temperature of 1250 °C, where a relative density of 95.1% was detected. The complex chemical bonding theory manifests that the ε r value of A5SO is mainly affected by the ionicity of A-O (A = Mg, Ni, Zn, Co, Mn) bond, while the dielectric loss is affected by both A-O and Si–O lattice energy. The τ f value is mainly influenced by the [A(2)O 6 ] oxygen octahedral distortion (1.8 × 10 −3 ). The experimental results of this study provide both theoretical and practical guidance for high-entropy microwave dielectric ceramic applications.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2019
·Vol. 103
·期 3
·1789-1797
·
IF 3.094
Junqi Chen,Ying Tang,Changzhi Yin,Mingyang Yu,Huaicheng Xiang,Chunchun Li,Xianran Xing,Liang Fang
An ultra-low dielectric loss ceramics Mg 2 Ge 0.98 O 4 with olivine structure was fabricated by conventional solid-state route. The phase composition, crystal structure, and microwave dielectric properties were investigated. The phase of Mg 2 Ge 0.98 O 4 is formed to the orthorhombic forsterite structure with a space group Pmnb (62). The dense microstructure and excellent microwave dielectric properties of Mg 2 Ge 0.98 O 4 ceramic were obtained at 1360°C for 4 hours, with relative density ~96.4%, ε r ~ 7.3, Q × f = 112 400 GHz, and τ f ~ −64.6 ppm/°C. The conductive mechanism of Mg 2 Ge 0.98 O 4 in the low frequency (<1 MHz) was studied by the dielectric spectroscopy and the result with E dc = 0.93 eV demonstrates that the defect was contributed to the double ionized oxygen vacancies. The intrinsic dielectric properties of Mg 2 Ge 0.98 O 4 in the microwave region were obtained by infrared reflectivity spectra with ε r ~ 7.13, Q × f = 120 400 GHz. And, acceptable τ f (~+2.6 ppm/°C) of 0.92Mg 2 Ge 0.98 O 4 –0.08CaTiO 3 composite ceramic was obtained by adding the CaTiO3.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2024
·Vol. 53
·期 5
·2229-2239
·
IF 2.2
Wang Xi,Shi Xiaofei,Lin Kehuan,Cheng ZeLai,Huang FangYi,Wu XiaoHui,Su Hua,Tang XiaoLi
Mg 1+ x Co 1− x SiO 4 ( x = 0–0.2) microwave dielectric ceramics were prepared via a solid-phase reaction method. X-ray diffraction (XRD) data revealed a single-phase structure for these ceramics, with no phase changes with increasing Mg content, and Mg 1+ x Co 1− x SiO 4 ( x = 0–0.2) possessed an olivine structure. X-ray diffraction (XRD) patterns were refined via the Rietveld method to obtain crystal structure information. P–V–L bond theory was applied to analyze the crystal structure changes. Scanning electron microscopy (SEM) images highlighted a dense and uniform surface grain distribution with scarce pores. Raman spectroscopy was employed to characterize the impact of lattice vibrations on the Q×f factor. Excellent microwave dielectric properties were exhibited by the MgCoSiO 4 ceramics sintered at 1250 °C for 4 h (ε r = 7.17, Q×f = 46120 GHz, and τ f = −61.7 ppm/°C) and the Mg 1+ x Co 1− x SiO 4 ( x = 0.05–0.2) ceramics sintered at 1400 °C (ε r = 6.9, Q×f = 118575 GHz, and τ f = −47.7 ppm/°C).
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2025
·
IF 4.7
Wenzhuo Chen,Jian Yang,Jiazheng Hao,Feiran Shen,Lunhua He,Xia Deng,Jiasheng Lv,Jing Fang,Laijun Liu,Jungu Xu
The undoped K2ZnV2O7 material has a melilite-like structure, with the K+ ions distributed orderly on two distinguishable crystallographic sites, which is the main difference with the case in a typical A2B3O7 melilite material where the A site cations occupy only one crystallographic position. Herein, we report that substitution of Ga for Zn in K2ZnV2O7 would induce the K+ ions’ order-to-disorder transition and transform the K2ZnV2O7 from the melilite-like structure to a typical melilite phase, coupled with significantly enhanced oxide ion conductivity, e.g. ∼1.01 × 10–1 S/cm at 600 °C for the K2Zn0.7Ga0.3V2O7.15 sample, which is about 2 orders of magnitude higher than the parent material. The powder neutron diffraction data analysis results revealed two sites for the interstitial oxygen defects that are introduced by the donor-doping. The introduction of interstitial oxygen into the K layer strongly correlated with the K ions’ order-to-disorder transition, while the interstitial oxygens within the 5-fold (Zn/Ga/V)O4 tetrahedral rings are responsible for the enhanced oxide ion conductivity. These findings provided a comprehensive understanding of the melilite-like and typical melilite materials for the mechanism of the stabilization and migration of interstitial oxygen defects.
研究领域:
材料科学
·
固体化学
·
电化学
·
晶体学
·
无机化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Wei Peng,Jinquan Liu,Weijing Yuan,Qiqiang Huang,Peng Zhang,Chenxi Li,Yi Guo,Lianghao Wen,Zuoguo Xiao,Jinli Liu,Yang Li,Dongsheng Ren,Languang Lu,Minggao Ouyang,Xiang Liu
Conventional LiFePO4 cathodes face limitations due to their low operating voltage (3.4 V) and discharge capacity. Partial Mn substitution in LiMn0.6Fe0.4PO4 (LMFP) elevates the discharge potential to 4.1 V, yet challenges such as Mn dissolution and structural degradation persist during charge/discharge cycling. Traditional solid-state approaches often produce inhomogeneous phases and impurities, while hydrated phosphate precursors synthesized via coprecipitation offer a promising alternative─though their thermal evolution remains poorly characterized. This study deciphers the phase transformation mechanisms during LMFP synthesis from Mn0.6Fe0.4PO4·0.25H2O precursors, employing in situ heating X-ray diffraction (XRD) to map structural evolution under thermal treatment. Carbon integration promotes structural decoupling, enabling efficient Li+ insertion into the olivine lattice. Contrasting with the conventional single-step process, the gradient-sintered (multistage heating) based on the phase transition mechanism enhances phase purity, suppresses impurities, and improves crystallinity by optimizing intermediate phase transitions. Electrochemical evaluations confirm that gradient-sintered LMFP delivers a higher specific capacity than the non-gradient counterparts. These findings establish a paradigm for controlled reaction pathways in LMFP synthesis, emphasizing the critical role of staged thermal treatment and carbon mediation in minimizing parasitic reactions. This work advances scalable strategies for high-performance manganese-stable lithium-ion battery cathodes.
研究领域:
材料科学
·
电化学
·
储能
·
电池技术
·
固态化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Energy Storage Materials
·
2025
·
IF 20.2
Cheng Cheng,Wei Mao,Xuan Cao,Kaijun Xu,Shaochun Tang
With the retirement of a large number of lithium-ion batteries, how to efficiently recycle cathodes, especially for spent LiFePO 4 (S-LFP) olivine materials with low content of valuable elements, has become a research focus. Moreover, upcycling S-LFP to high-voltage olivine LiMn x Fe 1-x PO 4 (LMFP) is crucial for advancing next-generation cathode materials. Herein, this study proposes a solvothermal upcycling strategy that achieves complete elemental recovery and converts S-LFP into high-voltage LMFP. The resulting LMFP exhibits a uniform elemental distribution, attributed to the atomic-level miscibility of Fe and Mn. As a result, the regenerated LMn 0.5 Fe 0.5 PO 4 exhibits remarkable cycle stability with 83.8 % capacity retention after 2500 cycles at 5 C and a 40 % improvement in energy density (561 Wh kg -1 ) over that of S-LFP (402 Wh kg -1 ). This study presents an effective, direct upcycling route for the large-scale production of next-generation, high-performance olivine cathode materials while achieving sustainable reutilization of S-LFP through closed-loop life cycle management.
研究领域:
材料科学
·
储能
·
电化学
·
可持续化学
·
电池回收
✓ 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）