POLYMER
·
2024
·
IF 4.1
Quan Yuan,Liwei Yan,Jinfeng Tian,Weiyi Ding,Zhengguang Heng,Mei Liang,Yang Chen,Huawei Zou
Silicon/phenolic hybrid resins are one of the most commonly used materials for thermal protection. However, the weak ability of SiO 2 generated by silicone during ablation to resist the impact of high-speed hot gas flow hinders further improvement of the performance. Therefore, in this work, the ultrahigh-temperature ceramic elements Zr 4+ and Hf 4+ were integrated into hyperbranched polysiloxanes in the form of coordination bond and then introduced into phenolic resin (PR), obtaining hybrid resin with excellent ablative resistance. During ablation, Zr 4+ and Hf 4+ will first undergo ceramization, producing ZrO 2 and HfO 2 . Subsequently, they will undergo a solid solution sintering reaction to produce complex-phase ceramic particles (Zr x Hf 1-x )O 2 , which are embedded in the SiO 2 liquid film and provide excellent pinning effect. This gives the hybrid resin excellent ablation resistance, whose linear ablation rate can be as low as 0.038 mm/s, a 58 % decrease compared to pure PR. This work not only provides a new pathway for ceramization through metal ion coordination bonding, but also provides a new way to prepare high-performance TPS materials.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2024
·
IF 8.1
Yu Han,Yonghui Chen,Xueting Pei,Maolin Zhang,Dongyan Zhang,Zhimin Li,Guozhong Cao,Yuan Wang
The development of Li 7 La 3 Zr 2 O 12 solid state electrolyte is retarded by its low ionic conductivity and surface passivation. A few studies suggest those two hurdles can be solved together. Capitalizing on similar physical and chemical properties of Hf 4+ and Zr 4+ , Hf 4+ doped Li 7 La 3 Zr 2- x Hf x O 12 ( x = 0.3, 0.4, 0.5, and 0.6) is prepared and the influence of Hf 4+ on the structure and electrochemical performance of LLZO is investigated systematically. LLZO with Hf 4+ doping is transformed into cubic phase, and also reduces the secondary reaction between H 2 O, CO 2 and LLZO, while increasing the ionic conductivity of the electrolyte to 2.01 × 10 −4 S cm −1 . The electrochemical window between the LLZHO and lithium metal reaches 4.7 V, which is 0.8 V higher than that of LLZO. The specific capacity of the 1st discharge of the all-solid-state batteries assembled with the LiFePO 4 cathode at 0.1C reaches 110.00 mAh·g −1 . The coulombic efficiency reaches 99.18 % after 100 cycles, and the cycle retention rate is 65.82 %.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 106
·期 5
·2941-2952
·
IF 4.186
Kang Du,Tailai Wen,Mengdie Zhou,Zheyu Liu,Changzhi Yin,Wei Zhu,Cai Zhou,Bohan Zhang,Shengxiang Wang,Wen Lei
The traditional solid-state reaction method was used to prepare Ca 2 Sn 2− x M x Al 2 O 9 (M = Ti, Zr, and Hf) ceramics. Then, the impact of an M 4+ substitution of Sn 4+ on the phase transition, crystal structural parameter, and microwave dielectric properties of Ca 2 Sn 2− x M x Al 2 O 9 (0 ≤ x ≤ 0.4) ceramics were investigated. Ti 4+ could not replace the Sn 4+ of Ca 2 Sn 2 Al 2 O 9 due to its small ionic radius, and the Al-based second phases of Ca 2 Sn 2− x Ti x Al 2 O 9 ceramics were confirmed by the X-ray diffractometer and EDS map scanning results. With the Zr 4+ and Hf 4+ substitutions of Sn 4+ , the SnO 2 and CaSnO 3 second phases of Ca 2 Sn 2 Al 2 O 9 ceramic were inhibited, and the Ca 2 Sn 2− x M x Al 2 O 9 (M = Zr and Hf) (0.05 ≤ x ≤ 0.2) single-phase ceramics with orthorhombic structure ( Pbcn space group) were obtained. New MO 2 (M = Zr and Hf) and CaAl 2 O 4 second phases appeared in the Ca 2 Sn 2− x M x Al 2 O 9 (M = Zr and Hf) (0.3 ≤ x ≤ 0.4) ceramics, and their contents increased gradually with the increase in x . The Ca 2 Sn 2− x M x Al 2 O 9 (M = Zr and Hf) (0.05 ≤ x ≤ 0.2) ceramics exhibited high Q × f because of their pure phase compositions, and the Q × f of Ca 2 Sn 2 Al 2 O 9 ceramic was improved to 77 800 GHz (12.6 GHz) in the Ca 2 Sn 1.9 Zr 0.1 Al 2 O 9 ceramic. The Q × f values of Ca 2 Sn 2− x M x Al 2 O 9 single-phase ceramics were mainly controlled by r c (Sn/M–O) and r c (Al–O). The τ f values of single-phase Ca 2 Sn 2− x M x Al 2 O 9 ceramics were related to octahedral distortions. The Zr 4+ and Hf 4+ substitution of Sn 4+ optimized the phase compositions and microwave dielectric properties of the Ca 2 Sn 2− x M x Al 2 O 9 ceramics, and the Ca 2 Sn 1.9 Zr 0.1 Al 2 O 9 ceramic sintered at optimal temperature exhibited excellent microwave dielectric properties ( ε r = 8.67, Q × f = 77 800 GHz at 12.6 GHz and τ f = −69.8 ppm/°C).
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
TALANTA
·
2015
·
IF 3.545
Haizhu Lin,Chunhui Deng
In this work, we first designed and synthesized an IMAC material with Hf 4+ immobilized on polydopamine-coated magnetic graphene and applied it to phosphopeptides enrichment successfully. The newly prepared material gathered the advantages of large specific surface area of graphene, good hydrophilicity and biocompatibility of polydopamine and superparamagnetism of Fe 3 O 4 . We investigated the performance of Hf 4+ -immobilized polydopamine-coated magnetic graphene (denoted as magG@PDA-Hf 4+ ) in phosphopeptides enrichment and the results showed high selectivity and sensitivity of the new material. Finally, we successfully applied magG@PDA-Hf 4+ to phosphopeptides enrichment from non-fat milk digests and human serum, further demonstrating excellent performance of this new material in phosphopeptides enrichment.
研究领域:
生物化学
·
分析化学
✓ 已验证
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Kewen Shu,Kaifu Yu,Guoquan Ma,Pan He,Meicheng Zhang,Yang Li,Lijian Ma
The coexistence in nature, similar chemical properties, and completely different applications of zirconium (Zr) and hafnium (Hf) make their separation difficult but extremely important. Although solid-phase extraction has shown considerable promise in achieving effective separation of Zr 4+ and Hf 4+ ions, the critical challenge is to develop suitable extractant matrices. Herein, a carbon aerogel with high specific surface area and porosity, derived from covalent organic frameworks was prepared for the first time as an extractant matrix. Subsequently, a phosphonate ligand as the effective functional group was further used to modify the carbon aerogel to prepare the solid-phase extractant. The spectroscopic analysis revealed a tight host-guest interaction between the phosphonate ligand and the carbon aerogel matrix. Impressively, adsorption studies indicated that the phosphonate-functionalized carbon aerogel exhibits Langmuir-type adsorption, affording maximum capacities of 16.8 mg/g for Zr 4+ and 12.0 mg/g for Hf 4+ . Moreover, the Zr 4+ /Hf 4+ separation factor calculated from equilibrium data reached as high as 3.3. Further analysis and theoretical calculation exhibited that the phosphonate in the solid-phase extractant play a decisive role in the adsorption and separation of Zr 4+ and Hf 4+ . Beyond introducing an exceptional solid-phase extractant for Zr 4+ /Hf 4+ separation, this research diversifies the range of potential extractant matrices, thereby creating valuable methodological references for future research.
研究领域:
材料科学
·
环境化学
·
无机化学
·
分离科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Weijia Guo,Yiming Yang,Zhiyu Ma,Yutian Lu,Zhenxing Yue
Microwave dielectric ceramics with high relative permittivity ( ε r ) are commonly used for the miniaturation of microwave devices. The dielectric loss mechanism of microwave dielectric ceramics , as well as the property modification, has been a concerned topic among scholars. Herein, the lattice structure, defects, and broadband dielectric response of Zr 4+ and Hf 4+ substituted Ba 4 Sm 9.33 Ti 18 O 54 (BST) ceramics are systematically examined. The negative temperature coefficient of resonant frequency ( τ f ) of BST ceramics can be tuned to near zero via ion substitution, owing to the Sm 2 Ti 2 O 7 second phase with a large positive τ f . Optimal microwave dielectric properties of ε r = 81.3, Q × f = 10,800 GHz, and τ f = −4.6 ppm/°C are achieved. The lattice vibration behavior and defect concentration are analyzed by Raman spectra and thermally stimulated depolarization currents (TSDC), respectively. The increasing volume of the unit cell and TiO 6 octahedra, which is because of the large-radius substitution ions, leads to an increase in lattice vibration damping factor and the generation of more oxygen vacancies ( V O ∙ ∙ ). Therefore, the dielectric losses in the microwave and terahertz (THz) bands increase after substitution. Meanwhile, the low-frequency dielectric losses at high temperatures also increase due to the weak restraint of carriers by the lattice. The broadband loss mechanism of Zr 4+ and Hf 4+ substituted BST ceramics related to lattice vibration and defects might be referenced for developing low-loss dielectric ceramics.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·Vol. 47
·期 5
·6842-6847
·
IF 3.83
Shunjin Xiong,Rongxia Huang,Congfei Peng,Yejing Dai,Jiajiu Li,Wen Bai,Hua-Tay Lin
A series of HfO 2 -modified (Bi 0 .475 Na 0 . 405 K 0 . 055 Li 0.015 ) 0.95 Ba 0 . 05 Ti (1- x ) Hf x O 3 ( x = 0–0.015) lead-free ceramics were prepared. Results of detailed characterizations showed that the addition of HfO 2 had little influence on the grain size, and all of the samples showed the pure perovskite structure. As the Hf 4+ content increases, the samples changed from the normal ferroelectric phase to the ergodic relaxor state at room temperature, and the ceramics with x = 0.01 showed a high electro-strain of 0.295% at 6 kV/mm. Therefore, this study provides a new insight into of how the HfO 2 addition influences the ferroelectric property of the BNT-based ceramics by B-site substitution.
研究领域:
材料科学
·
无机非金属材料
·
功能陶瓷
·
铁电材料
·
压电材料
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2026
·
IF 3.8
Yuqian Zheng,Ziwang Zhang,Zhuo Li,Deqiang Liu,Huaiyu Wu,Junhui Liang,Enxi Song,Jianxin Shi,Jing Wang
Single-host white light-emitting phosphors have been one of the research hotspots in the field of white light-emitting diodes (WLEDs) in recent years. Herein, white light emission is realized in Sr 8 ZnSc(PO 4 ) 7 :Eu 2+ phosphor by using the defect engineering strategy, i.e. the heterovalent substitution of Sc 3+ with Hf 4+ . Based on the charge compensation mechanism of the substitution, electron paramagnetic resonance (EPR) analysis confirms a positive correlation between cation vacancy concentration and dopant content. Photoluminescence spectra indicates that there are two different emissions at 408 and 520 nm in the phosphor. Under 335 nm excitation, the SZSP:0.02Eu 2+ ,0.03Hf 4+ exhibits cold white light emission with CIE coordinates (0.2992, 0.3214) and an enhanced color rendering index (Ra = 80.02), showing superior performance compared to commercial YAG:Ce 3+ phosphor. This work not only elucidates the critical role of Hf 4+ dopants in defect engineering but also establishes a novel material for developing high-efficiency phosphors with tunable color temperature for WLED applications.
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2025
·Vol. 36
·期 29
·1-17
·
IF 2.8
Sun Shuhui,Pei Qingyin,Zheng Guangwei,Zhang Haixia,Jing Zhenfeng,Zhang Sen,Li Xingfu,Tian Qingbo,Zhang Fengqing
In this study, Hf 4+ -doped BiFe 1− x Hf x O 3 ( x = 0–1.5 mol%) thin films were synthesized via the sol–gel method, and the effects of Hf doping on the structural and electrical properties were systematically investigated. The results reveal that 1.2-mol% Hf incorporation induces lattice distortion and grain refinement, significantly suppressing the formation of oxygen vacancies. Consequently, the Fe 3+ /Fe 2+ ratio increases to 2.03, and the relative concentration of oxygen vacancies decreases to 0.14. Under an applied electric field of 100 kV/cm, the leakage current density is reduced to 2.98 × 10 –6 A/cm 2 , while the remanent polarization reaches 93.92 μC/cm 2 . The dielectric constant is enhanced to 171, showing stable frequency dependence. Aging tests indicate a low polarization degradation rate of only 10.5%, and the optical band gap is widened to 2.60 eV. These results demonstrate that Hf 4+ doping synergistically improves the overall performance of BiFeO 3 thin films through defect suppression and lattice regulation. This work clarifies the mechanism by which Hf 4+ doping enhances the ferroelectric properties of BiFeO 3 films by inhibiting oxygen vacancy formation and optimizing the lattice structure, thereby providing a solid experimental foundation for the development of low-leakage, high-stability ferroelectric memory devices.
✓ 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）