CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Jianbo Xu,Xinchao Qiu,Bowen Zhang,Gangfu Zhong,Maokang Shen,Xiangli Liu,Jun Ou-Yang,Yue Zhang,Benpeng Zhu,Xiaofei Yang,Shi Chen
Hafnium oxide (HfO 2 ) fibers can be widely used in ultra-high temperature ceramics (UHTCs) as reinforced material in order to achieve better antioxidant performance and less cracks and flaking on surface of UHTCs in field of ultra-high temperature thermal protectors. Calcination temperature is one of essential parameters for forming HfO 2 fiber. In this work, one-dimensional (HfO 2 ) fibers were prepared through the electrospinning method and further post-calcination treatment. During the calcination treatment, the monoclinic-HfO2 (m-HfO 2 ) was formed from as-spun HfO 2 fibers at 432 °C, and only a small amount of m-HfO 2 was converted into the tetragonal HfO 2 at 1013 °C, which can increase the fiber density and decrease the grain size. However, the remaining m-HfO 2 was directly converted into the cubic HfO 2 at 1351 °C. The unique temperatures of forming monoclinic, tetragonal, cubic phase were much lower than the phase-transition temperature. The prepared HfO 2 fiber could still maintain fibrous morphology after 10 times cyclic thermal shock in air. Moreover, the fibers calcined at 900 °C and 1200 °C have better thermal shock resistance for their stable phase and fibrous morphology with uniform grain growth after the thermal shock test.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2020
·Vol. 35
·期 16
·2230-2238
·
IF 2.502
Zhou Ying,Gan Guoyou,Ge Zhenhua,Feng Jing,Song Peng
HfO 2 –Sm 3 TaO 7 ceramics are prepared through a solid-state reaction method. The X-ray diffraction and structural refinement show that the phase structures of HfO 2 –Sm 3 TaO 7 ceramics are an ordered orthorhombic phase and the space groups are belonging to Ccmm . The degree of the structural disorder increases with increasing HfO 2 content. The solid solution mechanism reveals that Hf 4+ exists in the form of interstitial ions that cause crystal expansion when the doping content is less than 4 mol%. When the doping concentration of HfO 2 ≥ 4 mol%, the Hf 4+ ions can substitute an equal number of Sm 3+ and Ta 5+ ions. The phase transition of Sm 3 TaO 7 ceramics is removed with increasing HfO 2 content, and the 8 mol% HfO 2 –Sm 3 TaO 7 ceramics have a high thermal expansion coefficient of 10.2 × 10 −6 K −1 at 1200 °C. The 2 mol% HfO 2 –Sm 3 TaO 7 ceramics have the lowest thermal conductivity (1.03 W/m K at 900 °C), which is lower than previous research of the 7–8 YSZ. The outstanding thermophysical properties of HfO 2 –Sm 3 TaO 7 ceramics indicate that they are potential thermal-barrier coating materials.
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
·
2024
·
IF 4.2
Xiaoqin Liu,Jianbo Liu,Wei Li,Qingqing Sheng,Yeming He,Yangyang Wang
Sol–gel method is a low-cost material preparation method; however, it is difficult to obtain a stable sol containing easily hydrolyzable metal ions via this method. In this study, a stable hafnium(IV) oxide (HfO 2 ) sol was prepared by adding benzoyl acetone (BzAcH) modifier. Infrared absorption spectroscopy results showed that the BzAcH additive chelated with the Hf 4+ ions in the sol, thus improving the hydrolysis resistance of the HfO 2 sol, which in turn improved its stability. It was also found that the BzAcH-modified HfO 2 gel film exhibited ultraviolet (UV) photosensitivity. After UV exposure, the film did not dissolve easily in organic solvents . Based on these properties, the micro processing of the HfO 2 film was preliminarily explored, and HfO 2 microstructures were successfully obtained. Additionally, the relative permittivity ( ε r ) of HfO 2 exhibited minimum (∼10.9) and maximum (∼20.6) values at heat-treatment (HT) temperatures of 350 and 450 °C, respectively. With the continuous increase in the HT temperature, ε r first decreased and then increased slightly. Moreover, the current–voltage curves showed that the Pt/HfO 2 /LaNiO 3 (LNO) structure exhibited a pronounced bipolar resistive switching (RS) effect, which was attributed to the fact that LNO could be used as an electrode and an oxygen vacancy (OV 2+ ) storage layer for RS materials. Notably, the oxygen ions in HfO 2 with a low degree of crystallinity are more likely to migrate within its body (which makes it easier to form OV 2+ s), therefore, the “Set” voltage of low-crystallinity HfO 2 films is lower than that of high-crystallinity HfO 2 films. The RS mechanism can be explained by the OV 2+ conductive filament model. These results are of great practical significance for the low-cost preparation of HfO 2 and the application of LNO as an oxide electrode.
研究领域:
材料科学
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电子工程
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2022
·Vol. 13
·期 1
·39
·
IF 5.719
Yuan-Dong Xu,Yan-Ping Jiang,Xin-Gui Tang,Qiu-Xiang Liu,Zhenhua Tang,Wen-Hua Li,Xiao-Bin Guo,Yi-Chun Zhou
Resistive random-access memory (RRAM) is a promising candidate for next-generation non-volatile memory. However, due to the random formation and rupture of conductive filaments, RRMS still has disadvantages, such as small storage windows and poor stability. Therefore, the performance of RRAM can be improved by optimizing the formation and rupture of conductive filaments. In this study, a hafnium oxide-/aluminum-doped zinc oxide/hafnium oxide (HfO2/Al-ZnO/HfO2) tri-layer structure device was prepared using the sol–gel method. The oxygen-rich vacancy Al-ZnO layer was inserted into the HfO2layers. The device had excellent RS properties, such as an excellent switch ratio of 104, retention of 104s, and multi-level storage capability of six resistance states (one low-resistance state and five high-resistance states) and four resistance states (three low-resistance states and one high-resistance state) which were obtained by controlling stop voltage and compliance current, respectively. Mechanism analysis revealed that the device is dominated by ohmic conduction and space-charge-limited current (SCLC). We believe that the oxygen-rich vacancy concentration of the Al-ZnO insertion layer can improve the formation and rupture behaviors of conductive filaments, thereby enhancing the resistive switching (RS) performance of the device.
研究领域:
材料科学
·
电气工程
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纳米技术
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半导体器件
✓ 已验证
DOI
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2023
·
IF 3.3
Bowen Zhang,Fugang Zhong,Xinchao Qiu,Jianbo Xu,Mengchen Hu,Jun Ou-Yang,Yue Zhang,Benpeng Zhu,Xiaofei Yang,Shi Chen
Hafnium carbide (HfC) whiskers were successfully synthesized by combining hydrothermal and carbothermal reduction. The precursor of HfC whiskers was prepared by the hydrothermal method, subsequently pyrolyzed, and reduced to HfC whiskers at 1500–1700 °C. The synthesis parameters of HfC whiskers at various temperatures, C/Hf molar ratios, and NaF concentrations were investigated in detail. The whiskers with diameters of 1–3 μm and lengths of 50–90 μm were prepared by pyrolyzing the precursors with a C/Hf molar ratio of 6 at 1700 °C. The experimental results and thermodynamic analysis demonstrated that the growth of HfC whiskers was governed by the vapor-liquid-solid (VLS) mechanism. Furthermore, the prepared HfC whiskers were added to the ZrB 2 -HfO 2 coatings on the surface of tungsten-rhenium substrates in different ratios to toughen the coatings. The thermal shock test results indicated that the coatings toughened with HfC whiskers had better thermal shock resistance. In particular, the maximum number of thermal shock cycles that 6%HfC W -ZH could withstand was five times higher than that of W–Re alloy and about one time higher than that of ZH coatings without HfC whiskers. The thermal shock resistance of the ZrB 2 -HfO 2 coatings was significantly improved by adding HfC whiskers.
研究领域:
材料科学
·
陶瓷材料
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2019
·Vol. 30
·期 6
·5771-5779
·
IF 2.195
Liu Heng,Zheng Shuaizhi,Chen Qiang,Zeng Binjian,Jiang Jie,Peng Qiangxiang,Liao Min,Zhou Yichun
HfO 2 thin films with different praseodymium doping contents (Pr:HfO 2 ) were fabricated by chemical solution deposition (CSD) method at ambient conditions. The chemical bonding and the composition of Pr doped HfO 2 thin film were characterized by X-ray photoelectron spectroscopy (XPS), while the structural properties were investigated by glancing incidence X-ray diffraction (GIXRD) and high resolution transmission electron microscopy (HRTEM). It is found that the ferroelectric orthorhombic phase was induced in the HfO 2 based thin films by Pr doping. The combined results of P–E (polarization–electrical field) and C–V (capacitance–voltage) measurements demonstrated that the 5 mol% Pr doped HfO 2 film exhibited a distinct ferroelectricity, with a maximum remanent polarization ( P r ) of 6.9 µC/cm 2 and a coercive field ( E c ) of 1.2 MV/cm. Notably, the polarization did not show obvious degradation over 1 × 10 8 switching cycles, suggesting good endurance performance of the Pr doped HfO 2 thin film. These results indicate that Pr dopant could effectively induce ferroelectricity in HfO 2 thin films, thereby becoming a new member of dopants for HfO 2 based ferroelectrics.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
RENEWABLE ENERGY
·
2023
·
IF 8.7
Feiyi Chen,Yue Wang,Junhua Zhang,Huai Liu,Lincai Peng
Although metal oxide has unique advantages in catalytic transfer hydrogenation (CTH) of furfural (FAL) into furfuryl alcohol (FOL), the excessive stability of the metal site and oxygen coordination leads to the inert Lewis acid site in the oxide, which affects the catalytic activity and limits its broader application. It is known that the hydroxyl group on the oxide surface can promote the adsorption of isopropanol in an alkoxide species by assisting its deprotonation, thereby activating the metal site and enhance the overall reaction activity. However, constructing metal oxide with rich hydroxyl groups is always challenging. This contribution prepared a series of HfO 2 nanoparticles (NPs) with rich hydroxyl groups through hydrothermal methods . Systematic characterizations proved the presence of hydroxyl groups on the surface of HfO 2 NPs, which promoted its adsorption capacity for isopropanol (hydrogen donor and reaction solvent) and substrate (FAL), thus accelerating the subsequent reaction for CTH of FAL into FOL. As a result, a 100% of FAL conversion with 95.2% of FOL yield was obtained at 160 °C in 4 h, which has significant advantages over commercial and other literature reported oxides. This finding provides a new idea for designing of efficient metal oxides for the CTH reaction by enhancing the hydroxyl group.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Zhezhe Deng,Yongshuai Xie,Wei Liu,Jianhong Dong,Ying Peng,Ze Zhu,Luyi Zhu,Guanghui Zhang,Xinqiang Wang,Dong Xu
HfO 2 is an important high temperature resistant material, which has a high melting point (2810 °C), good chemical stability and high thermal radiation. Fibrous material has some advantages for heavy refractory matter, such as large aspect ratio, light weight, more energy saving, flexibility and further can be processed into a variety of product forms. In this paper, high strength HfO 2 crystalline nanofibers were prepared through self-synthesis polyacetylcatonahafnium (PAHf) with electrospinning method. Phase variation process was discussed in detail, and the HfO 2 fibers that use Y 2 O 3 as stabilizer with phase stability were prepared finally. The fibers were composed of nanocrystals with good flexibility even folded in half, tensile strength of 1.6 MPa @ 1000 °C and can lifting up 1288 times its own weight, low density around 35 mg/cm 3 . The thermal conductivity was stable around 26 mW / (m·K) @ 1200 °C and the temperature can be cooled from 1200 °C to 396 °C after 180 s through 7 mm fibrous membranes . And after treated at 1200 °C for 5 h, the fibrous membranes also maintain high strength and good flexibility. By this kind of precursor method, high strength oxide fibers can be obtained, which has a wide application prospect in field of high temperature thermal protection.
研究领域:
材料科学
·
高温防护领域
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 24
·15555-15563
·
IF 4.036
Rong Tu,Ziming Liu,Chongjie Wang,Pengjian Lu,Bingjian Guo,Qingfang Xu,Bao-Wen Li,Song Zhang
The use of hafnia (HfO2) has facilitated recent advances in high-density microchips. However, the low deposition rate, poor controllability, and lack of systematic research on the growth mechanism limit the fabrication efficiency and further development of HfO2 films. In this study, the high-throughput growth of HfO2 films was realized via laser chemical vapor deposition using a laser spot with a large gradient temperature distribution (100 K mm−1), in order to improve the experimental efficiency and controllability of the entire process. HfO2 films fabricated by a single growth process could be divided into four regions with different morphologies, and discerned for deposition temperatures increasing from 1300 K to 1600 K. The maximum deposition rate reached 362 μm h−1, which was 102 to 104 times higher than that obtained using existing deposition methods. The dielectric constants of high-throughput HfO2 films were in the range of 16–22, which satisfied the demand of replacing the traditional SiO2 layer for a new generation of microchips.
研究领域:
材料科学
·
微电子学
✓ 已验证
DOI
PubMed
高影响因子
Photonics
·
2024
·Vol. 11
·期 10
·976
·
IF 2.1
Haojie Liu,Ziwei Hao,Zirun Peng,Miao Zhang,Peizhong Feng,Cheng Xu
Laser damage in films under long-term high-temperature conditions is a significant concern for advancing laser applications. This study focused on HfO2films prepared using the sol–gel method with HfCl4as a precursor. It examined the effects of temperature on various properties of the films, including their optical properties, microstructure, surface morphology, absorption, and laser-induced damage threshold (LIDT). The prepared film demonstrated desirable characteristics at the high temperature of 423 K, such as high transmittance, low absorption, and high LIDT. As the duration of its high-temperature exposure increased, the LIDT of the films gradually decreased. An intriguing finding was that the film’s LIDT exhibited an exponential decay pattern with prolonged heating time. This observation could be attributed to the power-law increase in defects on both the internal and surface areas of the film as the duration of high-temperature exposure lengthened. Moreover, even after a 15-day heating period at 423 K, the film maintained an LIDT of 12.9 J/cm2, indicating its potential applicability in practical high-temperature environments. This study provided a general pattern and a universal formula for understanding the laser damage of sol–gel films at high temperatures over time. Furthermore, it opened possibilities for future developments of laser films suitable for extreme environments.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Miao Zhang,Yongqiao Zhu,Dawei Li,Peizhong Feng,Cheng Xu
In this study, HfO 2 films were prepared using the sol–gel method with HfCl 4 as a precursor, HNO 3 as a hydrolysis inhibitor and polyethylene glycol as an additive. Investigations were then made into the properties and laser damage characteristics of the films after annealing at different temperatures. The prepared films have high transmittance, low absorption and high laser-induced damage threshold (LIDT). Specifically, the LIDT of the film was as high as 31.6 J/cm 2 after annealing at 353 K, and it gradually dropped to 21.7 J/cm 2 after annealing at 573 K, indicating its strong resistance to high temperature. This study reported a novel method for preparing sol–gel HfO 2 films with high LIDT and pinpointed the potential application of the films under high-temperature conditions.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2020
·
IF 5.578
Muhammad Irfan,Aimin Li,Lei Zhang,Guozhao Ji,Yuan Gao
Catalytic gasification, coupled with in-situ CO 2 capture over Ni-CaO catalyst, is considered to be an effective approach for H 2 -rich and tar-free syngas production. However, the poor stability of Ni-CaO based catalyst raises a question regarding its large scale application. In this study, HfO 2 was used as a stabilizer and promoter for the Ni-CaO catalyst system. The stability of catalyst was evaluated through cyclic carbonation-calcination test with a thermogravimetric analyzer. The results showed that HfO 2 incorporated catalysts performed better stability towards cyclic CO 2 capture. The effect of different HfO 2 additions in catalyst, catalyst to municipal solid waste (C/MSW) ratio, gasification temperature, and moisture content (MC) of MSW was investigated on syngas composition, H 2 yield, dry gas yield (DGY) and product distribution (syngas, tar and char). The results indicated that H 2 yield was improved from 212 mL/g (without catalyst) to 442 mL/g with Ni-CaO (NC) catalyst and further improved with the application of HfO 2 promoted catalysts (Ni-CaO-HfO 2 ). The catalyst with 20% HfO 2 (NCH-20) exhibited maximum H 2 yield of 597 mL/g. Moreover, a significant reduction in tar content from 8.79 wt% (without catalyst), 3.19 wt% (with Ni-CaO) to 2.81 wt% (with NCH-20) was also recorded with HfO 2 promoted catalysts.
研究领域:
化学工程
·
环境科学
·
能源技术
✓ 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）