JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2021
·
IF 5.302
Le Fu,Fuqing Jiang,Bo Li,Yongxin Cheng,Guofu Xu,Jiwu Huang,Håkan Engqvist,Wei Xia
The addition of dopant(s) is an effective strategy to regulate the microstructure and properties of ZrO 2 -based ceramics. In this study, we investigated the effects of ternary element alloying, namely tantalum (Ta), niobium (Nb), and hafnium (Hf) elements, on the microstructure and transformability of ZrO 2 nanocrystallites in a ZrO 2 -SiO 2 nanocrystalline glass-ceramic (NCGC) during sintering and thermal treatments. The ternary dopants enhanced the transformability of tetragonal ZrO 2 (t-ZrO 2 ) nanocrystallites during sintering, i.e., the dopants acted as t-ZrO 2 destabilizer. The Ta, Nb and Hf elements dissolved in ZrO 2 nanocrystallites, forming ZrO 2 solid solution. Meanwhile, lamella nanotwins were formed within many ZrO 2 nanocrystallites. No obvious segregation of dopants was detected at ZrO 2 grain boundaries. t-ZrO 2 and monoclinic (m) ZrO 2 nanocrystallites were metastable in thermal treatments process, with “t” to “m” and the reverse “m” to “t” polymorphic transformation occurred simultaneously. Meanwhile, t-ZrO 2 and m-ZrO 2 nanocrystallites had a great tendency to grow larger during thermal treatments.
研究领域:
材料科学
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陶瓷工程
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产品关联
DOI
高影响因子
Engineering
·
2019
·
IF 4.568
Lin Chen,Jing Feng
Ferroelastic AB O 4 type RETaO 4 and RENbO 4 ceramics (where RE stands for rare earth) are being investigated as promising thermal barrier coatings (TBCs), and the mechanical properties of RETaO 4 have been found to be better than those of RENbO 4 . In this work, B -site substitution of tantalum (Ta) is used to optimize the thermal and mechanical properties of EuNbO 4 fabricated through a solid-state reaction (SSR). The crystal structure is clarified by means of X-ray diffraction (XRD) and Raman spectroscopy; and the surface microstructure is surveyed via scanning electronic microscope (SEM). The Young’s modulus and the thermal expansion coefficient (TEC) of EuNbO 4 are effectively increased; with respective maximum values of 169 GPa and 11.2 × 10 −6 K −1 (at 1200 °C). The thermal conductivity is reduced to 1.52 W·K −1 ·m −1 (at 700 °C), and the thermal radiation resistance is improved. The relationship between the phonon thermal diffusivity and temperature was established in order to determine the intrinsic phonon thermal conductivity by eliminating the thermal radiation effects. The results indicate that the thermal and mechanical properties of EuNbO 4 can be effectually optimized via the B -site substitution of Ta, and that this proposed material can be applied as a high-temperature structural ceramic in future.
研究领域:
材料科学
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固态物理
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Haijian Qin,Zelong Yang,Qing Xia,PeifeiYao,Chunzhi Zheng,Guangpin Lin,Zhaolian Ye,Songjian Zhao,Fengli Yang
Because the combination of Co and common support (Al, Ti, et al.) usually shows poor catalytic activity, tantalum has been introduced for CO conversion as a novel carrier due to the excellent performance. In this work, Co 3 O 4 was loaded on four forms of tantalum support (amorphous, mesoporous, crystalline and crystalline mesoporous, abbreviated as Co/Ta-am, Co/Ta-me, Co/Ta-cry and Co/Ta-cm, respectively). And among these four states, Co/Ta-cm presents the highest CO conversion rate. The temperature of 90% CO conversion rate of Co/Ta-cm is approximately 130 ℃ at the high space velocity of 780,000 h −1 , which is 70%, 82% and 88% higher than that of Co/Ta-cry, Co/Ta-me and Co/Ta-am, respectively. Moreover, the characteristics of the catalyst have been studied by XRD, SEM, BET, TGA, and H 2 -TPR, and the results reveal that Co/Ta-cm has the excellent crystallinity and stability, and the morphology is regular. X-ray photon spectroscopy and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) have been performed to investigate the reaction mechanism, which indicates that Co 3+ is the active component and lattice oxygen plays a critical role in CO oxidation.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2017
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IF 5.951
Bo Niu,Zhenyang Chen,Zhenming Xu
The demand for tantalum (Ta) is rapidly increasing due to the manufacture of Ta capacitors (TCs) for electronic devices. With the increasing awareness of environmental protection and conservation of rare metal Ta, recycling of Ta from waste TCs (WTCs) is becoming a hot topic in current society. In this study, an efficient and environmentally friendly process for recycling Ta from WTCs by chloride metallurgy (CM) is proposed. In the CM process, the nontoxic FeCl2 is chosen as the chlorination agent. Thermodynamic analysis demonstrates that Ta can selectively react with FeCl2, and the generated TaCl5 can be easily separated and then condensed in the condensation zone. The recovery of Ta can reach 93.56% under the optimal chlorination parameters as follows: heating temperature of 500 °C, FeCl2 addition amount of 50%, holding time for 2 h, and particle size of Ta-rich powder less than 0.24 mm. Moreover, the kinetic mechanism is discussed, and the rate-controlling step in the chlorination reaction of Ta is determined by mixed control. No hazardous gas and liquid waste is produced during the whole process. Therefore, this study presents an environmentally friendly and promising method for the cyclic regeneration of rare metal Ta from WTCs.
研究领域:
材料科学
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环境科学
✓ 已验证
DOI
高影响因子
ACS Nano
·
2024
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IF 15.8
Yanzhi Dong,Gang Shu,Yibo Wei,Jinbin Pan,Dong Li,Shao-Kai Sun
Tantalum (Ta) emerges as a promising element for advanced computed tomography (CT) imaging probes owing to its high X-ray attenuation coefficient and excellent biocompatibility. Nevertheless, the synthesis of renally clear Ta-based imaging probes through simple methods remains a significant challenge. Herein, we introduce a simple and gram-scale approach for the synthesis of renal-clearable Ta nanodots with high water solubility for CT imaging in vivo. The Ta nanodots, coordination polymers, are fabricated via coordination reactions involving Ta(OH)5, citric acid (CA), and hydrogen peroxide. The Ta nanodots exhibit an ultrasmall hydrodynamic diameter (2.8 nm), high water solubility (1.88 g/mL, 688 mg Ta/mL), superior X-ray absorption capacity, gram-scale production capability (>10 g in lab synthesis), renal-clearable ability, and good biocompatibility. The Ta nanodots possess superior CT imaging efficacy across diverse tube voltages, enabling highly sensitive gastrointestinal CT imaging, renal CT imaging, and CT angiography (CTA). Moreover, Ta nanodots maintain robust CT imaging capabilities even at high X-ray energies, and Ta nanodots-based spectral CT achieves metallic artifacts-minimized CTA. The proposed Ta nanodots present substantial potential as a potent CT imaging probe for diagnosing various diseases.
研究领域:
医学影像学
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材料科学
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生物医学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Crystals
·
2018
·Vol. 8
·期 3
·113
·
IF 2.144
Hui Wang,Qin Li,Chaoyue Wang,Huan He,Jianding Yu,Jiayue Xu
High-quality Ta-doped La2Ti2O7(Ta-LTO) single crystal of about 40 mm in length and 5 mm in diameter was successfully prepared by the optical floating zone method. An X-ray rocking curve reveals that the crystal of LTO has excellent crystalline quality. As-grown crystals were transparent after annealing in air and the transmittance is up to 76% in the visible and near-infrared region. X-ray diffraction showed that this compound possessed a monoclinic structure with P21space group. The dielectric properties were investigated as functions of temperature (0~300 °C) and frequency (102Hz~105Hz). Dielectric spectra indicated an increase in the room-temperature dielectric constant accompanied by a drop in the loss tangent as a result of the Ta doping. One relaxation was observed in the spectra of electric modulus, which was ascribed to be related to the oxygen vacancy. The dielectric relaxation with activation energy of 1.16 eV is found to be the polaron hopping caused by the oxygen vacancies.Keywords:Ta-LTO single crystal;floating zone method;dielectric properties;oxygen vacancy
研究领域:
材料科学
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物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF LUMINESCENCE
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2014
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IF 2.367
Jiansheng Huo,Jiadan Zhu,Shunhua Wu,Haijie Zhang,Qianming Wang
Red emissive phosphors of YTa 1− x Nb x O 4 :Eu 3+ ( x =0–1) have been successfully synthesized by a molten salt method. Powder characteristics were studied by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. The effects of Nb concentration ( x ), flux nature and firing temperature on photoluminescence behavior of YTa 1− x Nb x O 4 :Eu 3+ were extensively investigated. The results showed that the photoluminescence spectra of the samples exhibited strong red emissions (615 nm) upon the ultraviolet excitation and the emission intensities strongly dependent on the host-lattice composition and particle morphology .
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2024
·Vol. 26
·期 46
·28971-28979
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IF 2.9
Yuhan Fan,Yongze Cao,Meiling Li,Sai Xu,Yichao Wang,Xizhen Zhang,Jinsu Zhang,Baojiu Chen
A series of Tb3+, Pr3+ and Dy3+ monodoped CaTa4O11(CTO) persistent luminescence (PersL) phosphors have been successfully synthesized using the molten salt method with KCl flux. The PersL color is green and orange for Tb3+ and Pr3+ or Dy3+ doped samples, respectively. The trap depth of Tb3+, Pr3+ and Dy3+ monodoped CTO is 0.33, 0.31 and 0.30 eV, respectively. The PersL time of 3 mol% Tb3+, 1 mol% Pr3+ and 1 mol% Dy3+ monodoped samples is 52.20, 35.00 and 59.46 s, respectively. Tb3+, Pr3+ and Dy3+ monodoped CTO phosphors can be used in luminescence displays and anti-counterfeit labels under commercial 254 nm UV light.
研究领域:
材料科学
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光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Zaizhi Yang,Xi Wang,Liang Zhang,Hailin Li,Hui Zhang,Dong Xu
(Ca, Ta) co-doped TiO 2 ceramics were successfully prepared using flash sintering technology, and the effects of oxygen vacancies on the rapid densification and giant dielectric properties were studied. The results suggest that the maximum volume fraction of oxygen vacancies in flash-sintered samples is approximately 10%. Oxygen vacancies decrease the barrier energy level of atomic diffusion and provide convenient diffusion channels, resulting in rapid densification of the sample within 24 min at 1100 °C. All flash-sintered samples exhibit high relative density, exceeding 95%. Oxygen vacancies promote the electron-pinning defect dipole effect at low temperatures. As the temperature increases, carriers such as oxygen vacancies move to the grain boundary, forming an internal barrier layer capacitance effect. The optical dielectric constant reaches 7.25 × 10 4 , and the dielectric loss drops to 0.09. Oxygen vacancy play an important role in both flash sintering technology and the giant dielectric properties of co-doped TiO 2 ceramics.
研究领域:
材料科学
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物理学
✓ 已验证
产品关联
DOI
高影响因子
NANOTECHNOLOGY
·
2014
·Vol. 25
·期 21
·215401
·
IF 3.672
Lin Mao,Shenmin Zhu,Jun Ma,Dian Shi,Yixin Chen,Zhixin Chen,Chao Yin,Yao Li,Di Zhang
A H2O2-mediated hydrothermal method was developed for the fabrication of hydrophilic Ta2O5/graphene composite. The composite shows a superior H2 productivity, up to 30 mmol g−1 h−1 when used as a photocatalyst for water splitting, corresponding to an apparent quantum efficiency of 33.8% at 254 nm. This superior performance is due to the hydrophilic nature of the composite and more importantly due to the ultrafine Ta2O5 nanoparticles (about 4.0 ± 1.5 nm) which are covalently bonded with the conductive graphene. The hydrophilic property of the composite is attributed to the use of H2O2 in the hydrothermal process. The ultrafine size of the Ta2O5 particles which are covalently bonded with the graphene sheets is attributed to the use of sonication in the synthesis process. Furthermore, the hydrophilic Ta2O5/Gr composite is durable, which is beneficial to long term photocatalysis. The strategy reported here provides a new approach to designing photocatalysts with superior performance for H2 production.
研究领域:
材料科学
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能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanomaterials
·
2018
·Vol. 8
·期 12
·983
·
IF 3.504
Shiman He,Yuying Meng,Yangfei Cao,Senchuan Huang,Jingling Yang,Shengfu Tong,Mingmei Wu
TiO2is one of the most attractive semiconductors for use as a photoanode for photoelectrochemical (PEC) water oxidation. However, the large-scale application of TiO2photoanodes is restricted due to a short hole diffusion length and low electron mobility, which can be addressed by metal doping and surface decorating. In this paper we report the successful synthesis of hierarchical Ta doped TiO2nanorod arrays, with nanoparticles on the top (Ta:TiO2), on F-doped tin oxide (FTO) glass by a hydrothermal method, and its application as photoanodes for photoelectrochemical water oxidation. It has been found that the incorporation of Ta5+in the TiO2lattice can decrease the diameter of surface TiO2nanoparticles. Ta:TiO2-140, obtained with a moderate Ta concentration, yields a photocurrent of ∼1.36 mA cm−2at 1.23 V vs. a reversible hydrogen electrode (RHE) under FTO side illumination. The large photocurrent is attributed to the large interface area of the surface TiO2nanoparticles and the good electron conductivity due to Ta doping. Besides, the electron trap-free model illustrates that Ta:TiO2affords higher transport speed and lower electron resistance when under FTO side illumination.Keywords:hierarchical TiO2;Ta doping;charge separation;photoelectrochemical water oxidation
研究领域:
材料科学
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能源科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nanoscale Research Letters
·
2018
·Vol. 13
·期 1
·1-7
·
IF 3.125
Hu Yiwei,Hao Qiaoyan,Zhu Baichuan,Li Biao,Gao Zhan,Wang Yan,Tang Kaibin
Tantalum disulfide nanosheets have attracted great interest due to its electronic properties and device applications. Traditional solution-ased ultrasonic process is limited by ultrasound which may cause the disintegration into submicron-sized flake. Here, an efficient multi-step intercalation and ultrasound-free process has been successfully used to exfoliate 1T-TaS 2 . The obtained TaS 2 nanosheets reveal an average thickness of 3 nm and several micrometers in size. The formation of few-layer TaS 2 nanosheets as well as monolayer TaS 2 sheets is further confirmed by atomic force microscopy images. The few-layer TaS 2 nanosheets remain the 1T structure, whereas monolayer TaS 2 sheets show lattice distortion and may adopt the 1H-like structure with trigonal prism coordination.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）