JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Le Fu,Bo Li,Guofu Xu,Jiwu Huang,Håkan Engqvist,Wei Xia
Thermal stability of nanocrystallites plays an important role in the manufacturing and application of nanocrystalline ceramics/glass-ceramics. This study explores the effects of thermal treatments on the microstructures of two ZrO 2 -SiO 2 nanocrystalline glass-ceramics (NCGCs), an undoped one and a yttria-doped one. The two as-sintered NCGCs were composed of tetragonal (t) and monoclinic (m) ZrO 2 nanocrystallites, and SiO 2 component was amorphous. t-ZrO 2 and m-ZrO 2 nanocrystallites were metastable during thermal treatment. The content of m-ZrO 2 in the undoped ZrO 2 -SiO 2 NCGC first increased after thermal treating at 850 °C for 5 h, then decreased after thermal treating at and above 950 °C. After thermal treating at 1250 °C for 5 h, t-ZrO 2 nanocrystallites experienced a rapid phase transformation during cooling, resulting the formation of 88.6 vol% m-ZrO 2 . Size-driven phase transformation was utilized to explain the metastability of t-ZrO 2 and m-ZrO 2 nanocrystallites. In contrast, the content of m-ZrO 2 in the yttria-doped ZrO 2 -SiO 2 NCGC continuously decreased with the increase of thermal treatment temperature. The addition of yttria improved the phase stability of t-ZrO 2 up to at least 1250 °C. Crystallite size of both t-ZrO 2 and m-ZrO 2 nanocrystallites increased with the increase of thermal treatment temperature in the two NCGCs. The presence of residual thermal stress in the as-sintered NCGCs changed the lattice spacing of t-ZrO 2 and m-ZrO 2 nanocrystallites, and the stress can be released after thermal treatment. Thermal treatment exerts significant influences on the microstructure of ZrO 2 -SiO 2 NCGCs.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
·
2018
·Vol. 20
·期 6
·1-13
·
IF 2.127
Yang Runnong,Liu Yumei,Yu Lin,Zhao Xiangyun,Yang Xiaobo,Sun Ming,Luo Junyin,Fan Qun,Xiao Jianming,Zhao Yuzhong
A simple hydrothermal procedure is introduced, which leads to the successful synthesis of a new composite material with fine CeO 2 -ZrO 2 nanocrystallites embedded in amorphous and porous SiO 2 matrices. The composite material possesses an extraordinary high thermal stability. After being calcined at 1000 °C, it retains CeO 2 -ZrO 2 nanocrystallites of the size around 5 nm, a BET-specific surface area of 165 m 2 /g, and an oxygen storage capacity of 468 μmol/g. No phase segregation for CeO 2 -ZrO 2 nanocrystallites is detected and the SiO 2 matrices remain not crystallized. The composite material shows a great potential as a support of three-way catalyst, as evidenced in catalytic tests with supported Pt.
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
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Yi Xia,Jie Shi,Qian Sun,Dan Wang,Xiao-Fei Zeng,Jie-Xin Wang,Jian-Feng Chen
Colloidal nanocrystals can offer exquisite control of physical and chemical properties for technological applications by tuning their sizes, shapes and crystal forms. Herein, a convenient phase-transfer route was presented to controllably prepare transparent dispersions of monodispersed ZrO 2 nanocrystals in an aqueous-organic two-phase medium. By adjusting the surfactants, solvents and basicity, the controllability of crystal forms from monoclinic to tetragonal phases, the particle length from 5 to 20 nm, and the different shapes including spindle, cobblestone, sphere, branch, rod and cube can be achieved. The as-prepared ZrO 2 nanocrystals can be readily dispersed in nonpolar solvents, thereby forming the ultra-highly concentrated (60 wt%), highly stable (>18 months) and highly transparent nanodispersions. Density functional theory (DFT) calculations were further used to elucidate the root causes of underpinning growth mechanisms. This work not merely enriches the methodology of controllable fabrication of monodispersed sub-10 nm ZrO 2 nanocrystals, but also enables a platform to synthesize rare-earth-doped nanophosphors using ZrO 2 as the host matrix. The fluorescent ZrO 2 :Yb 3+ /Er 3+ nanocrystals, which can be easily monodispersed in organic solvents, were also prepared with visible luminescene properties under near-infrared irradiation.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2021
·Vol. 50
·期 43
·15688-15695
·
IF 4.39
Minghui Li,Jun Zhou,Ruoshan Lei,Huanping Wang,Feifei Huang,Shiqing Xu
Nowadays, there is enthusiastic effort to develop luminescent thermometers used for remote and high-sensitivity temperature readout over a wide sensing range. Herein, Pr3+ and Gd3+ co-doped ZrO2 nanocrystals are designed, prepared and investigated by XRD, Raman spectroscopy, XPS, TEM, EDS, DRS, PLE and PL spectroscopy. Upon 275 nm irradiation, the PL spectrum of ZrO2:Pr3+,Gd3+ is found to be composed of a narrow emission peak at 314 nm (Gd3+ 6P7/2–8S7/2), a broad defect-related emission band at 400 nm, and several emission peaks in the wavelength region of 585–700 nm (Pr3+ 1D2–3H4, 3P0–3H6, and 3P0–3F2), which exhibit different thermal responses owing to the effects of the various non-radiative relaxation processes and trap energy levels. Accordingly, the luminescence intensity ratio (LIR) between the Pr3+ 1D2–3H4 and Gd3+ 6P7/2–8S7/2 transitions demonstrates excellent relative sensing sensitivity values ((2.32 ± 0.01)% K−1–(8.32 ± 0.05)% K−1) and low temperature uncertainties (0.08 K–0.28 K) over a wide temperature sensing range of 303 K to 573 K, which are remarkably better than those of many other luminescence thermometers. What is discussed in the present study may be conducive to broadening the research region of RE3+ doped luminescence thermometric phosphors, especially for materials with rich 4f–4f transition lines and defect-related luminescence.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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