SURFACE & COATINGS TECHNOLOGY
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2022
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IF 4.865
Zhuo Chen,Xiufang Cui,Yongchao Fang,Chao Yan,Rui Wang,Yongzhi Jing,Xinhe Wang,Guo Jin,Xiang Wang
Gd 2 O 3 and Sm 2 O 3 co-doped LZ ceramic ((La 0.5 Gd 0.25 Sm 0.25 ) 2 Zr 2 O 7 /YSZ) are designed and prepared by atmospheric plasma spraying (APS). It is the aim of this study to investigate the similarities and differences between co-doped sample and mono-doped samples, (La 0.5 Gd 0.5 ) 2 Zr 2 O 7 /YSZ and (La 0.5 Sm 0.5 ) 2 Zr 2 O 7 /YSZ on hot corrosion behaviors exposed to Na 2 SO 4 + V 2 O 5 molten salts . Thermodynamic calculations are used to predict the hot corrosion mechanism before experiments. Characterization and hot corrosion behavior are analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). Results indicate that the main hot corrosion products are composed of rare-earth vanadates ((La, Gd)VO 4 , (La, Sm)VO 4 and (La, Gd, Sm)VO 4 , respectively) and ZrO 2 . After 10 h of corrosion, the reaction layer evolves into trilayered structure containing Zr-rich layer, V-rich layer and mixed-layer. The formation mechanism is discussed in detail. The co-doped sample exhibits excellent degradation resistance, which can be attributed to the higher entropy value. The formation of the particular trilayered structure occurs earlier in the co-doped sample, which also provides a role in reducing the degradation rate of ceramics.
研究领域:
材料科学
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表面工程
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DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2017
·
IF 3.454
Chunhui Xu,Hongyun Jin,Qifeng Zhang,Can Huang,Daifeng Zou,Fujian He,Shuen Hou
Pure pyrochlore Lanthanum zirconate (LZ) was synthesized by co-ions complexation method (CCM) at 1300 °C, which is 300 °C lower than that by solid-state method (SSM). At 1450 °C, the LZ prepared by CCM possessed lower thermal conductivity (1.15 W/m K) than that obtained by SSM (1.99 W/m K). This significant decrease may be caused by the different grain size, which is 300 nm and 2.5 μm synthesized by CCM and SSM, respectively. LZ precursor was belt-shaped and the belt shorten and the grain grown with the temperature increasing. Fourier transform infrared spectroscopy suggested the solidification in CCM forms from the complexation between La 3+ , Zr 4+ and CH 3 COO − , which is the key for solidification. Compared to SSM, CCM is a lower temperature and simpler technology to synthesize nano-size LZ and other rare-earth oxides .
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高影响因子
CERAMICS INTERNATIONAL
·
2025
·Vol. 51
·期 19
·28455-28459
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IF 5.6
Zaohui Lei,Xiuyun Zhang,Shining Zhang,Guisheng Zhu,Yunyun Zhao,Laijun liu,Huarui Xu
The properties of the raw ceramic powder, such as particle size, dispersibility and homogeneity, play a crucial role in its performance in practical applications. Therefore, in the study, a novel coprecipitation method using tartaric acid as a precipitating agent is proposed for the preparation of La 2 Zr 2 O 7 (LZ) nanopowder . Owing to the excellent properties of the precipitated precursor, including ultrafine particle size, uniform composition as well as high chemical activity, fluorite-phase LZ nanopowder with an average particle size of 32.6 nm is synthesized through a low-temperature calcination treatment at 600 °C, which subsequently transforms as pyrochlore-phase LZ nanopowder with an average particle size of 68.4 nm when the calcination temperature reaches 800 °C. Meanwhile, a compact LZ ceramic with fine grains and a high relative density of 98.52 % is obtained via a low-temperature sintering process at 1200 °C, indicating that it has a promising prospect of application in various ceramic devices.
研究领域:
材料科学
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陶瓷
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纳米材料
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无机化学
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产品关联
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2014
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IF 4.086
Tian Xu,Guangjin Wang,Cong Liang,Mu Pan
Nitrogen shows a positive influence on the ORR activity of certain catalysts, such as N-doped carbon and N-doped ZrO 2 . In this paper, we report a method to dope nitrogen into La 2 Zr 2 O 7 nanoparticles by the sol-gel process combined with ammonolysis. XPS results indicate that the nitrogen content in La 2 Zr 2 O 7 is approximately 0.92 at.%. Compared to the ORR activity of La 2 Zr 2 O 7 , ORR activity of the N-doped La 2 Zr 2 O 7 is considerably enhanced. Density functional theory (DFT) calculations indicate that the band gap is reduced in N-doped La 2 Zr 2 O 7 , which may be one of the factors that contribute to the improvement.
研究领域:
材料科学
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电化学
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催化
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纳米材料
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能量转换
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DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2021
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IF 5.302
Xiaoyi Chen,Xiaohui Li,Bo Gao,Wenwen Kong,Pengjun Zhao,Aimin Chang
A novel negative temperature coefficient material based on lanthanum zirconate ceramics was proposed for high-temperature applications. This material was synthesized through a solid-state reaction by sintering at 1923 K for 10 h in air. The X-ray diffraction and scanning electron microscopy results confirmed that La 2 Zr 2 O 7 ceramics exhibited a pyrochlore phase with a relative density of 98.2 %. The resistance–temperature characteristics of the material revealed that La 2 Zr 2 O 7 ceramics exhibited an NTC feature within the broad temperature range of 973–1773 K in addition to maintaining high thermal constant B , and resistivity to ensure good sensitivity at high temperatures. These properties, along with high ceiling temperature, unique oxygen insensitivity, and excellent ageing coefficient of <0.7 % at 1773 K, render La 2 Zr 2 O 7 ceramics a promising candidate as thermistor materials with high-temperature NTC.
研究领域:
材料科学
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热电学
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产品关联
DOI
高影响因子
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
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2018
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IF 2.207
Renping Cao,Guanjun Quan,Zhihui Shi,Ting Chen,Zhiyang Luo,Guotai Zheng,Zuofu Hu
La 2 Zr 2 O 7 :R (R = Sm 3+ , Bi 3+ , Sm 3+ /Bi 3+ ) phosphors are synthesized by solid-state reaction method in air. Blue emission band peaking at ∼462 nm of La 2 Zr 2 O 7 :Bi 3+ phosphor with excitation at 312 nm is observed in the range of 370–610 nm due to 3 P 1 → 1 S 0 transition of Bi 3+ ion and D → 1 S 0 transition between Bi 3+ and Zr 4+ ions. La 2 Zr 2 O 7 :Sm 3+ phosphor with excitation at 407 nm shows reddish orange light in the range of 550–750 nm owing to 4 G 5/2 → 6 H J ( J = 5/2, 7/2, 9/2, and 11/2) transitions of Sm 3+ ion. Tunable emission from blue to white of La 2 Zr 2 O 7 :Sm 3+ , Bi 3+ phosphor with excitation at 312 nm can be observed due to the changing Bi 3+ or Sm 3+ ion concentration . La 2 Zr 2 O 7 :Sm 3+ , Bi 3+ phosphor with excitation at 407 nm only emits reddish orange because Bi 3+ has no absorption at 407 nm. The energy transfer from Bi 3+ to Sm 3+ is discussed. The luminous mechanism is explained by the energy level diagrams of Bi 3+ and Sm 3+ ions.
研究领域:
材料科学
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光学
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DOI
高影响因子
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
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2019
·Vol. 64
·期 11
·1464-1468
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IF 0.822
Kangkang Yuan,Jin Xiaotong,Wang Xinqiang,Zhang Guanghui,Zhu Luyi,Xu Dong
Abstract ZrO 2 ceramic fibers have gained widespread study for the high temperature stability, low thermal conductivity and high mechanical properties. While for oxide fibers, grain growth is one of the limiting factors for long-term high temperature applications. In the present study, polycrystalline ZrO 2 –6 mol % Y 2 O 3 ceramic fibers with the addition of ~0–5 mol % La 2 O 3 to refine the grain size were fabricated by the dry-spinning method. The XRD and Raman spectral results showed that the pyrochlore La 2 Zr 2 O 7 phase was formed as a second phase in the tetragonal zirconia fiber matrix. The formation of a second phase was an effective way to hinder grain growth for the competition phase effect and solid solution mechanism. With the addition of La 2 O 3 , the grain size decreased and concentrated in a smaller range of 50–250 nm compared with the ZrO 2 –6 mol % Y 2 O 3 matrix at 1400°C. Furthermore, the thermal conductivity of the fibers decreased with the additive of La 2 O 3 less than 3 mol %. The present system is a promising candidate for high temperature applications.
研究领域:
材料科学
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陶瓷材料
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高温材料
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纤维材料
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产品关联
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2024
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IF 1.8
Pengju Chen,Peng Xiao,Tian Tian,Yang Li
Ytterbium silicate (Yb 2 Si 2 O 7 ) and lanthanum zirconate (La 2 Zr 2 O 7 ) ceramic powders were synthesized by the sol–gel method. A novel tri-layer La 2 Zr 2 O 7 /Yb 2 Si 2 O 7 /SiC environmental barrier coating was prepared on the surface of C/SiC composites to improve the service temperature of the coating (above the Si melting point, 1683 K). Results show that both Yb 2 Si 2 O 7 and La 2 Zr 2 O 7 ceramic powders had extremely high purity and were accompanied by a large number of nanoparticles. The tri-layer La 2 Zr 2 O 7 /Yb 2 Si 2 O 7 /SiC coating can efficiently prevent the oxidation failure of C/SiC composites in 1773 K air environment for more than 100 h with slight weight loss of 5.71 × 10 −3 g·cm −2 and the matching weight loss rate of 5.71 × 10 −5 g·cm −2 ·h −1 . No significant chemical reaction was observed between Yb 2 Si 2 O 7 middle and La 2 Zr 2 O 7 outer coatings during the oxidation process at 1773 K, indicating that the tri-layer La 2 Zr 2 O 7 /Yb 2 Si 2 O 7 /SiC coating had better oxidation stability in 1773 K air environment.
研究领域:
材料科学
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涂层技术
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DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·Vol. 43
·期 15
·13020-13024
·
IF 2.986
Yanfei Wang,Huan Yang,Rongjun Liu,Yingbin Cao,Siqing Wang
The poor fracture toughness of La 2 Zr 2 O 7 hinders its practical application as a thermal barrier coating topcoat material. To toughen La 2 Zr 2 O 7 , metastable tetragonal 8 wt% yttria-stabilized zirconia ( t ’-8YSZ), has been introduced into the La 2 Zr 2 O 7 matrix by plasma spray quenching of 8YSZ powders and spark plasma sintering . An evident fracture toughness improvement has been achieved due to ferroelastic domains switching. The resulting toughness increase has a quadratic relationship with t ’ phase volume fraction below a critical value (30 vol%), beyond which it is far smaller to what expected owing to the residual stress being smaller than the ferroelastic coercive stress.
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高影响因子
TRIBOLOGY INTERNATIONAL
·
2023
·
IF 6.2
Yongzhi Jing,Yongchao Fang,Xiufang Cui,Zhuo Chen,Dianchao Liu,Anying Liu,Xinhe Wang,Qicheng Li,Guo Jin,Haoliang Tian
Lanthanum zirconate coatings (La 2 Zr 2 O 7 , LZ) have a high Poisson’s ratio and low fracture toughness , making it indescribable for long service life at high temperatures. Rare earth doped lanthanum zirconate (RE-LZ) is an effective way to improve its mechanical properties . In this study, the lanthanum zirconate ceramic coating modified by binary rare earth ((La 1/3 Gd 1/3 Y 1/3 ) 2 Zr 2 O 7 , LGYZ; and (La 1/3 Sm 1/3 Yb 1/3 ) 2 Zr 2 O 7 , LGYZ) and multi-principal rare earth modified ((La 1/5 Gd 1/5 Y 1/5 Sm 1/5 Yb 1/5 ) 2 Zr 2 O 7 , HEC-LZ) was studied, aiming to improve the intrinsic mechanical properties of lanthanum zirconate ceramic coating. By comparing the mechanical properties such as fracture toughness, bonding strength , microhardness dissipation parameter, and solid erosion properties of various types of coatings, the results show that compared with binary rare earth modified coatings such as LGYZ and LSYZ, the elastic modulus of the HEC-LZ ceramic coating is reduced by 4.7–6.3%, the microhardness dissipation parameter (MDP) is increased by 4.8–10.2%, and the fracture toughness is increased by 5.2–7.4%. The HEC-LZ ceramic coating showed favorable toughness and crack resistance. Regarding the erosion resistance of the coatings, the ability of RE-LZ coatings is significantly better than that of LZ coatings, and the erosion rate at 45° and 90° is reduced by 44.9–66.0% and 45.7–62.9%, respectively.
研究领域:
材料科学
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表面工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2026
·
IF 6
Chao Ma,Li Feng,Junpeng Cui,Zhipeng Hu,Qianqian Chu,Shipeng Xu,Weiqian Chen,Bo Chen,Putsiata Artur,Luoyi Zhang
To improve the service reliability of components used during spent nuclear fuel electrorefining, La 2 Zr 2 O 7 (LZO) protective coatings were prepared on SS 316L by atmospheric plasma spraying (APS) followed by vacuum annealing. The effects of annealing temperature and holding time on the phase structure, apparent porosity, and surface wettability of the LZO coatings were systematically investigated. The optimized coating was then exposed to KCl-LiCl molten salt at 600 °C for up to 640 h to evaluate its corrosion behavior and degradation mechanism. Annealing at 1200 °C for 2 h reduced apparent porosity from 18.96% to 8.21% and suppressed spreading of the salt-containing test solution. Within the initial 80 h, the as-sprayed and annealed coatings gained 1.3 and 0.6 mg·cm -2 , respectively, with apparent mass-change rates of 0.015 and 0.0075 mg·cm -2 ·h -1 . Both coatings shifted from mass gain to mass loss during 80-160 h, and the apparent mass-change rate of LZO-C640 reached -0.0525 mg·cm -2 ·h -1 . During 160-320 h, the apparent rates became positive as connected defects enabled deeper salt penetration and local interaction with the NiCrAlY bond coating. Preferential degradation of Al- and Cr-rich regions exposed and redistributed Ni-bearing material. NiO and NiCr 2 O 4 were subsequently detected at 320 h as secondary products. LaOCl was also detected at 320 h, whereas LiAlO 2 appeared after extended exposure. Throughout the final stage of 320-640 h, LZO-C640 maintained a low positive rate of 0.0075 mg·cm -2 ·h -1 . In contrast, the cumulative mass-change of H/LZO-C640 increased from -0.6 to -0.3 mg·cm -2 as its apparent rate approached zero. After 640 h, the annealed coating retained its overall skeleton, whereas the as-sprayed coating underwent top-layer disintegration. These results indicate that vacuum annealing did not completely prevent degradation, but limited molten-salt ingress and improved the long-term corrosion resistance of LZO coating.
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高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2015
·
IF 3.453
Shengxue Wang,Wei Li,Song Wang,Jinming Jiang,Zhaohui Chen
Hierarchical porous lanthanum zirconate (La 2 Zr 2 O 7 , LZO) monoliths have attracted numerous attentions as adsorption, catalysis, especially in high-temperature and high water-vapor-containing environments. Herein, La 2 Zr 2 O 7 monoliths with hierarchially distributed pores have been synthesized via a spontaneous route based on a non-alkoxide sol–gel process accompanied by phase separation. Nitrates of Zr(IV) and La(III) were used as precursors, propylene oxide and formamide were used as gelation inducers, and polyethylene glycol was used as phase separation inducer. The mechanisms of Zr(IV)/La(III) binary gelation process and competitive reaction between gelation and phase separation have been discussed. Zr(IV)/La(III) binary gels exist in the form of Zr(IV)-rich gel networks coupled with La(III)-rich discrete entities. The size of the pores can be controlled by adjusting the amount of gelation and separation inducers. The surface area of the as-prepared La 2 Zr 2 O 7 monoliths is 89 m 2 /g. La 2 Zr 2 O 7 monoliths are amorphous and heating in air at more than 600 °C leads to the formation of pyrochlore structure La 2 Zr 2 O 7 . With further increase in temperature, the crystalline degree of LZO monoliths increased. After heat treatment, the macroporous skeleton can be well retained. However, the macropores became slightly smaller and the solid skeleton became fragile. Sintering of the continuous skeleton occurred after heat treatment.
研究领域:
材料科学
·
化学工程
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DOI
高影响因子
危险品化学品经营许可证（带存储）