MATERIALS SCIENCE AND TECHNOLOGY
·
2020
·
IF 1.835
Yan Lu,Tong Zhao,Li Ye,Xudong Sui,Shuaituo Zhang,Junying Hao
La2Zr2O7 nanocrystals doped with Er3+ were prepared from curing and pyrolysis of La2Zr2O7 preceramic precursor modified by erbium acetylacetonate for the purpose of photoluminescence applications. The crystallisation behaviour, microstructure and photoluminescence of the generated ceramics were investigated. The nanocrystals derived from the precursor annealed at 900 °C for 2 h exhibit a single-phase solid solution with an average crystallite size of about 20 nm. The emission band centred at 528 nm was attributed to the 2H11/2→4I15/2 transition, while those at 550 and 562 nm were ascribed to the 4S3/2→4I15/2 transition. The optimal molar ratio of Er3+/Zr4+ for max emission intensity was between 0.04 and 0.06.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Wenyuan Ma,Yubo Luo,Zheng Ma,Chengjun Li,Yongxin Qian,Wang Li,Tianshun Xiong,Zheng Wang,Xin Li,Qinghui Jiang,Guanchun Wang,Junyou Yang
Herein, five new La 2 Zr 2 O 7 based high-entropy ceramic materials, such as (La 0.2 Ce 0.2 Gd 0.2 Y 0.2 Er 0.2 ) 2 Zr 2 O 7 , (La 0.2 Ce 0.2 Gd 0.2 Er 0.2 Sm 0.2 ) 2 Zr 2 O 7 , (La 0.2 Gd 0.2 Y 0.2 Er 0.2 Sm 0.2 ) 2 Zr 2 O 7 , (La 0.2 Ce 0.2 Y 0.2 Er 0.2 Sm 0.2 ) 2 Zr 2 O 7 , (La 0.2 Ce 0.2 Gd 0.2 Y 0.2 Sm 0.2 ) 2 Zr 2 O 7 ), were synthesized using a sol-gel and high-temperature sintering (1000 °C) method. The spark plasma sintered (SPS) (La 0.2 Ce 0.2 Gd 0.2 Er 0.2 Sm 0.2 ) 2 Zr 2 O 7 pellet shows a low thermal conductivity of 1.33 W m -1 K -1 at 773 K, and it also exhibits better CaO–MgO–Al 2 O 3 –SiO 2 corrosion resistance than that of Y 2 O 3 stabilized ZrO 2 . It shows that (La 0.2 Ce 0.2 Gd 0.2 Er 0.2 Sm 0.2 ) 2 Zr 2 O 7 has a promising application potential as a thermal barrier coating .
研究领域:
材料科学
·
能源工程
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2014
·
IF 2.086
Kuo Jiang,Songbai Liu,Guohua Ma,Lilin Zhao
Dense composite ceramics composing of pyrochlore La 2 Zr 2 O 7 and metastable tetragonal (Zr 0.92 Y 0.08 )O 1.96 phases were synthesized by sol-spray pyrolysis method and were densified by using spark plasma sintering at 1450 °C. The microstructure and mechanical properties of the composites were studied. Microstructure analysis showed that particle size of the La 2 Zr 2 O 7 and (Zr 0.92 Y 0.08 )O 1.96 phases of the composites was in the range of 0.2–1.3 μm. The results of mechanical property measurement revealed that high fracture toughness, almost twice that of single phase La 2 Zr 2 O 7 has been achieved for the La 2 Zr 2 O 7 –(Zr 0.92 Y 0.08 )O 1.96 composite ceramics with 50 mol% 4YSZ addition. The improved toughness was attributed to crack blocking of the (Zr 0.92 Y 0.08 )O 1.96 crystals.
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
CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
Kangkang Yuan,Cong Feng,Xinzhu Gan,Zhichao Yu,Xinqiang Wang,Luyi Zhu,Guanghui Zhang,Dong Xu
Despite La 2 Zr 2 O 7 ceramic fiber has been fabricated by electrospinning method, the effects of thermal pyrolysis process on the microstructures and properties of the fibers have seldom been considered. Three La 2 O 3 precursors were used to prepare La 2 Zr 2 O 7 ceramic fibers. Phase transformation of La 2 Zr 2 O 7 ceramic fibers were characterized by XRD and Raman spectra. The influence of the decomposition process on the microstructure of the fibers was studied by TG/DSC, XPS and SEM. The results show that slow weight loss leads to smaller grain size which could obtain higher strength fibers while fast weight loss could develop pores which are benefit to the decrease of the thermal conductivity .
研究领域:
材料科学
·
陶瓷材料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Dehua Ma,Yongshuai Xie,Lin Wang,Ying Peng,Yunguang Yin,Xinqiang Wang,Benxue Liu,Guanghui Zhang,Luyi Zhu,Dong Xu
La 2 Zr 2 O 7 fibrous membrane (LZFM), with high uniform distribution and single phase, was fabricated by sol–gel method combined electrospinning technique and the precursor of lanthanum zirconium bimetallic complex, polyacetylacetone lanthanum-zirconium (PALZ) with the ceramic yield of 57.8% was synthesized for the first time. The LZFM had high heat radiation reflectivity (750–2500 nm: Avg 93.2%@1200 °C), low thermal conductivity (25.4 mW·m −1 ·K −1 @-40 °C, 57.5 mW·m −1 ·K −1 @1000 °C), low density (28–50 mg/cm 3 ) and excellent flexibility until 1300 °C. The grain arrangement on the fiber surface was tight with no obvious defects and pores, and the average grain size was only 47.1 nm at 1000 °C for 8 h. The LZFM exhibited excellent high-temperature insulation performance using silicon carbide rod and butane flame as the heat source up to 1530 °C and 1400 °C, respectively. Furthermore, the layered assemblage of LZFM and Al foil was designed, serving as a thermal insulation layer, low-infrared-emission, and high-infrared-reflection layer. The combined structure effectively hid high-temperature targets and achieved infrared stealth (>1300 °C). From the above results, one could find that the LZFM possessed a super high-temperature insulation effect with high thermal stealth performance, implying that LZFM will have a good prospect in thermal insulation protection and infrared stealth.
研究领域:
材料科学
·
热能工程
✓ 已验证
产品关联
DOI
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2016
·
IF 3.349
Shengxue Wang,Wei Li,Song Wang,Zhaohui Chen
Mesoporous La 2 Zr 2 O 7 was successfully prepared by combining epoxide-mediated sol-gel process and solvothermal treatment. The gelation was controlled by addition of propylene oxide to the ethanol solutions of nitrates. Solvothermal treatment was adopt to strengthen the mesopore structure and inhibit the collapse of pores during abiment pressure drying, and it obviously increased surface area. The as-synthesized mesoporous La 2 Zr 2 O 7 showed nanoparticles assembling and mesoporous structure, and the nanoparticles has a surface area of 302.9 m 2 /g and an average pore size of 22.2 nm. The mesoporous La 2 Zr 2 O 7 has an amorphous structure with some organic component. After heat treatment, the inorganic transformation occurred and it crystallized into pyrochlore structure. With increase of heat treatment temperature, the particles of mesoporous La 2 Zr 2 O 7 become larger for the sintering of nanocrystalline La 2 Zr 2 O 7 . The surface area can retain at 92.7 m 2 /g after 600 °C, and decreased to 12.4 m 2 /g after 1200 °C for 3 h. This facile route provides a low-cost strategy for the preparation of mesoporous metal oxide with high surface area.
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
CORROSION SCIENCE
·
2024
·
IF 7.4
Pengsen Zhao,Haizhong Zheng,Guifa Li,Yongxiang Geng,Yixin Xiao,Hongbo Guo,Gang Wang,Shixian Zhao,Ping Peng
The thermal cycling behavior of Yb 3+ -Ce 4+ -La 2 Zr 2 O 7 /YSZ (LYZCO/YSZ) TBCs was systematically investigated via experiment and first-principles calculation. Results suggest that ceramic grain boundary cracking is the root cause of LYZCO/YSZ TBCs thermal cycle failure. Compared to La 2 Zr 2 O 7 /YSZ TBCs, LYZCO/YSZ TBCs own an outstanding thermal cycle life at 1100 ℃, which is attributed to LYZCO's higher TEC (10.431×10 −6 /K, 1100 ℃) and lower thermal conductivity (1.299 W/(m·K), 1100 ℃). Furthermore, Griffith's separation work of the LYZCO/YSZ interface is merely −0.576 J/m 2 , implying that the LYZCO/YSZ TBCs are particularly prone to cracking at this interface. Weakly bonded La-O is the first site at this interface cracking.
研究领域:
材料科学
·
计算物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 105
·期 4
·2772-2782
·
IF 3.784
De-bao Liu,Fei-fei Zhou,Li-jie Qu,Yi-guang Wang,Bao-sheng Xu,Shi-gang Ai
Porous La 2 Zr 2 O 7 ceramic aerogels (CAs) were prepared by sol-gel template method and thermal treated process. The microstructure and crystallisation behavior of the samples were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. The results indicated that the as-prepared porous La 2 Zr 2 O 7 CAs had a single-phase pyrochlore structure with typical three-dimensional (3-D) porous structure. Meanwhile, the formation mechanisms of the as-prepared porous La 2 Zr 2 O 7 CAs were investigated. At the same time, the as-prepared porous La 2 Zr 2 O 7 CAs presented an ultralow room-temperature thermal conductivity of 0.07 W/(m K), high specific surface areas of 325.17 m 2 /g, and a relatively high compressive strength of 11.95 MPa. What's more, the as-prepared porous La 2 Zr 2 O 7 CAs possessed ideal photocatalytic activities due to its high crystallinity, large surface area as well as unique 3-D porous structure. Therefore, the present work is proposing some new insight to prepare rare-earth zirconates CAs with porous structures for thermal insulation and dye degradation applications.
研究领域:
材料科学
·
纳米技术
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化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Fei Liu,Yuntao Huang,Jingjing Qu,Qingzhi Xu,Jianping Ma,Qihan Chen,Lifu Lin
Pyrochlore-type zirconates, particularly La 2 Zr 2 O 7 , are considered highly promising materials for high-temperature applications owing to their excellent thermal and mechanical properties. However, the fabrication of high-performance La 2 Zr 2 O 7 ceramics with complex geometries remains challenging. In this study, dense La 2 Zr 2 O 7 ceramics with complex structures were fabricated via digital light processing (DLP) vat photopolymerization. The entire process was systematically examined, from raw material powder pre-calcination, suspension formulation optimization (including the selection of surface modifier KH570 and dispersant KOS110), rheological and curing behavior control, to green body debinding and final sintering. The results indicated that the La 2 O 3 /ZrO 2 powders pre-calcined at 1100 °C significantly suppressed cracking during the debinding process. By using 1 wt% KH570 as a surface modifier and 2 wt% KOS110 as a dispersant, a ceramic suspension with 35 vol% solid loading, low viscosity, and good stability could be obtained. The La 2 Zr 2 O 7 ceramic sintered at 1600 °C for 6 h achieved a high relative density of 99.23 %, a flexural strength of 257 ± 27 MPa, and a thermal conductivity of 3.4 W/m·K. The XRD and Raman analyses confirmed the improved crystallinity with increasing sintering temperature, and the observed changes in peak intensity were attributed to the densification and microstructural evolution. Finally, the complex La 2 Zr 2 O 7 ceramic structures were successfully fabricated, demonstrating the high shaping precision and the compact, uniform microstructure. This study provides an experimental basis for manufacturing high-performance La 2 Zr 2 O 7 ceramics using DLP technology.
研究领域:
材料科学
·
先进陶瓷
·
增材制造
·
无机非金属材料
·
高温功能材料
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 40
·27045-27052
·
IF 3.3
Junwei Xu,Xusheng Zhong,Rumeng Ouyang,Ying Gong,Yameng Liu,Xianglan Xu,Xiuzhong Fang,Xiang Wang
To elucidate the effect of the A2B2O7 phase on the oxidative coupling of methane (OCM) while excluding elemental influences, La2Zr2O7 compounds with a disordered defect fluorite (La2Zr2O7-F) structure and an ordered pyrochlore phase (La2Zr2O7-P) have been synthesized. Irrespective of their element composition, the catalytic performance of La2Zr2O7-F exceeds that of La2Zr2O7-P. Furthermore, the La2Zr2O7-F surface has more oxygen vacancies/defects than the La2Zr2O7 surface because La2Zr2O7-F exhibits a higher lattice disorder degree and lower B–O bond strength, which leads to the formation of more reactive oxygen anions (O2− and O22−) and basic sites for OCM. Isotopic exchange results have testified that surface-active oxygen sites are generated due to the gaseous O2 adsorption/activation occurring on the surface vacancies via both simple and multiple hetero-exchange mechanisms. In conclusion, crystal structure is the primary factor that governs the catalytic performance of A2B2O7 compounds, with the disordered defect fluorite phase being the most optimal structure for OCM.
研究领域:
催化
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 14
·7645-7651
·
IF 3.049
Xin Wang,Min Xue,Songbai Liu,Kuo Jiang,Zhuli Zhang
Herein, powders composed of La2Zr2O7 (LZ) and ZrO2 phases were synthesized by an in situ reaction using a sol-spray pyrolysis method; moreover, 24 mol% LaO1.5–ZrO2 (volume ratio = 1 : 1) powders were characterized by XRD, Raman spectroscopy, SEM, and TEM. XRD and Raman results showed that the samples maintained a tetragonal ZrO2 and a pyrochlore LZ phase from 900 to 1100 °C. The addition of LZ could be helpful in the stabilization of t-ZrO2 and decreasing the grain size of ZrO2. The SEM results revealed that the LZ and ZrO2 phases were homogeneously distributed in the sintered bulk. The HRTEM results suggested that the crystal orientations of the nano-LZ and nano-ZrO2 phases were accordant; this was in agreement with the characteristics of the coherent boundaries. The fracture toughness of LZ–ZrO2 was markedly improved by the transformation toughening of the ZrO2 phase, and a value that was 2.2-fold that of the LZ prepared by a similar technique was achieved.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 33
·18954-18962
·
IF 3.049
Jingjing Niu,Xiang Wu,Haibin Zhang,Shan Qin
In situ high-pressure experiments on La2Zr2O7 and La0.5Gd1.5Zr2O7 have been carried out at up to approximately 40 GPa using synchrotron X-ray diffraction and Raman spectroscopy combined with a diamond anvil cell technique. Both La2Zr2O7 and La0.5Gd1.5Zr2O7 undergo a phase transition from a pyrochlore phase (Fdm) into a cotunnite-like phase (Pnma) at 22.7 and 23.3 GPa, respectively. This type of phase transition is mainly controlled through the order-disorder occupancy of cations, and Gd3+ substitution of La3+ reduces the stability of zirconate pyrochlore. However, abnormal changes to the unit-cell volumes and vibrational modes observed at 5.5 GPa in La2Zr2O7 and 6.5 GPa in La0.5Gd1.5Zr2O7 are attributed to an anion disorder in the pyrochlore.
研究领域:
材料科学
·
凝聚态物理
·
高压物理
·
陶瓷学
·
固态化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）