Anisotropic growth of La2NiO4+: Influential pre-treatment in molten-flux synthesis

Hinterding, Richard; Zhao, Zhi‐Jun; Zhang, Chao; Feldhoff, Armin

doi:10.1016/j.jcrysgro.2019.06.021

Cited by 6 publications

(14 citation statements)

References 60 publications

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“…The presence of lanthanum oxycarbonate in the sol-gel product between 773 K and 1023 K could be attributed to the reaction kinetics, which is supported by the fact that no oxycarbonate was found in the powder gained between 873 K and 1073 K after 20 h [17]. The detection of NiO in the sol-gel intermediates has, so far, proven difficult [17,39]. No sharp NiO reflections could be found by XRD, which means that the NiO particles are too small or still amorphous [39].…”

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 91%

“…In the next step, the bluecolored gel was heated to 573 K. As a result of the liquid loss, a xerogel powder was produced [47,48]. The powder still contained residues of incompletely burned carbon and nitrogen-based components that could have an impact on the MFS, and they were therefore removed by a calcination step [39]. The calcination of the xerogel powder at 773 K resulted in a crystalline product, hereinafter called sol-gel intermediates.…”

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 99%

“…The calcination of the xerogel powder at 773 K resulted in a crystalline product, hereinafter called sol-gel intermediates. A calcination temperature of 773 K was chosen because, in previous works, the formation of the first crystalline intermediates, La2O2CO3 and NiO, instead of LNO, was observed between 673 K and 773 K [39]. Temperatures between 773 K and 1173 K led to the generation of LNO, accompanied by La2O2CO3 in different phases, La2O3 and NiO.…”

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 99%

“…La2O3 is formed as the result of the decomposition of the lanthanum precursor. The chemical reactions during the combustion of the La(NO3)3•6 H2O and the formation of lanthanum oxycarbonate can be described by Equations ( 4)- (7), involving the decomposition of lanthanum oxynitrate species [49]: A calcination temperature of 773 K was chosen because, in previous works, the formation of the first crystalline intermediates, La 2 O 2 CO 3 and NiO, instead of LNO, was observed between 673 K and 773 K [39]. Temperatures between 773 K and 1173 K led to the generation of LNO, accompanied by La 2 O 2 CO 3 in different phases, La 2 O 3 and NiO.…”

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 99%

“…In earlier work, plate-like LNO crystals were synthesized by MFS using NaOH as the flux. Nevertheless, in addition to LNO, the secondary phase La(OH) 3 was also identified, which can represent an obstacle for possible future applications due to its size of at least 10 µm [39,40]. LNO plates, obtained via solidstate route-mediated MFS, have already been used in our research group to fabricate the ceramic composite from Ca 3 Co 4-x O 9+δ and a small amount of LNO (max.…”

Section: Introductionmentioning

confidence: 99%

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Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+δ Particles

et al. 2022

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La2NiO4+δ particles with a plate-like morphology were prepared from a NaOH melt by molten-flux synthesis. For this purpose, the intermediates from a sol–gel process were used as reactants. Using powder X-ray diffraction, the sol–gel intermediates were identified as a mixture of tetragonal La2O2CO3 and cubic NiO. The existence of NiO was also confirmed by transmission electron microscopy in combination with electron-energy loss spectroscopy. The ultrafine mixed sol–gel intermediates were then mixed with NaOH powder and additional water in a nickel crucible and heated to 673 K for 8 h. The chemical reactions in the air during the molten-flux synthesis and the influence of the salt on the formation of La2NiO4+δ were examined by thermogravimetric analysis. The powder X-ray diffraction indicated a K2NiF4-type tetragonal structure with the I4/mmm space group for the reaction product. The scanning electron microscopy showed plate-like La2NiO4+δ crystals with a length and thickness of approximately 9 µm and 2 µm, respectively, while the energy-dispersive X-ray spectroscopy revealed a homogeneous distribution of lanthanum and nickel in the product powder. The influence of the processing parameters on the product generation, as well as on the size and morphology of the La2NiO4+δ particles, was systematically studied.

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Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 91%

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 99%

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 99%

Section: Synthesis Of Precursors Via Sol-gel Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+δ Particles

et al. 2022

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Towards the development of textured polycrystalline La2NiO4+δ membranes and their oxygen-transporting properties

Escobar Cano,

Zhao,

Riebesehl

et al. 2024

J Solid State Electrochem

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Textured La2NiO4+δ membranes were fabricated by pressureless sintering in air using uniaxially pressed powder mixtures consisting of fine-grained equiaxial La2NiO4+δ matrix particles and plate-like La2NiO4+δ template particles in varying mass ratios. The template particles, obtained by molten-flux synthesis, were aligned perpendicular to the pressing direction. Subsequent sintering resulted in ceramic membranes with enhanced texturing along the crystallographic c-axis of La2NiO4+δ. X-ray diffraction patterns revealed a direct relationship: The higher the fraction of template particles in the ceramics, the more pronounced the c-axis texturing. The Lotgering orientation factor, calculated from the X-ray diffraction patterns, also demonstrated that an increasing proportion of the template particles in the ceramic materials led to stronger (00l) reflections. Additionally, the texturing degree in selected membranes was quantified by measuring pole figures. Scanning electron micrographs of the La2NiO4+δ samples with a small amount of template particles showed some individual plate-like grains well integrated into the matrix. Membrane porosity was observed to increase with higher quantities of template particles utilized. This was supported by measuring the membrane density using the Archimedes method: The larger the proportion of template particles in the ceramics, the lower the sample density. Besides, the presence of lanthanum, nickel, and oxygen in the membranes was confirmed by energy-dispersive X-ray spectroscopy. Finally, the effect of texturing on the oxygen permeation performance of the La2NiO4+δ membranes, in which the template particles are arranged along their c-axis, parallel to the oxygen flux direction, was investigated. The results indicated a reduction in oxygen flux as the level of c-axis texturing increased. Graphical abstract

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Synthesis of La2NiO4 by the molten salt method and its infrared radiation properties

Liu

Chen

et al. 2023

Journal of Alloys and Compounds

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Anisotropic growth of La2NiO4+: Influential pre-treatment in molten-flux synthesis

Cited by 6 publications

References 60 publications

Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+δ Particles

Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+δ Particles

Towards the development of textured polycrystalline La2NiO4+δ membranes and their oxygen-transporting properties

Synthesis of La2NiO4 by the molten salt method and its infrared radiation properties

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