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Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La₂NiO₄+d Particles
Publikationstyp
Journal Article
Date Issued
2022-09-24
Sprache
English
Author(s)
Journal
Volume
12
Issue
10
Article Number
1346
Citation
Crystals 12 (10): 1346 (2022)
Publisher DOI
Publisher
MDPI AG
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.
Subjects
crystal growth
crystal morphology
La₂NiO₄+d |molten-flux synthesis
NaOH melt
sol–gel process
DDC Class
540: Chemistry