TY - JOUR

T1 - Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+δ Particles

AU - Escobar Cano, Giamper Eliseo

AU - Brinkmann, Yannick

AU - Zhao, Zhijun

AU - Kißling, Patrick André

AU - Feldhoff, Armin

N1 - Funding Information: This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—project number 435833397.

PY - 2022/9/24

Y1 - 2022/9/24

N2 - 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.

AB - 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.

KW - crystal growth

KW - crystal morphology

KW - La2NiO4+δ

KW - molten-flux synthesis

KW - Sol-gel process

KW - sol–gel process

KW - La NiO

KW - NaOH melt

UR - http://www.scopus.com/inward/record.url?scp=85140924535&partnerID=8YFLogxK

U2 - 10.3390/cryst12101346

DO - 10.3390/cryst12101346

M3 - Article

VL - 12

JO - Crystals

JF - Crystals

SN - 2073-4352

IS - 10

M1 - 1346

ER -