Influence of synthesis conditions on microstructure and phase transformations of annealed Sr2FeMoO6-xnanopowders formed by the citrate-gel method.
The sequence of phase transformations during Sr2FeMoO6-xcrystallization by the citrate-gel method was studied for powders synthesized with initial reagent solutions with pH values of 4, 6 and 9. Scanning electron microscopy revealed that the as-produced and annealed powders had the largest Sr2FeMoO6-xagglomerates with diameters in the range of 0.7-1.2 µm. The average grain size of the powders in the dispersion grows from 250 to 550 nm with increasing pH value. The X-ray diffraction analysis of the powders annealed at different temperatures between 770 and 1270 K showed that the composition of the initially formed Sr2FeMoO6-xchanges and the molybdenum content increases with further heating. This leads to a change in the Sr2FeMoO6-xcrystal lattice parameters and a contraction of the cell volume. An optimized synthesis procedure based on an initial solution of pH 4 allowed a single-phase Sr2FeMoO6-xcompound to be obtained with a grain size in the range of 50-120 nm and a superstructural ordering of iron and molybdenum cations of 88%.
Scientific-Practical Materials Research Centre, NAS of Belarus, Minsk 220072, Belarus; National Research University of Electronic Technology "MIET", Moscow 124498, Russia.
Marta
M
Yarmolich
Scientific-Practical Materials Research Centre, NAS of Belarus, Minsk 220072, Belarus.
Nikolai
N
Kalanda
Scientific-Practical Materials Research Centre, NAS of Belarus, Minsk 220072, Belarus.
Sergey
S
Demyanov
Research Group Electrochemical and Surface Engineering, Vrije Universiteit Brussel, Brussel 1050, Belgium.
Herman
H
Terryn
Research Group Electrochemical and Surface Engineering, Vrije Universiteit Brussel, Brussel 1050, Belgium.
Jon
J
Ustarroz
National Research University of Electronic Technology "MIET", Moscow 124498, Russia.
Maksim
M
Silibin
Belarusian State University of Informatics and Radioelectronics, Minsk 220013, Belarus,; ITMO University, St. Petersburg 197101, Russia.
Gennadii
G
Gorokh
magnetic materials; microstructure; nanoparticles; phase transformation; sol–gel preparation