Effects of annealing temperature on microstructural, optical and FTIR properties of NiFe2O4 spinel nanoparticles.

[Display omitted] • The NiFe 2 O 4 nanoparticles are prepared in different annealing temperature using the facile hydrothermal method. • The microstructure parameters are determined by XRD and SEM images. • The BET and BJH analysis are used to determine the specific surface areas and the pore size distribution. • The optical band gaps of samples are investigated. • Correlation between optical, FTIR properties and microstructure parameters is studied. In this study, NiFe 2 O 4 spinel nanoparticles were prepared using the hydrothermal method and annealed at different temperatures of 550, 650, 750, and 850 °C. The crystallite size increased from 19.0 to 28.6 nm and the dislocation density decreased from 7.2 × 10 14 to 5.3 × 10 14 m - 2 . Also, the Fourier-transform infrared (FTIR) shifted absorption bands, ν 1 (594 to 616 cm−1) and ν 2 (400 to 422 cm−1), were observed. The FTIR-shifted absorbance bands have a good correlation with lattice microstructure parameters. Finally, the obtained results can provide useful information about the synthesis of spinel nanoparticles sensitive to lattice defects, using changes in physical properties. [ABSTRACT FROM AUTHOR]