Abstract：Because of its unique crystal structure and excellent physical and chemical properties, ZnAl2O4 has a
broad application prospect in magnetic storage devices, catalysts, high temperature ceramics, laser and fluorescent
substrate materials, sensors and optoelectronic devices. The microstructure and optical properties of ZnAl2O4 binary
metal oxide were investigated by doping the transition metal Fe ions into the octahedral position.Fe- doped
ZnAl2-xFexO4 nanoparticles (x=0, 0.025, 0.05 and 0.10) were synthesized by hydrothermal method and heat treatment.
X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray
spectroscopy (EDX), X-ray photoemission spectroscopy (XPS), UV-Visible spectrum (UV-Vis), photoluminescence
(PL) and Fourier transform infrared spectroscopy (FT-IR) were used to study the microstructure of Fe doped
samples and optical properties. XRD patterns show that the structures of all ZnAl2-xFexO4 samples are similar, and
Fe doping into ZnAl2O4 lattice does not change the structure of ZnAl2O4 nanoparticles. The crystal plane of the sample
is obtained by using the jade software parameters, spacing and grain size, with the increase of Fe doping concentration,
crystal grain size decreases, Fe doping has a regulating effect on grain size. In order to prove that Fe3 +
successfully replaced Al3+ as dopant into ZnAl2O4 matrix without forming impurity enrichment phase, FE-SEM was
used to scan the distribution of elements in ZnAl1.90Fe0.10O4 samples. The samples are mainly regular spherical, relatively uniform particle size, with an average particle size of less than 50 nm. The chemical composition and elemental
chemical states of ZnAl2-xFexO4 were studied by X-ray photoelectron spectroscopy. Ultraviolet-visible absorption
spectra shows that doping samples have absorption in the visible area, moreover with the increase of doped with
iron content in sample, the absorption peak intensity in the ultraviolet and visible light wavelength region increases
significantly, Fe doping in the visible light range near 470 nm produce an additional absorption peak, the octahedral
coordination of iron ion d-d transition. This indicates that Fe ions replace Al ions and exist as Fe+3 in octahedral
crystals. The band gap of the sample is calculated to be less than the corresponding pure ZnAl2O4 (3.8 eV). The
band gap of doped samples decreases with the increase of Fe ion concentration. This phenomenon is attributed to
the change of band structure caused by the sp-d exchange between band electrons and the local d electrons of Fe
ions replacing Al ions. FT-IR results show that the spinel structure is still present in Fe-doped ZnAl2- xFexO4 samples.
PL spectra show that, compared with pure ZnAl2O4, the luminescence intensity of ZnAl2- xFexO4 samples
decreases sharply with the increase of Fe ion concentration, and quenching phenomenon occurs. The chromaticity
diagram shows that the chromaticity distribution of the sample can be controlled by controlling the doping concentration,
and the peak value decreases regularly with the increase of the doping concentration, indicating that
ZnAl2- xFexO4 nanoparticles have excellent luminescence ability. The microstructure and optical properties of
ZnAl2O4 can be effectively changed by preparing transition metal Fe ions doped into the octahedral position of binary
metal oxide ZnAl2O4, which provides reference value for the subsequent research and production and application
of ZnAl2O4.
2022, Vol. 32 
