Influence of Cr and Mn co-doping on the microstructure and optical properties of spinel structured Zn_0.95−<i>_x</i>Cr_0.05Mn<i>_x</i>Al₂O₄ nanoparticles

Abstract

Cr and Mn co-doped Zn 0.95¹x Cr 0.05 Mn x Al 2 O 4 nanoparticles with different contents of Mn were synthesized via simple hydrothermal route and heat treatment technology. The influences of Cr and Mn doping on the microstructure, morphology, binding energy and optical property of the as-synthesized samples were characterized. X-ray diffraction confirm that Zn 0.95¹x Cr 0.05 Mn x Al 2 O 4 nanoparticles exhibit cubic spinel structure, the average crystallite size decrease and the lattice parameter increase with the increase of Mn doping concentration. X-ray energy dispersive spectroscopy and X-ray photoemission spectroscopy demonstrate Cr and Mn ions are successfully substituted for the lattice site of Zn 2+ , enter ZnAl 2 O 4 matrix and mainly occupy the tetrahedral sites of the doped samples. Scanning electron microscopy and high-resolution transmission electron microscopy show the morphology of the samples are irregular spherical or ellipsoid particles with small particle size and good dispersion. Ultravioletvisible spectra indicate co-doped samples possess strong visible light absorption ability, and the band gap decrease as Mn ions concentration increase and occur red shift. Photoluminescence spectra show the intensity decrease and occur luminescence quenching phenomenon for doped samples. The intensity of Fourier transform infrared spectroscopy for doped samples decrease slowly and occur red shift.

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications

“…A broadband peak observed from 3719 to 3905 cm –1 represents the vibration band of the oxygen and hydrogen bonds, which is related to the moisture. Other peaks, identified at 1768 and 2345 cm –1 , represent the oxygen bonds, while a stretching vibration peak at 1515 cm –1 is identified as the Al–O bond . A stretching vibration band of aluminum and oxygen was also noticed at a wavenumber of 666 cm –1 .…”

“…Other peaks, identified at 1768 and 2345 cm −1 , represent the oxygen bonds, while a stretching vibration peak at 1515 cm −1 is identified as the Al−O bond. 20 A stretching vibration band of aluminum and oxygen was also noticed at a wavenumber of 666 cm −1 . A stretching mode peak, Zn-O-Al of ZnO is anticipated from 420 to 464 cm −1 , not shown here.…”