Structural, Optical, Magnetic, and Dielectric Properties of Cr{sup 3+} Substituted Cobalt Aluminate Nanoparticles
- Damanhour University, Physics Department, Faculty of Science (Egypt)
The present study investigates the influence of Cr{sup 3+} substitution on structural, optical, dielectric, and magnetic properties of cobalt aluminates in the aluminates series CoAl{sub 2-x}Cr{sub x}O{sub 4}, 0.00 ≤ x ≤ 0.20. These series of nanoparticles are effectively synthesized using the co-precipitation method. The cubic spinel aluminate structure is confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic measurements. Transmission electron microscopy (TEM) analysis shows the formation of spherical nanoparticles, which are homogeneous in shape and size. The optical properties of the prepared samples have been investigated by means of optical absorbance spectra. The optical band gap E{sub opt}{sup i} and Urbach energy E{sub u} are estimated. At room temperature, the magnetization of undoped CoAl{sub 2}O{sub 4} reveals a weak ferromagnetic behavior. This ferromagnetism is increased for the sample with x = 0.05, and the samples with higher Cr{sup 3+} content have a tendency to be superparamagnetic on account of the formation of single-domain particles as a consequence of small particle size. Real part of dielectric constant (ε{sup ′}), dielectric loss (tanδ), ac conductivity (σ{sub ac}), real part of impedance (Z{sup ′}), and imaginary part of impedance (Z{sup ″}) are analyzed as a function of frequency and Cr{sup 3+} content. The results show that the dielectric loss (tanδ), dielectric permittivity (ε{sup ′}), and ac conductivity (σ{sub ac}) decrease with the increase in Cr{sup 3+} content, x = 0.05, and then increase with a further increase in Cr{sup 3+} content. The increase in these parameters has been explained on the basis of the hopping mechanism. From the Cole–Cole diagram, the value of the relaxation time τ can be calculated and it has been found to increase with increasing the Cr{sup 3+} content. Actually, a high dielectric constant makes these materials good for energy storage at high frequencies.
- OSTI ID:
- 22921188
- Journal Information:
- Journal of Superconductivity and Novel Magnetism, Vol. 32, Issue 7; Other Information: Copyright (c) 2019 Springer Science+Business Media, LLC, part of Springer Nature; Country of input: International Atomic Energy Agency (IAEA); ISSN 1557-1939
- Country of Publication:
- United States
- Language:
- English
Similar Records
Temperature dependence anomalous dielectric relaxation in Co doped ZnO nanoparticles
Structural and Electrical Dependence in Zn-Doped Li-Ferrite Nanostructures
Related Subjects
ALUMINATES
CHROMIUM ADDITIONS
COBALT COMPOUNDS
DIELECTRIC PROPERTIES
DOPED MATERIALS
FERROMAGNETISM
FOURIER TRANSFORMATION
FREQUENCY DEPENDENCE
INFRARED SPECTRA
MAGNETIC PROPERTIES
MAGNETIZATION
NANOPARTICLES
OPTICAL PROPERTIES
RELAXATION TIME
SPINELS
SUPERPARAMAGNETISM
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION