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7147823 
Journal Article 
Dielectric properties of calcium-substituted lanthanum ferrite 
Andoulsi-Fezei, R; Sdiri, N; Horchani-Naifer, K; Ferid, M; , 
2020 
TAYLOR & FRANCIS LTD 
ABINGDON 
94-105 
WOS:000506292200001 
Among La1-xCaxFeO3-delta (0 <= x <= 0.5) compounds, the optimal value of the direct current conductivity was registered for a 20% substituted amount. We therefore attempted to study the impedance and dielectric properties of 20% calcium-substituted lanthanum ferrite. We investigated the electric properties in depth between 5 Hz and 13 MHz from 350 to 800 degrees C. The results reveal interesting properties. Indeed, the perovskite shows a huge dielectric constant which promotes its utilization in high-performance dielectric material applications. At a given temperature, epsilon' and tan(delta) decrease with increases in frequency. This trend was explained based on the Maxwell Wagner polarization model. The variations in dielectric loss (epsilon") with frequency obey the Giuntini theory based on the hopping model. As the temperature increases from 350 to 800 degrees C, the binding energy increases from 0.22 to 0.34 eV, while the minimum hopping distance decreases from 2.16 to 0.12 pm. Consideration of the electric modulus analyzes showed that the relaxation mechanism is dominated at below 400 degrees C by a short-range movement of charge carriers, whereas at above that temperature, a long-range movement of charge carriers is dominant. This study presents a solid foundation for the polarization and dielectric properties of lanthanum ferrite, which is a lead-free, environmentally friendly material and a promising candidate for use in nonlinear optical applications and microwave devices.[GRAPHICS].