Browsing by Author "Dhahri, Radhia"
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- MnCr2O4: A suitable material with significant optical response for optoelectronic devicesPublication . Hajji, Ala Ben Abderrazak; Wali, Mouna; Dhahri, Radhia; Kammoun, Souha; Dhahri, Essebti; Mariano, José; Jemmali, MosbahIn current high-tech electronics, a power-efficient and compact light source has an essential role to play in the development of non-destructive and non-invasive detection applications as well as for advancing of technological innovation. In this order, an innovative investigation has been taken into consideration in this paper to characterize the optoelectronic behaviour of MnCr2O4 spinel chromite compound based on both experimental and theoretical approaches. The room temperature X-ray diffraction gives rise to a single-phase spinel compound which crystallises in the cubic system with the space group (Fd 3 m). Thanks to the UV-Visible/NIR absorbance and reflectance measurement, the direct semiconducting behaviour (Edg = 2.41 eV) of chromite sample have been verified. The spectral behaviour of absorbance proves that the sample under study exhibit a broad absorption in the visible range. The high localized state density is confirmed by the significant high Urbach energy value that was observed (Eu = 2.86 eV). Various optical parameter such as refractive index, extinction coefficient, dielectric real and imaginary optical permittivity have been analysed to more investigate experimentally the optoelectronic behaviour of the studied sample. Owing to the Wemple Di-Domenico model additional dispersive parameters have been identified. A comprehensive analysis of the crystal field theory based on the theoretical evaluation of the algebraic Racah tensor was taken into consideration on trivalent chromium Cr3+ (3 d3) according to the Oh symmetry site.The demonstrated results are undoubtedly a road to achieving high-power conversion efficiency making our material promising for multitude optoelectronic application.
- The effect of transition metal substitution on the structural, elastic, optical, electrical and dielectric properties of M0.5Fe2·5O4 (M=Co and Mg) synthesized by the auto combustion methodPublication . El Heda, Issa; Massoudi, Jalel; Dhahri, Radhia; Dhahri, Essebti; Bahri, Fathi; Omari, L.H.; Mariano, JoséSpinel nanoparticles M0.5Fe2.5O4 (M = Co,Mg) were elaborated by the auto-combustion method using glycine as a fuel. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy have been invested to investigate the structural and morphological properties of these compounds. The optical study reveals that these samples exhibit a strong absorption in the visible range. They possess intermediate gap energies 2.91 eV for Co0.5Fe2.5O4 and 3.16 eV for Mg0.5Fe2.5O4 which makes them good candidates in terms of photovoltaic applications. Electrical analysis demonstrates a semiconductor [300-520 K] -metallic [540-660 K] transition at 540 K. Correlated Barrier Hopping (CBH) and No Overlap Small Polaron Tunneling (NSPT) models dominate the conduction mechanisms in both compounds. The Nyquist diagrams are modelled by two series-connected circuits reflecting grain (Rg//Cg) and grain boundary effects (Rgb//CPEgb). Quantitative analysis of the dielectric constant is indicative that these compounds are promising at the level of electronic systems industry, LTCC devices and super capacitor applications.