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Structure and Dielectric Properties of V and Y Disorder Doped SrBi2Nb2O9 Ceramics

Afqir Mohamed, Elaatmani Mohamed, Zegzouti Abdelouahad, Tahiri Nabiha, Daoud Mohamed

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1455--1458

EN

Y and V codoped SrBi2Nb2O9 ceramics, which have been characterized by XRD, FTIR and SEM techniques, were prepared through molten salt using NaCl-KCl medium. Through X-ray diffraction analysis, all prepared samples were matched by undoped SrBi2Nb2O9. The lattice parameters do not depend on the amount of dopants. Under the optimized experimental conditions, the compounds are composed of small crystallites of varying size and orientation, resulting in many micros train defects. FTIR spectra revealed that the dopant promotes a slight decrease in the 612 cm-1 band. A plate-like morphology was revealed by scanning electron microscopy, while Nyquist plots indicate non-Debye relaxation for all compounds. V and Y were incorporated into SrBi2Nb2O9 lattice in order to reduce dielectric loss tangent. Thus, the codoping increases the of SrB1.9Y0.1Nb1.95V0.05O9 (Y0.1V0.05) ceramic whereas, they were significantly decreased in the case of SrB1.8Y0.2Nb2O9 (Y0.2) ceramic. Y0.1V0.05 sample makes up the highest efficient charge transfer, followed by Y0.2 sample representing the lowest.

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Hydrothermal Synthesis, Impedance and Optical Properties of Tm-Doped SrBi2Nb2O9 Ceramics

Afqir Mohamed, Stojadinović Stevan, Elaatmani Mohamed, Zegzouti Abdelouahad, Tahiri Nabiha, Daoud Mohamed

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

45--50

EN

In this study, Strontium Bismuth Niobate (SrBi2-xTmxNb2O9 with 0 ≤ x ≤ 0.1) doped by Tm was synthesized using by the hydrothermal method. The microstructure and electrical properties were mainly investigated. XRD analysis showed a single-phase orthorhombic structure for Tm-doped SrBi2Nb2O9 samples. The crystallite size is anisotropic and the strain is apparently independent of Tm amount. Dielectric properties for doped SrBi2Nb2O9 with Tm3+ ion have the same trend discussed for the pure sample. FTIR resulats showed that NbO6 octahedral is formed, on one hand, and on the other hand, it shows that spectras for doped and undoped samples are nearly the same. The Cross-section of ceramics showed the plate-like morphology, also the distribution of the pore in ceramics are observed for all samples. Tm dopants produce only minor changes in the impendence parameter values at room temperature. The luminescent (PL) properties of Tm-doped SrBi2Nb2O9 ceramic powders were investigated. The optimum Tm3+ concentration for the maximum PL intensity was found to be at x = 0.075.

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Effects of long-term storage of phosphate sludges on their physicochemical properties, the distribution and mobility of heavy metals, and acid generation

Arroug Lamya, Elaatmani Mohamed, Zegzouti Abdelouahad, Afqir Mohamed, Ibnoussina Mounsif, Babram Mohammed Ait

Environment Protection Engineering

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2021

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Vol. 47, nr 2

59--81

EN

Some phosphate sludges (Ps) were collected in 2009, 2014, and 2018. Results of their analyses by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM-SED), differential thermal and thermogravimetric analyses (TG-DTA) and X-ray fluorescence spectrometry (XRF) confirmed that the Ps are highly carbonated. Descriptive and exploratory statistical procedures for heavy metals (HM) concentrations and chemical parameters were performed and revealed the differences between the Ps of three different ages. The results indicate that there are three sources responsible for the behavior of Ps over years: common origin and accumulation of HIM and solar radiation exposure. The sequential extraction shows that the residual fractions of Cd, Ni, Zn, Pb, and Cr were predominant The mobility factor was quite low and did not change over the years, except for Cd. The net acid generation pH for the three samples was greater than 4.5 classifying the Ps as non-acid-generating.