A study on structural properties, conductivity and FT-IR spectroscopy of Cu–Al doubly substituted Bi4V2O11

The double-substituted solid solutions Bi4V2-xCux/2Alx/2O11-5x/4, with identical quantitative compositions of Cu2+ and Al3+ ions, can occur for a substitution rate 0.1 ​≤ ​x ​≤ ​0.6. The compound with x ​= ​0.1 is found to be a monoclinic α-form of Bi4V2O11, whereas compounds with 0.2 ​≤ ​x ​≤ ​0.6 are found to be tetragonal γ and γ’ polymorphs. We used electrochemical impedance spectroscopy to measure the electrical conductivity of doped samples in the temperature range of 250–700 ​°C. The slope changes observed in the Arrhenius plots might be related to the microstructural transitions occurring in these compounds. The sample with x ​= ​0.2 shows the highest ionic conductivity values

New silicon substituted BiMeVOx: synthesis and study of structural properties in relation to ionic conductivity

Partial substitution of vanadium with silicon in the compound Bi4V2O11, which belongs to the Aurivillius family, leads to the creation of a solid solution Bi4V2−xSixO11−δ (0 ≤ x ≤ 0.4). The compound with x = 0.1 turns out to be a monoclinic α-form of Bi4V2O11, while the compounds with x = 0.2 and x = 0.3 are orthorhombic β-polymorphs, and the compound with x = 0.35 is of tetrahedral γ-polymorph. Electrochemical Impedance Spectroscopy has been used to measure the ionic conductivity of doped samples. The ceramic sample with x = 0.1 has the highest ionic conductivity values

High-conducting Bi4V1.8Cu0.2-xSbxO10.7+3x/2 ceramics: Structural, microstructural, electrical and optical properties

The partial substitution of copper by antimony in Bi4V1.8Cu0.2O10.7 compounds leds to the solid solution Bi4V1.8Cu0.2-xSbxO10.7+3x/2 (0.00 ≤ x ≤ 0.20). X-ray diffraction and thermal analysis showed that for all compositions, the obtained phases are isotype to the tetragonal γ or γ′ form of Bi4V2O11. The effect of Sb5+ doping on electrical conductivity was studied using electrochemical impedance spectroscopy in the temperature range 200–700 °C. The changes in slope observed in the Arrhenius plots correspond to the structural transitions that occur within the material. The band gap was determined by DRS spectra, BiCuSbVOx materials have a very low gap band (1.77–1.80 eV) compared to parent phase Bi4V2O11 and the most of BIMEVOX semiconductor materials. The band located around 860 cm−1 in Raman spectroscopy is attributed to V–O bond and more especially to V–O2 bond

Structural study and ionic conductivity of Bi4V2−xSix/2Px/2O11−δ (0.0 ≤ x ≤ 0.5) compounds

The solid solution of general formula Bi4V2−xSix/2Px/2O11−δ (0.0 ≤x≤ 0.5) has been synthesized and characterized by XRD, SEM, FTIR, ATD, Raman spectroscopy and Electrochemical Impedance Spectroscopy. The present study showed that compounds with x ​≤ ​0.3 are isostructural with the monoclinic α polymorph, while the compound with x ​= ​0.4 is crystallize with the β polymorph. In the temperature range from 25 to 700 ​°C, the electrical conductivity of the substituted samples has been measured as a function of composition. In the low temperature range, the conductivity of the doped compounds is higher than that of the parent compound Bi4V2O11. The highest conductivity was obtained for x ​= ​0.1

Effect of the doping element on the structure and UV–visible properties in the system Bi4V1.7(Si,Me)0.3O11-δ (Me = Si, P, Cu, and Co)

While BIMEVOX systems have attracted the attention of researchers for their electrical conductivity by O2− oxide ions at relatively low temperatures, there is only a limited number of works concerning their local structure. In this work, the Bi4V1.7(Si.Me)0.3O11-δ (Me = Si, P, Cu, and Co) system is studied using X-ray powder diffraction (XRD), Raman spectroscopy, IR spectroscopy, SEM–EDX, UV–visible spectrophotometry, and differential scanning calorimetry (DSC). The three main polymorphs α, β, and γ are obtained at room temperature. In the case of the Bi4Si0.15P0.15V1.70O11-δ compound, two successive structural transitions were observed, while only one structural transition was observed for the Bi4Si0.30V1.70O11-δ compound. The UV–vis diffuse reflectance spectroscopy (DRS) indicates that the double-doped Bi4V1.7(Si.Me)0.3O11-δ compounds present a band gap energy in the range 1.76 ≤ Eg ≤ 2.36 eV and Bi4Si0.15Co0.15V1.70O11-δ presents the narrowest band gap

Effect of simultaneous Cu and Nb doping Bi4V2O11 on structural and electrical properties of Bi4V2−xCux/2Nbx/2O11−3x/4

BiMeVOx compounds Bi4V2-xCux/2Nbx/2O11-3x/4 doubly substituted solid solution, with identical compositions of Cu2+ and Nb5+ ions, show an area of existence from x ​= ​0 to 0.5. X-ray diffraction measurements and thermal analysis have shown that, depending on the composition, the three main Bi4V2O11 polymorphs α, β and (γ/γ′) are observed at room temperature. The evolution of the electrical conductivity with the rate of substitution has been investigated by electrochemical impedance spectroscopy (EIS) in the temperature range 120–720 ​°C. The highest values of conductivity are observed for samples with x ​= ​0.2. Scanning electron microscopy (SEM) shows an important grain growth and the presence of micro-cracks in the ceramics with x ​= ​0.5 composition

Electrical conductivity characterization of Bi4V2O11 doped with sulfur prepared by hydrothermal process

International audienceBi4V2−xSxO11+δ (BiSVOx) compounds (0.0 ≤ x ≤ 0.5), prepared by the hydrothermal method, were characterized by various techniques, such as X-ray diffraction (XRD), Raman spectroscopy, IR spectroscopy, thermo-gravimetric analysis (DTA/TGA), and scanning electron microscopy (SEM). It is confirmed that this synthesis method has an important impact, especially on the crystallinity and morphology of these materials. The BiSVOx phases obtained crystallize in the tetragonal γ-Bi4V2O11 structure type. Spherical grains made of nanoparticles characterize the morphology of the powders resulting from the synthesis. The stability of the BiSVOx samples has been studied by DTA/TGA analysis performed up to 1000 °C. Electrochemical impedance spectroscopy was used to measure the electrical conductivity of these compounds. Contrary to what is generally observed in BiMeVOx, The conductivity increases with the substitution rate. The highest conductivity values were obtained in the case of the sample with composition x = 0.4