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a–c Nyquist plot Z″ vs. Z′ at low temperatures range fitted with R-CPE equivalent circuit model. d–f Nyquist plot Z″ vs. Z′ at high temperatures range fitted with R-CPE equivalent circuit model. g Equivalent circuit model used for fitting non-ideal (Cole–Cole) behavior
Source publication
The barium iron niobate material BaFe1/2Nb1/2O3 (BFN) was prepared using the solid-state reaction route. At room temperature, the Rietveld refinement technique showed a cubic phase with the space group Pm\(\overline{3 }\)m. In the low temperature range, the conductivity (versus frequency) followed the double power law. An appropriate model is used...
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Citations
The evolution of multifunctional materials is an outstanding research area, which aims to improve the versatility of materials according to their broad domains of usage. Focus interest was paid here to the orthophosphate compound, in particular, the olivine NaMnPO4 material. This compound was synthesized by a solid‐state method and investigated using numerous techniques. Primary room‐temperature structural analysis evidences the sample synthesized in the orthorhombic structure and its phase purity. The sample‘s average grain size was calculated to be around 420 nm. Further, the band gap for our material was found to be (Eg=4.4 eV) by optical analysis of UV‐visible spectroscopy, revealing that our compound is a potential candidate for optoelectronic applications. The electrical behavior study‘s main results confirm the ferroelectric character of the sample and support the aim of deepening the knowledge of the material according to its thermally stimulated conduction processes through impedance spectroscopy. Electrical studies revealed the dominant transport processes across various temperature and frequency ranges, leading to the NSPT model. The frequency dependency relates to frequency‐dispersive dielectric spectra, conduction mechanisms, and relaxation phenomena. The obtained results show perspective and suggest that the material under study has a wide range of potential electronic applications.
This work focuses on the structural, optical and electrical properties of sodium bismuth titanate Bi1/2Na1/2TiO3 (NBT) lead-free ceramic for its possible application in capacitors, batteries and as an electrolyte in SOFC. NBT material was prepared by the solid-state method. X-ray diffraction analysis performed at room temperature revealed a rhombohedral structure with R3c space group. Rietveld refinement confirmed a good agreement between the calculated and the observed pattern. Scanning electron microscopy analysis revealed a polycrystalline nature of the material with a grain size of 29.17 µm. FT-IR analysis showed the presence of different bonds. The band gap energy was extracted through diffuse reflectance spectroscopy and was found to be 2.61eV. Detailed studies of dielectric and impedance properties carried out in the frequency range of 40–10⁷ Hz at different temperatures (from 400K-700K) provided many interesting properties. The dielectric loss and dielectric constant with frequency increase. This behavior could be interpreted by the Maxwell–Wagner type of polarization in agreement with Koop's theory. To explain the complex impedance plane plots, an equivalent circuit template was employed, reflecting semiconducting behavior of NBT. The Ac-conductivity spectrum satisfied Jonscher’s power law below 460K and followed Jonscher’s double power law (DPL) above 480K. The correlated barrier hopping (CBH) and small polaron hopping (SPH) models could explain the conduction mechanism at the studied temperature range. The study of the Dc-electrical conductivity confirmed that NBT followed the variable range hopping (VRH) model. The present work could give further insights into this kind of material from a physical point of view and thus enhance its presence in the industrial field.
BaTiO3 ceramics doped with double cation couple (Fe³⁺, Mo⁶⁺) or (Fe³⁺, W⁶⁺) are fabricated via solid-state reaction technology with 6H-[BaTi0.5(Fe0.33M0.17)O3-δ (M = Mo or W)] as a chemical formula. The effects of (Fe³⁺, M⁶⁺) dopants on the electrical and magnetic properties are systematically studied. In this work, the working temperature range and frequency range are: 320 K < T < 700 K and 10³ Hz < f < 10⁶ Hz, respectively. The highest value of ε’ can be associated to the presence of many types of polarizations mechanisms. The hopping relaxation model was used to study the variation of conductivity with frequency and fit to the dual power law. The materials' electrical conductivity has been examined and analyzed over a wide range of frequencies at selected temperatures. The magnetism observed in the doped compositions is strongly influenced by the nature of the second phase detected, resulting in an enhanced magnetic effect in the case of 6H-[BaTi0.5(Fe0.33Fe0.17)O3-δ. The contributions of microstructures and defects to magnetism and conduction were clarified in this study. It is critical for a correct understanding of the electrical and magnetic properties of 6H-BaTiO3-related ceramics, as well as process modification to optimize ceramic performance.
