Magnetoelectric, magnetodielectric and magneto-impedance couplings in Bi1−xNdxFe0.99Co0.01O3 compounds

In this work Bi1−xNdxFe0.99Co0.01O3 ceramics compositions were synthesized for x = 0.05, 0.20 and, y = 0.01. Structural refinement results show that most of the samples crystallized in a rhombohedral symmetry with R3c. Measurements magnetoelectric coefficient, show that the magnetoelectric coefficients are of second order. The electrical impedance characterization of in function external magnetic fields, has a relative variation of the real dielectric response, the loss tangent and the electrical impedance. The systems, as the DC magnetic field strength increased a gain in both the values of the dielectric constant variation, as well as the variation of the electrical impedance. In other words, the greater the intensity of the magnetic field, the greater your response. There were also significant variations with of the magnetic field AC.

Structural, Optical and Magnetic Properties of (1−x)Bi0.5Na0.5TiO3+xBaCoO3−δ Solid Solution Systems Prepared by the Sol–Gel Method

A new solid solution, (1−x)Bi0.5Na0.5TiO3+xBaCoO3−δ materials, was fabricated using the sol–gel method. X-ray diffraction showed that the crystal structure of the compound exhibited rhombohedral symmetry and is similar to the crystal structures of host Bi0.5Na0.5TiO3 materials. Distortions in the structures and reduction in the optical band gaps of the Bi0.5Na0.5TiO3 materials were possibly due to the random incorporation of Ba and Co cations into host lattice materials. The magnetic properties of the Bi0.5Na0.5TiO3 materials were tuned by controlling the concentrations of BaCoO3−δ as the solid solution. We expect that our work will provide valuable information on current methods for integrating ferromagnetic properties into lead-free ferroelectric materials for the development of multiferroic materials.

Structural, Dielectric and Magnetic properties of Yttrium doped Hematite Nanoparticle

Applicability of magnetic crystalline nanoparticles particularly in the diagnostic field of health care and magnetic data storage makes them highly important for various technological researches. Novel properties of prepared nanoparticles can be tuned with doping of rare earth metals. In the present research, Yttrium (Y) doped hematite nanocrystalline samples have been prepared at various compositions, Fe2 − 2xY2xO3 (x = 0.00, 0.02, 0.05, 0.08, 0.10) and magnetic properties are seen sensitive with dopants concentration. The variation in grain size from FE-SEM is found well collaborated with the crystallite size and strain determined by XRD measurements. Rietveld refinement of XRD patterns reveals the formation of rhombohedral symmetry with Rˉ3c space group of the samples. The dielectric and magnetic properties show wiggling behaviour with the concentration of doping metal. A shift towards weakly ferromagnetic conduct like behaviour has been confirmed with the doping of Y in hematite crystalline particles.

Influence of the PbO-excess on the structural, microstructural and ferroelectric properties of PLZT ceramics

The physical properties of lead lanthanum zirconate titanate (PLZT) ceramics have been investigated as a function of a PbO excess from 0 to 20 mol% in samples of Pb0.94La0.06(Zr0.6895Ti0.2955)O3 (composition that reveals the best performance for piezoelectric applications for materials with rhombohedral symmetry). Results are presented in a compressive way in the frame of an overview on PLZT. Structural, microstructural and ferroelectric properties were investigated as a function of the PbO content. The X-ray diffraction results confirmed the formation of the perovskite structure for all the cases. However, the presence of the Pb2O3 secondary phase has been observed for the sample containing 15 mol% PbO excess. Raman spectroscopy studies revealed a strong influence of the PbO content on the active modes shifts. The ferroelectric properties have shown a decrease of both remnant (PR) and saturation (PS) polarizations for compositions up to 10 mol% PbO, whereas an increase of PR and PS was observed for the higher PbO content samples. Results reveal the effect of the PbO excess on the long-range order interactions for the studied system.

Effect of the incorporation of BiFeO3 on the structural, electrical and magnetic properties of the lead-free Bi0.5Na0.5TiO3

<abstract> <p>Powders of the system (1–<italic>x</italic>)Bi_0.5Na_0.5TiO₃–<italic>x</italic>BiFeO₃ (<italic>x</italic> = 0, 0.02, 0.08, 0.10) are synthesized by the combustion reaction method. The crystal structure and the particle size of Bi_0.5Na_0.5TiO₃ are modified by the incorporation of BiFeO₃, as can be seen from the infrared spectroscopy and X-ray diffraction results. The inclusion of iron and the increase in the molar percentage of bismuth in the BNT matrix generate new bonds with a different force constant. The structural analysis showed that the addition of BFO to the BNT does not induce any structural phase transition, preserving the rhombohedral symmetry of the Bi_0.5Na_0.5TiO₃ system. The electrical measurements show that the incorporation of iron increases the conductivity of the system generated by an increase in the concentration of oxygen vacancies; alternatively, the addition of 10% of BiFeO₃ generates ferrimagnetic behavior reflected in the magnetic hysteresis curves obtained at room temperature.</p> </abstract>

Influence of pretreatment on the properties of α-Fe2O3 and the effect on photocatalytic degradation of methylene blue under visible light

The hematite (α-Fe2O3) nanostructures were synthesized by thermal oxidation of metal at 500 °C under atmospheric pressure. We studied the effect of the electrochemical pretreatment of the substrate before calcinations and its impact on the morphology, crystalline structure, lattice microstructural, and optical properties of α-Fe2O3. Uniform nanosheets were observed on the sample surface after calcination; their dimension and morphology were accentuated by the pretreatment, as confirmed by the SEM images. The characteristics of the nanostructures, analyzed by X-ray diffraction (XRD), revealed a rhombohedral symmetry with the space group R-3c and lattice constants: a = 0.5034 nm and c = 1.375 nm. The average crystallite size and strain, determined from the Williamson-Hall (W-H) plot, showed substantial variations after the substrate pretreatment. The Raman spectroscopy confirmed the changes in the crystal properties of the hematite submitted to pretreatment. The diffuse reflectance allowed to evaluate the optical gap which lies between 1.2 and 1.97 eV, induced by the electrochemical processing. The photocatalytic activity of α-Fe2O3 films was assessed by the degradation of methylene blue (MB) under LED light; 15% enhancement of the degradation for the pretreated specimens was noticed.

Experimental investigation on thermodynamic properties and crystal structure of La 0.78Ba0.22MnO3 compounds

In this work, powder [Formula: see text] samples (purity of 99.99 % and density of [Formula: see text] were used. The crystal structure of [Formula: see text] compound was studied by X-ray diffraction method. It was determined that the crystal structure of this compound consists of two phases at room-temperature and under normal condition. These structure phases correspond to the cubic symmetry with Pm-3m space group and rhombohedral symmetry with the R-3c space group. Thermo Gravimetric (TG), Differential Scanning Calorimetry (DSC), Differential Thermo Gravimetric (DTG) and Differential Thermal Analysis (DTA) of [Formula: see text] compound were carried out in a high-temperature range of [Formula: see text]. It has been found that at high-temperatures, two-phase transition occurs in this compound. The value of thermodynamic parameters was found out for each phase transit.

Synthesis, microstructure and dielectric properties of Sb-doped multiferroic Bi0.8Ba0.2Fe1−xSbxO3 ceramics

The multiferroic ceramics Bi[Formula: see text]Ba[Formula: see text]Fe[Formula: see text]SbxO3 with [Formula: see text], 0.01, and 0.02 were synthesized using the solid-phase reaction technique. The samples were sintered at two different temperatures, 850∘C and 900∘C. Scanning electron microscopy revealed the effect of antimony concentration on grain size and formation. The effect of Sb-doping on the crystal structure and ferroelectric properties of these ceramics was investigated using X-ray diffraction, Raman spectroscopy, and dielectric measurements. The dielectric constant was enhanced upon Fe[Formula: see text] substitution by Sb[Formula: see text] without affecting the dielectric loss of the ceramics. The tetragonal distortion of the rhombohedral symmetry of BiFeO3 caused by Ba-doping at Bi[Formula: see text] site was lifted by Sb-doping at Fe[Formula: see text] site.