Fe-doped Samples Research Articles

The role of pH on the vibrational, optical and electronic properties of the Zn1-xFexO compound synthesized via sol gel method

Herein, was investigated the role of pH on vibrational, morphological, optical, and electronic properties for pure and Fe-doped ZnO nanoparticles. The Zn1-xFexO compound with x = 0.00 and 0.02, were synthesized by the sol gel method with pH = 3, 6 and 9. For pure (x = 0.00) and Fe-doped (x = 0.02) ZnO samples Raman spectra showed slight variations, as the pH changed from the acidic to alkaline state. Two vibrational modes (580 cm−1 and 650 cm−1) were observed for Fe-doped samples, with shifted increasing as the pH values grow. Fourier transform infrared analysis revealed functional groups confirming the ZnO hexagonal structure for all x values. The samples corresponding to lower pH values showed spherical particles that are self-assembled to form irregular three-dimensional prisms-like, while the samples synthesized with basic and alkaline pH, the spherical nanoparticles are self-assembled in plates meshes-like. Pure and Fe-doped samples showed optical band gap values lower than expected for the bulk ZnO, with the lowest values for compounds synthesized at acidic pH (band gap = 3.23 ± 0.05 eV for pure ZnO and 3.21 ± 0.06 eV for Fe-doped ZnO). Structural defects such as zinc vacancies, interstitial zinc, singly ionized oxygen vacancy, and doubly ionized oxygen vacancy were detected through the photoluminescence spectra. The pH effect on electronic properties for pure and Fe-doped ZnO nanoparticles was also confirmed by electron paramagnetic resonance (EPR) measures. The simulation of EPR data for the spin S = 5/2 (Fe3+) demonstrated that pH variation induces strains in the ZnO lattice.

Iron (Fe)-doped mesoporous 45S5 bioactive glasses: Implications for cancer therapy

The utilization of bioactive glasses (BGs) in cancer therapy has recently become quite promising; herein, a series of Fe-doped mesoporous 45S5-based BGs (MBGs) were synthesized via the sol-gel method in the presence of Pluronic P123 as a soft template. The physico-chemical and biological properties of the prepared glasses were well-characterized through structural assessments, thermal analyses, and electron microscopic studies. Electrochemical analyses, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were also performed to investigate the actual potential of the Fe2O3-containing MBGs in modulating the Fenton's reaction. The XRD results confirmed the glassy state of the Fe-doped samples before immersion in simulated body fluid (SBF). The prepared Fe-doped MBGs exhibited a particle size in the range of 11–86 nm, surface charge of 27–30 mV, SBET of 95–306 m2/g, and Ms of 0.08 to 0.2 emu/g. The incorporation of Fe2O3 led to a negligible decrease in the bioactivity of the glasses. The CV analysis indicated that the Fe-doped MBGs could generate H2O2 in a cathodic potential higher than -0.2 V (vs. Ag/AgCl) in the O2-saturated Na2SO4 solution. Additionally, the data of the EIS test revealed that the Fe2O3-doped MBGs could increase the standard rate constant of Electro-Fenton's (EF) reaction up to 38.44 times as compared with the Fe-free glasses. In conclusion, Fe-doped 45S5-derived glasses may be useful in cancer therapy strategies due to their capability of activating Fenton's reaction and subsequent production of reactive oxygen species (ROS) such as •OH free radicals.

X-ray line profile analysis and magnetic and optical properties of FexZn0.95-xCr0.05O nanoparticles fabricated by sol-gel route

FexZn0.95-xCr0.05O nanoparticles have been obtained for the different concentrations of Fe ions by using the sol-gel method. The hexagonal wurtzite structure of all the samples was confirmed by Rietveld refined X-ray diffraction patterns. The addition of Fe ions decreased lattice constants a and c from 3.2487 to 3.2474 Å and 5.2043 to 5.2029 Å, respectively. Uniform deformation, uniform stress deformation, and uniform deformation energy density models were assumed to obtain the crystallite size and strain values from Williamson-Hall analysis. The average crystallite size obtained from all four methods showed increasing variation with the addition of Fe ions in Zn-Cr-O, which was found in good agreement with the Scherrer equation, scanning electron microscopy, and high-resolution transmission electron microscopy results. Energy-dispersive X-ray spectra of typical samples confirmed the stoichiometric proportion of constituent elements. Room temperature ferromagnetism was observed in all the Fe-free and Fe-doped samples. Optical studies were carried out by UV-visible spectrophotometry. The band gap values lay in the range of 3.275 to 3.215 eV.

Preparation and thermoelectric properties of Co/Ni stabilized cubic Cu3SbS3 compounds

The anharmonicity of the lattice vibrations caused by 5s2 lone-pair electrons at Sb site has been considered to be the main reason for the low thermal conductivity of the compounds such as Cu3SbSe3, Cu3SbS3 and Cu12Sb4S13. In this study, by substituting Sb with Ni/Co without 5s2 lone-pair electrons, the cubic Cu3Sb1-x(Ni/Co)xS3 compounds were successfully synthesized by SPS and the effect of lone-pair electrons was further studied. The results demonstrate that both of the alloying effect and the change of valence bond environment of the Sb site caused by doping have a great influence on phonon transport. In addition, the increase of thermal conductivity caused by the latter is much greater than the inhibition of thermal conductivity by the former, which indicates the vital effect of the 5s2 lone-pair electrons on the decrease of thermal conductivity. When x= 0.05, the figure-of-merit zT values of the Ni and Co doped samples reach the maximum of 0.94 and 0.85 ​at 623 ​K, respectively, which are much higher than those of the undoped sample and the Fe doped samples, showing the potential of the Ni and Co doped compounds as high performance thermoelectric materials.

Fe–Co co-doping effects on antiferromagnetic core of NiO nanoparticles

The Fe and Co single and co-doping effects on the structural and magnetic properties of NiO nanoparticles (NPs) have been studied. The Fe and Co doping into NiO system did not induce any other possible secondary phase (other than NiO) and the average crystallite size was found to be in a narrow range of 33–40 nm which is suitable for studying the doping effects. Room temperature ferromagnetic resonance (FMR) measurements demonstrated the existence of a net magnetization in antiferromagnetic (AFM) NiO NPs which was observed to be increased with an increasing Fe doping and decreasing Co doping concentration. The scattered differential FMR signal for 8% Co doped NiO NPs revealed the presence of randomly oriented magnetic moments in the core of the NPs. However, decreasing the Co doping concentration and increasing the Fe doping concentration increased the degree of homogeneity of the spin structure in the system. The M − H loops taken at room temperature with S-like shape confirmed the presence of a weak ferromagnetism in the Fe doped samples in accordance with FMR analysis and attributed to the double exchange mechanism in these NPs. In ZFC/FC curves, a small peak at low temperatures, in the range of 9–18 K for all the samples, indicates the magnetization contribution from the uncompensated surface spins of these NPs. In addition, a relatively broad peak for higher Fe doping concentrations at higher temperatures indicates the onset of magnetization from the core of these NPs, where Fe and Ni ions may couple parallel or anti-parallel to each other. In summary, Co–Fe co-doping induced a core magnetization in AFM NiO NPs system and makes it attractive for various magnetic applications.

Defect dipole induced improved electrocaloric effect in modified NBT-6BT lead-free ceramics

The Rietveld refinement of the polycrystalline powders of 1% Fe and Mn-doped (Na0.5Bi0.5)0.94Ba0.06Ti0.98V0.02O3 at the Ti-site confirmed a single rhombohedral (R3c) phase. The bandgap, (Eg) was affected by the anti-phase octahedral tilt angle and the spin-orbit splitting energy of Ti4+2p3/2 and Ti4+2p1/2 states. The decrease in Bi loss and increase in the binding energy of Ba due to Fe/Mn doping has been correlated to the strengthening of Bi-O and Ba-O bonds which was revealed from the XPS studies thereby further related to the average A-O bond length from structural studies. Hence, a reduction of oxygen vacancy (VO) for the doped samples has been justified. A significant improvement of the dielectric constant, relaxation time (τ0), and the decrease in conductivity due to doping was revealed from the frequency-dependent (10 Hz-1 MHz) dielectric measurement study. The conduction and relaxation process are dominated by the short-range movement of defects. The activation energy (Ea~1 eV) revealed that there is a presence of double-ionized VOs. The ECE study showed a significant enhancement of the changes in entropy, ΔS, and the adiabatic temperature difference, ΔT, due to doping, with ΔT being highest in the Fe-doped sample. Such improvement of dielectric and ECE properties was confirmed due to the reduction of the mobility of oxygen vacancy because of the formation(MnTi′′−Vo••)/(MnTi′−Vo••)• and FeTi′′−Vo••/(FeTi′−Vo••)• defect dipoles.

Giant magnetoresistance effect in Fe-doped SrCoO2.9-δF0.1 perovskites

Excellent magnetoresistive materials have attracted people's attention due to their wide applications. Unfortunately, few cobalt-based perovskite oxides can demonstrate good magnetoresistance (MR) properties. Herein, a new series of SrCo 1-x Fe x O 2.9-δ F 0.1 (x = 0, 0.1, 0.2, and 0.3) perovskites are prepared and studied as potential magnetoresistive materials. Room temperature X-ray diffraction (XRD) and Rietveld refinement confirm the simple cubic structure of all samples. The magnetization vs temperature measurement reveals that the magnetic transition temperature goes down with the increase of Fe content, suggesting the weakened ferromagnetism caused by Fe 4+ -O-Co 3+ , Fe 3+ -O-Fe 3+ and Fe 4+ -O-Fe 4+ interactions. And the resistivity data of all Fe doped samples can be better fitted using Mott's variable range hopping (VRH) model, suggesting its disordering semi-conduction behavior. Astonishingly, the SrCo 0.8 Fe 0.2 O 2.9-δ F 0.1 ceramic sample owns the giant negative magnetoresistance value of approximately 90% at 5 K in 90 kOe, which is almost the largest negative magnetoresistance in cobalt-based perovskite oxides, indicating that cobalt-based perovskites can be an underlying material system for the research of the potential material applying to magnetic sensors or other spintronic devices.

Oxygen reduction activity of Fe/Co/Ni doped MnOx @ graphene nanohybrid: A comparative study

• Fe, Co, and Ni doped MnO x was grown on NG. • Doped catalysts show better ORR activity than the undoped one. • Doping can tune the Mn valence. • Enhanced activity for doped MnO x owing to increase in Mn valence on doping. We report the electrochemical activity of transition metal ion (Fe, Co and Ni) doped MnO x @ N -graphene (MnO x @NG) hybrid catalysts towards oxygen reduction reaction (ORR). The doped catalysts displayed significantly enhanced electrochemical performance than the undoped one. The Fe doped MnO x @NG exhibited highest positive shift in onset potential (0.93 V vs. RHE), highest electron transfer number (n) (3.87) and lowest peroxide yield (6.35 %) in 0.1 M KOH solution. The Co doped catalyst showed highest current density, which is comparable to that of benchmark 20 wt% Pt/C. The XRD analysis showed that the catalyst samples are poorly crystalline and the doping of either Fe or Co or Ni cation induces formation of Mn 2 O 3 , whereas the undoped catalyst consists of both Mn 2 O 3 and MnOOH. The STEM (scanning transmission electron microscope) micrographs revealed that in all the samples the MnO x nanostructures are well dispersed on NG and the elemental mapping of the doped catalysts showed uniform distribution of dopants. The X-ray photoelectron spectroscopy (XPS) studies revealed that doping of either cation results an increase in the average Mn valency of the host MnO x . The change in crystal structure and corresponding ORR activity has also been investigated with increase in dopant amount for Fe doped samples.

Photocatalytic degradation of Congo red dye using Fe-doped TiO2 nanocatalysts

Fe-doped TiO2 (2, 5, 10, 15 and 20% wt. of Fe) photocatalysts have been synthesized by sol-gel method using titanium aquacomplex precursor. The structure and morphology have been characterized by XRD, BET, SEM, and EDS analyses, Mossbauer and IR spectroscopies. XRD analysis confirmed the anatase structure. The introduction of ferric ions into the titania structure causes its amorphization. The crystallite sizes of obtained samples are around 3 nm. Fe-doped TiO2 samples possess mesoporous structure and high specific surface area (from 274 m2g-1 for 5Fe-TiO2 to 416.4 m2g-1 for 20Fe-TiO2). Mossbauer spectroscopy data confirms the incorporation of Fe3+ ions in the anatase structure. Photocatalytic degradation of Congo red dye using Fe-doped TiO2 photocatalysts was studied under the UV-A light. Optimized conditions for photocatalytic degradation of CR in the presence of hydrogen peroxide are obtained. It was found that the 2Fe-TiO2 sample in the presence of 20 mM H2O2 solution showed highest efficiency in dye photodegradation (99.4%) under UV-A light. The photodegradation kinetics was analyzed using a smartphone and fits well with first-order kinetics model.

Room temperature multiferroicity with enhanced ferroelectric and ferromagnetic properties in Ba0.75Pb0.25Ti1-xFexO3

Polycrystalline Ba0.75Pb0.25Ti1-xFexO3 (0≤ x ≤0.148) (BPTF) ceramics have been synthesized by sol-gel auto combustion method. The structural, vibrational, electrical, and magnetic properties have been investigated. A detailed structural and vibrational analysis confirms the tetragonal phase in all samples. The proportion of a hexagonal phase increases with increasing Fe-doping. An elemental and morphological investigation reveals the presence of these two different phases. A relaxor-type phase transition is observed in high Fe-doped samples. These samples reveal a high dielectric constant for a wide temperature range. A tetragonal to the cubic phase transition is observed, and the transition temperature, Tm, decreases with increasing Fe concentration. However, Tm remains well above room temperature, ensuring the ferroelectric nature of all samples at room temperature. The ferroelectric nature of all the samples was confirmed from the presence of room-temperature P-E hysteresis loops. Simultaneously, an increase in ferromagnetic ordering at room temperature was confirmed from the presence of a notable ferromagnetic loop for higher doped samples. Hence, the presence of both ferroelectric and ferromagnetic components at room temperature ensures a multiferroic nature in the Fe-doped Ba0.75Pb0.25TiO3 system.

Hydrothermal preparation of iron doped nickel oxide for electrochemical sensing of urea

This study is devoted to the synthesis of iron-doped nickel oxide nanomaterials with the help of the hydrothermal technique, to study the effect of different dopant concentrations on the structural, morphological, and Direct current properties. Various testing has been performed on the materials for their utilization in some potential chemical applications. X-ray study showed that the material is pure single phased NiO. A cubic crystalline structure was shown by pure NiO Morphology and was analyzed by SEM revealed oval/spherical crystallites of Fe-doped NiO samples where concentration was much low i.e., 2%. The materials showed unsymmetrical morphology when dopant concentration was increased (4% to 8%). Doped NiO material (8%) was utilized to modify the glassy carbon electrode (GCE) for electrochemical sensing of various chemical analytes. The results show that as-synthesized material exhibits a good sensing response towards urea (CH4N2O) detection with high selectivity and sensitivity as compared to different interfering compounds.

Fe-related optical transitions in floating zone and Czochralski grown β-Ga2O3 crystals

Gallium oxide (Ga2O3), a promising candidate for high-power electronics, may be doped with Fe to control the native n-type conductivity and produce semi-insulating single-crystalline substrates. Here, intentionally as well as unintentionally Fe-doped β-Ga2O3 crystals grown by the Czochralski (Cz) and the floating zone (FZ) methods are studied. While the Cz samples contain Ir on the order of 1017 cm−3 due to the Ir crucible, the FZ samples are free of this contaminant. Photoinduced electron paramagnetic resonance (EPR) is performed by illuminating the samples with light emitting diodes from 0.7 to 4.7 eV while monitoring the intensity of the EPR signal. The following optical transitions associated with Fe are observed: one between 1 and 2 eV occurs in both Cz and FZ samples, another near 2.5 eV is unique to Cz Ga2O3, and a third near 3 eV appears in FZ material. The transition below 2 eV is the well-studied Fe2+-to-Fe3+ transition, intrinsic to Fe. Near 2.5 and 3 eV, the amount of Fe3+ decreases by capturing electrons excited from other defects present near or below the middle of the bandgap. By comparing Cz and Ir-free FZ crystals, we show that the 2.5 eV transition is primarily caused by Ir in Fe-doped Cz samples, whereas the ∼3 eV transition observed in FZ samples could be caused by isolated or complex intrinsic defects. By differentiating transitions between Cz and FZ material, the results will be relevant to epitaxial films, which do not contain the Ir present in the commonly studied Cz material.

The crystal chemistry and electrical properties of Fe doped Ca12Al14O33 (Mayenite)


 
 
 X-ray and neutron powder diffraction have been used to study the crystal chemistry of Fe doped mayenite (Ca12Al14-xFexO33). Solid- state synthesis was used to prepare Ca12Al14-xFexO33 where x = 0, 0.1, 0.2, 0.5 and 0.6 and the citrate gel route was used to prepare Ca12Al14-xFexO33 where x = 0, 0.05, 0.1, 0.2, 0.3 and 0.4. X-ray powder diffraction data indicate that samples with the same composition but synthesized by the citrate gel route were more likely to be phase pure than samples obtained by traditional solid-state synthesis. The refined lattice parameters were observed to increase with increasing Fe concentration, irrespective of the synthesis method. Refined neutron powder data confirm that Fe is going into Al site rather than Ca site. A 2-point probe was used to measure the electrical properties of the Fe doped citrate gel synthesized samples and showed that the resistivity increases for the Fe doped samples compared to the undoped mayenite.
 
 

Growth, optical, and wettability properties of iron modified titania and ferropseudobrookite thin films

Iron (Fe)-modified titanium dioxide, Fe–TiO2, thin films with molar ratios Fe:Ti = 1:360, 1:60, and 1:30 and Fe-pseudobrookite, FeTi2O5 (molar ratio Fe:Ti = 1:2), were grown by the sol-gel process using acid-catalyzed solutions prepared with titanium isopropoxide and iron(III) chloride hexahydrate as Ti and Fe precursors, respectively. The layers were deposited by dip-coating onto soda–lime glasses and (100)-Si substrate wafers, and their chemical composition, crystal structure, and surface morphology were investigated in detail. For the low Fe-doped samples, the experimental results clearly indicate the formation of Fe–O–Ti heterolinkages. The films have an amorphous structure and high flatness surfaces if grown onto glass substrates. On the contrary, if grown onto (100)-Si substrates, they exhibit a granular structure (domain size ∼12 nm) made of a solid solution of Fe3+ ions within the anatase TiO2 lattice. For coatings with the molar ratio Fe:Ti = 1:2 (high Fe content), morphological investigations show the formation of wrinkled surfaces characterized by dendritic structures. X-ray diffraction measurements confirm the formation of nanocrystallites (domain size ∼15 nm) of pure, single-phase orthorhombic FeTi2O5. Wettability measurements conducted on amorphous low Fe-doped TiO2 samples revealed superhydrophilic properties with a surface–water contact angle <1°, whereas optical absorption and reflectance measurements yield bandgap widening and narrowing. A bandgap narrowing occurs with the formation of oxygen vacancies and of Ti3+ levels, but if the concentration of oxygen vacancies and Ti3+ levels increases, more electron donors are generated, which shift the Fermi level to the conduction band. This widening of the bandgap (blue shift) can be explained by the Burstein–Moss effect. The correlation of the large optical bandgap (3.61 < Eg < 3.74 eV) and the wettability results are interpreted and discussed with the presence of oxygen vacancies and Ti3+ and Fe3+ sites in the TiO2 matrix.

Influence of Fe-doping on the structural and photoluminescence properties and on the band-gap narrowing of SnO2 nanoparticles

In this study the structural and optical properties of Fe-doped SnO2 (Sn1-xFexO2, for x = 0, 0.03, 0.05, 0.07) nanoparticles synthesized by co-precipitation technique and using short durations of sample sintering is reported. The prepared samples are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Thermogravimetric analysis – differential scanning calorimetry (TG-DSC), UV–Visible spectroscopy (UV-VIS) and Photoluminescence (PL) measurements. The Rietveld refined XRD data shows that all the samples are in tetragonal rutile crystalline phase. Fe doping in the samples hinder grain growth as the average crystallite size (ranging in between 13 and 29 nm) reduces with doping concentration. Information on the phase purity of the samples is obtained via the FTIR and Raman measurements while the Thermogravimetric–Differential Scanning Calorimetric (TG-DSC) studies give an idea on the crystallization process of and the presence of oxygen vacancies in the samples. The finger print wave number region of rutile phase of SnO2 corresponds to the A1g mode, which shows a red shift in the Raman studies undertaken. This is indicative of the effect of the defects arising due to the dopant introduced, which affects the crystallite size and leads to phonon confinement, observed as the red shift of the Raman peaks. The addition of Fe leads to a band-gap narrowing process due to the d – d transition and a feeble absorption occurs in the near infrared region. The Photoluminescence (PL) curve shows a broad and intense emission in the UV region, near ~ 375 nm (3.31 eV), owing to the presence of oxygen vacancies. Apart from this, two additional feeble emission peaks for the 5% and 7% Fe-doped samples also evolve. The substitution of Fe, existing in the Fe2+/Fe3+ state, in place of Sn, existing in the Sn4+ state, gives rise to a charge/oxidation state imbalance. This creates a vacancy in the crystal, which acts as the emission center in the doped semiconductor type SnO2. The PL studies confirm the existence of Fe induced inter bands in the energy band-gap of these samples. The CIE chromaticity diagram shows that the prepared materials are suitable and tunable for blue light LED applications.

Magnetotransport properties of Fe substituted Ca3CoMnO6

Ca3CoMnO6, a quasi-1D Ising chain at low temperature offers rich fundamental physics and applications. We have studied the dielectric and magnetoelectric coupling in Fe doped Ca3CoMnO6 (CCMO) bulk ceramics prepared by co-precipitation technique. Single phase hexagonal crystal structure having R-3C space group was confirmed by x-ray diffraction. Extremely low currents were observed up to 20% Fe doping. Doping dependence of magnetoresistance (MR) revealed both positive and negative MR, with anomalously high MR values beyond 3000% in diluted Fe doped CCMO; whereas the higher doping of Fe was found to result in negative MR due to enhanced magnetostriction effects. The dielectric study was carried out for a range of 20 Hz to 10 MHz. The negative value of the colossal magnetodielectric induced in the Fe doped samples can be attributed to the magnetostriction effect along with interfacial Maxwell-Wagner polarization.

Doubling of the Phase Transition Temperature of VO2 by Fe Doping.

Vanadium dioxide (VO2) undergoes a fully reversible first-order metal-insulator transition from the M1 monoclinic phase (P21/c) to a high-temperature tetragonal phase (P42/mnm) at around 68 °C. Modulation of the phase transition of VO2 by chemical doping is of fundamental and technological interest. Here, we report the synthesis of highly crystallized Fe-doped VO2 powders by a carbo-thermal reduction process. The impact of Fe doping on the structural and phase transition of VO2 is studied. The as-prepared Fe-doped VO2 samples crystallize in the M2 monoclinic form (C2/m), which is linked to segregation of the doping ions in the V2 zigzag chains. A large increase in the transition temperature to 134 °C is observed, which does correspond to a breakthrough in VO2-type thermochromic materials.

Weak-ferromagnetism for room temperature thermoelectric performance enhancement in p-type (Bi,Sb)2Te3

Unceasing efforts have been devoted to performance enhancement of thermoelectric (TE) materials, and recently reports suggested a new approach by utilizing magnetism to increase power factor. This work investigated the doping effect of Fe on the TE properties of Bi2Te3-based materials. A series of Fex(Bi,Sb)2-xTe3 bulk samples were synthesized via mechanical alloying combined with spark plasma sintering. XRD results and DFT calculations indicate that Fe2+ and Fe3+ would coexist and substitute Bi3+ site firstly and shrink lattice. The co-doped Fe2+/Fe3+ in (Bi,Sb)2Te3 is helpful to reduce carrier concentration (nH), band gap (Eg) and increase effective mass (m∗). With further increase of x, ferromagnetic FeTe2 second phase was precipitated from (Bi,Sb)2Te3 matrix. A weak-ferromagnetism was observed in all Fe-doped samples via M-H curve, which could scatter low energy carriers along with little effect on high-energy carriers, whereby the mobility was enhanced effectively. Owing to the synergistic effect of weak-ferromagnetism and optimized band structure, the maximum power factor reaches up to 45 μWcm−1K−2 as x = 0.05, which is 28.5% higher than that at x = 0. The peak ZT value reaches up to 1.2 at 323 K along with a theoretical ηmax of 7.6% in the range of 303–473 K were achieved in x = 0.05 sample. The results suggest that introducing weak-ferromagnetism is an effective way to enhance room temperature TE performance of Bi–Sb–Te based materials.

Effect of Fe doping on the structural, morphological, optical, magnetic and dielectric properties of BaSnO3

Doping at the possible A or B site in the ABO3 perovskite can alter the structural, morphological and optical properties of the compounds. Perovskite alkaline earth stannate BaSnO3 doped with Fe resulted in BaSn1-xFexO3 compounds having different concentrations (x = 0.00, 0.01, 0.02, 0.03, 0.05 and 0.07) were prepared by solid-state method. The Rietveld analyzes were performed to determine the phase purity and the changes in structural parameters. Morphological analysis identifies the formation of hexagonal nanorods with doping. The non-linear optical property of the prepared samples shows optical power limiting behavior. Magnetic property signifies the existence of ferromagnetic order and EPR studies reveal the possible ferromagnetic ordering of Fe-doped samples. Dielectric loss decreases with Fe doping and has a gradual decrease in the higher frequency regime and has applications in high frequency devices.

Ferroelectricity and ferromagnetism in Fe-doped barium titanate ceramics

In this work, structural, dielectric, ferroelectric, and ferromagnetic properties of BaTi1– x Fe x O3 (0 <x < 0.5) ceramics have been investigated. Structural investigations using X-ray diffraction reveal that Fe doping leads to the development of hexagonal phase as well as an increase in average grain size. The coexistence of tetragonal and hexagonal phases strongly depends upon the Fe concentration. The lattice strain and dislocation density are found decreasing with increasing Fe content from x = 0 to 0.5. A reduction in dielectric constant (from 1534 to 305) and Remnant polarization (from 1.105–0.015 μC/cm2) was observed with increasing x from 0 to 0.5. All Fe-doped samples exhibit ferromagnetic ordering with increasing saturation magnetization (Ms) 0.084 emu/g at x = 0.1–0.511 emu/g for x = 0.5 samples.