Ferromagnetic Behavior Research Articles

Structural, Optical, Magnetic and Electrical Properties of Zinc Oxide Doped with Iron: A Review

This study reviewed the structural, optical, magnetic and electrical properties of zinc oxide (ZnO) nano-particles doped with iron relative to zinc oxide. ZnO is an excellent nanomaterial in semiconductor industries because of its properties such as low cost, high stability and high absorbance. However, its application has been limited because of some undesirable characteristics. Hence, doping with iron has proven essential in overcoming these limitations. The X-ray diffraction studies show that the structure is hexagonal with wurtzite structure, ZnO films prefer to grow in the (002) direction. This is because each apex is parallel to the c-axis in the wurtzite structure. This review reported that optical band gap ZnO nano-particles doped with iron was found to be in the range to (3.26 - 3.35) eV. The electrical properties of these films indicated low resistivity and consequently high electrical conductivity at high dopant iron concentration. Consequently, higher electrical resistivity was observed with lower conductivity at lower iron dopant concentration. Higher iron-doped ZnO (x=0.10 and 0.20) samples exhibited obvious ferromagnetic behaviors suggesting that saturation magnetization of Zn1-xFexO nano-particles increases with the increasing of Fe doping concentration compared with pure ZnO. Hence the SEM of iron-doped zinc oxide nano-particles consists of ellipsoidal shape particles, which are well dispersed with smooth surface and uniform size.

Measuring anisotropy field of patterned soft magnetic films by anisotropic ferromagnetic resonances.

Patterned magnetic films have been applied widely in communication technology for meeting the development of miniaturization and high frequency. However, there has been some debate about the measuring of the anisotropy field, which is significant for deciding the electromagnetic performance. In the paper, we proposed the measurement of the anisotropy field using anisotropic ferromagnetic resonances in patterned permalloy magnetic films. The anisotropy in patterned permalloy with different magnetic stripe widths can be observed qualitatively by the hysteresis loop along in-plane x and y directions, which induces the anisotropic ferromagnetic resonant behaviors. The anisotropy field can be calculated quantificationally by fitting the Kittel equation when the single resonant peak appears under applied magnetic fields. The values of the anisotropy field obtained by anisotropic ferromagnetic resonances are on the lower side to compare with the ones obtained by the energy difference between easy anis and hard axis. Our results can provide an extra method for measuring the anisotropy field, which can be useful for designing electromagnetic devices and potential applications in next-generation wireless communication.

Theoretical investigation of structural, elastic, mechanical, thermodynamic, electronic, and half-metallic ferromagnetic behavior of quaternary Ti2Fe-based full-Heusler alloys Ti2FeGe1-xSnx (x = 0, 0.25, 0.5, 0.75, and 1) for spintronic applications: DFT computation

Theoretical investigation of structural, elastic, mechanical, thermodynamic, electronic, and half-metallic ferromagnetic behavior of quaternary Ti2Fe-based full-Heusler alloys Ti2FeGe1-xSnx (x = 0, 0.25, 0.5, 0.75, and 1) for spintronic applications: DFT computation

Mechanism of magnetic phase transition in correlated magnetic metal: insight into itinerant ferromagnet Fe3−δGeTe2

Developing a comprehensive magnetic theory for correlated itinerant magnets poses challenges due to the difficulty in reconciling both local moments and itinerant electrons. In this work, we investigate the microscopic process of magnetic phase transition in ferromagnetic metal Fe3−δGeTe2. We find that Hund’s coupling is crucial for establishing ferromagnetic order. During the ferromagnetic transition, we observe the formation of quasiparticle flat bands and an opposing tendency in spectral weight transfer, primarily between the lower and upper Hubbard bands, across the two spin channels. Moreover, our results indicate that one of the inequivalent Fe sites exhibits Mott physics, while the other Fe site exhibits Hund’s physics, attributable to their distinct atomic environments. We suggest that ferromagnetic order reduces spin fluctuations and makes flat bands near the Fermi level more distinct. The hybridization between the distinctly flat bands and other itinerant bands offers a possible way to form heavy fermion behavior in ferromagnets. The complex interactions of competing orders drive correlated magnetic metals to a new frontier for discovering outstanding quantum states.

Separate magnetic and structural phase transitions in Mn50−xFexRh50 films grown on MgO

Abstract Investigations of the magnetic and structural characteristics of Mn50−x Fe x Rh50 alloys are important due to their notable phase transition behavior. In this study, a series of highly ordered epitaxial films with varying Fe concentrations are grown on MgO (001) substrate. At low Fe concentrations (x = 0, 2, 6), a separation between the structural phase transition and the magnetic phase transition is observed. Unlike structural phase transitions, temperature-dependent magnetization exhibits fairly large temperature hysteresis. In addition, the structural transition induces further tetragonal distortion, resulting in an intermediate phase between the B2 and L10 structures. This separated magnetic and structural phase transitions have been further validated through x-ray diffraction, anisotropic magnetoresistance and spin-pumping measurements. Moreover, as the Fe concentration is increased, the Mn50−x Fe x Rh50 films exhibit ferromagnetic behavior due to competitive magnetic exchange interactions, while the structural phase transition is suppressed.

Biosynthesis; Characterization; and Antibacterial, Antioxidant, and Docking Potentials of Doped Silver Nanoparticles Synthesized from Pine Needle Leaf Extract

The current study focused on the synthesis of doped silver nanoparticles (doped AgNPs) with yttrium (Y), gadolinium (Gd), and chromium (Cr) from pine needle leaf extract (PNLE). X-ray diffraction (XRD) was performed to assess the phase formation, detecting 61.83% from Ag and 38.17% for secondary phases of AgCl, AgO, Y, Cr-, and Gd phases. The size and shape of the NPs were determined by transmission electron microscopy (TEM), showing a spherical shape with an average particle size of 26.43 nm. X-ray photoelectron spectroscopy (XPS) detected the oxidation state of the presented elements. The scanning electron microscope (SEM) and the energy-dispersive X-ray analysis (EDX) determined the morphology and elemental composition of the NPs, respectively. Fourier transform infrared spectroscopy (FTIR) determined the different functional groups indicating the presence of Ag, Y, Gd, Cr, and other groups. Photoluminescence (PL) spectroscopy showed the optical properties of the NPs. A vibrating sample magnetometer (VSM) revealed the ferromagnetic behavior of the doped AgNPs. The antibacterial activity of the doped AgNPs was tested against six uro-pathogenic bacteria (Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa) using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) microdilution assays, agar well diffusion assay, time–kill test, and antibiofilm screening assays, revealing significant activity, with MICs ranging between 0.0625 and 0.5 mg/mL and antibiofilm activity between 40 and 85%. The antioxidant activity was determined by the 1,1, diphenyl 1-2 picrylhydrazyl (DPPH) radical scavenging assay with a potential of 61.3%. The docking studies showed that the doped AgNPs had the potential to predict the inhibition of crucial enzymes such as penicillin-binding proteins, LasR-binding proteins, carbapenemase, DNA gyrase, and dihydropteroate synthase. The results suggest that the doped AgNPs can be applied in different medical domains.

Study on physical, electrical, magnetic and energy harvesting performances of eco-friendly piezoelectric ceramics (1 − x)[0.995BNKT–0.005LN]–xFe2O3 complex system

ABSTRACT In this work, the complex lead-free piezoelectric ceramics with formula (1 − x)[0.995 Bi0.5(Na0.80K0.20)0.5TiO3–0.005LiNbO3]–xFe2O3, where x = 0, 0.010, 0.015 and 0.020 mol fraction, have been prepared via a conventional solid-state method. The effects of Fe2O3 doping on the physical, microstructural electrical, energy harvesting and magnetic properties have been systematically investigated. All ceramics were sintered at 1150°C for 2 hours with obtained relative density of ~ 96-97%. The XRD and Raman data revealed the coexisting rhombohedral and tetragonal phases for all samples. SEM image presented angular grain packing with the average grain size range of 0.43–1.03 μm. The addition of Fe2O3 content improved in electrical properties of undoped sample particularly at a composition of x = 0.015. The maximum values of ε m = 6250, S max = 0.29, d*33 = 578 pm/V, d 33 = 211 pC/N and FOM = 3.54. All ceramics indicated ferromagnetic behavior with slim hysteresis shape. The results suggest a potential for its applications as an eco-friendly compound for further use in sensor, spintronic and microelectronic devices applications.

Structural, Optical, Magnetic, and Dielectric Investigations of Pure and Co-Doped La0.67Sr0.33Mn1-x-yZnxCoyO3 Manganites with (0.00 < x + y < 0.20)

Here, we report the structural, optical, magnetic, and dielectric properties of La0.67Sr0.33Mn1-x-yZnxCoyO3 manganite with various x and y values (0.025 < x + y < 0.20). The pure and co-doped samples are called S1, S2, S3, S4, and S5, with (x + y) = 0.00, 0.025, 0.05, 0.10, and 0.20, respectively. The XRD confirmed a monoclinic structure for all the samples, such that the unit cell volume and the size of the crystallite and grain were generally decreased by increasing the co-doping content (x + y). The opposite was true for the behaviors of the porosity, the Debye temperature, and the elastic modulus. The energy gap Eg was 3.85 eV for S1, but it decreased to 3.82, 3.75, and 3.65 eV for S2, S5, and S3. Meanwhile, it increased and went to its maximum value of 3.95 eV for S4. The values of the single and dispersion energies (Eo, Ed) were 9.55 and 41.88 eV for S1, but they were decreased by co-doping. The samples exhibited paramagnetic behaviors at 300 K, but they showed ferromagnetic behaviors at 10 K. For both temperatures, the saturated magnetizations (Ms) were increased by increasing the co-doping content and they reached their maximum values of 1.27 and 15.08 (emu/g) for S4. At 300 K, the co-doping changed the magnetic material from hard to soft, but it changed from soft to hard at 10 K. In field cooling (FC), the samples showed diamagnetic regime behavior (M < 0) below 80 K, but this behavior was completely absent for zero field cooling (ZFC). In parallel, co-doping of up to 0.10 (S4) decreased the dielectric constant, AC conductivity, and effective capacitance, whereas the electric modulus, impedance, and bulk resistance were increased. The analysis of the electric modulus showed the presence of relaxation peaks for all the samples. These outcomes show a good correlation between the different properties and indicate that co-doping of up to 0.10 of Zn and Co in place of Mn in La:113 compounds is beneficial for elastic deformation, optoelectronics, Li-batteries, and spintronic devices.

DFT and Monte Carlo simulations of the intermetallic compound MnZnSb

The present work aims to investigate the structural, magnetic and electronic properties of ternary intermetallic MnZnSb using density functional theory (DFT) and Monte Carlo simulation (MCs). The obtained ground state results reveal that MnZnSb is stable in the ferromagnetic state with a metallic nature and high magnetic anisotropy. The calculated total and local magnetic moments are 2.96 μ B and 3.05 μ B for MnZnSb. Ferromagnetic behaviour was confirmed using the Stoner criterion. The elastic constants are used to verify the mechanical stability of the MnZnSb compound, demonstrating that the compound is mechanically stable and has a brittle character with low Debye temperature. The magnetic behaviour of MnZnSb is studied using MCs and the obtained results show that undergoes a transition from ferromagnetic to paramagnetic state at a critical temperature ( T C ) of 320 K. The computed magnetocaloric effect indicates that the compound exhibits large values of relative cooling power at 14 T, around 502.2 J/K.

Multiferroic properties in poly(vinylidene-fluoride)-based magnetostrictive/piezoelectric laminate composites

Multiferroic materials (MFM) have drawn considerable attention for developing smart multifunctional devices. Herein, poly(vinylidene-fluoride)-based (PVDF) MFM composite films of Ba0.85Ca0.15Zr0.1Ti0.9O3-PVDF/CoFe2O4-PVDF/Ba0.85Ca0.15Zr0.1Ti0.9O3-PVDF with sandwich-laminated structure are developed and investigated for its dielectric, magnetic, ferroelectric and magnetodielectric (MD) properties. An improved polar β–phase is formed with the particles of CoFe2O4 and Ba0.85Ca0.15Zr0.1Ti0.9O3 embedded in PVDF matrix. Both magnetic (M–H) and ferroelectric polarization (P–E) hysteresis loops indicate the multiferroic nature at room temperature, i.e., the coexistence of ferroelectric and ferromagnetic ordering in composite films. An enhanced ferroelectricity is obtained for the maximum polarization (Pmax∼1.57 μC/cm2 at 750 kV/cm) and the higher dielectric constant (εr∼16.84) as well as a lower dielectric loss tanδ < 0.04, compared to the pristine PVDF matrix (Pmax∼0.88 μC/cm2, εr∼10.26). A recyclable energy density of Wrec∼0.84 J/cm3 at 750 kV/cm is observed, together with a high efficiency (η∼87.82 %). The ferromagnetic behavior is confirmed by the M-H hysteresis loop, which exhibits significant magnetic properties, i.e., saturation magnetization (MS∼0.58 emu/g) and coercivity (HC∼1.72 kOe). Additionally, a robust magnetodielectric effect with a large negative coefficient (∼8.23 %) is achieved at a low magnetic field H∼3 kOe. The laminate composite film exhibits room temperature multiferroic with a large MD response, making it a promising candidate for utilization in intelligent multifunctional devices.

Study of structural, magnetic, and thermoelectric properties of rare earth-based CdCe2X4 (X = S, Se, Te) spinels for Spintronic and energy harvesting applications

Controlling the spin degree of freedom in electronics paves the way for novel approaches to employ, relocate, and store data at accelerated rates. In this regard, an in-depth examination of the structural, electronic, magnetic, and transport behaviour of CdCe2×4 (X = S, Se, Te) is undertaken. It is observed that ferromagnetic states exhibit higher energy release compared to antiferromagnetic states. Room temperature ferromagnetism is characterized by the Tc and spin-polarized density of states. The underlying mechanism in ferromagnetic behaviour is elicited in terms of crystal field energy, double exchange mechanism, exchange energies, and constants. The magnetic moment shift from Ce to other NM sites (Cd, X) is identified as a mechanism sustaining ferromagnetic character through electron exchange, thereby preventing clustering. Furthermore, the temperature-dependent thermoelectric properties are investigated, encompassing electrical and thermal conductivity, Seebeck coefficient, and power factor, recommending exploration of spinels as potential candidates for sustainable energy devices.

Sulphanilamide degradation by undoped and copper doped ZnO, and ferromagnetic properties of fresh, aged, and heat-treated aged ZnO

This work looks into how well Cu-doped zinc oxide works as a photocatalyst when exposed to visible light to break down sulphanilamide. The synthesized samples were characterized by XRD and then FTIR techniques for structural besides compositional analysis. The approximate value of bandgap found out by NBE values of PL spectra showed a decrease in bandgap with doping. Deconvoluted PL spectra revealed the presence of radiative recombination pathways associated with zinc interstitial and zinc vacancy in addition to band-to-band recombination in all samples. FESEM images showed a nanoflake shape for pure ZnO, while Cu-ZnO had a pseudo-spherical shape. SQUID-VSM was adopted to understand the magnetic nature of freshly prepared, heated, and unheated aged samples. Ferromagnetic behavior was observed with saturation magnetization of 5.56×10–4, 2.88×10–4, and 2.78×10–4 emu/g for freshly prepared, heated, and unheated aged samples, respectively. A 2% Cu-doped sample exhibited the highest efficiency of 92.3% towards the degradation of sulphanilamide. Since we got better efficiency for 2% Cu-ZnO, we should further decrease the doping percentage and check whether we will get even higher efficiency in the future. The photocatalytic degradation efficiency of ternary ZnO compounds, codoped ZnO, should be evaluated, yet another future scope.

Role of divalent doping at A-sites (A=Ca2+, Sr2+, Ba2+ & Pb2+) on thermoelectric and magnetoresistive properties in La0.67(Bi0.0835Na0.0835) A0.165MnO3

The present work reports on the effect of divalent ion doping (Ca2+, Sr2+, Pb2+ & Ba2+) ions at A-site in the compound with compositional formula La0.67(Bi0.0835Na0.0835)A0.165MnO3 on structural, magnetic, magneto-transport and thermoelectric properties. X-ray diffraction reveals orthorhombic structure for calcium and barium doped with no peak splitting observed at ~ 32o whereas rhombohedral structure for strontium and lead dopants with a peak splitting in the main intensity. Doping with divalent ions at A-site in La0.67(Bi0.0835Na0.0835)A0.165MnO3 manganites has introduced Mn2+ ions, changing the ratio of Mn3+/Mn4+ in octahedral site and this has been confirmed from X-ray photospectroscopy studies. The field emission scanning electron microscope images confirm different grain sizes and morphologies for different doping elements and distinguished variation is noticed for strontium doped manganites with a grain size of 1.08µm. Room temperature ferromagnetic behavior was observed in the samples at room temperature except for calcium doped sample and magnetic behavior has been discussed on the basis of the various interactions between mixed valence manganese ions and Mn3+/Mn4+ ratio. Electrical resistivity (ρ) as a function of temperature (T) without magnetic field indicates the double peak behavior and with the application of external magnetic fields, the double peak disappears, in all the investigated samples. Highest MR% at their respective transition temperatures (TP1) has been obtained for lead doped samples when compared to barium, strontium and calcium samples. Activation energies (EP) estimated decreases initially for calcium and strontium whereas it increases for lead and barium dopants i.e. for further increases in ionic radii. The change of sign from positive to negative in Seebeck coefficient (S) was noticed with increasing ionic radii suggesting the variation in the nature of charge carriers. The electron-electron, electron-magnon, magnon-magnon scattering mechanism contributes to the temperature dependent resistivity and thermopower in the low temperature region while in the paramagnetic insulating region is governed by a small polaron hopping mechanism.

Exploring Co2TiRE (RE = Nd and Tb) as a promising shape memory alloy using DFT methods

Our study employs self-consistent ab-initio calculations using highly precise spin-polarized density functional theory with both GGA and GGA+U approaches, coupled with the Boltzmann transport scheme. This comprehensive approach investigated the structural stability, magneto-electronic behavior, thermophysical characteristics, and thermoelectric transport properties of Co2TiRE (RE = Nd, Tb) Heusler alloys. Through structural optimizations, we confirm that these materials exhibit ferromagnetic behavior. Analysis of band occupation and density of states using GGA and GGA+U methods reveals that both compounds are metallic in both spin configurations. We evaluated key transport properties such as the Seebeck coefficient, electrical and thermal conductivity and the figure of merit to understand their potential in thermoelectric applications. Conservative estimates of the Seebeck coefficient and the figure of merit suggest promising applications in thermoelectric energy harvesting technologies. Additionally, we provide a comprehensive analysis of the thermophysical behavior, including the Debye temperature, thermal expansion, and specific heat, to assess the alloys thermodynamic stability across varying temperature and pressure conditions.

Physicochemical, optical and magnetic properties of ZrO2/Fe2O3 nanocomposite and its application in photocatalysis and antibacterial treatment

In this work ZrO2/Fe2O3 nanocomposite was synthesised through hydrothermal method using an innovative approach. X-ray diffraction (XRD) analysis revealed the formation of tetragonal ZrO2 and α-Fe2O3 in the nanocomposite. The FTIR spectra of the prepared samples exhibited characteristic peaks corresponding to ZrO2 and Fe2O3 and UV–Visible spectroscopy reveals that the nanocomposite exhibits a significantly lesser bandgap than the pure nanoparticles as determined by the Kubelka Munk function used for bandgap computation. Photoluminescence analysis substantiates the reduction in the recombination rate in the ZrO2/Fe2O3 nanocomposite as compared to the pure ZrO2 nanoparticles. Reduction in the bandgap as well as the recombination rate makes the nanocomposite favourable in the photocatalytic treatment of organic pollutants. Raman analysis was carried out to study the vibrational characteristics of the samples. Further, the prepared nanocomposite was examined for its applicability in photocatalysis, by analysing its degradation ability on Eosin yellow and Eosin Blue dyes under white light LED irradiation. The composite exhibited significant degradation ability than the pure nanoparticles, which makes it an ideal candidate for the treatment of organic pollutants. The nanocomposite exhibited ferromagnetic behaviour as confirmed through Vibrating sample Magnetometry, so it can be easily retrieved after the treatment. The prepared ZrO2/Fe2O3 nanocomposite was tested for its antibacterial efficacy against two Gram positive bacteria (Enterococcus faecalis, Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa). From the antibacterial studies it was validated that the nanocomposite exhibited significant antibacterial efficiencies against the bacteria. Hence the prepared nanocomposite has been proved to be a potential candidate for the treatment of organic pollutants as well as for antibacterial treatment.

Correlation Between the Crystal Structure and Magnetic Properties of Bi1−yCayFe1−xMnxO3 Multiferroics near the Polar-Anti(non)polar Phase Boundary

This paper reports the results of a systematic investigation into the magnetic properties of Bi1−yCayFe1−xMnxO3 (0.1 ≤ y ≤ 0.175, 0.35 ≤ x ≤ 0.45) solid solutions. The substitution of Bi3+ with Ca2+ and the concurrent introduction of Mn3+/Mn4+ ions result in the stabilization of various structural phases, with each exhibiting distinct magnetic characteristics. The investigation indicates that the samples containing the polar rhombohedral phase display metamagnetic transitions at low temperatures, characterized by pronounced jumps in magnetization. Single-phase samples with a nonpolar orthorhombic structure exhibit weak ferromagnetic behavior without metamagnetic features. The observed metamagnetic behavior, accompanied by anomalies in temperature-dependent magnetization and significant remnant magnetization at low temperatures, particularly in samples near the polar-anti(non)polar phase boundary, highlighted the presence of both antiferromagnetic and glassy magnetic components.

Removal of Radioactive Co(II) and Sr(II) using (Co0.5Zn0.5)Fe2O4 Nanoparticles Co-doped with Barium and Antimony

Radioactive pollution poses significant environmental and health risks, including increased cancer rates, genetic mutations, and ecosystem damage, making the removal of radioactive ions from water crucial. Spinel ferrite nanoparticles are promising adsorbents for this purpose owing to their magnetic and adsorption properties. Herein, the novel synthesis of (Co0.5−xZn0.5−xBaxSbx)Fe2O4 nanoparticles (0 ≤ x ≤ 0.1) is reported as an effective solution for adsorbing radioactive Co(II) and Sr(II) ions. Co-doping with Ba and Sb enhances the structural stability, magnetic behavior, and adsorption efficiency of these nanoparticles. X-ray diffraction analysis confirmed sample purity with minimal hematite phase, while Fourier transform infrared spectroscopy verified the spinel structure. Transmission electron microscopy analysis revealed spherical morphology and indicated that increasing x from 0.00 to 0.10 reduced crystallite and grain sizes of nanoparticles from 11.28 to 6.49 nm and 24.47 to 10.88 nm, respectively. Energy-dispersive X-ray spectroscopy confirmed pure elemental compositions and the successful substitution of host ions with dopant ions in the nanoparticles, while X-ray photoelectron spectroscopy analysis provided insights into the chemical oxidation states. Vibrating sample magnetometer results indicated soft ferromagnetic behavior. In adsorption experiments, we examined contact time (0–180 min), pH (2–10), adsorbent dosage (0.04–0.10 g), initial ion concentration (10–250 mg.L−1), and temperature (293–313 K) to determine their effects on adsorption efficiency and optimize conditions for maximum contaminant removal. Nanoparticles with x = 0.06 exhibited the highest ion-removal efficiencies, achieving 88.3% for Co(II) and 96.3% for Sr(II) after contact time of 180 min, with maximum efficiencies observed at pH 8 for Co(II) and pH 6 for Sr(II). Co(II) adsorption followed the Freundlich isotherm, while Sr(II) adsorption adhered to the Temkin model. Kinetics for both ions conformed to the pseudo-second-order model, demonstrating the potential of Ba and Sb co-doped ferrite nanoparticles for efficient radioactive-water purification.

First-principle study origin of ferromagnetism in non-magnetic perovskite BaSnO3 doped with 2p-X (X=C, N)

In this study, our goal is to analyze the origin of magnetization in non magnetic cubic structure perovskite BaSnO3 doped with 2p-X (X=C, N) using the full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). For the exchange and correlation potential we have applied the generalized gradient approximation (GGA) and the GGA plus-modified Becke-Johnson potential (mBJ-GGA). The results show that BaSnO3 doped with C then with N and finally with C and N exhibit half-metallic ferromagnetism behavior with the integer magnetic moment of 1, 2 and 3 μB per cell respectively. The origin of the ferromagnetism that occurs within these compounds is mainly caused by the p-p hybridization between 2p-impurities and its neighboring oxygen atoms. These results allowed to conclude that doped perovskite could provide a new type of materials, called half-metallic for future spintronic devices.

Multifunctional hybrid films made from CoT3OTx4 and CoFeT2OT4 nanoparticles inside a poly 3-hydroxybutyrate matrix and study of their impact in methyl orange photodegradation.

This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co3O4) or cobalt ferrite (CoFe2O4) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co3O4@P3HB and CoFe2O4@P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co3O4 and CoFe2O4 NPs and the P3HB, Co3O4@P3HB and CoFe2O4@P3HB films. The optical band gap for Co3O4 and CoFe2O4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co3O4 and CoFe2O4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe2O4 nanoparticles and CoFe2O4@P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe2O4@P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles.

Synthesis, characterization, magnetic and morphological properties of poly(m-phenylenediamine)/ZnCoFe2O4 nanocomposites

In this work, poly(m-phenylenediamine) (PmPD)/ZnCoFe2O4 nanocomposites (NCs) were synthesised by in-situ chemical oxidative polymerisation method. The ZnCoFe2O4 nanoparticles (NPs) were prepared by auto-combustion method. The crystalline size of PmPD/ZnCoFe2O4 NCs and ZnCoFe2O4 NPs were calculated using the Powder X-ray diffraction (XRD) analysis. The functional group of the samples was analysed by Fourier transform infrared spectral (FTIR) analysis. The XRD and FTIR results were clearly indicated that the formation of PmPD/ZnCoFe2O4 NCs. The spherical morphology of the PmPD/ZnCoFe2O4 NCs was confirmed through Field emission electron microscopy (FESEM). The magnetic hysteresis (M-H) loops of ZnCoFe2O4 NPs and PmPD/ZnCoFe2O4 NCs were revealed their ferromagnetic behaviour. Thermogravimetric analysis (TGA) was indicated that thermal stability of PmPD/ZnCoFe2O4 NCs increases with increase in concentration of ZnCoFe2O4 NPs. The dielectric properties of PmPD/ZnCoFe2O4 NCs were also examined with different frequency.