Co-substituted Samples Research Articles

Effective incorporation of cobalt near surface region for cobalt-free cathodes in lithium-ion batteries

Cobalt-free cathode materials, particularly Ni-rich layered oxide cathode materials, are ideal for electric vehicle Li-ion batteries, offering high energy density and cost-effectiveness. However, high Ni content in high-temperature synthesis leads to issues like increased Li/Ni cation mixing and reduced rate capability, mainly due to the absence of Co. Therefore, this study investigated the utilization of a small amount of Co instead of completely removing it to enhance electrochemical performance. A simple pre-calcination process was used to induce Co substitution beneath the Ni-rich layered oxide cathode materials surface. A coating process was also performed for comparison. The Li/Ni cation mixing in the Co-substituted sample during high-temperature calcination was 2.43%, demonstrating a superior value compared to the Co-coating process. Rate capability tests showed superior performance for Co-substituted sample (164.2 mAh g−1) at 2 C compared to coated sample (151.0 mAh g−1). Moreover, Co substitution improved not only the cycle stability but also the high-temperature stability at an elevated state of charge.This study focuses on the surface modification of cobalt-free cathode, providing direct insight into the effects of Co substitution and typical Co coating and suggests an optimal process that uses small amounts of Co.

On the correlation between mechanical, optical, and magnetic properties of co-substituted Sn1-x-yZnxMyOz metal-oxide ceramics with M = Fe, Co, Ni, and Mn

We report here the FTIR, optical, and magnetic properties of Sn1-x-yZnxMyOz ceramics with various x, y, and M. The pure samples are called S1, S2, and S3 for ZnO, SnO2, and SnZn. The co-substituted samples are called S4, S5, S6, and S7 for SnZnFe, SnZnCo, SnZnNi, and SnZnMn, with Zn = 0.50, Sn = 0.25, and M = 0.25. The Young's modulus, was decreased from 5.70 (D/cm2) for S3 to 4.59, 3.14, 2.59, and 3.05 (D/cm2) for S4, S5, S6, and S7. The Eg was decreased from 2.13 eV for S3 to 2.16, 2,2, and 1.6 eV for S4, S5, S6, and S7. The pure samples (S1–S3) exhibit ferromagnetic behavior at 300 K, and combination of paramagnetic and ferromagnetic behaviors at 10K. In contrast, the samples (S4–S7) exhibit a combination of paramagnetic and ferromagnetic behaviours at both temperatures. The Curie temperature (Tc) obtained through zero-field cooling (ZFC) and field cooling (FC) is close to 300 K for S1–S3, S5, S6, 200 K for S4, and 20 K for S7. The real saturated magnetization (Ms) of the ZnO sample was decreased by the addition of SnO2, and then increased by the addition of Mn, Ni, Fe, and Co sequentially. Ms was increased from 12.31 (emu/g) for S3 at 300 to 16.24, 31.04, 27.27, and 10.49 (emu/g) for S4, S5, S6, and S7, and from 16 (emu/g) to 87, 730, 83, and 29 at 10 K. Remnant magnetization (Mr) decreases with the addition of SnO2 to ZnO and is not affected by the addition of TMs, just in the case of Co, where it increases. The coercive field decreases, but the switching field increases markedly with the addition of Mn and Ni, transforming the system from a hard magnetization to a soft magnetization system.

Dry reforming of methane by La2NiO4 perovskite oxide: B-site substitution improving reactivity and stability

The development of highly active and stable catalyst materials is the focus of dry reforming of methane (DRM) technology. The effect of substituting transition metals (Mn, Fe, Co, and Cu) on the B-site of La2NiO4 perovskite on the DRM catalytic performance was investigated. Compared to the unsubstituted sample, the Co-substituted sample exhibited reduced reactivity but increased carbon deposition; the Mn-substituted and Fe-substituted samples demonstrated decreased reactivity and carbon deposition; the Cu-substituted sample displayed a slight decrease in CH4 conversion but a substantial increase in carbon resistance. The effect of the substitution ratios of Cu elements was further investigated. The results showed that Cu substitution could maintain the perovskite phase in the samples. In the 5-h DRM reaction, the reactivity of the samples exhibited a decreasing trend as Cu substitution ratios increased. All Cu-containing samples displayed carbon deposition rates lower than 0.4 mg/(g*h), resulting in an over 90-fold improvement in carbon resistance compared to the La2NiO4 sample. Further investigations revealed that the La2Ni0.6Cu0.4O4 sample exhibited stable activity during the 50-h DRM reaction with only a small amount of amorphous carbon in the reacted sample (no obvious carbon nanotubes were observed). Characterization results indicated that the enhanced carbon resistance in Cu-substituted samples was attributed to the Ni-Cu alloy formation, which inhibited CH4 decomposition reactions and reduced solid carbon generation rates. Density functional theory (DFT) calculations showed that the partial substitution of Cu could increase the energy barrier of the CH* dehydrogenation step, which in turn reduced the rate of solid carbon generation.

A comparative investigation of structural, magnetic and photocatalytic properties of pure, Ce-Ni and Cd-Ni co-doped BiFeO3 nanoparticles

Bismuth ferrite, BiFeO3 (BFO) as well as Ce-Ni, Cd-Ni co-substituted BiFeO3 nanoparticles were prepared using the sol–gel route. XRD and Raman results show a structural phase transformation from rhombohedral (pristine BFO) to orthorhombic in the case of Bi0.94Cd0.06Fe0.94Ni0.06O3 (BCdFNO6), which implies that Cd substitution can induce the obvious transition of crystal structure while Ce substitution Bi0.94Ce0.06Fe0.94Ni0.06O3 (BCeFNO6) cannot. An apparent blue shift can be noted in all the substituted samples and with a reduction of the direct optical bandgap compared with the pristine BFO. The XPS findings show that Ce-Ni and Cd-Ni substitution increases the Fe3+ ions (Cd-Ni co-doped samples reveal the best outcomes), which would be evidence for reducing oxygen vacancies and improving magnetism. Cd-Ni co-substituted into BFO can improve magnetic properties because the ionic radii of Cd2+ ion are smaller than that of Bi3+ ion; moreover, intriguingly, the room temperature magnetic (M−H) hysteresis loops reveal the greatest saturation magnetization value in Cd-Ni co-substituted samples. The co-doped of Cd-Ni, has the greatest degradation activity 99.48 % of MB and 98.76 % of RhB would be successes after 90 min irradiation, which was raised by 9.49 %, 25 % of MB and 9.52 %, 26.92 % of RhB from that of the Ce-Ni co-doped and pristine BFO.

Effect of Pr and Mn co-substitution on Structural and Optical Properties of Bismuth Ferrite

One of the most recent developments in the area of modern optics arises due to perovskite materials. The ABO3 perovskite materials like bismuth ferrite is an appealing alternative for various optical devices. Hence, in the present study, Praseodymium (Pr) and Manganese (Mn) co-substituted bismuth ferrite ceramics are prepared by the modified sol-gel method and the correlation between structural and optical properties with the variation in co-substitution concentration has been investigated. Rietveld refinement of X-ray diffraction patterns demonstrates a structural phase change in crystal symmetry from rhombohedral to orthorhombic phase with the increase in concentration for x ≥ 0.025. Lattice deformation in the co-substituted samples is confirmed by Fourier Transform Infrared (FTIR) and Raman spectra. UV–vis diffuse reflectance spectra confirm the strong absorption of light in the visible region. Furthermore, optical energy band gap decreases from 1.95 eV to 1.50 eV with increase in concentration from x = 0.000 to x = 0.100. The refractive index attains the maximum value i.e. 6.16 for x = 0.025 whereas it drops to minimum value of 4.06 for x = 0.100. This demonstrates that the structural modification in bismuth ferrite can be used to tune its optical parameters for the device applications.

Investigation of crystal structure, Raman spectroscopy and magnetic properties of La-Zn substituted oriented M-type hexagonal barium ferrites

M-type hexagonal barium ferrite (BaM) has received much attention in the application of self-biased microwave devices because of its large anisotropic field (Ha) and high saturation magnetization (Ms), but the increased Ha inevitably increases the microwave magnetic loss of the device. In addition, the devices need to have a high Ms for high frequency applications. To address these issues, we used La3+ and Zn2+ instead of Ba2+ and Fe3+ ions to modulate the Ha and Ms of BaM, respectively. Ba1-yLayFe12-xZnxO19 (x=y=0.1–0.5) M-type hexagonal ferrite was synthesised by conventional solid-phase methods. The La-Zn co-substituted BaM samples were shown to be purely single phase by X-ray diffraction (XRD) analysis. The lattice parameters, specific surface area, crystallite size, dislocation density and microstrain of the samples were also calculated using the XRD data. Furthermore, La3+ and Zn2+ can not only modulate the sample Ha and Ms between 10,214–12,102 Oe and 62.94–78.23 emu/g, respectively, while making the sample more denser. At x=0.3 BaM detects relatively satisfactory properties: large Ms=63.12 emu/g, suitable Ha=10,214 Oe and Hc=2248.87 Oe, high Mr/Ms=0.832 and narrow ferromagnetic resonance linewidth (= 903 Oe), which provide good candidates for next-generation self-biased and low-loss microwave wave devices.

Role of A site and B site ion substitutions on the low-temperature magnetic behaviour of Ca2Fe2O5

In the present paper, we report the structural and low-temperature magnetic properties of Sm-substituted Ca2Fe2O5 (Ca2(1-x)Sm2xFe2O5, x = 0.05, 0.1) and Co-substituted Ca2Fe2O5( Ca2Fe2(1-y)Co2yO5, y = 0.1, 0.2). The polycrystalline samples of Sm and Co-based compounds, synthesised by a solid-state reaction route, are found to be crystallised with space group Icmm and Pnma respectively. The gradual substitution/doping of Sm3+ (5 % and 10 %) replacing Ca shows a significant change in temperature dependant magnetic behaviour, assumed to originate from complex interactions of Sm and Fe ions. For Co-substituted samples, the magnetic study as a function of temperature suggests the signature of ferri/ferromagnetic interactions along with the probable signature of a glassy feature. Isothermal magnetisation characterisations indicate the pure antiferromagnetic interactions in Sm samples, whereas the onset of hysteresis in Co samples can be correlated with the ferri/ferromagnetic nature of samples with the antiferromagnetic ground state.

Ca-Sn co-substituted BiIn-YIG ferrite with narrow FMR linewidth for microwave device application

The requirements for improving the performance and miniaturizing microwave devices have led to higher demands for the yttrium iron garnet (YIG) ferrite materials. To achieve YIG ferrite materials with narrow ferromagnetic resonance (FMR) linewidths, and stable magnetic and dielectric properties, Ca-Sn co-substituted YIG samples with the composition Bi0.4Y2.6-xCaxFe4.65-xIn0.35SnxO12 were synthesized via solid-state sintering at 1230 °C. The microstructural, magnetic, and dielectric properties of the samples were systematically tested and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), impedance analyzer, vibrating sample magnetometry (VSM), and ferromagnetic resonance (FMR). The results indicate that the co-substitution of Ca2+ and Sn4+ ions did not alter the crystal structure of YIG ferrites, and effectively improved the microstructure and performance of the material. When the doping concentration (x) was 0.40, the obtained sample exhibited the narrowest FMR linewidth (ΔH = 43.46 Oe) and excellent magnetic and dielectric properties (4πMs = 1555.68 G, ε′ = 14.12 @ 100 MHz). The material proposed in this study demonstrates significant potential for applications in microwave devices.

Tunnel/Layer Composite Na0.44MnO2 Cathode Material with Enhanced Structural Stability via Cobalt Doping for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) are the most promising alternative to lithium-ion batteries (LIBs) due to their low cost and environmental friendliness; therefore, enhancing the performance of SIBs' components is crucial. Although most of the studies have focused on single-phase cathode electrodes, these materials have difficulty in meeting the requirements in practice. At this point, composite materials show superior performance due to balancing different structures and are offered as an alternative to single-phase cathodes. In this study, we synthesized a Na0.44MnO2/Na0.7MnO2.05 composite material in a single step with cobalt substitution. Changes in the crystal structure and the physical and electrochemical properties of the composite and bare structures were studied. We report that even if the initial capacity is slightly lower, the rate and cyclic performance of the 1% Co-substituted composite sample (CO10) are superior to the undoped Na0.44MnO2 (NMO) and 5% Co-substituted (CO50) samples after 100 cycles. The results show that with the composite cathode phase transformations are suppressed, structural degradation is prevented, and better battery performance is achieved.

High thermoelectric power factor of Ag and Nb co-substituted SrTiO3 perovskite nanostructures

Ag substituted and Ag & Nb co-substituted SrTiO3 were synthesized by hydrothermal method and their structural, morphological and thermoelectric properties were studied. The crystal structure and crystallinity of the samples were examined by X-ray Diffraction analysis. The morphology of the samples was analysed using FESEM and TEM analysis. X-ray Photoelectron Spectroscopic analysis revealed the presence of Ag and the binding state of each element present in the prepared samples. The variations of electrical resistivity with Ag content was studied in Ag substituted SrTiO3. The electrical resistivity of Ag & Nb co-substituted SrTiO3 was relatively higher than that of pure SrTiO3 and Ag alone substituted samples. The Seebeck coefficient increased as the Ag content increases in the sample. Higher Seebeck coefficient was observed for Ag & Nb co-substituted SrTiO3 when compared with other samples. The power factor of the sample significantly improved with Ag content due to high Seebeck Coefficient. The Ag & Nb co-substituted samples exhibited high power factor compared to other samples. Moreover, the Ag-substituted SrTiO3 shows relatively low thermal conductivity and thereby high figure of merit of 0.15 compared to the reported values of similar materials. The experimental results demonstrated that Ag and Nb substitution plays an important role in enhancing the thermoelectric properties of SrTiO3.

Cluster-glass freezing and antiferromagnetic phase transitions in corundum structure Mg3−xCoxTeO6

We investigate polycrystalline powder samples of the Co-substituted Mg3−xCoxTeO6 (x = 0.0–2.4) by X-ray diffraction, magnetic susceptibilities, and specific heat. The non-magnetic parent compound Mg3TeO6 crystallizes in the trigonal R3¯ space group. All Co-substituted samples have a similar crystal structure as the parent compound. The Rietveld refinements of synchrotron X-ray diffraction data reveal distorted (Mg/Co)O6 and TeO6 octahedra. Remarkably, we find the evolution of a magnetic phase from a non-magnetic ground state to an antiferromagnetic order through a cluster glass. The antiferromagnetically ordered state emerges above the percolation threshold (x ≥ 1.0), while the cluster glass state is stabilized for x = 0.8.

Effect of Mn and Zn binary Co-substitution on structure and magnetic properties of cobalt ferrites

Mn-Zn binary co-substituted cobalt ferrite (Co1-x(MnZn)xFe2O4 (0 ≤ x ≤ 0.4)) was synthesized by conventionally compacting and magnetic field assisted injection molding. XRD and SEM analysis characterized the single-phase spinel structure, preferred 〈001〉 orientation, and uniform grain size. XPS analysis reveals the cation redistribution in the mixed spinel structure of co-substituted samples, which has a direct consequence on magnetic properties. The addition of Mn-Zn increases the saturation magnetization (Ms), while decreases magnetocrystalline anisotropy constant (K1), leading to a decrease of magnetostrictive saturation field (HS). For pressure samples, the maximum (dλ/dH)max is −0.15 ppm/Oe under 300 Oe applied field at x = 0.2. The samples with 〈001〉 fiber texture were prepared by magnetic field alignment of the semi-solid slurry to achieve higher magnetostrictive properties. The highest magnetostriction λS reaches −432 ppm, which is 200 % higher than pressed samples, and the corresponding maximum strain derivative (dλ/dH)max reaches −0.88 ppm/Oe at a lower magnetic field.

Simultaneous Substitution of Fe and Sr in Beta-Tricalcium Phosphate: Synthesis, Structural, Magnetic, Degradation, and Cell Adhesion Properties.

β-tricalcium phosphate is a promising bone graft substitute material with biocompatibility and high osteoinductivity. However, research on the ideal degradation and absorption for better clinical application remains a challenge. Now, we focus on modifying physicochemical properties and improving biological properties through essential ion co-substitution (Fe and Sr) in β-TCPs. Fe- and Sr-substituted and Fe/Sr co-substituted β-TCP were synthesized by aqueous co-precipitation with substitution levels ranging from 0.2 to 1.0 mol%. The β-TCP phase was detected by X-ray diffraction and Fourier transform infrared spectroscopy. Changes in Ca–O and P–O bond lengths of the co-substituted samples were observed through X-ray photoelectron spectroscopy. The results of VSM represent the M-H graph having a combination of diamagnetic and ferromagnetic properties. A TRIS–HCl solution immersion test showed that the degradation and resorption functions act synergistically on the surface of the co-substituted sample. Cell adhesion tests demonstrated that Fe enhances the initial adhesion and proliferation behavior of hDPSCs. The present work suggests that Fe and Sr co-substitution in β-TCP can be a candidate for promising bone graft materials in tissue engineering fields. In addition, the possibility of application of hyperthermia for cancer treatment can be expected.

Hydrothermal synthesis of Ce/Zr co-substituted BiFeO3: R3c-to-P4mm phase transition and enhanced room temperature ferromagnetism

A facile hydrothermal method was used for fabricating phase-pure Bi1−xCexFe1−xZrxO3 (x = 0.00, 0.03, 0.06) multiferroic ferrites, and the dependence of structural, optical, and magnetic properties on the composition have been investigated. The samples were investigated by X-ray diffraction, Raman and Fourier transform infrared spectroscopies, scanning electron microscopy, UV–Vis spectroscopy, and vibrating sample magnetometer at room temperature. Structural results show that the structure of Bi1−xCexFe1−xZrxO3 ferrites is indexed to a rhombohedral structure with the R3c space group. However, the weakening in the intensity, the expansion of the line-width of all bands, and some band shifts observed in Raman spectra indicate a structural transition from rhombohedral (R3c) to pseudo-tetragonal (P4mm) phase as the content of Ce/Zr increases. Also, a significantly enhanced intensity of the A1–2 mode in Raman spectra means that there is a novel behavior of magnetic anisotropy in the Ce/Zr co-substituted samples. A significant increase in optical bandgap with increasing of the Ce/Zr co-substitution suggests that the materials are suitable for technological applications. Magnetic properties of the samples show a magnetic transition from antiferromagnetic to ferromagnetic phase due to the presence of the rhombohedral to the tetragonal phase transition, and exchange interaction between the 4f orbitals of the Ce3+/Ce4+ and the 3d orbitals of the Fe3+/Fe2+.

Effect of defects on the band gap and photoluminescence emission of Bi and Li co-substituted barium strontium titanate ceramics

Since the discovery of an effective role for defects in improving the performance of ceramic materials in practical application, investigation of defects and their impact on the development of optical properties in condensed matter physics have received widespread attention. In this work we synthesized a lead free (Ba0·60Sr0.40)(1-x)(Bi,Li)xTiO3 (BST6:BLx%); (0%≤x ≤ 8%) ceramics using a conventional solid-state reaction method. X-ray diffraction patterns along with Rietveld refinement, Micro-Raman (MR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), UV–visible, Electron Spin Resonance (ESR) and photoluminescence (PL) measurements are utilized to characterize these ceramics. XRD, and Raman analysis have proven cubic phase symmetry with a contraction in bond length as the Bi and Li concentrations increased. XPS and ESR results confirm the presence of Ti3+ surface defects (TSD) and oxygen vacancies (VO) on the co-substituted samples sintered at high temperature. The optical results show a decrease in the bandgap energy from 3.14 eV to 2.76 eV and a wide-PL band emission on the green band, caused by recombination of the radiative free electrons and holes trapped around the surface oxygen vacancies. Defect levels created within the bandgap might act as recombination centres, and this can give the possibility of using BST6:BLx as a green light emission source in future practical applications.

A comparative study of thermoelectric Cu2TrTi3S8 (Tr = Co and Sc) thiospinels: Enhanced Seebeck coefficient via electronic structure modification

We studied the electronic structures of Cu2TryTi4–yS8 (Tr = Sc, Co) thiospinels by combining thermoelectric measurements and first-principles calculations. The thiospinels showed n-type and metallic properties governed by a conductive network composed of edge-shared (Ti/Tr)S6 octahedra. The substitutions of Sc and Co for Ti decreased the electron carrier concentration in a similar manner, leading to increases in both the electrical resistivity and Seebeck coefficient. Although the electrical resistivity was equivalent for Tr = Sc and Tr = Co, the Seebeck coefficient was remarkably enhanced for Tr = Co as compared to that for Tr = Sc. The enhanced Seebeck coefficient in the Co-substituted system was ascribed to the increased density of states of conduction band near the Fermi level due to the partial replacement of Ti-3d orbitals by Co-3d orbitals. Owing to the electronic structure modification, a higher dimensionless thermoelectric figure of merit (ZT = 0.2 at y = 1–1.5) was achieved for the Co-substituted samples at 673 K.

Electrical and magnetic properties of BiFeO3 nanoparticles substituted with high concentrations of cobalt

The 10% and 20% Co-substituted BiFeO3 (BFO) samples were prepared by co-precipitation method. The microstructure, phases formed, electrical and magnetic properties were investigated. The cobalt-substituted BiFe1−xO3 (where x = 0.0, 0.1, and 0.2) showed formation of BiFeO3 (BFO), Bi25FeO40, CoFeO4, and Bi2Fe4O9 phases. The lattice parameter value “a” decreased and “c” increased for BFO as a result of Co substitution, thereby increasing lattice cell volume. The surface morphology and grain shape and size were studied by scanning electron microscope. Enhanced dielectric properties are studied for the Co-substituted BFO nanoparticles. At low frequency, BFO showed dielectric constant value of 40 which increased to 52 and 402 for 10% and 20% Co-substituted BFO samples, respectively. The electrical conductivity in the temperature range 300–700 °C showed semiconducting behavior. Remanence (Mr), saturation magnetization (Ms), and coercivity (Hc) values for BFO are 0.123 emu/g, 6.178 emu/g, and 108.59 G, respectively. The Ms, Mr, and Hc values for 10% cobalt and 20% Co-substituted BFO are 5.742 emu/g, 0.213 emu/g, and 124.86 G and 42.777 emu/g, 24.255 emu/g, and 4127.55 G, respectively. It is concluded that synthesis of pure BiFeO3 is not possible and increase in magnetic parameters are due to the formation of cobalt ferrite.

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi).

CaCu3Ti4-x((A0.05Nb0.05))xO12 ceramics (A: Al and Bi; x = 0, 0.3) were synthesized by high-energy mechanical ball milling and reactive sintering at 1050 °C in air. Rietveld refinement of XRD data revealed the pure and (Al3+, Nb5+) cosubstituted ceramics contained a minor CuO secondary phase with a mole fraction of about 3.2% and 6.9%, respectively, along with a CaCu3Ti4O12 (CCTO)-like cubic structure. In addition, (Bi3+, Nb5+) cosubstituted ceramics had a pyrochlore (Ca2(Ti, Nb)2O7) secondary phase of about 18%. While the (Al3+, Nb5+) cosubstituted CCTO showed the highest relative permittivity (ε’ = 3.9 × 104), pure CCTO showed the lowest dielectric loss (tanδ = 0.023) at 1 kHz and 300 K. Impedance-spectroscopy (IS) measurements showed an electrically heterogeneous structure for the studied ceramics, where a semiconducting grain was surrounded by highly resistive grain boundary. The giant relative permittivity of the ceramics was attributed to the Maxwell–Wagner polarization effect at the blocking grain boundaries and domain boundaries. The higher tanδ of the cosubstituted samples was correlated with their lower grain boundary’s resistivity, as confirmed by IS analysis. Modulus-spectrum analysis revealed two relaxation processes for the pure and (Bi3+, Nb5+) cosubstituted CCTO samples. Dissimilar behavior was observed for the (Al3+, Nb5+) cosubstituted CCTO, where three relaxation mechanisms were observed and attributed to the grain, domain-boundary, and grain-boundary responses.

Effect of transition metal element substitution on magnetoelectric properties of BiFeO3-BaTiO3 ceramics

BiFeO3 is the most typical multiferroic materials. However, the poor magnetoelectric coupling effect limits its practical application. In this work, the transition metal elements (Co, Mn) were introduced to suppress the spin cycloid structure of BiFeO3-based ceramics. The structure, ferroelectric, magnetic and magnetoelectric properties were investigated thoroughly. The XRD and SAED analysis confirmed the coexistence of tetragonal (T) and rhombohedral (R) phases of all samples. The piezoelectric properties were enhanced in Co-substituted samples. In addition, the magnetic properties were enhanced with the addition of Co/Mn ions. According to the analysis of the M-H loops and XRD patterns before and after poling, the electric-field induced magnetic change was observed in all samples, which can be attributed to the phase transition from R-phase to T-phase during poling. The room-temperature linear magnetoelectric coefficient αME was analyzed, and the maximum αME was obtained at BF-BT-005BC sample, where αME = 0.66 mV/cm Oe. The enhanced magnetic and magnetoelectric properties were ascribed to the distortion of the spiral spin structure by transition metal ions.

Enhanced photoluminescence characteristics and intrinsic ferromagnetism in Co-substituted CeO2 nanoparticles

The creation of oxide based magnetic materials has attracted a great deal of scientific attention, owing to their novel applications in optoelectronic, memory, and spintronic device applications. In this study, the authors report upon the structural, optical, and magnetic properties of Co-substituted CeO2 nanocrystals synthesized via the wet chemical precipitation method. The obtained nanoparticles show good crystallinity as well as an FCC structure with an Fm3m space group of host CeO2 lattice, as confirmed by an X-ray diffraction results. It is noted that Co substitution at low concentrations enhances the photoluminescence characteristics of CeO2 nanoparticles, while higher concentrations significantly reduce the intensity of PL emission, as revealed by PL studies. The estimated M − H loops illustrate that pristine CeO2 shows a paramagnetic nature, while all Co-substituted samples were ferromagnetic in nature. Furthermore, magnetic parameters such as saturation magnetization (MS) and residual magnetization (MR) increased with the inclusion of Co content, reaching a maximum at 4 at% Co and quenching at 6 at% and 8 at% of Co-substitution. In particular, Ce1-xCoxO2 (x = 0.04) nanoparticles show better luminescence and magnetic characteristics than the remaining concentrations.