Low Coercive Field Research Articles

Near-sensor analog computing system based on low-power and self-assembly nanoscaffolded BaTiO3:Nd2O3 memristor

Near-sensor analog computing systems have received a lot of attention as they can effectively reduce the large amount of redundant data transferred between sensor terminals and computing units, thereby shortening the data processing time and reducing power consumption. However, ensuring the reliability and stability of memristor devices used in the hardware circuits of near-sensor analog computing systems remains a considerable challenge. In this paper, we describe a robust ferroelectric memristor based on Pd/BaTiO3:Nd2O3/La0.67Sr0.33MnO3 grown on a silicon structure with SrTiO3 as the buffer layer. Through optimized growth temperature, the device exhibits a low coercive field voltage (−1–2 V), robust endurance characteristics (>1010 cycles), and a power consumption as low as 0.45 fJ per synaptic event. Also in this study, a near-sensor analog computing system based on an array of pressure sensors and ferroelectric memristors was constructed. It is shown that this system can accurately calculate multiple raw analog pressure signals in real time without the need for peripheral circuitry and that the system can classify object shapes and perform edge detection with a maximum deviation of only about 58.6 nA. This study highlights the great potential of ferroelectric memristors for use as fundamental components of near-sensor analog computing systems.

Polar Organic Charge-Transfer Complex of the Asymmetrical Component for Flexible Piezoelectric Energy Harvesting and Self-Powered Wearable Sensors.

Organic piezomaterials have attracted much attention because of their easy processing, lightweight, and mechanic flexibility properties. Developing new smart organic piezomaterials is highly required for new-generation electronic applications. Here, we found a novel organic piezomaterial of organic charge-transfer complex (CTC) consisting of dibenzcarbazole analogue (DBCz) and tetracyanoquinodimethane (TCNQ) in the molecular-level heterojunction stacking mode. The DBCz-TCNQ complex exhibited ferroelectric properties (the saturated polarization of ∼1.23 μC/cm2) at room temperature with a low coercive field. The noncentrosymmetric alignment (Pc space group) led to a spontaneous polarization of this architecture and thus was the origin of the piezoelectric behavior. Lateral piezoelectric nanogenerators (PENGs) based on the thermal evaporated CTC thin-film exhibited significant energy conversion behavior under mechanical agitation with a calculated piezoelectric coefficient (d31) of ∼33 pC/N. Furthermore, such a binary CTC thin-film constructed single-electrode PENG could show steady-state sensing performance to external stimuli as this flexible wearable device precisely detected physiological signals (e.g., finger bending, blink movement, carotid artery, etc.) with a self-powered supply. This work provides that the polar CTCs can act as efficient piezomaterials for flexible energy harvesting, conversion, and wearable sensing devices with a self-powered supply, enabling great potential in healthcare, motion detection, human-machine interfaces, etc.

Single-domain Fe2CoGa0.5Al0.5 Heusler alloy nanoparticles with enhanced properties.

Fine quaternary single-domain Heusler alloy nanoparticles with a composition of Fe2CoGa0.5Al0.5 have been synthesized using a simple template-less chemical route for the first time. Ab initio calculations and standard models have been used to analyze and interpret the experimental findings. The synthesized nanoparticles with an average crystallite size of 42 nm exhibited high saturation magnetization (>5 μB f.u.-1), high effective anisotropy constant (≈8 × 106 erg cc-1), high Curie temperature (>1200 K), low magnetic remanence (<0.2 μB f.u.-1) and low coercive field (<90 Oe), declaring their suitability for fabricating various nanomagnetic devices.

Unveiling the crystal and magnetic texture of iron oxide nanoflowers.

Iron oxide nanoflowers (IONF) are densely packed multi-core aggregates known for their high saturation magnetization and initial susceptibility, as well as low remanence and coercive field. This study reports on how the local magnetic texture originating at the crystalline correlations among the cores determines the special magnetic properties of individual IONF over a wide size range from 40 to 400 nm. Regardless of this significant size variation in the aggregates, all samples exhibit a consistent crystalline correlation that extends well beyond the IONF cores. Furthermore, a nearly zero remnant magnetization, together with the presence of a persistently blocked state, and almost temperature-independent field-cooled magnetization, support the existence of a 3D magnetic texture throughout the IONF. This is confirmed by magnetic transmission X-ray microscopy images of tens of individual IONF, showing, in all cases, a nearly demagnetized state caused by the vorticity of the magnetic texture. Micromagnetic simulations agree well with these experimental findings, showing that the interplay between the inter-core direct exchange coupling and the demagnetizing field is responsible for the highly vortex-like spin configuration that stabilizes at low magnetic fields and appears to have partial topological protection. Overall, this comprehensive study provides valuable insights into the impact of crystalline texture on the magnetic properties of IONF over a wide size range, offering a deeper understanding of their potential applications in fields such as biomedicine and water remediation.

Physical mechanism of Ge doping enhanced Ruddlesden-Popper structure quasi-2D Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; ceramic hybrid improper ferroelectricity

Hybrid improper ferroelectricity with quasi-two-dimensional (quasi-2D) structure has attracted much attention recently due to its great potential in realizing strong magnetoelectric coupling and room-temperature multiferroicity in a single phase. However, recent studies show that there appears high coercive field and low remnant polarization in ceramics, which severely hinders the applications of this material. In this work, high-quality Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; and Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;1.99&lt;/sub&gt;Ge&lt;sub&gt;0.01&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; ceramics with a Ruddlesden-Popper (R-P) structure are successfully prepared, and their crystal structures and electrical properties are investigated in detail. It is found that the Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; ceramic exhibits a lower coercive field that is close to that of Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; single crystal. Moreover, via a small amount of Ge doping, the polarization reaches 0.34 μC/cm&lt;sup&gt;2&lt;/sup&gt; for Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; and 0.61 μC/cm&lt;sup&gt;2&lt;/sup&gt; for Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;1.99&lt;/sub&gt;Ge&lt;sub&gt;0.01&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt;. Combining crystal lattice dynamic studies, we analyze the Raman and infrared responses of the samples, showing the information about the tilting and rotation of the oxygen octahedra in the samples. The improved ferroelectricity after doping may be attributed to the increased amplitude of the tilt mode and the reduced amplitude of rotation mode. Besides, the enhanced ferroelectric properties through Ge doping and its mechanism are further investigated by the Berry phase approach and the Born effective charge method. Furthermore, via the UV-visible spectra, the optical bandgap is determined to be 3.91 eV for Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; ceramic and 3.95 eV for Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;1.99&lt;/sub&gt;Ge&lt;sub&gt;0.01&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; ceramic. Using the Becke-Johnson potential combined with the local density approximation correlation, the bandgap is calculated and is found to be in close agreement with the experimental result. And the electronic excitations can be assigned to the charge transfer excitation from O 2p to Sn 5s (Ge 4s). The effects of Ge doping on the ability of Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; to gain and lose electrons and the bonding strength of Sn-O bond are analyzed via two-dimensional charge density difference. In conclusion, this study provides insights into the synthesis method and modulation of ferroelectric properties of hybrid improper ferroelectrics Sr&lt;sub&gt;3&lt;/sub&gt;Sn&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt;, potentially facilitating their widespread applications in various capacitors and non-volatile memory devices.

Highly ordered single domain Fe2-xCo1+xGa (0 ≤ x ≤ 1) nanoparticles synthesized by a template-less chemical route

A comprehensive study has been carried out on chemically synthesized Fe2-xCo1+xGa (0 ≤ x ≤ 1) nanoparticles using both experimental and theoretical tools. Adoption of a template-free preparation route ensured impurity-free and phase-pure Heusler alloy nanoparticles. Depending on the composition, these nanoparticles exhibit highly ordered L21 or X type Heusler alloy structure. These nanoparticles have high saturation magnetization (3.90 – 5.15 µB/f.u.), high Curie temperature (≥ 1100 K) and high effective anisotropy constant (∼ 106 erg/cc) along with low coercive field (≤ 12 Oe) and low remnant magnetization (≤ 0.03 µB/f.u.). Emergence of superparamagnetism in these single (magnetic) domain nanoparticles is another interesting aspect. The electronic density of states of these alloys near Fermi level have also been evaluated as a function of composition using ab initio calculations. These results indicate Fe2-xCo1+xGa nanoparticles to be promising candidates for high density magnetic media and nanomagnetic sensor applications.

Effect of Film Thickness on Microstructural and Magnetic Properties of Lithium Ferrite Films Prepared on Strontium Titanate (001) Substrates

Epitaxial lithium ferrite (LiFe5O8) films with different thicknesses were successfully fabricated on strontium titanate (SrTiO3) (001) substrates using the magnetron sputtering deposition technique. The microstructural and magnetic properties of the films were characterized by an advanced transmission electron microscope and a magnetic measurement device. It was found that the formation of structural defects can be influenced by the thickness of the film. In addition to misfit dislocations, orientation domains form in thinner films and twin boundaries appear in thicker films, respectively, contributing to the misfit strain relaxation in the heterosystem. The magnetic measurement showed that the thinner films have enhanced magnetization and a relatively lower coercive field compared with the thicker films containing antiferromagnetic twin boundaries. Our results provide a way of tuning the microstructure and magnetic properties of lithium ferrite films by changing the film thickness.

Soft magnetic composite of Ni3Fe/ZnFe2O4 type obtained by mechanical alloying/milling and spark plasma sintering

Soft magnetic composite powder of Ni3Fe/ZnFe2O4 type has been obtained by mechanical milling of nanocrystalline Permalloy (Ni3Fe) particles with ZnFe2O4 particles. The nanocrystalline Ni3Fe particles were synthesised by mechanical alloying of elemental Ni and Fe powder. During the milling time, some of the ZnFe2O4 particles are embedded on the surface, and others are encapsulated in the volume of the Permalloy particles, creating a „raisin-bread” like structure. Also, at the surface of the Ni3Fe particles, a quasi-continuous layer of zinc ferrite is formed. The as formed composite particles have a structure of pseudo core-shell type, with a “raisin-bread” core. Upon mechanical milling, the phases are preserved according to X-ray diffraction (XRD) investigations, although the system magnetisation presents a slight decrease. The densification of the composite powder has been carried out using spark plasma sintering (SPS) technique at a sintering temperature range of 500–700 °C without holding time. The density and the electrical resistivity of the samples increase upon increasing the sintering temperature. Higher magnetisation is obtained for the sample sintered at 700 °C and accompanied by a lower coercive field. Upon sintering, a reaction at interface, between the Ni-based alloy and zinc ferrite occurs, leading to the formation of a new phase. The testing of the toroidal-shaped magnetic composite in the alternative current regime shows that the best results are obtained on the sample sintered at 700 °C. The losses decomposition was performed and showed that the dynamic losses become predominant after 1 kHz. The samples have been investigated by X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), vibrating sample magnetometer (VSM) for powder samples and by DC and AC magnetic investigation by hysteresisgraph method and electrical resistivity investigations for the sintered compacts.

Optimized hybrid improper ferroelectricity of (Ca1-xNdx)3Ti2O7 ceramics based on soft doping effects

Low remnant polarization and high coercive field are the main factors limiting the practical application of Ca3Ti2O7-based hybrid improper ferroelectric ceramics. Based on sol-gel method and soft doping effect, (Ca1-xNdx)3Ti2O7 (x=0.003) ceramics with higher remnant polarization of ∼3.53 μC/cm2 and lower coercive field of ∼91 kV/cm were obtained. More interestingly, thanks to the large distortion amplitude of TiO6 octahedron and effective suppression of defects such as oxygen vacancies caused by Nd3+ as a donor dopant, the remnant polarization of (Ca1-xNdx)3Ti2O7 (x = 0.003 and 0.006) ceramics measured at 10 Hz using the DHM mode were as high as 7.33 μC/cm2 and 5.85 μC/cm2. These findings prove that the soft doping at A sites of Ca3Ti2O7 material is a simple and effective strategy to enhance its hybrid improper ferroelectricity.

Room temperature ferroelectricity and ferromagnetism in Ni-substituted Bi5Ti3FeO15

Aurivillius-type bismuth layer-structured ferroelectric (BLSF) Bi5Ti3FeO15 (BTF) has recently attracted considerable attention as a typical multiferroic material because ferroelectric and magnetic orders coexist, but bulk BTF exhibits antiferromagnetic (AFM) orders and negligible intrinsic magnetoelectric (ME) coupling effects. In this study, nickel-substituted Bi5Ti3FeO15 (Bi5Ti3Fe0.5Ni0.5O15, abbreviated as BTF-Ni) was synthesized using a solid-state reaction method to explore and enhance both the magnetic and ferroelectric properties of BTF. Polarization-electric field P-E loops indicate that the BTF-Ni exhibits considerable maximum polarization P m of 11.9 μC/cm2 and remnant polarization P r of 5.8 μC/cm2, but still keeps a very high ferroelectric Curie temperature (FE T c) of 1029 K, which are much superior to those of pure BTF. Moreover, magnetization-magnetic field M-H loops indicate that BTF-Ni exhibits significant ferromagnetic properties with a large saturation magnetization M s of 60 memu/g, low coercive field H c of 31 Oe at room temperature, and a high ferromagnetic Curie temperature (FM T c) of 698 K, whereas pure BTF has an antiferromagnetic Néel temperature (T N) of 80 K. Our work suggests that nickel-substituted BTF is a potential room-temperature magnetoelectric multiferroic material.

Out-of-plane ferroelectricity and robust magnetoelectricity in quasi-two-dimensional materials.

Thin-film ferroelectrics have been pursued for capacitive and nonvolatile memory devices. They rely on polarizations that are oriented in an out-of-plane direction to facilitate integration and addressability with complementary metal-oxide semiconductor architectures. The internal depolarization field, however, formed by surface charges can suppress the out-of-plane polarization in ultrathin ferroelectric films that could otherwise exhibit lower coercive fields and operate with lower power. Here, we unveil stabilization of a polar longitudinal optical (LO) mode in the n = 2 Ruddlesden-Popper family that produces out-of-plane ferroelectricity, persists under open-circuit boundary conditions, and is distinct from hyperferroelectricity. Our first-principles calculations show the stabilization of the LO mode is ubiquitous in chalcogenides and halides and relies on anharmonic trilinear mode coupling. We further show that the out-of-plane ferroelectricity can be predicted with a crystallographic tolerance factor, and we use these insights to design a room-temperature multiferroic with strong magnetoelectric coupling suitable for magneto-electric spin-orbit transistors.

Unveiling the polar properties on barium bismuthate perovskite thin films with distinct Ba/Bi ratios

This research aims to investigate the domain structure of BaBiO3 (80:20), BaBiO3 (50:50), and BaBiO3 (30:70) thin films obtained by the polymeric precursor method. For better sample designations, the following codes were employed: (80:20) (BBO82), (50:50) (BBO55), and (30:70) (BBO37). The piezo-ferroelectric coupled behavior observed for barium bismuthates thin films was elucidated in terms of bismuth and oxygen vacancies as well as grain morphology, which can be controlled by stoichiometric changes (Ba/Bi ratios). The films crystallize in a rhombohedral BaBiO3 structure with an R-3R space group without any deleterious secondary phase. Additionally, the hysteretic strain, dielectric, ferroelectric, and piezoelectric properties of BaBiO3 thin films are strongly dependent on the film texture. Sample BBO55 showed a distinguished preferred orientation along the (341) plane with a low associated coercive field (66.87 kV/cm), free of imprint and with no polarizations gap compared to samples BBO37 and BBO82. Sample BBO55 presented the highest piezoelectric (d33-eff ≈ 45.7 pm/V) and ferroelectric (Pr≈19.87 μC/cm2) responses. This behavior can be ascribed to a highly textured film, which generates less strain throughout the crystal lattice, facilitating the polarization switching mechanism and improving piezo/ferroelectricity. These findings are significant for developing novel, high-performance, lead-free piezoelectric materials to be applied in different electronic components such as magnetic field sensors, switches, actuators, and other types of memory devices.

Effect of Hf alloying on magnetic, structural, and magnetostrictive properties in FeCo films for magnetoelectric heterostructure devices

Materials with high magnetoelectric coupling are attractive for use in engineered multiferroic heterostructures with applications such as ultra-low power magnetic sensors, parametric inductors, and non-volatile random-access memory devices. Iron–cobalt alloys exhibit both high magnetostriction and high saturation magnetization that are required for achieving significantly higher magnetoelectric coupling. We report on sputter-deposited (Fe0.5Co0.5)1−xHfx (x = 0 – 0.14) alloy thin films and the beneficial influence of Hafnium alloying on the magnetic and magnetostrictive properties. We found that co-sputtering Hf results in the realization of the peening mechanism that drives film stress from highly tensile to slightly compressive. Scanning electron microscopy and x-ray diffraction along with vibrating sample magnetometry show reduction in coercivity with Hf alloying that is correlated with reduced grain size and low film stress. We demonstrate a crossover from tensile to compressive stress at x ∼ 0.09 while maintaining a high magnetostriction of 50 ppm and a low coercive field of 1.1 Oe. These characteristics appear to be related to the amorphous nature of the film at higher Hf alloying.

Sub-10 nm HfZrO ferroelectric synapse with multiple layers and different ratios for neuromorphic computing

To break the von Neumann bottleneck, emerging non-volatile memories have gained extensive attention in hardware implementing neuromorphic computing. The device scaling with low operating voltage is of great importance for delivering a high-integrating and energy-efficient neuromorphic system. In this paper, we fabricated sub-10 nm ferroelectric capacitors based on HfZrO (HZO) film with varying HfO and ZrO components. Compared to the conventional HZO capacitors (a constant component of 1:1), the varying component ferroelectric capacitors show similar remnant polarization but a lower coercive electric field (Ec). This enables the partial domain switching processed at a lower pulse amplitude and width, which is essential for emulating typical synaptic features. In the MNIST recognition task, the accuracy of sub-10 nm ferroelectric artificial synapse can approach ∼85.83%. Our findings may provide great potential for developing next-generation neuromorphic computing-based ultra-scaled ferroelectric artificial synapses.

A Comparative Study of Pt/Al0.72Sc0.28N/Pt-Based Thin-Film Metal-Ferroelectric-Metal Capacitors on GaN and Si Substrates.

AlxSc1-xN is a nitride-ferroelectric compatible with both CMOS and GaN technology. The origin of ferroelectricity in these ternary nitrides relies on the full inversion of nitrogen atom positions, which is a significantly different structural mechanism than conventional perovskites. Therefore, its ferroelectric characteristics exhibit a high remanent polarization and a tunable coercive field but suffer heavily from leakage currents during the switching event. In this article, we studied epitaxially grown Al0.72Sc0.28N thin films on epitaxial Pt electrode layers deposited on GaN/Al2O3 substrates. The results are compared both structurally and electrically with similar systems on SiO2/Si substrates. Our X-ray diffraction analysis showed that Al0.72Sc0.28N/epi-Pt/GaN is always a complete epitaxial stack without any significant strain gradient. Electrically, this system has an overall lower leakage current and coercive field compared to directly grown, highly crystalline, strained epitaxial Al0.72Sc0.28N/GaN, despite having a lower crystalline quality of the ferroelectric layer. In addition, decreasing the epi-Pt thickness from 100 to 10 nm resulted in further improvement of the leakage profile, which we attribute to a decrease in surface roughness in the thinner Pt. In contrast, the dominant factor of leakage in a fiber-textured system on Si substrates is the Pt(111) texture. Finally, with the combination of in-plane X-ray diffraction and high-resolution scanning transmission electron microscopy, we have demonstrated an all-epitaxial 20 nm Al0.72Sc0.28N/Pt/GaN MFM stack with a sharp interface thickness of less than 1 nm.

Molecular Ferroelectric with Directional Polarization Field for Efficient Tin‐Based Perovskite Solar Cells

AbstractDue to the relatively inferior dielectric constant, Sn‐based perovskites exhibit lower defect tolerance and insufficient dielectric shielding effect compared with Pb‐perovskites. Upgrading built‐in electric field (BEF) in Sn‐based perovskite solar cells (PSCs) can be effective to reduce large voltage deficit and improve poor performance caused by the low defect tolerance resulting from the intrinsic inferior dielectric of Sn‐based perovskites. Herein, 2‐methylbenzimidazole (MBI) molecular ferroelectric with low coercive field and high Curie‐temperature is introduced to construct an additional ferroelectric field in FASnI3‐based PSCs. The ferroelectric effect of MBI can promote exciton dissociation, enhance carrier population, and suppress the adverse effect of the residual defects on carriers, and the directional polarization of MBI in FASnI3 film can be driven by the BEF in PSCs to broaden the width of depletion region. Additionally, the MBI molecules with amine functional groups effectively regulate perovskite crystallization, passivate Sn‐related defects, and enhance the oxidation barrier. Profiting from the above advantages, the MBI‐modified device achieves a champion power conversion efficiency (PCE) of 12.91%, keeping over 94% average PCE after 1056 h in N2 glovebox for the unencapsulated device. This study highlights the significant role of molecular ferroelectrics in perovskite photovoltaics.

Enhanced coercivity and emergent spin-cluster-glass state in 2D ferromagnetic material, Fe[formula omitted]GeTe[formula omitted

Two-dimensional (2D) van der Waals (vdW) magnetic materials with high coercivity and high TC are desired for spintronics and memory storage applications. Fe3GeTe2 (F3GT) is one such 2D vdW ferromagnet with a reasonably high TC, but with a very low coercive field, HC (≲100 Oe). Here we present a phase-engineered sample of F3GT with enhanced coercivity (7–10 times), without compromising its fundamental magnetic properties (TC≃ 210 K). The parent F3GT phase is infused with a small percentage of randomly embedded clusters of a coplanar FeTe (FT) phase, which serves as both mosaic pinning centers between grains of F3GT above its antiferromagnetic transition temperature (TC1∼ 70 K) and also as anti-phase domains below TC1. As a result, the grain boundary disorder and metastable nature are greatly augmented, leading to highly enhanced coercivity, cluster spin glass, and meta-magnetic behavior. The enhanced coercivity (≃1 kOe) makes F3GT-2 much more useful for memory storage applications.

Studies of the microstructural, magnetic, electrical, and dielectric properties of Mg0.6T0.4Cr2O4 (T = Ni, Cu) spinel chromites for magnetic, high frequency, and microwave applications

In this study, the structural, morphological, magnetic, electrical, and dielectric properties of Mg0.6T0.4Cr2O4 (T = Ni, Cu) spinel chromites were studied. The X-ray diffraction data reveal that the average crystallite size, lattice constant, and X-ray density increase with the substitution of Ni by Cu. The average crystallite size value rises from 58 nm (for Mg0.6Ni0.4Cr2O4) to 73 nm (for Mg0.6Cu0.4Cr2O4). However, saturation magnetization (Ms) decreases from 0.061 emu/g for Mg0.6Ni0.4Cr2O4 to 0.058 emu/g for Mg0.6Cu0.4Cr2O4. The decline in Ms is due to the lower magnetic moment of Cu2+ ions compared to that of Ni2+ ions. Low Hc coercive fields were obtained (53 Oe and 40 Oe for Mg0.6Ni0.4Cr2O4 and Mg0.6Cu0.4Cr2O4, respectively), indicating that the synthesized samples are suitable for use in soft magnetic devices. Temperature and frequency-dependent impedance spectroscopy measurements have been used to study the samples' electrical properties. The NSPT and CBH models were used to explain the samples' conduction process. Due to the increase in crystallite size, the activation energy (Ea) is lower for Mg0.6Cu0.4Cr2O4 (0.136 eV) than Mg0.6Ni0.4Cr2O4 (0.250 eV). The sample impedance properties were interpreted by modeling Nyquist diagrams considering grain and grain boundary contributions. Dielectric-relaxation phenomenon is observed from sample impedance curves. Mg0.6Ni0.4Cr2O4 conductivity data collapse into a single master curve, as predicted by the Ghosh scaling model. However, for Mg0.6Cu0.4Cr2O4, the Summerfield scaling model is more appropriate. Furthermore, the synthesized materials demonstrate high electrical resistivity, as well as low dielectric constants and losses at higher frequencies, making them appropriate for use in microwave absorption devices and high-frequency applications.

Structural, dielectric, and magnetic properties of nickel rich manganese substituted Li2Ni6MnxCo2-xO10 nanomaterial synthesized via sol-gel method

Manganese-substituted nickel-rich lithium-cobalt oxide Li2Ni6MnxCo2-xO10 was synthesized via the sol-gel auto-combustion method. The structure and morphology were investigated respectively by X-ray diffraction technique (XRD) and scanning electron microscopy (SEM) technique. Hexagonal structure was confirmed by XRD pattern with secondary phase. The crystallite size of the prepared nanomaterial was determined by modified Scherer modified (MSM), size-strain plot (SSP), and Williamson-Hall (W–H) method approaches. The average crystallite size has been correlated for each method and found to range from 12 to 27 nm. SEM was performed to investigate the surface morphology, particle size, and their distribution. The dielectric characteristics have been investigated with the effect of applied frequency in the range of 1 MHz–3 GHz. Synthesized material's dielectric characteristics such as impedance, electrical conductivity, modulus, and dielectric constant have been studied and found frequency dependent. Sensitivity response at high frequency suggested that the material is applicable for high-frequency devices. Magnetic measurements were made using M − H loops of coercivity (Hc), saturation magnetization (Ms), and retentivity (Mr). Both saturation magnetization and coercivity varied with increasing Mn concentration. The maximum value of Ms found at x = 0.50 and subsequently decreases with increasing Mn-content. Prepared samples are soft magnetic materials due to low coercive field. Further, the obtained dielectric properties suggested that the prepared materials can be used for energy storage applications.

Biosynthesis of a tri‐metallic nanoalloy for magnetic and biomedical applications

The tri‐metallic magnetic nanoalloy synthesized via the eco‐friendly procedure discussed here contains cobalt (Co), nickel (Ni), and zirconium (Zr) metals in a 3:1:1 M ratio (Co3O4.NiO.ZrO2 nanoalloy). Two different plant extracts which are rich in biologically active compounds from Spermacoce hispida and Vernonia cinereum were combined to get a multispecies nanoalloy with magnetic properties and medicinal values. The Fourier transform infrared, X‐ray diffraction, and transmission and scanning electron microscopes analyses confirmed the spherical shape of the bioinspired Co3O4.NiO.ZrO2 nanoalloy. The average size of our nanoalloy was 32 nm, but the individual nanoparticles are between 21 and 73 nm in size. A vibrating sample magnetometer study of the magnetic characteristics of the nanoalloy reveals strong saturation magnetization (12.42 emu/g), low retentivity (Mr), and low coercivity (Hc) (282.36 Oe). The higher saturation magnetization in nanoalloy is attributed to their larger particle size, a high degree of crystalline structure, and slight external spinning deformation. The low coercive field (Hc) value reveals the unique soft nature of our nanoalloy. The disc diffusion study confirms that a 6.3 μg/mL solution of the nanoalloy kills almost 96% of the harmful bacteria like Bacillus subtilis (29 mm), Bacillus cereus (26 mm), and Escherichia coli (21 mm). It shows a moderate effect of 85% killing factor against Staphylococcus albus (17 mm), Pseudomonas aeruginosa (13 mm), and Klebsiella pneumoniae (15 mm) bacteria.