System for achieving magnetoelectronic tunability in spinel ferrites for next-generation AI devices

Abstract

A system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles, comprising: a) a precursor preparation unit for the preparation of a homogeneous nitrate precursor solution, wherein the precursor preparation unit facilitates the dissolution of stoichiometric amounts of magnesium nitrate hexahydrate, nickel nitrate hexahydrate, iron(III) nitrate nonahydrate and chromium(III) nitrate nonahydrate in deionized water; b) a fuel mixing unit configured to introduce a binary mixture of urea and glucose into the dissolved homogeneous nitrate solution in a fuel-oxidant ratio that achieves fuel equivalence; c) a gel formation unit configured to maintain the temperature at 70-80 °C under continuous stirring to convert the fuel mixture into a viscous gel; d) a combustion unit comprising a preheated muffle furnace maintained at 450 ± 10 °C and enabling the initiation of a self-propagating combustion reaction; and e) a calcination plant configured for the thermal treatment of crushed precursor ash at 600 °C for 2 hours and subsequently at 750 °C for 2 hours to produce phase-pure cubic spinel Mg 1-x Ni x To produce FeCrO4 nanoparticles.

Description

AREA OF INVENTION

[0001] The present disclosure relates to a system for achieving magnetoelectronic tunability in spinel ferrites for next-generation AI devices. More specifically, the present invention relates to a system for synthesizing magnetoelectronically tunable spinel ferrite nanoparticles using a solution combustion synthesis pathway that allows precise control of the composition stoichiometry and nanoparticle characteristics. BACKGROUND OF THE INVENTION

[0002] Spinel ferrites of the general formula AB₂O₄ have established themselves as a multifunctional class of materials with diverse applications in magnetic data storage, spintronics, catalysis, electrochemical energy storage, and neuromorphic computing systems. Their technological significance stems from the flexible distribution of divalent and trivalent cations across tetrahedral (A) and octahedral (B) lattice sites. This enables the simultaneous control of electron transport, magnetic exchange, redox activity, and defect chemistry within the same crystal lattice. The strong interplay of charge, spin, lattice, and ions makes ferrites promising candidates for next-generation multifunctional devices requiring coexisting memory, logic, and sensor functions—capabilities increasingly in demand in novel AI accelerators, neuromorphic processors, and in-memory computing systems.

[0003] Among classical ferrite systems, magnesium-based chromites and ferrites such as MgFe₂O₄ and MgFeCrO₄ are characterized by high chemical stability, large band gaps, and soft magnetic behavior. However, their low intrinsic conductivity, limited redox activity, and weak magnetic anisotropy restrict their applicability in energy storage, electrocatalysis, and spintronics. Substitution with transition metals, particularly nickel, has been investigated as an effective strategy for performance enhancement, since Ni 2+ (3d 8 ) causes a strong magnetocrystalline anisotropy, facilitates electron transport between the B positions, and the Ni 2+ / Ni 3+The redox couple is activated. While previous studies have shown improvements in individual functional properties such as magnetic order, dielectric behavior, or catalytic activity through partial Ni substitution, a systematic correlation between Ni-induced structural modification, magnetic anisotropy, electronic band structure, and electrochemical redox behavior in the entire Mg is still lacking. 1-x Ni x FeCrO4 (0 ≤ x ≤ 1) solid solution series.

[0004] Furthermore, recent advances in neuromorphic computing and AI hardware have increased the need for materials that enable ion-driven conductivity modulation, resistive switching, and magnetic threshold control simultaneously in a single phase. Metal oxides such as HfΌ2, TiO2, and VO2 are promising candidates. xWhile some successes have been achieved in a few of these modes, only a few material families inherently combine electronic, ionic, and magnetic tunability. Spinel ferrites, with their mixed-valence B-site network, numerous redox centers, and strong magnetic interactions, are ideally suited to meet this requirement. However, ferrite-based neuromorphic devices remain largely unexplored, primarily due to a lack of detailed structure-property-device correlation studies that link nanomaterial development with advanced device functionalities such as neuromorphic switching, resistive memory operation, and electrochemical synaptic plasticity.

[0005] Therefore, there is a need for a comprehensive system that enables the synthesis and characterization of magnetoelectronically tunable spinel ferrite nanoparticles across the entire composition range and establishes systematic correlations between structural modifications, optical properties, magnetic behavior and electrochemical performance, in order to facilitate their integration into next-generation AI and neuromorphic computing devices. SUMMARY OF THE INVENTION

[0006] The present disclosure relates to a system for achieving magnetoelectronic tunability in spinel ferrites for next-generation AI devices. The present invention relates to a system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles of the composition Mg 1-x Ni xFeCrO4 (0 ≤ x ≤ 1) for use in next-generation AI and neuromorphic computing devices. The system uses a solution-combustion synthesis pathway that allows precise control of composition stoichiometry and nanoparticle characteristics.

[0007] The present disclosure relates to a system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles. The system comprises: a) a precursor preparation unit (102) for the preparation of a homogeneous nitrate precursor solution, wherein the precursor preparation unit enables the dissolution of stoichiometric amounts of magnesium nitrate hexahydrate, nickel nitrate hexahydrate, iron(III) nitrate nonahydrate, and chromium(III) nitrate nonahydrate in deionized water; b) a fuel mixing unit for the addition of a binary mixture of urea and glucose in a fuel-oxidant ratio that achieves fuel equivalence; c) a gel formation unit for maintaining a temperature of 70-80 °C with continuous stirring in order to convert the fuel mixture into a viscous gel.d) a combustion unit consisting of a preheated muffle furnace maintained at 450 ± 10 °C, enabling the initiation of a self-propagating combustion reaction; and e) a calcination unit configured for the thermal treatment of crushed precursor ash at 600 °C for 2 hours and subsequently at 750 °C for 2 hours to produce phase-pure cubic spinel Mg. 1-x Ni x To produce FeCrO4 nanoparticles.

[0008] The aim of the present disclosure is to provide a system for achieving magnetoelectronic durability in spinel ferrites for next-generation AI devices.

[0009] Another objective of the present disclosure is the synthesis of phase-pure cubic spinel ferrite nanoparticles of composition Mg 1-x Ni xFeCrO4 (0 ≤ x ≤ 1) by solution combustion process with precise control over crystallite size, lattice parameters and composition homogeneity.

[0010] Another objective of the present disclosure is the synthesis of spinel ferrite nanoparticles with systematically tunable magnetic properties, in particular the achievement of increased coercive field strengths in the range of 2.18 Oe to 146.35 Oe by controlled nickel substitution for applications in magnetic logic elements and spin-based data storage devices.

[0011] Another objective of the present disclosure is the evaluation of the magnetoelectronic tunability of the manufactured nanoparticles.

[0012] However, another objective of the present disclosure is the comprehensive evaluation of the structural, optical, magnetic and electrochemical properties of the manufactured nanoparticles.

[0013] To further clarify the advantages and features of the present disclosure, the invention is described in more detail with reference to specific embodiments illustrated in the accompanying drawing. It is understood that this drawing merely shows typical embodiments of the invention and is therefore not to be understood as limiting its scope of protection. The invention is described and explained in more detail and with reference to the accompanying drawing. BRIEF DESCRIPTION OF THE IMAGE

[0014] These and other features, aspects and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawing, in which the same symbols represent the same parts, wherein: Fig. Figure 1 shows a block diagram of a system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles according to an embodiment of the present disclosure.

[0015] Furthermore, those skilled in the art will recognize that the elements in the drawing are simplified and not necessarily drawn to scale. For example, the flowcharts illustrate the process by highlighting the main steps to facilitate understanding of the present disclosure. With regard to the construction of the device, one or more components may be represented in the drawing by conventional symbols. The drawing may show only those specific details relevant to understanding the embodiments of the present disclosure, so as not to clutter the drawing with details that are already apparent to those skilled in the art from the description contained herein. DETAILED DESCRIPTION:

[0016] To facilitate understanding of the principles of the invention, reference is made below to the embodiment shown in the drawing, which is described using specific terms. It is understood, however, that this does not limit the scope of protection of the invention. Rather, modifications and further developments of the depicted system, as well as further applications of the inventive principles shown therein, are conceivable, insofar as they would normally occur to a person skilled in the art in the field of the invention.

[0017] It will be clear to those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not to be understood as a limitation thereof.

[0018] References to “an aspect”, “another aspect”, or similar phrases in this description mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, phrases such as “in one embodiment”, “in another embodiment”, and similar expressions in this description may, but do not necessarily, all refer to the same embodiment.

[0019] The terms "includes," "comprehensive," or similar expressions denote non-exclusive inclusion. Thus, a procedure or method containing a list of steps does not only include those steps but may also include further steps not explicitly listed or inherent in the procedure or method. Likewise, the statement "includes..." for one or more devices, subsystems, elements, structures, or components, without further limitations, does not preclude the existence of other devices, subsystems, elements, structures, or components.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meanings generally known to those skilled in the art in the field to which this invention belongs. The systems, methods, and examples described herein serve only for illustration and are not to be understood as limiting.

[0021] Embodiments of the present disclosure are described in detail below with reference to the attached drawing.

[0022] Fig. Figure 1 shows a block diagram of a system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles according to an embodiment of the present disclosure.

[0023] According to Fig.1 The system (100) consists of: a) a precursor preparation unit (102) for producing a homogeneous nitrate precursor solution, wherein the precursor preparation unit (102) facilitates the dissolution of stoichiometric amounts of magnesium nitrate hexahydrate, nickel nitrate hexahydrate, iron(III) nitrate nonahydrate, and chromium(III) nitrate nonahydrate in deionized water; b) a fuel mixing unit (104) configured to introduce a binary mixture of urea and glucose into the dissolved homogeneous nitrate solution in a fuel-oxidant ratio that achieves fuel equivalence; c) a gel formation unit (106) configured to maintain the temperature at 70-80 °C with continuous stirring to convert the fuel mixture into a viscous gel;d) a combustion unit (108) comprising a preheated muffle furnace maintained at 450 ± 10 °C, enabling the initiation of a self-propagating combustion reaction; and e) a calcination unit (110) configured for the thermal treatment of crushed precursor ash at 600 °C for 2 hours and subsequently at 750 °C for 2 hours to produce phase-pure cubic spinel Mg; 1-x - Ni x To produce FeCrO4 nanoparticles.

[0024] In one embodiment, the precursor preparation unit (102) comprises a magnetic stirrer configured to perform the dissolution under continuous stirring.

[0025] In one embodiment, the fuel mixing unit (104) is configured to provide a fuel mixture in which urea ensures rapid combustion and gas expansion and glucose improves gel polymerization.

[0026] In one embodiment, the combustion unit (108) comprises a preheated muffle furnace which enables combustion, wherein the combustion during the self-propagating combustion reaction generates local temperatures of over 900-1100 °C for a short time.

[0027] In one embodiment, the system (100) further comprises a comminution device (112) configured to easily comminute the precursor ash produced after combustion.

[0028] In one embodiment, the calcination unit (110) is configured to eliminate residual carbon-containing species and to complete the crystallization of the spinel ferrite nanoparticles.

[0029] In one embodiment, the system is configured to produce phase-pure cubic spinel Mg 1-x Ni x FeCrO4 - Nanoparticles with crystallite sizes in the range of 10-16 nm are produced.

[0030] In one embodiment, the system (100) further comprises a characterization unit (114) configured to allow structural, optical and magnetic characterization of the manufactured nanoparticles.

[0031] In one embodiment, the system (100) further comprises an electrochemical characterization unit (116) configured to evaluate the charge storage capacity and capacity retention of the manufactured nanoparticles.

[0032] The present invention relates to a system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles of composition Mg 1-x Ni xFeCrO4 (0 ≤ x ≤ 1) for applications in next-generation AI and neuromorphic computing. The system utilizes a solution combustion process that allows for precise control of the composition and nanoparticle properties. The synthesis system includes a precursor preparation unit for dissolving stoichiometric amounts of magnesium nitrate hexahydrate, nickel nitrate hexahydrate, iron(III) nitrate nonahydrate, and chromium(III) nitrate nonahydrate in deionized water; a fuel mixing unit for adding a binary mixture of urea and glucose in an optimized fuel-oxidant ratio; a gelation unit for maintaining controlled temperature conditions to convert the solution into a viscous gel; a combustion unit for initiating self-propagating combustion reactions; and a calcination unit for two-stage heat treatment to produce phase-pure cubic spinel nanoparticles.The system also includes characterization units for determining the structural, optical, magnetic, and electrochemical properties of the synthesized nanoparticles. The resulting nanoparticles exhibit systematic lattice contraction, a reduction in crystallite size from 16.1 to 10.7 nm, a narrowing of the band gap from approximately 2.12 eV to 1.68 eV, an increased coercive field strength in the range of 2.18 to 146.35 Oe, and improved charge storage capacity with a capacity conservation of up to 86%, making them suitable for integration into artificial synaptic and neuronal devices.

[0033] The Mg 1-x Ni xFeCrO4 nanoparticles (0 ≤ x ≤ 1) were synthesized using a solution combustion system, which enables rapid mixing at the atomic level, low-temperature initiation, and the formation of high-purity, single-phase spinels. Stoichiometric amounts of the corresponding metal nitrates—magnesium nitrate hexahydrate, nickel nitrate hexahydrate, iron(III) nitrate nonahydrate, and chromium(III) nitrate nonahydrate—were prepared according to the formula Mg 1-x Ni x FeCrO4 was weighed out and dissolved in 100-150 ml of deionized water at 70-80 °C with constant stirring. The homogeneous nitrate solution served as the oxidizing agent matrix. A binary mixture of urea (CO(NH2)2) and glucose (C6H) was used. 12O6) was used in an optimized fuel-oxidant ratio (Φ ≈ 1). Urea ensured rapid combustion and gas expansion, while glucose improved gel polymerization and controlled the flame temperature, thus preventing the agglomeration of large particles. The resulting clear, greenish-brown solution gradually transformed into a viscous gel upon evaporation of the water, promoting uniform chelation and cation distribution at the molecular level.

[0034] The viscous precursor gel was transferred to a muffle furnace preheated to 450 ± 10 °C, initiating a self-propagating combustion reaction within minutes. The gel initially swelled due to trapped gases (CO₂, N₂, NH₃, H₂O vapors), followed by spontaneous ignition. A rapid exothermic reaction ensued, accompanied by bright flame fronts and vigorous gas evolution, producing a voluminous, flaky, ash-like mass. In this step, the organic fuel-nitrate matrix was transformed into an ultraporous mixed metal oxide framework, representing the precursor of the spinel-ferrite phase. The highly exothermic nature of the combustion generated localized temperatures exceeding 900–1100 °C for a very short duration, sufficient to initiate crystallite nucleation without external heating.After combustion subsided, the precursor ash was lightly crushed and subjected to controlled calcination at 600 °C for 2 hours, followed by 750 °C for 2 hours in air. This two-stage thermal treatment completed the crystallization process, eliminated any remaining carbonaceous compounds, and resulted in the formation of phase-pure cubic spinel magnesium. 1-x Ni x FeCrO4 powders with crystallite sizes in the range of 10-16 nm are safe.

[0035] The synthesized nanoparticles were investigated with respect to their structural, optical, magnetic, electrochemical, and neuromorphic properties. X-ray diffraction (XRD) analyses confirmed a single-phase cubic spinel structure with systematic Vegard lattice contraction and a reduction in crystallite size from 16.1 to 10.7 nm, which is attributed to the replacement of Mg. 2+ (0.72 Å) by Ni 2+(0.69 Å). X-ray fluorescence (XRF) analysis confirms the homogeneous incorporation of Ni. The reduction of the band gap from ~2.12 to ~1.68 eV is attributed to Ni 3d-O 2p hybridization and the formation of defect states. Magnetic measurements show ferrimagnetic behavior with an increase in coercive field strength from 2.18 to 146.35 Å and an effective magnetic anisotropy with a maximum at x ≈ 0.5, confirming the Ni-induced enhancement of the BB exchange interactions. Electrochemical studies show improved pseudocapacitive behavior, reduced charge transfer resistance, and excellent rate capability. At x = 0.75, capacitance conservation of ~86% is achieved, highlighting the superior charge storage capability due to Ni-induced electronic and ionic pathways.

[0036] In one embodiment, an optimized Mg is used. 0.25 Ni 0.75FeCrO4 composition integrated into a Pt / HfO2 / ferrite / Ag device stack. The demonstration showcased artificial synaptic and neuronal functionalities, including analog potentiation / depression, spike-controlled memristive switching, and neuronal spiking via the integrate-and-fire principle. The strong coupling between charge, ion, and spin degrees of freedom in Ni-substituted MgFeCrO4 enables a multifunctional neuromorphic platform that facilitates energy-efficient learning, memory, and spiking—thus representing a promising material foundation for next-generation AI hardware.

[0037] X-ray diffraction (XRD) analysis confirmed the formation of a single-phase cubic spinel structure in all compositions. This revealed a Vegard-like lattice contraction and a refinement of the crystallite size from 16.1 to 10.7 nm due to the substitution of Mg. 2+ through smaller Ni 2+-ions. X-ray fluorescence analysis (XRF) and elemental distribution analyses verified a homogeneous cation distribution and the precise incorporation of Ni without the formation of secondary phases. Optical investigations revealed a progressive reduction of the band gap from ~2.12 eV to ~1.68 eV, which is attributed to the hybridization of Ni 3d and O 2p as well as the generation of defect states and demonstrates a targeted adaptation of the electronic structure.

[0038] Magnetic measurements confirmed ferrimagnetic ordering in all samples, with a significant increase in coercive field strength (2.18 → 146.35 Oe) and optimized magnetic anisotropy at intermediate Ni concentrations. The magnetic hardening is attributed to enhanced BB superexchange interactions, cation redistribution, and developing spin-lattice coupling. Electrochemical analyses showed that Ni substitution significantly improved charge transfer kinetics, conductivity, and pseudocapacitive activity. The composition Mg 0.25 Ni 0.75 FeCrO4 exhibited the highest specific capacity, nearly symmetrical charge / discharge curves, low internal resistance, and excellent cycle stability (~86% at 5 A g). -1 ). These results underscore the synergistic influence of microstructure refinement, redox-active Ni centers, and increased electron-ion mobility.

[0039] Beyond material characterization, the optimized ferrite composition was integrated into a prototypical neuromorphic device structure that demonstrated analog synaptic plasticity, multi-level conductance modulation, and threshold-controlled neuronal action potentials. The simultaneous presence of redox-driven ion transport, electronic pathways, and tunable magnetic anisotropy positions Mg 1-x Ni x FeCrO4 is a rare multifunctional material that enables storage, computing and sensory functions on a single platform.

[0040] The drawing and the preceding description illustrate embodiments. Those skilled in the art will recognize that one or more of the described elements can be combined to form a single functional element. Alternatively, certain elements can be divided into several functional elements. Elements of one embodiment can be added to another. For example, the process flows described here can be modified and are not limited to the manner described herein. Furthermore, the actions of a flowchart need not be performed in the sequence shown; nor do all actions necessarily need to be carried out. Actions that do not depend on other actions can be performed in parallel with the other actions. The scope of protection of the embodiments is in no way limited by these specific examples. Numerous variations, whether explicitly stated in the description or not, such as...Differences in structure, dimensions, and materials are possible. The scope of protection of the embodiments is at least as comprehensive as described by the following claims.

[0041] The advantages, other benefits, and problem solutions have been described above with reference to specific embodiments. However, the advantages, benefits, problem solutions, and any components that can effect or enhance an advantage, benefit, or solution are not to be construed as critical, necessary, or essential features or components of the claims. REFERENCES 100 A System for the Synthesis of Magnetoelectronically Tunable Spinel Ferrite Nanoparticles. 102 Precursor preparation unit 104 Fuel mixing unit 106 Gel formation units 108 combustion unit 110 calcination units 112 Crushing apparatus 114 Characterization Unit 116 Electrochemical characterization unit

Claims

[1] A system for the synthesis of magnetoelectronically tunable spinel ferrite nanoparticles, comprising: a) a precursor preparation unit for the preparation of a homogeneous nitrate precursor solution, wherein the precursor preparation unit facilitates the dissolution of stoichiometric amounts of magnesium nitrate hexahydrate, nickel nitrate hexahydrate, iron(III) nitrate nonahydrate and chromium(III) nitrate nonahydrate in deionized water; b) a fuel mixing unit configured to introduce a binary mixture of urea and glucose into the dissolved homogeneous nitrate solution in a fuel-oxidant ratio that achieves fuel equivalence; c) a gel formation unit configured to maintain the temperature at 70-80 °C under continuous stirring to convert the fuel mixture into a viscous gel; d) a combustion unit comprising a preheated muffle furnace maintained at 450 ± 10 °C and enabling the initiation of a self-propagating combustion reaction; and e) a calcination plant configured for the thermal treatment of crushed precursor ash at 600 °C for 2 hours and subsequently at 750 °C for 2 hours to produce phase-pure cubic spinel Mg 1-x Ni x To produce FeCrO4 nanoparticles. [2] System according to claim 1, wherein the precursor preparation unit comprises a magnetic stirrer configured to perform the dissolution under continuous stirring. [3] System according to claim 1, wherein the fuel mixing unit is configured to provide a fuel mixture in which urea ensures rapid combustion and gas expansion and glucose improves gel polymerization. [4] System according to claim 1, wherein the combustion unit comprises a preheated muffle furnace which facilitates combustion, wherein the combustion during the self-propagating combustion reaction generates local temperatures above 900-1100 °C for a short time. [5] System according to claim 1, further comprising a comminution device configured to easily comminute the precursor ash produced after combustion. [6] System according to claim 1, wherein the calcination unit is configured to remove residual carbon-containing species and to completely carry out the crystallization of the spinel ferrite nanoparticles. [7] System according to claim 1, wherein the system is configured to produce phase-pure cubic spinel Mg 1-x Ni x FeCrO4 - Nanoparticles with crystallite sizes in the range of 10-16 nm are produced. [8] System according to claim 1, further comprising a characterization unit configured to allow structural, optical and magnetic characterization of the manufactured nanoparticles. [9] System according to claim 1, further comprising an electrochemical characterization unit for evaluating the charge storage capacity and capacity retention of the manufactured nanoparticles.

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