Synergistic effect of La and Co co-doping on room-temperature ferromagnetism enhancement of TiO2 nanoparticles

The synergistic influence of lanthanum and cobalt co-doping on room temperature ferromagnetism (RTFM) of TiO₂ system is investigated. A series of Ti_0.97?xCo_0.03La_xO₂ nanoparticles were prepared and their structures and properties were systematically studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, UV–vis spectrophotometer, Raman spectra and magnetic measurement techniques, respectively. Detailed experimental characterizations indicate that the as-prepared La and Co co-doped samples exhibit single anatase phase, and all the samples exhibit strong visible photoluminescence associated with oxygen vacancies and a clear ferromagnetic hysteresis loop, both of which were dramatically enhanced with La and Co co-doping, and the maximum saturation magnetization (M_s) reaches 1.38 emu/g at the La content of 6 mol%. It is speculated that oxygen vacancies modulated by ionic La play an important role in the enhanced RTFM, which can be attributed to the bound magnetic polarons (BMPs) formed via ferromagnetic coupling between two neighboring Co²⁺ ions mediated by oxygen vacancy (F⁺ center). Our results present an alternative method to obtain high performance RTFM.     

Magnetic and phonon transitions in B-site Co doped BiFeO3 ceramics

Magnetic susceptibility and phonons have been characterized in multiferroic Bi(Fe_1−xCo_x)O_3−δ ceramics for x=0.0, 0.05, and 0.10 (BFO100xCo) as functions of temperature. A preferred (100) crystallographic orientation and increasing average oxygen vacancies were observed in BFO5Co and BFO10Co. The Fe and Co K-edge synchrotron X-ray absorptions revealed mixed valences of Fe³⁺, Fe⁴⁺, Co²⁺, and Co³⁺ ions in BFO5Co and BFO10Co, which exhibit a ferromagnetic (or ferrimagnetic) phase below room temperature due to appearance of ferromagnetic B–O–B (B=Fe and Co) superexchange interactions. Field–cooled (FC) and zero–field–cooled (ZFC) magnetic susceptibilities exhibit a significant spin-glass splitting below room temperature in BFO5Co and BFO10Co. Two Raman-active phonon anomalies at ~170 K (or 200 K) and ~260 K were attributed to the Fe³⁺–O–Co³⁺ and Co³⁺–O–Co³⁺ magnetic orderings, respectively. This work suggests that the low-spin Co²⁺–O–Co²⁺, Fe³⁺–O–Fe³⁺ (or Fe⁴⁺), and high-spin Co²⁺–O–Co²⁺ superexchange interactions are responsible for phonon anomalies at ~290 (or ~300 K), ~400, and ~470 K (or ~520 K) in BFO5Co and BFO10Co.     

Resistive switching behavior and improved multiferroic properties of Bi0.9Er0.1Fe0.98Co0.02O3/Co1-xMnxFe2O4 bilayered thin films

Bilayered Bi_0.9Er_0.1Fe_0.98Co_0.02O₃/Co_1-xMn_xFe₂O₄ (BEFCO/CM_xFO) thin films were deposited by the sol-gel method. Structural variations between the triclinic-P1 and trigonal-R3c:H (two-phase coexistence) phases in the BEFCO layer were observed owing to the trigonal-R-3m:H phase existing in the CM_xFO layer. The oxygen vacancy concentrations of the BEFCO/CM_xFO bilayered films are reduced by Mn-doping in the bottom CFO layer. The BEFCO/CFO films showed high oxygen vacancy concentrations with a high leakage current. This induced changes of the significant potential barrier at the interface between the BEFCO and CM_xFO layers in the processes of electron capture and release. Thus, the BEFCO/CFO film exhibited obvious resistive switching (RS) effect. The high leakage current also caused a fake polarization phenomenon with a blow up of the P-E loop in the BEFCO/CFO films. However, the real and outstanding ferroelectric properties, which resulted from the fewer oxygen vacancies and the 38% triclinic-P1 structure, were obtained in the BEFCO/CM_0.3FO films (P_r~156.3?μC?cm^?2). In addition, the typical capacitance-voltage curve further confirmed its superior ferroelectric performance. The RS effect almost disappeared in the BEFCO/CM_0.3FO bilayered films. Moreover, the enhanced ferromagnetic properties (M_s~100.36?emu?cm^?3, M_r~55.38?emu?cm^?3) were obtained for the BEFCO/CM_0.1FO films, which was attributed to the magnetic properties of BEFCO (a more triclinic-P1 phase and numerous Fe²⁺ ions), in addition to the CM_xFO layer. The introduction of the doped magnetic layer into the bilayered films thus represented a highly effective method for enhancing the multiferroic properties of BFO.     

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

Co_1?xO–SnO₂ powders in molar ratio of 92:8 were reactively sintered at 1400 °C to form Co_1?xO–Co_2+xSn_1?xO₄ composite and then cooled in furnace or air quenched for secondary Co_2+xSn_1?xO₄ spinel precipitation from the Sn⁴⁺ doped Co_1?xO grains. Electron microscope observations indicated the secondary spinel to precipitate at grain boundaries when slowly cooled, but as parallel-epitaxial platelets within the Sn⁴⁺ doped Co_1?xO grains with a precipitate free zone near the grain boundary when air quenched. A process of thermal-mismatch induced {1 1 0} cleaving, taking advantage of cobalt vacancies, and spontaneous healing by oxidation precipitation accounts for the platy spinel precipitation within the grains. The precipitate free zone can be attributed to cobalt vacancy depletion, i.e. site saturation, near the grain boundary during rapid cooling in air. The spinel nanocrystals nucleated from cobalt vacancies in association with Sn⁴⁺ dopant have well-developed {1 1 1} habit plane in order to minimize the coherency strain energy.     

Enhancement of multiferroic properties of Aurivillius Bi5Ti3FeO15 ceramics by Co doping

Multiferroic Bi₅Ti₃Fe_1−xCo_xO₁₅ (BFCT-x, where x = 0, 0.1, 0.3, 0.5, 0.7) ceramics were synthesized via a conventional solid-state reaction process and their microstructural, ferroelectric, magnetic and magnetoelectric coupling properties were investigated in detail. All samples show layered perovskite Aurivillius phase with an orthorhombic structure. The highest remanent polarization (2P_r) (35 μC/cm²) has been observed in BFCT-0 ceramic while the BFCT-0.3 ceramic shows the highest remanent magnetization (M_r) (0.13 emu/g) and magnetoelectric coefficient (11.47 mV cm⁻¹ Oe⁻¹). The enhancement of magnetic properties and the magnetoelectric coupling of these ceramics are attributed to the structural distortion caused by Co substitution which subsequently led to ferromagnetic interactions via the Dzyaloshinskii-Moriya interaction.     

Facile electrodeposition of large-area CdO and Cd1−xCoxO curved nanowires

Herein, we developed a facile route to synthesize large-area polycrystalline CdO and Cd_1?xCo_xO curved nanowires by electrochemical deposition in the oxygen saturated solution of CdCl₂ + citric acid at the temperature of 90 °C. Cyclic voltammetry was used to study the electrochemical reactions relevant to the film growth, and it reveals that the stabilizing role of citric acid for the electrochemical reduction of Cd(II). The electrochemical formation process of CdO and the parameter effects on the morphologies of deposits were investigated. In addition, Cd_1?xCo_xO curved nanowires were synthesized, and the effects of the concentrations of Cd²⁺ and Co²⁺ ions and deposition potentials on the compositions of Cd_1?xCo_xO alloy nanowires were studied. The result of magnetic property measurement shows the ferromagnetism of Cd_1?xCo_xO curved nanowires. The coercivity field (H_c) is about 66.6 Oe, and the remanent magnetization (M_r) is about 0.0045 emu/g, revealing a ferromagnetic behavior.     

Kinetic demixing/decomposition of Ba0.5Sr0.5CoxFe1−xO3−δ (x = 0.2 and 0.8)

Microstructural changes due to kinetic demixing within sintered BSCF ceramics (Ba_0.5Sr_0.5Co_xFe_1?xO_3?δ, x = 0.2 and 0.8: BSCF5528 and BSCF5582, respectively) have been investigated. When the specimens were subjected to 2 A/cm² at 1000 °C and pO₂ = 10^?5 atm, there was a significant enhancement of grain growth as well as 2nd phase formation observed in BSCF5528. At the anode, cobalt deficient aggregates within the grains; and, at the cathode, cobalt rich 2nd phase particles were observed on the grain surfaces of the microstructure. Such phenomena were not observed in BSCF5582, even under higher current density (7 A/cm²) and longer delay time. These results were explained by the kinetic demixing/decomposition.     

Partial oxidation of methane in BaCe0.1Co0.4Fe0.5O3−δ membrane reactor

A new perovskite material, BaCe_0.1Co_0.4Fe_0.5O_3?δ used as dense oxygen permeable membrane for partial oxidation of methane (POM) reaction was investigated. In order to improve the synergetic effects between membrane and catalyst, LiLaNiO/γ-Al₂O₃ catalyst was directly packed onto the surface of the membrane to carry out POM. In BaCe_0.1Co_0.4Fe_0.5O_3?δ membrane reactor, high oxygen permeation flux, high CH₄ conversion and CO selectivity were obtained. At 950 °C, oxygen flux of 9.5 ml cm^?2 min^?1, CH₄ conversion of 99% and CO selectivity of 93% were achieved with a membrane thickness of 1.0 mm. There was an induction process at the initial stage of POM, which was related to the reduction of NiO to Ni⁰ in LiLaNiO/γ-Al₂O₃ catalyst. Experiments illustrated that higher reaction temperature would shorten the induction time. During continuously operating for 1000 h at 875 °C, no degradation of performance of the membrane reaction was observed. SEM characterization also demonstrated that the membrane disc maintained an integral structure without any cracks after long-term operation.     

Microwave dielectric properties of (Zn1/3B2/3)0.5(Ti0.8M0.2)0.5O2 (B = Nb5+, Ta5+, M = Sn4+, Ge4+) ceramics

Dielectric properties of (Zn_1/3Nb_(2?x)/3Ta_x/3)_0.5(Ti_0.8Sn_0.1Ge_0.1)_0.5O₂ (x = 0, 1, 2) and/or (Zn_1/3Nb_1/3Ta_l/3)_0.5(Ti_0.8Sn_0.2(l?y)Ge_0.2y)_0.5O₂ (y = 0, 0.5, 1) were investigated at the microwave frequencies. For the compositions with single phase of rutile structure, the dielectric constant (K) of specimens was not only dependent on the dielectric polarizabilities, but also on the bond length ratio of apical bond (d_apical) to equatorial bond (d_equatorial) of oxygen octahedron in the unit cell. Temperature coefficients of the resonant frequencies (TCF) of the specimens with B = Nb⁵⁺ and/or M = Sn⁴⁺ was larger than those with B = Ta⁵⁺ and/or M = Ge⁴⁺. These results could be attributed to the changes of the degree of oxygen octahedral distortion. Quality factors (Qf) of the specimens with B = Ta⁵⁺ and/or M = Sn⁴⁺ were larger than those with B = Nb⁵⁺ and/or M = Ge⁴⁺.     

The nonchalant magnetic ordering of vacancies in graphene

Magnetic properties of graphene monolayer with mono-, di-, and tri-vacancies are studied using spin polarized density functional theory. Detailed analysis of the projected density of the state shows that the magnetic moment associated with single vacancy is due to the combination of p_z π-bonding orbital and partially delocalized sp or sp² hybridized orbitals. A study on 6 × 6 and 9 × 9 supercell reveals the delocalized nature is size independent. The very small energy difference between ferro, anti-ferro and non magnetic states in di- and tri- vacancies predict the nonchalant magnetic ordering for vacancies. Our computational results explain the experimental observations in a recent publication by Nair et al. (2013), that the magnetic response of graphene is paramagnetic, and the single vacancy has a magnetic moment contributed by both itinerant p_z orbitals and localized dangling bond. Magnetic moment associated with triple vacancy configuration is 1 μB. This moment is purely localized moment with no role played by p_z orbitals in contrast to the magnetic moment associated with single vacancy. The hydrogen passivation of tri-vacancy reveals that the conductivity in the tri-vacancy can be varied from a p type to intrinsic semiconductor type.     

Dependence of dielectric properties on structural characteristics of (Zn1/3A2/3)0.5 (Ti1−xBx)0.5O2 (A = Nb5+, Ta5+, B = Ge4+, Sn4+) ceramics at microwave frequencies

The effects of structural characteristics on the dielectric properties of (Zn_1/3A_2/3)_0.5(Ti_1?xB_x)_0.5O₂ (A = Nb⁵⁺, Ta⁵⁺, B = Ge⁴⁺, Sn⁴⁺) (0.1 ≤ x ≤ 0.3) ceramics were investigated at microwave frequency. The sintered specimens showed solid solutions with a tetragonal rutile structure within the solid solution range of compositions. With an increase of BO₂, the temperature coefficient of resonant frequency (TCF) and dielectric constant (K) decreased with a decrease of oxygen octahedral distortion and dielectric polarizabilites, respectively. However, the quality factor (Qf) of the sintered specimens was increased with BO₂ due to the reduction of Ti⁴⁺ ions. The Qf value of the specimens with A = Ta was higher than that of the specimens with A = Nb.     

Influence of oxygen atmosphere annealing on the thermal stability of Mn1.2Co1.5Ni0.3O4±δ ceramic films fabricated by RF magnetron sputtering

This paper presents the optimal atmosphere annealing conditions for Mn_1.2Co_1.5Ni_0.3O_4±δ ceramic thin films fabricated by the RF magnetron sputtering method. The microstructure and oxygen distribution, together with electrical properties, are combined and applied for determining thermal stability. All of the Mn_1.2Co_1.5Ni_0.3O_4±δ films, which are annealed at various oxygen atmosphere from 1 × 10^?3 to 1 × 10⁵ Pa, exhibit a negative temperature coefficient characteristic and show a poly-crystalline spinel structure. The film which annealed at 10 Pa with the most uniform and most dense surface morphology has the minimum resistivity compared to the others. It is characterized by the highest Mn³⁺ and Mn⁴⁺ pair content, which gives the highest carrier concentration of ceramic films. Combined with the aging test at 125 °C for 500 h, the films annealed at 10 Pa have the minimum resistance drift (ΔR/R₀ = 2.35%), which is mainly affected by the oxygen vacancy concentration. This demonstrates that the film thermistors annealed in a hypoxia state will never be stable. This is because there will be several oxidation reactions leading to a continuous generation of cationic vacancies during high temperature aging. The present results will open a way to design desired stable negative temperature coefficient thermistors by adjusting the annealing oxygen atmosphere of films.     

Structural and magnetic properties of ZnMg-ferrite nanoparticles prepared using the co-precipitation method

We synthesized soft magnetic spinel ferrite ZnMg-ferrite (Zn_1?xMg_xFe₂O₄, where x=0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) nanoparticles using the co-precipitation method. Structural and magnetic properties have been studied in detail. XRD revealed that the structure of these nanoparticles is spinel with crystallite size lies in the range 21–31 nm. Lattice parameter decreases with increasing Mg concentration due to the smaller ionic radius of the Mg²⁺ ion. FTIR spectroscopy also confirmed the formation of spinel ferrite by showing the characteristic absorption bands at 420 cm^?1 and 545 cm^?1. Vibrational band of metal ion at tetrahedral site (M_tet.) with oxygen ions (O–M_tet.–O) is shifted toward higher wave numbers with the increase of Mg concentration. The magnetization showed an increasing trend with increasing Mg concentration due to the rearrangement of cations at tetrahedral and octahedral sites, while the corecivity remained constant due to the soft nature of the ferrite composition. Both structural and magnetic properties of ZnMg-ferrite nanoparticles strongly depend upon Mg²⁺ cation doping percentage.     

Synthesis,structure and oxygen thermally programmed desorption spectra of La1−xCaxAlyFe1−yO3−δ perovskites

Perovskites La_1−xCa_xAl_yFe_1−yO_3−δ (x, y = 0 to 1) were prepared by high-temperature solid-state synthesis based on mixtures of oxides produced by colloidal milling. The XRD analysis showed that perovskites La_0.5Ca_0.5Al_yFe_1−yO_3−δ with a high Fe content (1 − y = 0.8–1.0) were of orthorhombic structure, perovskites with a medium Fe content (1 − y = 0.8–0.5) were of rhombohedral structure, and perovskite with the lowest Fe content (1 − y = 0.2) were of cubic structure. Thermally programmed desorption (TPD) of oxygen revealed that chemical desorption of oxygen in the temperature range from 200 to 1000 °C had proceeded in the two desorption peaks. The low-temperature α-peak (in the 200–550 °C temperature range) was brought about by oxygen liberated from oxygen vacancies; the high-temperature β-peak (in the 550–1000 °C temperature range) corresponded to the reduction of Fe⁴⁺ to Fe³⁺. The chemidesorption oxygen capacity increased with increasing Ca content and decreased with increasing Al content in the perovskites. The Al³⁺ ions restricted, probably for kinetic reasons, the reduction of Fe⁴⁺ and the high-temperature oxygen desorption associated with it.     

Effect of Ni2+ substitution on structural,magnetic, dielectric and optical properties of mixed spinel CoFe2O4 nanoparticles

Nanoparticles of Co_1−xNi_xFe₂O₄ with x=0.0, 0.10, 0.20, 0.30, 0.40 and 0.50 were synthesized by co-precipitation method. The structural analysis reveals the formation of single phase cubic spinel structure with a narrow size distribution between 13–17 nm. Transmission electron microscope images are in agreement with size of nanoparticles calculated from XRD. The field emission scanning electron microscope images confirmed the presence of nano-sized grains with porous morphology. The X-ray photoelectron spectroscopy analysis confirmed the presence of Fe²⁺ ions with Fe³⁺. Room temperature magnetic measurements showed the strong influence of Ni²⁺ doping on saturation magnetization and coercivity. The saturation magnetization decreases from 91 emu/gm to 44 emu/gm for x=0.0–0.50 samples. Lower magnetic moment of Ni²⁺ (2 µ_B) ions in comparison to that of Co²⁺ (3 µ_B) ions is responsible for this reduction. Similarly, overall coercivity decreased from 1010 Oe to 832 Oe for x=0.0–0.50 samples and depends on crystallite size. Cation distribution has been proposed from XRD analysis and magnetization data. Electron spin resonance spectra suggested the dominancy of superexchange interactions in Co_1−xNi_xFe₂O₄ samples. The optical analysis indicates that Co_1−xNi_xFe₂O₄ is an indirect band gap material and band gap increases with increasing Ni²⁺ concentration. Dispersion behavior with increasing frequency is observed for both dielectric constant and loss tangent. The conduction process predominantly takes place through grain boundary volume. Grain boundary resistance increases with Ni²⁺ ion concentration.     

One-pot dual product synthesis of hierarchical Co3O4@N-rGO for supercapacitors,N-GDs for label-free detection of metal ion and bio-imaging applications

Cobalt oxide nanoparticles@nitrogen-doped reduced graphene oxide (Co₃O₄@N-rGO) composite and nitrogen-doped graphene dots (N-GDs) were synthesized by a one-pot simple hydrothermal method. The average sizes of the synthesized bare cobalt oxide nanoparticles (Co₃O₄ NPs) and Co₃O₄ NPs in the Co₃O₄@N-rGO composite were around 22 and 24 nm, respectively with an interlayer distance of 0.21 nm, as calculated using the XRD patterns. The Co₃O₄@N-rGO electrode exhibits superior capacitive performance with a high capability of about 450 F g^?1 at a current density of 1 A g^?1 and has excellent cyclic stability, even after 1000 cycles of GCD at a current density of 4 A g^?1. The obtained N-GDs exhibited high sensitivity and selectivity towards Fe²⁺ and Fe³⁺, the limit of detection was as low as 1.1 and 1.0 μM, respectively, representing high sensitivity to Fe²⁺ and Fe³⁺. Besides, the N-GDs was applied for bio-imaging. We found that N-GDs were suitable candidates for differential staining applications in yeast cells with good cell permeability and localization with negligible cytotoxicity. Hence, N-GDs may find dual utility as probes for the detection of cellular pools of metal ions (Fe³⁺/Fe²⁺) and also for early detection of opportunistic yeast infections in biological samples.     

An investigation of the titanium effect on the structural and magnetic properties of BaNi2 based W-type hexaferrites

The polycrystalline samples of the composition Ba(Ni_1?xTi_x)₂Fe₁₆O₂₇ were prepared by the conventional ceramic method with (x = 0.0–1.0). Effects of titanium (Ti) doping on structural and magnetic properties of BaNi₂ based W-type hexaferrites were analyzed. The samples were initially sintered in air at 1000 °C for 4 h and finally at 1300 °C for 9 h. The X-ray diffraction patterns confirm the presence of single W-hexagonal phase. The lattice parameters ‘a’ and ‘c’ were found to show irregular behavior by increasing Ti content. The variations of magnetic properties were observed by analyzing hysteresis loop of prepared samples. The results show that maximum magnetization (M) and remanence (M_r) decrease up to x ≤ 0.6 due to replacement of Ti ions for spin down (4f₂) and spin up (12k, 2a and 2b) sublattices, but a substantial increase of M and M_r for (x = 0.8 and1.0) could be attributed to the replacement of Ti ions for spin down sublattices (4f₂). The coercivity (H_c) was found to decrease with increasing Ti content. An increase of grain size with Ti content was also observed. Since, H_c is inversely proportional to the packing fraction of magnetic materials or the grain size.     

A comparative study of the magnetic and microwave properties of Al3+ and In3+ substituted Mg–Mn ferrites

The effect of substitution of diamagnetic Al³⁺ and In³⁺ ions for partial Fe³⁺ ions in a spinel lattice on the magnetic and microwave properties of magnesium–manganese (Mg–Mn) ferrites has been studied. Three kinds of Mg–Mn based ferrites with compositions of Mg_0.9Mn_0.1Fe₂O₄, Mg_0.9Mn_0.1Al_0.1Fe_1.9O₄, and Mg_0.9Mn_0.1In_0.1Fe_1.9O₄ were prepared by the solid-state reaction route. Each mixture of high-purity starting materials (oxide powders) in stoichiometric amounts was calcined at 1100 °C for 4 h, and the debinded green compacts were sintered at 1350 °C for 4 h. XRD examination confirmed that the sintered ferrite samples had a single-phase cubic spinel structure. The incorporation of Al³⁺ or In³⁺ ions in place of Fe³⁺ ions in Mg–Mn ferrites increased the average particle size, decreased the Curie temperature, and resulted in a broader resonance linewidth as compared to un-substituted Mg–Mn ferrites in the X-band. In this study, the In³⁺ substituted Mg–Mn ferrites exhibited the highest saturation magnetization of 35.7 emu/g, the lowest coercivity of 4.1 Oe, and the highest Q×f value of 1050 GHz at a frequency of 6.5 GHz.     

Processing and characterization of nano-magnetic Co0.5Ni0.5Fe2O4 system

Various techniques such as X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron micrographs (SEM), energy dispersive X-ray (EDX) and a vibrating sample magnetometer (VSM) were used to investigate the structural, morphological, and magnetic properties of spinel Co_0.5Ni_0.5Fe₂O₄ system. XRD and IR analyses enabled us to determine the functional group and structural parameters of Co_0.5Ni_0.5Fe₂O₄. EDX measurements showed the concentrations of O, Ni, Fe, and Co species involved in Co_0.5Ni_0.5Fe₂O₄ specimen from the uppermost surface to the bulk layers. The magnetization and coercivity of the as synthesized composite were 77 emu/g and 128 Oe, respectively.     

A new multiferroic ternary solid solution system: NdFeO3–Pb(Fe1/2Nb1/2)O3–PbTiO3

Ceramic materials were sintered from powders of the NdFeO₃–Pb(Fe_1/2Nb_1/2)O₃–PbTiO₃ (NF–PFN–PT) ternary system synthesized by the conventional solid reaction method and their multiferroic properties investigated. The structure, electric and magnetic properties of the ternary system have been investigated. The introduction of Pb(Fe_1/2Nb_1/2)O₃ into the NdFeO₃–PbTiO₃ binary system can effectively increase its electric properties. The ternary system exhibits enhanced piezoelectric property with optimal piezoelectric constants d₃₃=143 pC/N, reduced coercive fields E_C=5.78 kV/cm and remnant polarization P_r=12.8 μC/cm² for 0.10NF–0.56PFN–0.34PT, near tetragonal phase region. The Curie temperature (T_C) of the NdFeO₃–Pb(Fe_1/2Nb_1/2)O₃–PbTiO₃ ceramics varies in the range from 108.7 °C to 67.9 °C. The magnetic hysteresis loops show that the ternary system is paramagnetic originating from canting of paramagnetic sublattices in NF–PFN–PT, due to the rare earth ions Nd³⁺ influencing on the exchange interaction between Fe³⁺ ions at the octahedral sites.