Ions For Fe3 Research Articles

Structural, magnetic and optical characterization of 5 atomic % Fe doped In2O3 dilute magnetic semiconducting nanoparticles

We present the evidence of high-temperature ferromagnetism and optical behaviour of 5 atomic percent Fe doped In2O3 semiconductor. Enhanced transition temperature (927 K) is noticed for ferromagnetic to paramagnetic phase transition in the nanocrystalline material. Understanding of ferromagnetism in (In0.95Fe0.05)2O3 nanocrystalline material is explained by considering two basic indirect exchange interaction processes, one, in between spins of Fe2+ and Fe3+ magnetic ions through mediation of oxygen ion vacancy (i.e., Fe2+ − (↑) − Fe3+), and other, from exchange interaction processes which occurred in between spins of magnetic ions of Fe3+- Fe3+ or, Fe2+- Fe2+ through carrier mediation. From our calculation we have estimated the effective paramagnetic moment of (In0.95Fe0.05)2O3 nanocrystals as 1.62 μB/ formula unit. The optical band gap energy of (In0.95Fe0.05)2O3 magnetic semiconductor is evaluated as 3.6 eV.

Conjugated Polymer-Based Hydrogel Film for a Fast and Sensitive Detection of Fe(Ⅲ) in Vegetables.

Fluorescent film sensors are ideal for the real-time outdoor detection of heavy metal ions of Fe3+, but they are limited because of their low sensitivity and long response time due to their special structure. In this work, we constructed a fluorescent hydrogel for the specific detection of Fe3+, utilizing poly(9-fluorenecarboxylic acid) (PFCA) as the sensing moiety and sodium alginate (SA) as the cross-linking substrate, which exhibited a rapid and selective recognition of Fe3+ among a panel of 16 anions and 21 cations. It can sense Fe3+ at 0.1 nM immediately owing to the porous network structure of the PFCA-SA film that provided enhanced ion transport channels and active sites, and the "molecular line effect" of polymer PFCA. Moreover, we successfully applied this platform to detect Fe3+ in four different vegetable samples. This work provides an innovative and effective strategy for fabricating green and sustainable fluorescent sensors.

Influence of Fe3+ substitution by Al3+ on the structural, microstructural, and magnetic properties of Co0.2Ni0.3Zn0.5Fe2O4 nanoparticles

A series of aluminum-substituted ferrite nanoparticles, Co0.2Ni0.3Zn0.5Fe2-xAlxO4 (0 ≤ x ≤ 1) was synthesized using the polyol method. The structural analysis confirmed the formation of pure cubic ferrispinels. The unit cell parameter decreased monotonically with increasing Al3+ content obeying Vegard's law. Besides, it was found that Al3+ ions prefer to enter octahedral sites. The produced particles consisted of roughly spherical ultrasmall nanocrystals with an average particle size of ∼3-6 nm. The nanoparticles are superparamagnetic with magnetic features (blocking temperature, saturation magnetization and Curie temperature) showing a decrease with the increase in Al3+ content. The magnetic tendency correlates with the weakening of the superexchange interactions in the spinel sublattices caused by substituting the non-magnetic Al3+ ions for Fe3+ ones. While, the coercivity and effective magnetic anisotropy increased with the increase of Al3+ concentration, suggesting the development of high surface anisotropy that largely compensates for the decrease of intrinsic magnetic anisotropy caused by the magnetic dilution.

INFLUENCE OF HIGH-MOLECULARS COMPOUNDS OF DIFFERENT NATURE ON THE EFFICIENCY OF PURIFICATION THE MOTHER LIQUOR OF MAGNESIUM SULFATE PRODUCTION FROM IMPURITIES Fe3+, Al3+ AND Cr3+ BY ELECTROFLOTATION

The effect of flocculants and surfactants of different nature on the process of purification of the MgSO4 mother liquor from Fe3+, Al3+ and Cr3+ impurities by electroflotation was investigated. The study is aimed at increasing the yield of magnesium sulfate by returning the purified mother liquor to the head of the process at the stage of acid decomposition of serpentinitomagnesite. In the experiments, model solutions with a concentration of MgSO4 – 100 g/l, the content ions of Fe3+ – 50 mg/l, Al3+ – 10 mg/l and Cr3+ – 10 mg/l were used. It was determined that all impurities during pH adjustment turn into slightly soluble compounds at values 6 – 7. For the MgSO4 purification process by electroflotation, the optimal current density was established, which is 0.4 A/l. The duration of the process of purification by electroflotation is 30 min. When studying the effect of surfactants of cationic, anionic, nonionic and amphoteric types on the MgSO4 purification process by electroflotation, it was found that the degree of extraction of Fe3+, Al3+ and Cr3+ impurities does not exceed 10-30%, the exception is the presence of an amphoteric surfactant, in which the degree of extraction of Fe3+ is 77 – 78%. It was found that the greatest efficiency of extraction of Fe3+, Al3+ and Cr3+ impurities from MgSO4 solution is achieved in the presence of anionic flocculant Praestol 2540. The degree of extraction for all components reaches 98-99% already at the tenth minute of the process. Thus, the purification of MgSO4 from Fe3+, Al3+ and Cr3+ impurities by electroflotation in the presence of anionic flocculant Praestol 2540 will allow the purified mother liquor to be returned to the beginning of the process at the stage of sulfuric acid decomposition of serpentinitomagnesite during the production of magnesium sulfate, which will increase the yield of the product.

Preparation of sodium alginate gel microspheres catalysts and its high catalytic performance for treatment of ciprofloxacin wastewater

The discharge of the antibiotic wastewater has increased dramatically in our country with the development of medical science and wide application of antibiotic, resulting in serious harm to human body and ecological environment. In this work, ciprofloxacin (CIP) was selected as one of typical antibiotics and heterogeneous Fenton-like catalysts were prepared for the treatment of ciprofloxacin wastewater. The sodium alginate (SA) gel microspheres catalysts were prepared by polymerization method using double metal ions of Fe3+ and Mn2+ as cross-linking agents. Preparation conditions such as metal ions concentration, mass fraction of SA, polymerization temperature and dual-metal ions as crosslinking agent were optimized. Moreover, the effects of operating conditions such as initial concentration of CIP, pH value and catalyst dosage on CIP removal were studied. The kinetic equation showed that the effect of the initial concentration of CIP on the degradation rate was in line with second-order kinetics, and the effects of catalyst dosage and pH value on the degradation rate of CIP were in line with first-order kinetics. The SA gel microspheres catalysts prepared by dual-metal ions exhibited a high CIP removal and showed a good reusability after six recycles. The SA gel microspheres catalysts with an easy recovery performance provided an economical and efficient method for the removal of antibiotics in the future.

Determining the Actual Composition of Nb5+–Ni2+ Codoped Barium Ferrites to Controllably Regulate the Microwave Absorbing Properties

The substitution amount of foreign ions for Fe3+ ions significantly influences the electromagnetic and microwave absorption performance of barium ferrite. To establish the correlation between composition and property, Nb5+–Ni2+ codoped M-type barium ferrite powders with molar ratio of the added Ba2+, Fe3+, Nb5+, and Ni2+ ions being 1:(12–2x):x:x (x = 0–0.8) were prepared by the sol–gel method. The actual substitution amount of Nb5+ and Ni2+ ions for Fe3+ ions are theoretically determined based on the measured concentrations of Fe2+ ions, surface absorbed oxygen, and the lattice parameters of the doped barium ferrite. The calculation results demonstrate that the substitution amount of Ni2+ ions is obviously lower than that of Nb5+ ions in the doped barium ferrites, while the total substitution amount of Nb5+–Ni2+ is still higher than the only Nb5+ ions doping case. As a result, the multiresonant permeability is obviously achieved and dual reflection loss peaks with broad bandwidth ∼12 GHz are apparently observed in the BFNNO with x = 0.4–0.6 over 18–40 GHz. Moreover, the frequency of reflection loss peaks can be adjusted to cover wider frequency range −18 GHz to +40 GHz with variation of x from 0 to 0.8. The developed theoretical calculation approach provides powerful guidance for the controllable design of material composition and regulation of microwave absorption.

Computational modeling of the defect structure, hyperfine and magnetic properties of the Mn2+-doped magnetite of the composition MnxFe3-yO4 (y = ⅔ x)

The defect structure, hyperfine and magnetic properties of Mn2+-doped Fe3O4 of the composition MnxFe3-yO4(y=⅔x) are modeled using atomistic and DFT calculations. The atomistic simulations show the substitution of the Mn2+ ions for Fe3+ ones at the tetrahedral sites to be energetically favorable than their substitution at the octahedral sites. These Mn2+ impurities are charge-balanced by the occupation of either Mn2+ or Fe 3+ ions of interstitial tetrahedral sites. The method of GGA with on-site Coulomb interaction approximation for the exchange-correlation potential is used to calculate the electronic structure, hyperfine and magnetic moments of the structurally most preferred models. The results obtained show the model in which all the Mn2+ ions substitute for tetrahedral Fe 3+ ions with Fe3+ ions expelled to interstitial tetrahedral sites to be consistent with the observed experimental trends of the hyperfine and magnetic properties.

Effect of reentrant spinglass-like states on Schottky Anomaly and exchange bias in polycrystalline Sm0.5Y0.5Fe0.58Mn0.42O3

The specific-heat and exchange bias effects in polycrystalline Sm0.5Y0.5Fe0.58Mn0.42O3 [SYFM (58–42)] have been investigated within the temperature interval of 2–300 K. Specific-heat measurements as a function of temperature have revealed a sizable linear contribution at low temperature that may be associated with the glassy magnetic ordering, alongwith a diffused Schottky peak over a wide temperature range between 2 and 20 K. The observed distribution of Schottky levels is explained by the inhomogeneity of the molecular field in the spinglass (SG) state that leads to variable splitting of the Kramer’s ground-state doublets in Sm3 + ions. A finite zero field exchange bias (EB) effect have been observed at low temperatures for T < 70 K. The field dependency of the exchange bias showed the tuning of the sign of EB that can be attributed to the competition of the interfacial exchange bias and atomic EB arising from the cooling field induced anisotropy of the weak ferromagnetic moments of the constituent ions of Fe3+/Mn3+..

Cooling Field Dependence of Exchange Bias in Mn-Doped Metal- Organic Framework [NH2(CH3)2][FeIIIFeII(HCOO)6

Herein, an intriguing exchange bias (EB) effect manifesting itself from positive to negative with an increase in the cooling field (HFC) is reported in the single crystal of Mn-doped metal-organic framework (MOF) [NH2(CH3)2][FeIIIFeII(HCOO)6] (1) by finely tuning the exchange interactions between the magnetic ions. Note that the doping ratio of Mn relative to the total metal ions is about 15%. Negative magnetization and EB below the compensation temperature were both observed in 1, and the EB field (HE) changes its sign from positive to negative when HFC is larger than ∼10 kOe. The abnormal HFC dependence of EB can be interpreted explicitly by a combination of negative magnetization and couplings among the ions of Fe3+, Fe2+, and Mn2+ with varying the HFC. This work demonstrates a tunable EB in MOFs, in favor of designing novel magnetic devices.

Microwave Absorbing Material of Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) with Broadband Characteristic at X-band Frequency

In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition.

Heat dissipation in Sm3+ and Zn2+ co-substituted magnetite (Zn0.1SmxFe2.9-xO4) nanoparticles coated with citric acid and pluronic F127 for hyperthermia application

In this work, Sm3+ and Zn2+ co-substituted magnetite Zn0.1SmxFe2.9-xO4 (x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles, have been prepared via co-precipitation method and were electrostatically and sterically stabilized by citric acid and pluronic F127 coatings. The coated nanoparticles were well dispersed in an aqueous solution (pH 5.5). Magnetic and structural properties of the nanoparticles and their ferrofluids were studied by different methods. XRD studies illustrated that all as-prepared nanoparticles have a single phase spinel structure, with lattice constants affected by samarium cations substitution. The temperature dependence of the magnetization showed that Curie temperatures of the uncoated samples monotonically increased from 430 to 480 °C as Sm3+ content increased, due to increase in A-B super-exchange interactions. Room temperature magnetic measurements exhibited a decrease in saturation magnetization of the uncoated samples from 98.8 to 71.9 emu/g as the Sm3+ content increased, which is attributed to substitution of Sm3+ (1.5 µB) ions for Fe3+ (5 µB) ones in B sublattices. FTIR spectra confirmed that Sm3+ substituted Zn0.1SmxFe2.9-xO4 nanoparticles were coated with both citric acid and pluronic F127 properly. The mean particle size of the coated nanoparticles was 40 nm. Calorimetric measurements showed that the maximum SLP and ILP values obtained for Sm3+ substituted nanoparticles were 259 W/g and 3.49 nHm2/kg (1.08 mg/ml, measured at f = 290 kHz and H = 16kA/m), respectively, that are related to the sample with x = 0.01. Magnetic measurements revealed coercivity, which indicated that hysteresis loss may represent a substantial portion in heat generation. Our results show that these ferrofluids are potential candidates for magnetic hyperthermia applications.

Ultrafast Fabrication of Self-Healing and Injectable Carboxymethyl Chitosan Hydrogel Dressing for Wound Healing.

Herein, a new type of injectable carboxymethyl chitosan (CMCh) hydrogel wound dressing with self-healing properties is constructed. First, CMCh samples are homogeneously synthesized in alkali/urea aqueous solutions. Subsequently, trivalent metal ions of Fe3+ and Al3+ are introduced to form coordination bonds with CMCh, leading to an ultrafast gelation process. A series of hydrogels can be obtained by altering the concentration of CMCh and the relative content of metal ions. Owing to the dynamic and reversible characteristics of the coordination bonds, the hydrogel exhibits self-healing, self-adaption, and thermoresponsive ability. Moreover, due to the interaction between the amino groups on CMCh and SO42-, the hydrogel undergoes phase separation and can be painlessly detached from the skin with little residue. Taking advantage of all these characteristics, the hydrogel is used as a wound dressing and can significantly accelerate skin tissue regeneration and wound closure. This hydrogel has great potential in the application of tissue engineering.

Tannin Contents of Jackfruit Leaves (Artocarpus heterophyllus) Extract and Moringa Leaves (Moringa oleifera) Extract as Functional Additive Feed in Ruminan Livestock

Tannin compounds are polyphenolic compounds that function as antioxidants and inhibit tumor growth in plants, foods and drinks that can dissolve in water and organic solvents. This research’s objective is to identify tannin contents of Jackfruit leaf extract and Moringa leaf extrack as functional additive feed for ruminant. Detecting simple phenolic compounds the extract with 1% FeCl3 solution in water, which gives rise to strong green, red, purple, blue or black colors. The formation of a blackish green or blackish blue color in the extract after adding FeCl3 because tannins will form complex compounds with Fe3 ions. The research’s result shows that phytochemical test of tannins on moringa and jackfruit leaf extracts showed positive results and generated sediment. The conclusion of this study is the presence of tannin compounds in jackfruit and moringa leaves as a functional feed additive to increase the productivity of ruminants.

Structural and Magnetic Studies of Ga-doped Yttrium Iron Garnet

Ga-doped Yttrium Iron Garnet (Y3GaxFe5−xO12, Ga:YIG) was prepared by solid state reaction method and sintering at 1 300 °C. Rietveld analysis of X-ray diffraction patterns indicated that all samples crystallized in a single cubic structure (space group Ia-3d) with decreasing lattice constant as Ga concentration increased. SEM surface micrograph images of YIG samples showed highly compacted grains with small reduction in the grain size with increasing Ga concentration. Raman spectroscopy measurements confirmed the replacement of Fe3+ ions by Ga3+ ions in the garnet structure was revealed by the observed blue shifts in Raman spectra. The saturation magnetization decreased from 28.2 to 4.98 emu g−1 with increasing x from 0.0 to 1.0 due to the preferential substitution of Ga3+ ions for Fe3+ ions at tetrahedral sites. Room temperature Mossbauer spectra for the samples revealed a reduction of the hyperfine field values for octahedral and tetrahedral sites, and the development of additional components with increasing Ga concentration. Analysis of the magnetic data and Mossbauer spectra confirmed that spin canting in the substituted garnets plays an important role in explaining the observed reduction of the saturation magnetization as x increased.

Magnetic anisotropies of La–Co substituted M-type Sr hexaferrites studied by 57Fe Mössbauer spectroscopy with external magnetic fields

Magnetoplumbite-(M)-type hexaferrites are the most widely used base materials of permanent magnets. La–Co substitution in these M-type Sr hexaferrites improves these magnetic anisotropies. By 57Fe Mössbauer spectroscopy using the single-crystalline samples, we have investigated the Fe electronic states in the La–Co substituted M-type Sr hexaferrites, Sr1−xLaxFe12−yCoyO19, as a function of an external magnetic field to discuss the enhancement of these magnetic anisotropies. All observed 57Fe Mössbauer spectra were well analyzed using the five subspectra corresponding to the five crystallographic nonequivalent Fe sites. At one site of these five Fe sites, the 2a Fe site, the extracted hyperfine interaction parameters clearly show the Co substitution and external magnetic field dependences, revealing the increments of the 3d electrons in the Fe ions, which are caused by the substitution of Co2+ ions for Fe3+ ions at the neighbor 4f1 Fe site. This hybridization between the Fe ions and the Co ions induces the non-negligible unquenched orbital momentum in the Fe ions at the 2a Fe site. Our findings represent an enhancement of the magnetic anisotropies in Sr1−xLaxFe12−yCoyO19.

Mn-doped (Ba, Y)Fe12O19 hexaferrites: Crystal structure and oxidation states of Mn and Fe

We have fabricated Ba0.95Y0.05Fe12-xMnxO19 samples with large Mn-doping amounts of x = 4 and 6, using the mechanical milling and heat treatment. X-ray diffraction analysis indicated the samples crystallized in the M-type hexaferrite structure. The Mn doping caused the modification, shift and broadening of some characteristic phonon-vibration modes, which were recorded by Raman spectroscopy. This is due to an incorporation of Mn ions into the M-type structure that disorders the periodic lattice and changes symmetry. Basing on X-ray absorption spectroscopy, we have found Fe in all samples stable with an oxidation state 3+ (Fe3+). Though Mn2+ and Mn3+ ions coexist, the concentration of Mn2+ in x = 4 is larger than that in x = 6. The analysis of Fourier-transform spectra have demonstrated the replacement of Mn2+,3+ ions for Fe3+ in the M-type structure. The sites of Mn2+,3+ ions in this structure have been discussed.

Development of the tetrathioterephthalate filler incorporated PES nanofiltration membrane with efficient heavy metal ions rejection and superior antifouling properties

The novel antifouling nanofiltration membranes were developed for efficient heavy metal ions rejection from water. These membranes were fabricated by the introduction of the tetrathioterephthalate (TTTP) filler into Polyethersulfone (PES) matrix via the phase inversion. Surface roughness, pore radius distribution, average pore radius, surface charge, overall porosity, and water contact angle were also characterized. FTIR and XPS analysis were performed to confirm the presence of TTTP filler in the TTTP embedded PES (T-PES) membranes. As confirmed by FESEM images, more finger-like voids with higher connectivity were formed in the presence of TTTP fillers in the membrane matrix. Compared with the PES membrane, the T-PES membranes exhibited higher hydrophilicity, porosity, and mean pore radius. Besides, these membranes exhibited higher pure water permeation flux and superior antifouling properties. For 0.1 wt.% TTTP embedded PES membrane the FRR value stayed at a high level during five repeated filtration cycles. This improvement was mainly ascribed to the hydrophilic quiddity of TTTP fillers resulting from its functionalities like C = S and C–S bonds. Furthermore, these membranes showed high rejection towards heavy metal ions (Zn2+, 99.2%; Cu2+, 98.5%; Pb2+, 97.4%). Moreover, the metal ion removal experiments in the presence of foreign ions of Fe3+, Mg2+, and Na+ indicated acceptable results.

Correlation between the Chemical Composition, Crystal Structure, and Magnetic Properties of Hexagonal Barium Ferrite with Zn2+ Heterovalent Substitution

This paper presents a detailed study of the magnetic and crystal structures of BaFe12 –xZnxO19 (0.25 ≤ x ≤ 1.5) Zn-substituted barium hexaferrite by Mossbauer spectroscopy, vibrating sample magnetometry, and X-ray diffraction. Partial heterovalent substitution of Zn2+ ions for Fe3+ ions demonstrates limited heterovalent isomorphism according to the scheme 2Fe3+ → Zn2+ + Fe4+, which satisfies the electroneutrality constraint. Mossbauer spectroscopy results indicate the presence of Fe4+ in the BaFe12 –xZnxO19 materials. The heterovalent isomorphous substitution limit has been determined to be x = 1.0. The formation of a zinc spinel has been shown to begin at x = 0.50 and its content increases with increasing zinc content. Data are presented on the predominant character of the substituent ion (Zn2+) distribution in the structure of barium hexaferrite. A correlation has been found between the chemical composition, phase separation, anisotropy of properties, and the temperature of the magnetic phase transition of BaFe12 –xZnxO19 (0.25 ≤ x ≤ 1.5).

Magnetic structure and properties of Ca, Mn-doped bismuth ferrites near the polar/nonpolar phase boundary

Neutron diffraction and magnetization measurements of the Bi0.85Ca0.15Fe1-xMnxO3+δ (x = 0.4, 0.5) compounds have been performed at room and low temperatures to disclose the effect of the mixed-valence Mn substitution on the magnetic structure and properties of the Ca-doped bismuth ferrites near the polar/nonpolar phase boundary. It has been confirmed that the Mn substitution results in the filling of anion vacancies produced by the aliovalent replacement of Bi3+ by Ca2+. The Bi0.85Ca0.15Fe0.6Mn0.4O3+δ compound has the acentric structure specific to the pure BiFeO3 (space group R3c) and displays a G-type antiferromagnetic order at room temperature (m300K = 1.35(2) μB). The magnetic moments localized on the Fe/Mn ions are directed along the polar axis. The spin-reorientation transition from the c to a axis takes place with decreasing temperature. An increase in the Mn concentration gives rise to the polar → nonpolar (R3c → Pnma) structural phase transformation. The nonpolar (x = 0.5) compound has a G-type antiferromagnet structure (TN = 210 K) with spins aligned along the orthorhombic b axis. The low-temperature magnetic moments (m5K = 2.67(2) μB and m5K = 1.80(3) μB for the samples with x = 0.4 and x = 0.5, respectively) are considerably smaller than those predicted for complete spin ordering of the interacting ions of Fe3+, Mn3+ and Mn4+ (>4 μB). While the neutron diffraction measurements reveal no contribution associated with a long-range ferromagnetic order at T = 5 K, a significant increase in the magnetization of the samples, suggesting the formation of a glassy phase, is observed with decreasing temperature.

Structural, optical and electrical properties of multiferroic BiFe1-xNixO3 ceramic

BiFe1−xNixO3 (x = 0.7, 0.8 and 0.9) polycrystalline ceramics are synthesized by a solid-state reaction, and their structural, absorption, leakage current and electrical properties are investigated. The X-ray diffraction measurements show that the lattice parameter values increase with increasing the substitution of Ni2+ ions for Fe3+ ions. The optical absorption spectra indicate that the band gap energy increases with increasing Ni2+ ions. Leakage currents are much decreased by about three orders of magnitude with increasing Ni ions. The J-E hysteresis was also investigated. Both real and imaginary dielectric constants are investigated as a function of both frequency and temperature. The room temperature dielectric measurement with a wide frequency range of 1 KHz–1 MHz reveals that the real and imaginary dielectric constants are decreased with increasing frequency of BiFe1−xNixO3 (x = 0.7, 0.8, 0.9) ceramics. The real and imaginary dielectric constants are found to be increased with temperature. The temperature dependence of ε′ and ε″ exhibits an anomaly which shifted to lower temperature with increasing Ni2+. The anomaly indicates the possible existence of spin-glass states with Ni2+ ion substitution in places of Fe3+ ions.