Electromagnetic wave reflection loss and magnetic properties of M-type SrFe12−x(Mn0.5Sn0.5)xO19 hexagonal ferrite nanoparticles in the Ku microwave band

Ferrimagnetic nanoparticles of SrFe_12−x(Mn_0.5Sn_0.5)_xO₁₉ was synthesis by controlling the effective processing parameters of sol-gel techniques. Microwave, magnetic properties and structure of nanosize, high purity sol-gel synthesized SrFe_12−x(Mn_0.5Sn_0.5)_xO₁₉ hexaferrite ferrimagnetic nanoparticles were investigated by vector network analysis, vibrating sample magnetometry, EDS and XRD. 57Fe Mössbauer spectroscopy was employed to find the occupancy sites of incorporated cations. The position of manganese and tin in 12k sites caused reduction in coercivity and magnetization saturation. The values of coercivity and magnetization saturation show that superparamagnetism did not occur in the synthesized products. Results demonstrate that additions of manganese and tin to hexagonal ferrite enhance bandwidth and reflection loss. Such composition could be proposed as a suitable electromagnetic wave absorber in microwave frequencies.     

Synthesis and analysis of structural,compositional, morphological,magnetic, electrical and surface charge properties of Zn-doped nickel ferrite nanoparticles

Zn-doped nickel ferrite nanoparticles (Zn_xNi_(1-x)Fe₂O₄) were synthesized using the co-precipitation technique. The structural and compositional studies of the Zn_xNi_(1-x)Fe₂O₄ nanoparticles revealed their face-centred cubic spinel structure and an appropriate amount of Zn doping in nickel ferrite nanoparticles, respectively. The morphological analysis had been carried out to obtain the particle size of the synthesized nanoparticles. The magnetic studies revealed the superparamagnetic nature of the Zn_xNi_(1-x)Fe₂O₄ nanoparticles, and the maximum magnetization of 30 emu/g for the Zn_0.2N_0.8Fe₂O₄ sample. The M ? H curves were fitted with the Langevin function to obtain the magnetic particle diameter of Zn_xNi_(1-x)Fe₂O₄ nanoparticles. The electrical conduction in Zn_xNi_(1-x)Fe₂O₄ nanoparticles was explained through the Verway hopping mechanism. The Zn_0.2N_0.8Fe₂O₄ nanoparticle exhibited a higher electrical conductivity of 42 μS/cm and surface charge of ?29/7 mV due to the enhanced hopping of Fe³⁺ ions in the octahedral sites. Owing to this nature, they were identified as the suitable candidates in the applications such as thermoelectrics, hyperthermia, magnetic coating and for the preparation of conducting ferrofluids.     

The role of Co ion substitution in SnFe2O4 spinel ferrite nanoparticles: Study of structural,vibrational, magnetic and optical properties

In order to accurately investigate the effect of cobalt substitutions in tin ferrite (SnFe₂O₄) properties, we prepared Co_xSn_1-xFe₂O₄ nanoparticles for different Co concentrations, x?=?0.0, 0.25, 0.50, 0.75, and 1.00 using a simple co-precipitation method. X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX) and diffuse reflectance spectra (DRS) are used to study of structural, magnetic, morphology, and optical properties. The XRD and FTIR results confirmed the formation of cubic spinel structure. The lattice parameter and unit cell volume of tin ferrite nanoparticles were found to increase by entering and increasing Co⁺² content in 0.25, and then significantly decrease for higher contents. In accordance with the XRD results, a slight shift in main band υ₁ (${\mathit{Fe}}_{\mathrm{tetra}}^{+3}?O)$ to lower wavenumber and then to higher wavenumber were observed in the IR spectra of Co content x?<?0.25 and x?>?0.25, respectively. In turn to, saturation magnetization, remanent magnetization and anisotropy constant of SnFe₂O₄ nanoparticles were gradually increased for x?=?0.50 and then decreased for x?>?0.50.     

Cation distribution,saturation magnetization and magnetocrystalline anisotropy of mixed ferrite NiAlxFe2−xO4 nanoparticles

In a recently proposed model, the magnetocrystalline anisotropy of a mixed ferrite is assumed to be the weighted average of the contributions of the anisotropies of Fe³⁺ and M²⁺ ions in A and B sites. In the present work, this model is used to study the cation distribution, saturation magnetization and magnetocrystalline anisotropy of nickel-aluminum ferrite nanoparticles using ferromagnetic resonance data. The experimental results show that the saturation magnetization decreases continuously with aluminum addition, that the magnetocrystalline anisotropy is maximum when 10% of the Fe ions are replaced by Al ions and that replacement of 50% of the Fe ions by Al ions is enough to reduce the saturation magnetization and the magnetocrystalline anisotropy of the mixed ferrite NiAl_xFe_2-xO₄ to almost zero. This is consistent with the findings of other researchers, obtained by different methods.     

Evolution of microstructure,optical, and magnetic properties in multiferroic CuFe1-xSnxO2 (x = 0–0.05)

Evolution of the microstructure, optical, and magnetic properties have been investigated systematically in multiferroic CuFe_1-xSn_xO₂ (x?=?0–0.05) ceramics. Substitution of Sn⁴⁺ for Fe³⁺ results in expansion of CuFeO₂ lattice, and reduces the density of the material, but the metal oxidation states are unchanged. Observation of the optical properties shows that the value of the direct optical band gap (E_g) decreases with increasing Sn doping level, and that the CuFe_1-xSn_xO₂ (x?=?0–0.04) series with values >?3.1?eV. Magnetic susceptibility measurements show that Sn⁴⁺ doping decreases the Curie-Weiss temperature, i.e. weakens the strength of the antiferromagnetic interaction between high-spin Fe³⁺ ions, but does not affect the stability of the antiferromagnetic phase, and all samples undergo successive magnetic transitions at about T_N1 =?15?K and T_N2 =?11?K. However, magnetization curves show that changes occur in the magnetic interactions and both ferromagnetism and antiferromagnetism co-exist in the Sn⁴⁺-doped samples. The maximum value of the saturation magnetization of 1.8?emu·g^?1 was observed for the x?=?0.03 sample in a 2.5?kOe field. The changes in the magnetic behavior are closely related to the lattice distortion and charge compensation, which are discussed in detail in this work.     

Physical and magnetic properties of Mn–Zr doped La–Sr ferrite prepared by the auto-combustion route

This is the first report ever on (Mn²⁺–Zr⁴⁺) doped M-type lanthanum strontium hexaferrite with general formula, Sr_0.85La_0.15(MnZr)_xFe_12−2xO₁₉ where x=0.0, 0.25, 0.50, 0.75, and 1.0, prepared by citrate auto-combustion method. These ferrites were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX) and Vibrating sample magnetometer (VSM). X-ray diffraction patterns show the formation of high purity hexaferrite phase without other secondary phases for all the synthesized samples. It was observed from magnetic hysteresis data that the coercive force is reduced from 5692.5 Oe to 1669.2 Oe with increase in doping contents but the net magnetization of the samples varies slightly from 60.6 to 55.2 emu/gm. High saturation magnetization (M_s), low coercivity (H_c) and remanence magnetization (M_r) values of these materials make them particularly suitable for data recording.     

Neutron diffraction study and temperature variation of magnetic anisotropy in Bi substituted nickel ferrite

Bismuth doped NiFe₂O₄ (NFO) polycrystalline samples: Ni_1-xBi_xFe₂O₄ with x = 0.00, 0.05 and 0.10, were synthesized using solid-state reaction method. The crystal structural, magnetic structure and magnetic properties of parent NFO and Bi-doped NFO samples were characterized using X-ray diffraction (XRD), neutron powder diffraction (NPD) and magnetization (M) versus magnetic field (H) isotherms, respectively. Rietveld refinement of XRD and NPD patterns confirms the formation of a single-phase cubic spinel crystal structure. No observable change in the lattice parameter was found (within the error limits) with the 5 at % Bi doping to NFO, whereas ≈0.15% change in the lattice parameter was observed in case of 10 at % Bi-doped NFO. Room temperature magnetic structure studies using NPD reveal a net magnetic moment of 1.55(3) μ_B/f. u., in the case of NiFe₂O₄. The net magnetic moment at room temperature changes to 1.61(4) μ_B/f.u. and 1.47(5) μ_B/f.u. for Ni_0.95Bi_0.05Fe₂O₄ and Ni_0.90Bi_0.10Fe₂O₄, respectively. The same observation was also inferred from the spontaneous magnetization (M_sp) obtained from approach-to-saturation (ATS) analysis of M-H isotherms. Temperature (T) dependence of M_sp follows a T² decline. Approximately 14% increase in magnetic anisotropy was observed in Ni_0.95Bi_0.05Fe₂O₄ compared to NiFe₂O₄ in the temperature range 5 K -300 K.     

Hopkinson effect,structural and magnetic properties of M-type Sm3+-doped SrFe12O19 nanoparticles produced by a proteic sol–gel process

Samarium doped M-type strontium hexaferrites with chemical formula Sr_1−xSm_xFe₁₂O₁₉ (0≤x≤0.15) (SrM) were synthesized using the proteic sol–gel process. This low cost and environment friendly method yields easily reproducible magnetic powders. The crystal structure and phase purity were studied by X-ray diffraction (XRD). All the XRD patterns have been analyzed by Rietveld refinement technique using the P6₃/mmc space group which showed crystallite size in the nanoscale. Results of field emission scanning electron microscope show that the grains are regular hexagonal platelets. The saturation magnetization reaches a minimum at x=0.10 and increases at higher concentrations. The coercivity increases with Sm³⁺ concentration. The remarkable appearance of a Hopkinson peak at the M vs. T curve indicates that particles of the sample are composed of a single domain particles.     

Effect of neodymium ion on the structural,electrical and magnetic properties of nanocrystalline nickel ferrites

NiNd_xFe_2-xO₄ nanoferrites with different compositions of x?=?0.01, 0.03, 0.05, 0.07 and 0.09 were prepared using the sonochemical method. The structural, optical and morphological properties of the prepared nanoferrites were characterized by X-ray diffraction, ultra violet-diffuse reflectance spectroscopy, scanning electron microscopy and X-ray fluorescence techniques. The X-ray diffraction analysis of the prepared nanoferrites confirmed the presence of a cubic spinel structure. The average crystallite sizes of the prepared nanoferrites were 52, 49, 46, 44 and 40?nm for x?=?0.01, 0.03, 0.05, 0.07 and 0.09, respectively. The particle size of the prepared NiNd_xFe_2-xO₄ nanoferrites was in the range 60–40?nm. The dielectric parameters ranged from 2.9?GHz to 5.6?GHz. Decrease in the dielectric constant was observed with an increase in Nd³⁺ ions in the prepared NiNd_xFe_2-xO₄ nanoferrites. However, a reverse trend was observed in the dielectric loss. An impedance analysis of the prepared nanoferrites was carried out to explore the pseudo-capacitance behavior. The saturation magnetization and remnant magnetization values of the prepared nanoferrites decreased with an increase in the concentration of Nd³⁺ ions in NiNd_xFe_2-xO₄ nanoferrites.     

Structural,electrical, magnetic and magnetoelectric properties of Fe doped BaTiO3 ceramics

In the present work structural, electrical, magnetic and magnetodielectric properties of BaTi_1−xFe_xO₃ (0%≤x≤10%) ceramics have been investigated. X-ray diffraction (XRD) study reveals that the coexistence of tetragonal and hexagonal phases is strongly influenced by Fe doping concentration. The increase in Fe-doping content leads to the development of hexagonal phase along with an increase in average grain size. A reduction in the dielectric properties is also observed. All BaTi_1−xFe_xO₃ (BTFO) compositions exhibit ferroelectric behavior at room temperature. Remnant polarization (P_r) for pure BaTiO₃ (BTO) has been found to be 7.50 µC/cm² and further decreases with an increase in the Fe concentration. All Fe doped samples exhibit ferromagnetic ordering with saturation magnetization (M_s) being 26 memu/g for x=2.5%. Further, at x=5%, it decreases and thereafter again increases with Fe concentration. The magnetodielectric coefficient increases with Fe doping concentration and highest value found to be 2.80 at x=2.5%.     

Finite size effect on Sm3+ doped Mn0.5Zn0.5SmxFe2−xO4 (0≤x≤0.5) ferrite nanoparticles

Samarium doped Mn–Zn ferrite nanoparticles of composition Mn_0.5Zn_0.5Sm_xFe_2−xO₄ (0≤x≤0.5) have been synthesized by a chemical co-precipitation method for developing low Curie temperature stable ferrofluid. These samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Electron Paramagnetic Resonance (EPR) spectroscopy and search coil method analytical techniques for their structural, morphological and magnetic properties. X-ray diffraction patterns confirmed the formation of crystalline single spinel phase of as grown nanoparticles. Lattice parameter and lattice strain increases with the increase in Sm³⁺ content. SEM images revealed the presence of ultrafine particles and their agglomerated structures in higher Sm³⁺ ions concentration analogues. The stoichiometry of the final product agreed well with the initial substitution composition as evidenced by EDS data. Electron paramagnetic resonance (EPR) spectra proved the ferromagnetic nature of nanoparticles. The magnetic measurements by search coil method showed superparamagnetism for x=0, 0.1 the samples with saturation magnetization of 23.95 emu/g for Mn_0.5Zn_0.5Fe₂O₄ sample which increases with rise in Sm³⁺ ions content. The results are explained and correlated with the structural, morphological and magnetic properties for developing stable kerosene based ferrofluid by using these nanoparticles.     

The magnetization reversal and high temperature dielectric response in Y1−xHoxFe0.5Cr0.5O3

The structural, magnetic, and dielectric properties of the Y_1−xHo_xFe_0.5Cr_0.5O₃ (x=0, 0.05, 0.1, 0.3, and 0.5) compounds have been investigated. Rietveld refinement of the XRD patterns shows that the compounds possess orthorhombic perovskite structure. The dual magnetization reversal is observed in the samples with x=0.05 and 0.1, and it vanishes when x≥0.3. Ferromagnetic-like behavior with large coercive fields is observed in all Ho³⁺ doped YFe_0.5Cr_0.5O₃ samples, indicating a doping induced metamagnetic behavior. This abnormal magnetization behavior can be explained by the antiparallel magnetic coupling between the Ho³⁺ and the canted Cr³⁺/Fe³⁺ moments, as well as the Ho–O–Ho magnetic interaction. The dielectric behavior in the frequency range from 100 Hz to 10 MHz is investigated. The low doped samples (x=0, 0.05, and 0.1) exhibit relaxation-like dielectric behavior and colossal dielectric constant in a wide temperature and frequency range. The dual magnetization reversal under low magnetic field makes these materials attractive candidates for the magnetic dual sensor devices.     

Structural,interfacial, magnetic and dielectric properties of (1−x)(Mg0.95Zn0.05)2(Ti0.8Sn0.2)O4@xNi0.4Zn0.6Fe2O4 composite at high frequency

(Mg_0.95Zn_0.05)₂(Ti_0.8Sn_0.2)O₄ powder was synthesized by a solid state reaction. Then, Ni_0.4Zn_0.6Fe₂O₄ was grown on the (Mg_0.95Zn_0.05)(Ti_0.8Sn_0.2)O₄ particles in a hydrothermal environment to form a core-shell structure. (1-x)(Mg_0.95Zn_0.05)₂(Ti_0.8Sn_0.2)O₄@xNi_0.4Zn_0.6Fe₂O₄ composite ceramics were sintered at 1200 °C with these powders. XRD, SEM, TEM analyses indicated that high dense core-shell ceramics without any foreign phase were obtained. Different types of sharp interfaces were self-assembled owing to the minimization of direct elastic energy in the hydrothermal environment. The composites enjoy good magnetic and dielectric properties, especially, good microwave dielectric properties with high saturation magnetization when the ferrite content is 0.3–0.5. The results provided a powerful experimental basis for the sensor and transducer.     

Structural development and magnetic phenomenon in Zn–Cr–Fe multi oxide nano-crystals

The Cr³⁺ ions doped multi-oxide ZnFe_2−xCr_xO₄ ferrite nanoparticles have been synthesized by chemical co-precipitation method. Site occupancies of Zn²⁺, Cr³⁺ and Fe³⁺ ions were analyzed using X-ray diffraction data and Buerger's method. The effect of the constituent phase variation on the magnetic hysteresis behavior was examined by saturation magnetization which decreases with the increase in Cr³⁺ content in place of Fe³⁺ ions at octahedral B-site. Typical blocking temperature (T_B) around 90 K was observed by zero field cooling and field cooling magnetization study. Room temperature Mössbauer spectra show two paramagnetic doublets (tetrahedral and octahedral sites). The isomer shifts of both doublets decrease whereas quadrupole splitting and relative area of tetrahedral A-site increases with increasing Cr³⁺ substitution. The dielectric constant (measured on compositions x=0, 0.4, 0.8 and 1.0) increases when the temperature increases as in the semiconductor. This behavior is attributed to the hopping of electrons between Fe²⁺ and Fe³⁺ ions with a thermal activation.     

Structural and magnetic properties of Co1−xZnxFe2O4 nanorods prepared by the solvothermal annealing method

Co_1−xZn_xFe₂O₄ (0.1≤x≤0.9) nanorods have been prepared by the thermal decomposition of the corresponding oxalate precursor, which was synthesized by the template-, surfactant-free solvothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM). The obtained Co_1−xZn_xFe₂O₄ (0.1≤x≤0.9) nanorods were built by many nanoparticles with average sizes around 20 nm to form one-dimensional arrays. Vibrating sample magnetometry measurements show that the coercivity of the ferrite nanorods decreases with increasing Zn content, whereas the specific saturation magnetization initially increases and then decreases with the increase of Zn content. The maximum saturation magnetization value of the as-prepared sample (Co_0.5Zn_0.5Fe₂O₄) reaches 43.0 emu g⁻¹.     

Microstructures,magnetic, and dielectric properties of Ba-doped BiFeO3 nanoparticles synthesized via molten salt route

As the paradigm of magnetoelectric multiferroic materials, BiFeO₃ (BFO) has potential applications in spintronics, memory devices, sensors, and actuators. However, its large leakage current and small magnetism at room temperature restrict its practical applications. It is demonstrated that the substitutions of Bi by alkali earth elements at A-site of BFO can significantly reduce the leakage current and enhance the remanent magnetization of BFO. In this work, Ba-doped BFO nanoparticles Bi_1-xBa_xFeO₃ (x = 0, 0.05, 0.10, 0.15 and 0.20) were synthesized via molten salt route. X-ray diffraction patterns revealed that with increasing the Ba-doped content the formation of the impurity phase was depressed and the rhombohedral distortions of these nanoparticles were suppressed, as confirmed by Raman spectra. X-ray photoelectron spectroscopy measurements reveal that the Fe element in the nanoparticles exists in the dual valence states of Fe³⁺ and Fe²⁺, and two kinds of oxygen atoms (lattice oxygen atoms and the adsorbed oxygen atoms) exist in the nanoparticles. With increasing the Ba-doped content, the content ratios of Fe³⁺ to Fe²⁺ ions were generally increased, whereas the oxygen vacancy concentrations were decreased. The average particle sizes of the Ba-doped BFO nanoparticles were decreased as compared with that of nondoped BFO nanoparticles. In contrast, the room temperature magnetization of the Ba-doped BFO nanoparticles was greatly enhanced by Ba-substitution, as confirmed by the M-H loops. At room temperature, the remanent magnetization and coercive field of the Bi_0.8Ba_0.2FeO₃ nanoparticles were 0.51 emu/g and 1130 Oe, respectively. Furthermore, the leakage current density was reduced by one order of magnitude at x = 0.2 and the dielectric properties are also improved by Ba-substitution. The improvements on the remanent magnetization, leakage current density as well as dielectric properties of the Ba-doped BFO nanoparticles make them promising candidates for spintronics and dielectric energy storages.     

Thermomagnetization characteristics and ferromagnetic resonance linewidth broadening mechanism for Ca-Sn Co-substituted YIG ferrites

Yttrium iron garnet (YIG) ferrites own significant applications in microwave magnetic devices, such as circulators, isolators and filters. The excellent performance and reliability of these devices are strongly dependent on the saturation magnetization (M_s), ferromagnetic resonance (FMR) linewidth (ΔH), dielectric loss tangent (tan δ_ε) and Curie temperature (T_c) of the garnet ferrites. Here, we fabricate Ca-Sn co-substituted Y_3-xCa_xFe_5-xSn_xO₁₂ (x?=?0.0, 0.1, 0.2, 0.3 and 0.4) ferrites using solid-state reaction method, and investigate the thermomagnetization characteristics of Brillouin function and FMR linewidth based on Néel model of ferrimagnetism and spin wave approach, respectively. This study clarifies the intrasublattice molecular-field coefficients ω_aa, ω_dd and intersublattice coefficients ω_ad =?ω_da. More importantly, we propose an accurate formula of Curie temperature T_c for garnet ferrites. Furthermore, Ca-Sn co-substitution can tailor the FMR linewidth based on the adjustment of anisotropy and the realization of densification. Finally, Y_2.7Ca_0.3Fe_4.7Sn_0.3O₁₂ ferrite exhibits optimized magnetic property: 4πM_s =?2073 Gs, ΔH =?42?Oe, T_c =?491?K.     

Microwave assisted hydrothermal synthesis of (Fe,Co)3O4 nanoparticles in the presence of surfactants and effects of Co/Fe ratio on microstructure and magnetism

Microstructure and magnetic properties of nanoparticles can be tailored by optimising the synthesis procedure and changing chemical composition. In this study, a two-step procedure, i.e., coprecipitation in the presence of PEG 300 followed by microwave assisted (MW) hydrothermal synthesis, was introduced to obtain Co_xFe_3-xO₄ (x?=?0, 0.1 and 0.2) nanoparticles. It was found that with the increase of Co content, particle/crystallite size increased, with significant change of coercivity (H_c). The mixed samples of Co_xFe_3-xO₄ (x?=?0.1 and 0.2) were magnetically harder in comparison with Fe₃O₄. Тhe H_c of Fe₃O₄ was 91?Oe, while for Co_0.10Fe_2.90O₄ and Co_0.20Fe_2.80O₄, H_c was 256?Oe and 1070?Oe, respectively. Saturation magnetisation (M_s) of mixed samples also increased up to 6% compared to Fe₃O₄. A special effort was devoted to study the effects of introducing different surfactants (PEG 300, PEG 4000 or SDS) during the synthesis procedure in order to improve morphological and microstructural properties of CoFe₂O₄ nanoparticles. The influence of surfactants on physical/chemical properties of nanoparticles is discussed.     

The structure,vacancy characteristics,and magnetic properties of GdMn1-xCrxO3 ceramics

To investigate the evolution of the structural and enhanced magnetic properties of GdMnO₃ systems induced by the substitution of Mn with Cr, polycrystalline GdMn_1-xCr_xO₃ samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn_1-xCr_xO₃ compounds with single-phase structures crystallize well and that Cr³⁺ ions entering the lattice sites of GdMnO₃ induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn_1-xCr_xO₃ ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn_1-xCr_xO₃. The enhanced magnetization of GdMn_1-xCr_xO₃ is closely related to the vacancy defect concentration.     

Effect of Nb substitution on magnetic,ferroelectric and photocatalytic properties of Bi0.95Sm0.05Fe1-xNbxO3 (0 ≤ x ≤ 0.1) nanoparticles

The single phase Bi_0.95Sm_0.05Fe_1-xNb_xO₃ (0 ≤ x ≤ 0.1) nanoparticles were synthesized by the sol-gel route, and the effect of Nb substitution on their magnetic, ferroelectric and photocatalytic properties were studied. X-ray diffractometry confirms a phase transformation from rhombohedral to orthorhombic with an increase in Nb substitution. The grain size decreases significantly, and the morphology of grains becomes homogeneous with the increase of Nb concentration. The maximum remnant magnetization (0.014 emu/g), coercivity (565 Oe) and polarization (0.592 μC/cm²) are observed in Bi_0.95Sm_0.05Fe_0.9Nb_0.1O₃. It has been observed that the energy band gap has been slightly reduced from 2.14 to 2.03 eV with Nb substitution, indicating an improvement of photocatalytic activity. The methylene blue degradation is used to represent the photocatalytic ability of Bi_0.95Sm_0.05Fe_1-xNb_xO₃ nanoparticles. The highest degradation efficiency (~74%) of methylene blue is obtained in Bi_0.95Sm_0.05Fe_0.93Nb_0.07O₃, which is much higher than that of Bi_0.95Sm_0.05FeO₃ (~51%) and can be attributed to the optimum particle size and the smallest energy band gap.