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.     

Targeted design of polyaniline-graphene oxide,barium-strontium titanate,hard-soft ferrite,and polyester multi-phase nanocomposite for highly efficient microwave absorption

The current paper focuses on synthesizing a high-efficiency microwave absorber via incorporating the nanofillers of graphene oxide-polyaniline (GO-PANI), barium-strontium titanate (BST), and soft-hard ferrite within the polyester matrix. The nanocomposite magnets of (Ba_0.5Sr_0.5Fe₁₂O₁₉)_1-x hard/(CoFe₂O₄)_x soft (x = 0.2, 0.5, and 0.8) were prepared using sol-gel auto-combustion method. The GO-PANI and BST were successfully synthesized by in situ polymerization and improved polymerization, respectively. The phase structure, chemical structure, morphology, and microwave absorption properties of the synthesized nanocomposites were characterized by X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM), vector network analyzer (VNA) techniques, respectively. The results showed that the synergistic effects of the combination of dielectric (BST), conductive (GO-PANI), and magnetic materials (hard-soft ferrites) provided the reflection loss values of less than ?20 dB (>99% absorption) in the X-band region. The minimum reflection loss of ?35 dB (>99.99% absorption) was obtained by the optimal formulation including (Ba_0.5Sr_0.5Fe₁₂O₁₉)_0.2 (CoFe₂O₄)_0.8, and the weight ratio of 1: 2 for both BST/soft-hard ferrite and hard-soft ferrite + BST/GO-PANI with the thickness of 1 mm. According to the results, the thickness factor plays a key role in improving the impedance matching. Consequently, the proposed nanocomposite can be employed as a novel kind of microwave absorbers with good impendence matching and high absorption.     

Role of exchange coupling between the hard and soft magnetic phases on the absorption of microwaves by SrFe10Al2O19/Co0.6Zn0.4Fe2O4 nanocomposite

(1-x)SrFe₁₀Al₂O₁₉/(x)Co_0.6Zn_0.4Fe₂O₄-(SFAO/CZFO) hard/soft nanocomposite ferrite materials were synthesized by ‘one-pot’ self-propagating combustion route. The co-existence of the two magnetic phases were confirmed by XRD, FESEM, EDS and VSM. The prepared nanocomposite samples were also characterized by TGA/DSC, Raman spectroscopy and VNA. Exchange coupling between the hard and the soft magnetic grains was observed by determining the switching field distribution (SFD) curve. As a result of the competing effects of exchange interaction and dipolar interaction, magnetic parameters were observed to be sensitive to the incorporation of soft magnetic phase into the nanocomposite. Results showed that with the inclusion of soft magnetic phase, exchange coupling behaviour between the hard and the soft ferrite phases had significant influence on the microwave absorption capacity of the samples. Related electromagnetic parameters and impedance matching ratio of the nanocomposite system were discussed. A minimum reflection loss of ?42.9 dB with an absorber thickness of 2.5 mm was attained by the nanocomposite (90 wt%)SrFe₁₀Al₂O₁₉/(10 wt %)Co_0.6Zn_0.4Fe₂O₄ at a matching frequency of 11.45 GHz. This assured the candidacy of SrFe₁₀Al₂O₁₉/Co_0.6Zn_0.4Fe₂O₄ nanocomposite as a promising microwave absorption material in the X-band (8–12 GHz).     

Magnetic behavior of Ga doped yttrium iron garnet ferrite thin films deposited by sol-gel technique

Yttrium Iron Garnet (YIG) ferrites thin films having compositional formula Y₃Ga_xFe_5-xO₁₂, where (x = 0, 1, 2, 3, 4) are synthesized by sol gel dip coating technique. XRD, SEM and VSM characterizations are employed to explore structural, morphological and magnetic properties, respectively. XRD showed that Ga is completely doped in YIG and not formed any cluster or other phase with YIG. SEM confirmed the formation of agglomeration of YIG particles. Magnetic parameters like coercivity, remnant squareness, saturation magnetization, magnetic moment, anisotropy constant, initial permeability Y–K angles and microwave frequency were calculated of these films. The coercivity and moderate magnetization suggested that fabricated ferrite films are highly applicable in electromagnetic microwave absorption and frequency agile antenna for wireless communication.     

Structural,morphological, and electrochemical behavior of titanium-doped SrFe1-xTixO3-δ (x = 0.1–0.5) perovskite as a cobalt-free solid oxide fuel cell cathode

Titanium, Ti-doped SrFe_1-xTi_xO_3-δ (x = 0.1–0.5) perovskite-structured ceramics were synthesized via solution combustion. The structural, morphological, and electrochemical behaviors of the as-synthesized materials were investigated to determine the applicability of SrFe_1-xTi_xO_3-δ as a cobalt-free cathode material for intermediate-temperature solid oxide fuel cells. X-ray diffraction analysis confirmed the formation of a single-phase cubic perovskite structure. The unit volume of this perovskite structure increased as the amount of Ti dopant increased. Morphological analysis revealed that the porosity of the SrFe_1-xTi_xO_3-δ perovskite cathode film was inversely proportional to the amount of Ti dopant. The cathode SrFe_0·9Ti_0·1O_3-δ film exhibited a high porosity of 24.74 ± 0.52%, a low but acceptable hardness value of 0.70 ± 0.01 GPa and an area specific resistance of 0.57 Ω cm². These results suggested that cobalt-free SrFe_1-xTi_xO_3-δ cathode was still not good enough to be compared with the existing cobalt-containing cathode such as lanthanum strontium cobalt ferrite. But, the results obtained from this work can be considered as a major turning point as the literature works on SrFe_1-xTi_xO_3-δ cathode showed excellence electrochemical performance. The contradict result between the present and past studies proved that the use of SrFe_1-xTi_xO_3-δ cathode is worthy of being studied into details to confirm its capability.     

Multiple magnetic phase transitions in NixMn1-xCo2O4

We prepared pure-phase Ni_xMn_1-xCo₂O₄ (x = 0, 0.25, 0.5, 0.75 and 1) nanoparticles using a low-temperature solid-state reaction method. Magnetization measurement results showed that with Ni doping, the Curie temperature and coercivity of Ni_xMn_1-xCo₂O₄ increased. Multiple magnetic phases that transition from paramagnetic to ferrimagnetic to ferrimagnetic and antiferromagnetic were observed to coexist in the Ni_0.5Mn_0.5Co₂O₄ sample. At low temperatures, the ferromagnetic and antiferromagnetic phases coexist in Ni_xMn_1-xCo₂O₄ (x = 0 and 0.25), and as the concentration of Ni increases, Ni_xMn_1-xCo₂O₄ (x = 0.75 and 1) show a spin glass state. The structure of Ni_xMn_1-xCo₂O₄ (x < 0.5) is mainly affected by cation defects, and by cation substitution when x is greater than 0.5. The results of first-principles calculations show that covalent bonds exist in Ni_xMn_1-xCo₂O₄ and that the strength of the Ni-O bond is greater than that of the Mn-O bond.     

Valence state of europium and samarium in Ln2Hf2O7 (Ln = Eu,Sm) based oxygen ion conductors

Ln₂(Hf_2-xLn_x)O_7-x/2 (Ln = Sm, Eu; x = 0.1) pyrochlores have been prepared via mechanical activation of oxide mixtures, followed by heat treatment for 4h at 1450 and 1600 °C, respectively. According to the ESR data, the Eu cations on the Hf site in the Hf_1-xEu_xO₆ octahedra in pyrochlore Eu₂(Hf_2-xEu_x)O_7-x/2 (x = 0.1) are most readily oxidized and reduced. Oxidation at 840 °C for 24h in air reduces the total conductivity of the Ln₂(Hf_2-xLn_x)O_7-x/2 (Ln = Sm, Eu; x = 0.1) by a factor of 2.5–6, due to the decrease in the concentrations of oxygen vacancies and Ln²⁺ ions as a result of the oxidation. The anomalous low-frequency behavior of the permittivity of the Eu₂(Hf_2-xEu_x)O_7-x/2 (x = 0.1) at ~800 °C can be understood in terms of the changes in the oxygen sublattice of the pyrochlore structure as a result of the oxidation of divalent europium and partial filling of oxygen vacancies at this temperature.     

Low-temperature firing and microwave dielectric properties of MgNb2-xVx/2O6-1.25x ceramics

MgNb_2-xV_x/2O_6-1.25x (0.1≤x≤0.6) ceramics with orthorhombic columbite structures were prepared at low-temperature by a solid-phase process. The phase component, microscopic morphology, low-temperature sintering mechanism and microwave dielectric performance of MgNb_2-xV_x/2O_6-1.25x ceramics were comprehensively investigated. Low-temperature sintering densification of dielectric ceramics was achieved via the nonstoichiometric substitution of vanadium (V) at the Nb-site. In contrast to pure MgNb₂O₆ ceramics, the sintering temperature of MgNb_2-xV_x/2O_6-1.25x (x = 0.2) ceramics was reduced by nearly 300 °C owing to the liquid-phase assisted sintering mechanism. The liquid phase arises from the autogenous low-melting-point phase. Meanwhile, MgNb_2-xV_x/2O_6-1.25x (x = 0.2) samples with nonstoichiometric substitution could achieve a more than 900% improvement in the Q × f value, compared with stoichiometrically MgNb_2-xV_xO₆ (x = 0.1, 0.2) ceramics. Finally, MgNb_2-xV_x/2O_6-1.25x dielectric ceramics possess outstanding microwave dielectric properties: ε_r = 20.5, Q × f = 91000, and τ_f = -65 ppm/°C when sintered at 1030 °C for x = 0.2, which provides an alternative material for LTCC technology and an effective approach for low-temperature sintering of Nb-based microwave dielectric ceramics.     

Improved magnetic and electromagnetic absorption properties of xSrFe12O19/(1−x)NiFe2O4 composites

xSrFe₁₂O₁₉/(1−x)NiFe₂O₄ composites (0 ≤ x ≤ 1.0) were synthesized by using a conventional solid-state synthetic route. The results show that magnetic hysteresis loops of the xSrFe₁₂O₁₉/(1−x)NiFe₂O₄ composites are similar to those of individual component ferrites, except for the 0.1SrFe₁₂O₁₉/0.9NiFe₂O₄ and 0.3SrFe₁₂O₁₉/0.7NiFe₂O₄, suggesting that the hard/soft magnetic phases are well exchange-coupled. The saturation magnetization, coercivity, and remanent magnetization of the xSrFe₁₂O₁₉/(1−x)NiFe₂O₄ composites are increased with increasing content of SrFe₁₂O₁₉, with maximal values of 42.1 Am² kg⁻¹, 78.7 kA m⁻¹, 17.2 Am² kg⁻¹, respectively, as the content x is about 0.5. They are higher than those of the individual components, implying that interface coupling is present in the magnetic composites. The coercivity and remanent magnetization of the composites are increased initially with increasing sintering temperature and then show a downward tendency. For the component SrFe₁₂O₁₉ and NiFe₂O₄, the minimum reflection losses are −12.5 dB and −18.3 dB at match thicknesses of 2.5 mm and 2 mm, respectively. Compared with those of the component SrFe₁₂O₁₉ and NiFe₂O₄, the microwave absorption performances of the xSrFe₁₂O₁₉/(1−x)NiFe₂O₄ composites are improved remarkably, especially for the samples of x = 0.3 and x = 0.9. The minimum reflection losses values of the 0.3SrFe₁₂O₁₉/0.7NiFe₂O₄ composite are −31.6 dB (12.7 GHz) and −20.2 dB (13 GHz), while those of the 0.9SrFe₁₂O₁₉/0.1NiFe₂O₄ composites are −23.7 dB (16.3 GHz) and −33.5 dB (15.8 GHz), as the matching thicknesses are 2.5 mm and 2 mm, respectively. Therefore, the xSrFe₁₂O₁₉/(1−x)NiFe₂O₄ composites could be used as potential microwave absorption materials.     

Monodisperse hexagonal SrFe12O19 nanoflake with enchanced magnetic properties

Monodisperse SrFe₁₂O₁₉ (SrM) nanoflakes were successfully fabricated via a modified hydrothermal method. The effects of Fe³⁺/Sr²⁺ (R_F/S) and OH⁻/NO₃⁻ (R_O/N) molar ratio on phase, structure and morphology of the products were investigated by XRD, FT-IR, FESEM, and TEM. Meanwhile, the magnetic properties of the product were investigated via vibrating sample magnetisem (VSM). Results demonstrated that when the R_F/S=5 and R_O/N=2, the single phase SrFe₁₂O₁₉ particles were obtained. The as-obtained SrFe₁₂O₁₉ particles had monodisperse nanoflake structure and nano-micro scale in vertical and horizontal direction of SrM ferrite particle. The magnetic property results showed that such structure SrM ferrite particle had prospective saturation magnetization and coercivity, the largest values of Ms and Hc were 62.96 emu/g and 94.83 kA/m, respectively, which make it have a potential application as magnetic recording media and magneto-optical devices material.     

Synthesis and characterization of layered Mo1-xErxS2 (0≤x≤0.05) nanostructures via 1,2-ethanediolmono(2-methylpropenoate) assisted microwave approach for gas detection

A series of layered Mo_1-xEr_xS₂ (0 ≤ x ≤ 0.05) nanosheets was prepared using a 1,2-ethanediolmono(2-methylpropenoate) assisted microwave approach. The influence of the Er-atoms on the structure, morphology, optical, and electrical properties of the MoS₂ nanosheets was studied. The Mo_1-xEr_xS₂ (0 ≤ x ≤ 0.05) nanosheets were characterized using XRD, SEM, EDS, FTIR, Raman, and XPS measurements. The inclusion of the Er in Mo sites results in a decrease in the number of MoS₂ layers and the widening of their lateral dimensions. The UV–vis spectrum of the Mo_1-xEr_xS₂ (0 ≤ x ≤ 0.05) 2D-layered nanostructures showed an increase of the optical bandgap and an enhancement of the direct exciton transitions at the K-points of the Brillouin zone. A heterojunction Mo_1-xEr_xS₂/p-Si diode was fabricated for the detection of gases. The developed heterojunction diode exhibited high sensitivity toward NO₂ gas, under solar light illumination, with high stability and reproducibility.     

Sc3+-doping effects on porous Li3V2(PO4)3/C cathode with superior rate performance and cyclic stability

An enhanced sol-gel combustion method was used to synthesize different porous Sc³⁺-doped Li₃V_2-xSc_x(PO₄)₃/C (x = 0.00, 0.05, 0.10 and 0.15) compounds. The substitution of Sc³⁺ into the V³⁺ sites of Li₃V_2-xSc_x(PO₄)₃/C expands the lattice volume along with the enlargement of Li⁺ diffusion channel, which is beneficial for Li⁺ transportation and ionic conductivity improvement. Besides, the Sc³⁺ doping content exhibits a great impact on the morphology of Li₃V_2-xSc_x(PO₄)₃/C composite. The pristine Li₃V₂(PO₄)₃/C are constituted of porous particles and nanorods, and the ratio of nanorods to particles can be controlled by adjusting the amount of Sc³⁺ doping since the ratio of nanorods to particles decreases with increasing Sc³⁺ doping content. When Sc³⁺ doping content increases to a certain level (x = 0.15, Li₃V_1.85Sc_0.15(PO₄)₃/C), the nanorods are hardly seen. Li₃V_1.90Sc_0.10(PO₄)₃/C with higher tapped density, better reversibility, smaller resistance and larger Li⁺ diffusion coefficient demonstrates outstanding rate performance and cyclic stability, together with high specific discharge capacities of 130.2 and 92.9 mAh g⁻¹ at 0.5 and 20 C, respectively. Furthermore, a superior specific discharge capacity of 85.8 mAh g⁻¹ was retained at 20 C following 1000 cycles. Overall, a novel approach for the preparation of high-performance Li₃V_2-xSc_x(PO₄)₃/C cathodes with different morphologies for lithium-ion batteries is provided.     

Negative thermal expansion coefficient of Sc-doped indium tungstate ceramics synthesized by co-precipitation

Co-precipitation was successfully applied to synthesize the Sc³⁺ doped In_2-xSc_x (WO₄)₃ (x = 0, 0.3, 0.6, 0.9 and 1.2) compounds. The composition- and temperature-induced structural phase transition and thermal expansion behaviors of Sc³⁺ doped In₂(WO₄)₃ were investigated. Results indicate that In_2-xSc_x (WO₄)₃ crystalizes in a monoclinic structure at 300 °C for x ≤ 0.3 and changes into hexagonal structure for x ≥ 0.6. Hexagonal In_1.1Sc_0.9(WO₄)₃ displays negative thermal expansion (NTE) with an average linear coefficient of thermal expansion (CTE) of −1.85 × 10⁻⁶ °C ⁻¹. After sintering at 700 °C and above, a phase transition from hexagonal to orthorhombic phase was observed in In_2-xSc_x (WO₄)₃ (x ≥ 0.6). Sc³⁺ doping successfully reduce the temperature-induced phase transition temperature of In_2-xSc_x (WO₄)₃ ceramics from 250 °C (x = 0) to room temperature (x = 0.9). When x = 0.9 and 1.2, the average linear CTEs of In_2-xSc_x (WO₄)₃ ceramics are −5.45 × 10⁻⁶ °C⁻¹ and -4.43 × 10⁻⁶ °C⁻¹ in a wider temperature range of 25–700 °C, respectively.     

Investigation of structural,magnetic and dielectric properties of SrM/PEEK: A potential microwave absorber

The current study aims to investigate the effect of Polyether Ether Ketone (PEEK) on the structural, magnetic, and microwave properties of substituted M-type SrFe_11.5Co_0.5O₁₂ (SrM) hexaferrite. Nanocomposites based on SrM/PEEK in ratios 4:0, 3:1, 2:2, and 0:4 were prepared by employing the micro-emulsion method. The composites were further characterized using XRD, SEM, FTIR, and VNA. XRD results exhibited a single-phase hexaferrite structure with an average crystallite size of 40 nm for pure SrM, which decreased due to increasing PEEK concentration. FESEM micrographs revealed the surface morphology and nature of the grains in the prepared nanocomposites. EDAX plots showed the presence of the constituent elements e.g., Fe, Sr, C, and O, at the respective standard energies. VSM results revealed the diamagnetic and ferromagnetic nature of PEEK and pure SrM/nanocomposite samples, respectively. FTIR spectra of SrM depicted the formation of hexaferrite due to the presence of Fe–O stretching peak at 525 cm^?1. Reflection loss was found to decrease due to increasing ferrite concentration in PEEK. This indicates that SrM/PEEK composites are potential microwave absorbers for microwave applications in the X band.     

Effect of Gd and Nb co-substitution on enhancing the thermoelectric power factor of nanostructured SrTiO3

Oxide thermoelectric materials have attracted researchers in recent decade due to their attractive features such as low toxicity, low cost and high chemical robustness. Perovskite based oxide thermoelectric are considered as the promising materials, especially for high temperature thermoelectric applications. In the present work, pure SrTiO₃, Sr_1-xGd_xTiO₃ (0 < x < 0.09) and Sr_1-xGd_xTi_1-yNb_yO₃ were prepared by varying Gd concentration (0 < x < 0.09) using hydrothermal method. The XRD analysis confirmed the high crystalline cubic structured nanocomposite with Gd and Nb substitution. The FESEM images revealed cubic morphology of the particles and the size of the cubes varied with the concentration of the dopant. The chemical compositions of the samples were confirmed by EDX analysis. The binding states and elemental composition of the samples were analyzed by XPS. Both the pure SrTiO₃, Sr_1-xGd_xTiO₃ samples show low electrical resistivity and the co-substituted sample exhibited relatively high resistivity. Seebeck coefficient of the samples increased with Gd concentration. The Gd and Nb co-substituted sample shows relatively higher Seebeck coefficient value compared to Gd substituted samples. The power factor of the nanocomposite were calculated from the obtained Seebeck coefficient and resistivity; Gd and Nb co-substituted sample shows relatively high power factor of 311.7 × 10^?6 Wm^?1K^?2 at 550 K compared to other samples.     

Room-temperature multiferroic properties of Al-doped hexaferrites sintered at high oxygen atmospheric concentrations

The room-temperature magnetoelectric effects of Al-doped polycrystalline hexaferrites Sr₃Co₂(Fe_1-xAl_x)₂₄O₄₁(x = 0.00, 0.02, and 0.04) sintered under high oxygen atmospheric concentrations were comprehensively investigated. The magnetic phases and magnetic structures were modulated by high sintering oxygen atmospheric concentrations as demonstrated by M-T tests and magnetic hysteresis loops. Compared with previous specimens sintered under low oxygen atmospheric concentrations, the transverse conical spin structures of the Sr₃Co₂(Fe_1-xAl_x)₂₄O₄₁(x = 0.00, 0.02, and 0.04) were obviously strengthened by high sintering oxygen atmospheric concentrations, exhibiting magnetoelectric effects in high magnetic field ranges (>1 T).     

A/B-site cosubstituted Ba4Pr28/3Ti18O54 microwave dielectric ceramics with temperature stable and high Q in a wide range

High permittivity Ba₄(Pr_1-xSm_x)_28/3Ti_18-yAl_4y/3O₅₄(0.4≤x ≤ 0.7, 0≤y ≤ 1.5) ceramics were synthesized using a standard solid-state method. The effects of Sm³⁺ substitution into the A-site and Sm³⁺/Al³⁺ cosubstitution into the A/B-sites on the microstructure, crystal structure, Raman spectra, infrared reflectivity (IR) spectra and dielectric characteristics were investigated in a Ba₄Pr_28/3Ti₁₈O₅₄ solid solution. In the ceramic samples of Ba₄(Pr_1-xSm_x)_28/3Ti₁₈O₅₄(0.4≤x ≤ 0.7), Sm³⁺ partial substitution for Pr³⁺ could improve the quality factor (Qf) value and reduce the TCF value. Nevertheless, the quality factor (Qf~10,000GHz) needed further improvement and the TCF values (+12.3~+35.4 ppm/°C) were still too large. Therefore, Al³⁺ was introduced for further optimization of the TCF values and Qf values of the Ba₄(Pr_1-xSm_x)_28/3Ti₁₈O₅₄ ceramics. Sm/Al cosubstitution led to a good combination of high ε_r (ε_r ≥ 70), high Qf (Qf ≥ 12,000 GHz), and near-zero TCF (−10 < TCF < +10 ppm/°C) in a wide range (0.4≤x ≤ 0.7). Infrared reflectivity (IR) spectra indicated that A-TiO₆ vibration modes gave the primary contribution rather than Ti–O bending and stretching modes. The decrease in the degree of B-site cations order could be confirmed by Raman spectra. XPS results demonstrated that the improvement of quality factor (Qf) value was strongly related to the suppression of Ti³⁺. Excellent dielectric properties were achieved in Ba₄(Pr_1-xSm_x)_28/3Ti_18-yAl_4y/3O₅₄ microwave ceramics with x = 0.5 and y = 1.25: ε_r = 72.5, Qf = 13,900GHz, TCF = +1.3 ppm/°C.     

The influence of lanthanum concentration on microstructural and electrical properties of Mg-Cd-Bi ferrite nanoparticles

Lanthanum (La³⁺) substituted Mg-Cd-Bi ferrite nanoparticles were synthesized by sol-gel auto combustion route consuming high quality nitrates. The impact of lanthanum concentration on microstructural and electrical properties in the ferrite series Mg_0.5Cd_0.5Fe_1.95Bi_0.5-xLa_xO₄ (x = 0.0, 0.01, 0.02, 0.03, 0.04, 0.05) was investigated. The samples were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscope (SEM), and Current-voltage (I-V) analyzerfor compositional, structural, morphological and electrical analysis. Upon varying the lanthanum content, it is observed that all the samples retained perovskite BiFeO₃ phase with distorted rhombohederal structure. Furthermore, it is revealed that the sintering process can significantly control the structural defects and crystal imperfections which affect the electric and magnetic nature of ferrites. The conduction process in La³⁺-dopedferrite series is originated by the hopping of electrons between ions of same elementswhich reduced the electrical resistivity and depicts the semiconductor nature of synthesized samples.Thus, it is believed that the optimal doping of lanthanum content in La³⁺-substituted Mg-Cd-Bi ferrites followed by post-annealing can remarkably tune the electrical properties of synthesized ferrite nano particles.     

Effect of yttria substitution on structure,optical and mechanical properties of (Gd,Y)2O3–MgO nanocomposite ceramics

A citrate-nitrate combustion method was applied to synthesize fine composite Gd_2-xY_xO₃-MgO (x = 0, 0.02, 0.2, 0.3, 0.4, 0.6) nanopowders. Y₂O₃ substitution inhibited Gd₂O₃ phase transition from cubic structure to monoclinic structure during sintering, thereby stabilizing its cubic structure to room temperature. This approach led to nanocomposite ceramics with a grain size of about 190 nm and increased the transmittance to 85% over the 3–5 μm wavelength range when x = 0.3. However, the addition of Y₂O₃ weakened the mechanic properties of the nanocomposite ceramics.     

The Cobalt Zinc Spinel Ferrite Nanofiber: Lightweight and Efficient Microwave Absorber

To solve the heavy mass problem of the traditional spinel ferrite using as the microwave absorber, the Co_xZn_(1?x)Fe₂O₄ (x = 0.2, 0.4, 0.6, 0.8) ferrite nanofibres were synthesized by electrospinning method. The phase composition, morphology, and electromagnetic properties were analyzed. The results showed that all the as‐prepared Co_xZn_(1?x)Fe₂O₄ ferrites exhibited the homogeneous nanofibrous shape. The saturation magnetization and coercivity were enhanced by tuning the Co²⁺ content. The electromagnetic loss analysis indicated that the Co_0.6Zn_0.4Fe₂O₄ ferrite nanofiber performed the strongest microwave attenuation ability. The microwave absorbing coating containing 15 wt% of Co_0.6Zn_0.4Fe₂O₄ ferrite nanofiber showed the reflection loss less than ?10 dB in the whole X‐band and 80% of the Ku‐band frequencies. Meanwhile, the surface density was only 2.4 Kg/m².