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Hard/soft nanocomposites (NCs) of SrNi0.02Zr0.02Fe11.96O19 (SrNiZr)/MFe2O4 (M = Mn, Co, Cu, and Zn) were prepared using a one-pot sol-gel auto-combustion technique. All produced samples showed smooth M − H curves and single peaks on the dM/dH against H curves. This indicates that complete exchange-coupled effects between phases were achieved. Furthermore, the squareness ratio SQR=(Mr/Ms) was obtained and found to be higher than 0.5 at 300 K. This refers to the occurrence of excellent exchange coupling behavior among the soft and hard ferrites, and their structures consist of a single magnetic domain. The electrodynamic parameters were investigated in the 2–18 GHz frequency band using a coaxial line. The dependences of the real and imaginary parts of μ and e as a function of frequency were determined from the measured S-parameters. A strong correlation between the chemical composition of the soft magnetic phase and the electrodynamic parameters of the composite was observed. This was analyzed in terms of the atomic weight and configuration of the electronic shells of the A-cation in the soft phase. The electromagnetic absorption (EMA) of the investigated composites was estimated from the reflection losses calculated from μ and e. The maximal EMA value was observed.

In this study, a series of SrGa0.02Fe11.98O19-Zn0.5Ni0.5Fe2O4 hard/soft nanocomposites (SrGaFeO-ZnNiFeO H/S NCs) were synthesized via a single-pot (citrate sol–gel) approach by applying different calcination temperatures. The electrical and dielectric properties of the SrGaFeO-ZnNiFeO H/S NCs based on the calcination temperatures in between 800 and 1100 °C were systematically investigated with an impedance analyzer of up to 3.0 MHz frequency and within 20 and 120 °C temperature range. Both electrical and dielectric parameters, such as ac/dc conductivity, dielectric loss, dielectric constant, and tangent loss, were measured for a given calcination temperature. It has been found that AC conductivity generally conforms the power law rules, largely dependent on calcination temperatures. Impedance analysis has observed that the conduction mechanisms of SrGaFeO-ZnNiFeO H/S NCs at various calcination temperatures are mainly attributable to grain–grain boundaries. The dielectric constant of SrGaFeO-ZnNiFeO H/S NCs shows normal dielectric distribution with frequency, largely dependent on calcination temperatures. Ultimately, the observed change in dielectric properties with frequency can be attributed to the conduction mechanism in most compound ferrites, which can be phenomenologically explained by Koop’s model.

In this study, Co0.5Ni0.5Nd0.02Fe1.98O4 nanoparticles CoNiNd (NPs) were synthesized by combustion method linked with biosynthesis with and without different plant extracts such as Lavender, Ginger, Flax-Seed, Lemon Juice, Tragacanth Gum, and Dates Fruit. Co0.5Ni0.5Nd0.02Fe1.98O4 nanoparticles (NPs) with plant extracts (CoNiNd plant extracts) were analyzed by XRD, TEM and SEM methods. The structure of Co-Ni spinel ferrite was confirmed by XRD and the shape and the size of nanoparticles were examined via SEM and TEM and the size was found between 17 and 25 nm. The anti-cancer activity of NPs on cancer cells such as human colorectal carcinoma (HCT-116) and human cervical cells (Hela) were investigated. The cytotoxicity of was examined by MTT assay and followed by measuring the inhibitory concentration (IC50) values after 48h treatments. The cell viability assay confirmed a decrease in the cancer cell viability post NPs treatments and showed dose-dependent inhibitory action. The treatments of CoNiNd (NPs) and CoNiNd plant extracts via Lavender plant extract showed most profound inhibitory action on both cancer cells than extracts other plant extracts. The IC50 values were for HCT-116 cells were found to be in range of 15.75-42.55 µg/mL and 13.44 to 35.65 µg/mL for HeLa cells. In contrast, the treatment of CoNiNd (NPs) and CoNiNd plant extracts showed inhibitory action but the percentage of inhibition was higher in HEK-293 cells. Our results showed that CoNiNd (NPs) and CoNiNd plant extracts possess potential application in the colon and cervical cancer treatments and we recommend molecular analysis of NPs mediated cancer cell death for future applications.

International audience; 1-Propyl-2,3-dimethyl-1H-imidazol-3-ium ([pmIm] +), 3-(2,3-dihydroxypropyl)-1,2-dimethyl-1Himidazol-3-ium ([dhmIm] +) and 1-benzyl-2,3-dimethyl-1H-imidazol-3-ium ([bzmIm] +) cations were used as organic templates for crystallizing SAPO-5 with AFI microporous framework. The physicochemical influences of the functional groups of the templates (e.g. polarity/hydrophilicity, molecular dimension and size) on SAPO-5 formation were investigated. The results revealed that the crystallization rate, crystallinity and solid yield could be enhanced by increasing the polarity/hydrophilicity of the templates. In addition, the isomorphous Si substitution, morphology and particle size of the resulted SAPO-5 were also affected by the substituted groups of the imidazolium 2 templates. The thermogravimetry results further supported that the selection of organic template with proper polarity/hydrophilicity could be crucial to obtain SAPO-5 with high porosity (SBET, Smic, Sext and Vtotal) as high polar/hydrophilic template exhibited stronger chemical interaction with the AFI framework during template removal process via calcination process.

Tm-Tb co-substituted Co-Ni nanospinel ferrites (NSFs) as (Co0.5Ni0.5) [TmxTbxFe2&minus, 2x]O4 (x = 0.00&ndash, 0.05) NSFs were attained via the ultrasound irradiation technique. The phase identification and morphologies of the NSFs were explored using X-rays diffraction (XRD), selected area electron diffraction (SAED), and transmission and scanning electronic microscopes (TEM and SEM). The magnetization measurements against the applied magnetic field (M-H) were made at 300 and 10 K with a vibrating sample magnetometer (VSM). The various prepared nanoparticles revealed a ferrimagnetic character at both 300 and 10 K. The saturation magnetization (Ms), the remanence (Mr), and magneton number () were found to decrease upon the Tb-Tm substitution effect. On the other hand, the coercivity (Hc) was found to diminish with increasing x up to 0.03 and then begins to increase with further rising Tb-Tm content. The Hc values are in the range of 346.7&ndash, 441.7 Oe at 300 K to 4044.4&ndash, 5378.7 Oe at 10 K. The variations in magnetic parameters were described based on redistribution of cations, crystallites and/or grains size, canting effects, surface spins effects, super-exchange interaction strength, etc. The observed magnetic results indicated that the synthesized (Co0.5Ni0.5)[TmxTbxFe2&minus, x]O4 NSFs could be considered as promising candidates to be used for room temperature magnetic applications and magnetic recording media.

Highly active metal chlorides grafted on silicoaluminophosphate number 5, MClx/SAPO-5 (M = Cu, Co, Sn, Fe and Zn) catalysts via simple grafting of respective metal chlorides (MClx) onto SAPO-5 are reported. The study shows that thermochemical treatment after grafting is essential to ensure the formation of chemical bondings between MClx and SAPO-5. In addition, the microscopy, XRD and nitrogen adsorption analyses reveal the homogeneous distribution of MClx species on the SAPO-5 surface. Furthermore, the elemental microanalysis confirms the formation of Si&ndash, O&ndash, M covalent bonds in ZnClx/SAPO-5, SnClx/SAPO-5 and FeClx/SAPO-5 whereas only dative bondings are formed in CoClx/SAPO-5 and CuClx/SAPO-5. The acidity of MClx/SAPO-5 is also affected by the type of metal chloride grafted. Thus, their catalytic behavior is evaluated in the acid-catalyzed acylation of 2-methylfuran under novel non-microwave instant heating conditions (90&ndash, 110 &deg, C, 0&ndash, 20 min). ZnClx/SAPO-5, which has the largest amount of acidity (mainly Lewis acid sites), exhibits the best catalytic performance (94.5% conversion, 100% selective to 2-acetyl-5-methylfuran) among the MClx/SAPO-5 solids. Furthermore, the MClx/SAPO-5 solids, particularly SnClx/SAPO-5, FeClx/SAPO-5 and ZnClx/SAPO-5, also show more superior catalytic performance than common homogeneous acid catalysts (H2SO4, HNO3, CH3COOH, FeCl3, ZnCl2) with higher reactant conversion and catalyst reusability, thus offering a promising alternative for the replacement of hazardous homogeneous catalysts in Friedel&ndash, Crafts reactions.

In this paper, the structural, morphological, electrical and dielectric properties of hard/soft ferrite nanocomposites (NCs) of CoFe2O4/(NiSc0.03Fe1.97O4)x (where x = 1, 2, 3, 4, 5) have been investigated. The hard/soft NCs were manufactured with one pot sol-gel auto-combustion procedure. The electrical and dielectric properties of the products were explored with and between 20 and 120 °C temperature range up to 3 MHz. Dielectric and electrical features like ac/dc conductivity dielectric constant, dielectric loss and tangent loss were evaluated for a variety of compositional ratios of x = 1–5 including NiSc0.03Fe1.97O4 and CoFe2O4 NPs. The AC conductivity commonly obeys the power law rules, largely dependent on compositional ratios as mentioned earlier. Impedance analysis has the conduction mechanisms of hard/soft NCs at various compositional ratios are mainly due to grain-grain boundaries. The dielectric constant of the CoFe2O4 and NiSc0.03Fe1.97O4 NPs leads to normal dielectric distribution with frequency, largely dependent on compositional ratios. In general, the variation in the dielectric properties of hard/soft NCs caused by the conduction mechanism in ferrites.

In this study, bimetallic (Cu-Mn) substituted M-type Ba 1-2x Mn x Cu x Fe 12 O 19 (0.0 ? x ? 0.1) hexaferrites were fabricated via sol-gel auto-combustion route. The effect of bimetallic substitution on structure, morphology and magnetism of BaFe 12 O 19 was studied. Scanning Electron Microscopy confirm images reveal the nanosize of the prepared products with flake morphology. X-ray powder diffraction analysis confirmed their complete conversion to BaFe 12 O 19 hexagonal crystal phase. The results from the magnetic investigations conducted by Vibrating Sample Magnetometer (VSM) and 57 Fe Mössbauer suggested that the saturation magnetization (M s ) and the coercive field of Ba 1-2x Mn x Cu x Fe 12 O 19 hexaferrites decrease as the concentration of Cu and Mn increases. The cation distribution calculation showed that the occupancy of Fe 3+ ions is increased at 12k and 2b sites with the increase in Cu and Mn substitution. © 2017 Elsevier Ltd and Techna Group S.r.l.

Green pulsed laser ablation in liquid (PLAL) method was employed to synthesize the nanocomposites of SrGd0.03Fe11.97O19 (hard), and CoTm0.01Tb0.01Fe1.98O4 (soft) with different ratios by the application of a pulsed laser beam. The structural and morphological were carried out using XRD, SEM, TEM, and the observed magnetic behavior is elucidated in the light of these results. The magnetic hysteresis loop of the composite was found to be the convolution of the individual hysteresis loops of hard and soft magnetic materials at 300 and 10 K. This result along with the switching field distribution (SFD) plots at both temperatures revealed that the dipolar interaction between the hard-hard and soft–soft grains are more dominant than the exchange coupling interaction between the hard and soft grains. The saturation magnetization and remanent magnetization at both temperatures decreased with the increase of spinel ferrite content, whereas the coercive field increased with the increase of spinel ferrite content at low temperature.

Facile hydrothermal and sonochemistry approaches were employed to synthesize the spinel ferrite NPs Mn 0.5 Zn 0.5 Eu x Sm x Fe 2−2x O4 ( x = 0 .0–0.5), viz. hydrothermal (H-MZESF NPs) and ultrasonic (U-MZESF NPs), respectively. The products were analyzed and compared based on structure, morphology, magnetic and optical properties. The single phase and mixed spinel structures were evidenced by XRD analysis. The crystallite size of the H-MZESF and U-MZESF NPs are within the ranges 8.0–12.5 and 4.5–11.5 nm, respectively. HR-TEM, TEM and SEM analyses proved the cubic morphologies of all the products. DR% measurements indicated that an estimation of the direct energy band gap ( E g ) of all the samples was possible from Tauc plots. The E g values of the H-MZESF and U-MZESF NPs were 1.64 and 1.1 eV, respectively. Co-doping causes significant changes, particularly in the band gap of U-MZESF NPs. Magnetic field and temperature dependent VSM magnetization investigations revealed the superparamagnetic nature at RT and ferrimagnetic nature with a multi domain structure at low temperatures. The magnetization data obtained at 10 K and calculated magneton numbers are (2–2.4) times larger with respect to the data obtained at 300 K. Measured coercivities ( H C ) are in the ranges 210–690 and 318–1182 Oe for the H-MZESF and U-MZESF NPs, respectively. The calculated effective magnetocrystalline constants ( K eff ) are of the order of 104 Erg/g for both types of samples.

Barium hexaferrite is a well-known hard magnetic material. Doping using nonmagnetic cation such as Zn2+ were found to enhance magnetization owing to preferential tetrahedral site (4 f 1) occupancy of the zinc. However, the distribution of cations in hexaferrites depends on many factors such as the method of preparation, nature of the cation, and chemical composition. Here, Zn-doped barium hexaferrites (Ba1−xZnxFe12O19) were synthesized by sol-gel method. In this study, we summarized the magnetic properties of Ba1−xZnxFe12O19 (x = 0, 0.1, 0.2, 0.3) BaM, investigated by Mossbauer spectroscopy. Moreover, cation distribution was also calculated for all the products. Mossbauer parameters were determined from 57Fe Mossbauer spectroscopy and according to it, the replacement of Ba-Zn affects all parameters such as isomer shift, the variation in line width, hyperfine magnetic field, and quadrupole splitting. Cation distribution revealed the relative area of undoped BaM, 12k, 2a, and 4 f 2 positions which are close to theoretical values.

WOS: 000403590300015 In this study, Y3+ ion-substituted M-type barium hexaferrites (BaM; BaFe12O19) were fabricated via facile ceramic route. As-prepared powders were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and impedance spectroscopy. XRD (Rietveld) analyses confirmed the presence of a single characterization of all samples (except x = 0.0 and 0.1 samples). The crystallite sizes of products are found in the range of 47.2-63.2 nm. Spectral analysis (FT-IR) also presented the formation of spinel structure for all products. The ac conductivity of the substituted samples was found to initially decrease slightly with increase in Y3+ compared with unsubstituted, and then variation tendency changes at the medium substitution ranges are observed with a different attitude against temperature. In the end, the lower conductivity for high substitutions is recorded and increases as functions of frequency while it also increases with the elevation of temperature. It was observed that ac conductivities of products increased by increasing frequency which indicate that observed ac conductivity is due to both electronic and polaron hopping mechanism.

SrBi x La x Fe 12-2x O 19 (0.0≤x≤0.5) hexaferrites were synthesized by sol-gel auto combustion technique. The influence of Bi and La substitutions on structural, magnetic and optical properties were investigated by X-ray diffraction (XRD), Furrier transformed infrared (FT-IR), Vibrating sample magnetometer (VSM) and Percent diffuse reflectance spectroscopy (DR %). XRD analysis confirmed the single phase formation for all the samples, the purity of the products was also confirmed by FT-IR. The specific magnetization (σ-H) curves revealed the ferromagnetic nature of the samples. The extrapolated specific saturation magnetization (σ s ) decreases from 63.45 emu/g to 49.84 emu/g with increasing Bi, La substitutions. Similar decrement is observed from 32.6 emu/g to 25.8 emu/g at remnant magnetization (σ r ). The average crystallite size varies in a range of (43.28–51.40) nm. The coercive fields are between 4682 and 5315 Oe. Magnetic anisotropy was assigned as uniaxial and calculated effective anisotropy constants ( K eff ) are between 5.57×10 5 Ergs/g and 4.03×10 5 Ergs/g. The observed high magnitudes of intrinsic coercivity (H ci ) above 16,000 Oe confirm hard magnetic nature of the samples. The Tauc plots were used to extrapolate the direct optical energy band gap ( E g ) of hexaferrites. The E g values decreased from 1.81 to 1.68 eV with increasing Bi, La contents.

The formation of SAPO-5 molecular sieves is studied under hydrothermal conditions in the presence of a new templating agent, 1-benzyl-2,3-dimethylimidazolium hydroxide ([bzmIm]OH). The syntheses were carried out by varying the synthesis parameters, viz. crystallization temperature, heating time and reactants molar composition (SiO2, Al2O3, P2O5, [bzmIm]+, H2O) in order to investigate the role of each synthesis parameter on the formation of SAPO-5. The results showed that these synthesis parameters had significant influences on the entire crystallization process (induction, nucleation, crystal growth, and Ostwald ripening) and physicochemical properties of SAPO-5 (morphology and crystal size). Moreover, this study also demonstrated a fast hydrothermal synthesis approach where a SAPO-5 molecular sieve with hexagonal prism morphology could be crystallized within 10 h instead of days using a novel [bzmIm]OH heterocyclic template, thus offering an alternative route for synthesizing zeolite-like materials for advanced applications.

Arabian journal of chemistry 14(3), 102992 (2021). doi:10.1016/j.arabjc.2021.102992, Published by Saudi Chemical Soc., Riyadh

Yttrium doped barium hexaferrites with chemical composition BaYxFe12−xO19 (0.0≤x≤1.0) were synthesized by facile ceramic route. The effect of the yttrium ion concentration on the temperature-dependent magnetic properties of the BaYxFe12−xO19 hexaferrites (0.0≤x≤1.0) has been investigated in the temperature range of 10–300 K and magnetic field of 50 kOe. The structural, morphological, compositional and magnetic properties of the products were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM) techniques, respectively. XRD patterns demonstrated pure, single phase hexagonal crystal. The average crystallite size of the samples varies in the range of 47–63 nm. SEM images indicated hexagonal platelet-like particles. EDX measurements confirmed the expected formula of BaYFe11O19 hexaferrite. It has been observed that the preferential site occupancy of the nonmagnetic yttrium ions strongly changes the magnetic properties. The saturation magnetization value close to the bulk one was measured as 62.62 and 88.21 emu/g for 300 and 10 K, respectively. It has been found from the magnetization measurements that the saturation magnetization reaches its maximum value at x=0.4 and then decreases with further increasing of the concentration (x). As the temperature goes up, the saturation magnetization decreases due to the weakening of superexchange interaction. The coercive field increases by about three times with increasing of the concentration from x=0.0 to 1.0 due to an increasing of anisotropy field and reaches the maximum value of 3556 Oe at x=1.0.

BaBi x La x Fe (12−2 x ) O 19 (0.0≤ x ≤0.5) hexaferrites were synthesized by solid state synthesis route and the effects of Bi, La substitutions on structural, magnetic and optical properties were investigated. X-ray powder diffraction, Scanning electron microscopy, Vibrating sample magnetometer, and Percent diffuse reflectance spectroscopy were used to study the physical properties. Room temperature specific magnetization (M–H) curves revealed the ferromagnetic nature of all products. The increasing Bi, La compositions increased the magnetic properties at different magnitudes with respect to undoped BaFe 12 O 19 sample. The maximum values of remnant specific magnetization ( M r =30.3 emu/g), extrapolated specific saturation magnetization ( M s =62.12 emu/g), and magneton number ( n B =16.27) were recorded from BaBi 0.2 La 0.2 Fe 11.4 O 19 hexaferrite. The average crystallite size varies in a range of (37.35–51.36) nm. The coercive field ( H c ) of undoped hexaferrites is 1180 Oe and increased to maximum 2320 Oe belonging to BaBi 0.4 La 0.4 Fe 11.2 O 19 . Magnetic anisotropy was confirmed as uniaxial and calculated effective anisotropy constants ( K eff ) are between 4.27×10 5 Ergs/g and 5.05×10 5 Ergs/g. The high magnitudes of magnetocrystalline anisotropy ( H a ) above than 16,200 Oe revealed that all samples are magnetically hard materials. The Tauc plots were drawn to extrapolate the direct optical energy band gap ( E g ) of hexaferrites. The E g values decreased from 1.76 eV to 1.47 eV with increasing Bi, La compositions.

WOS: 000374075300165 La3+ and Bi3+ doped M-type strontium hexaferrites (SrM) were prepared by sol-gel-auto combustion. X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Simple Magnetometer (VSM), Mossbauer Spectroscopy and Novo electrical conductivity system were used for structural, morphological, and electrical characterizations of the products. The cation distribution calculations of the products were also provided. Single-phase M-type SrM with a chemical composition SrFe12-2xLaxBixO19 (0.0

Barium hexaferrite, BaFe12O19, substituted by Bi3+ and La3+ (BaBixLaxFe12−2xO19 where 0.0≤x≤0.5) were prepared by solid state synthesis route. The effect of substituted Bi3+ and La3+ ions on the structure, morphology, magnetic and cation distributions of barium hexaferrite were investigated by X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR) and Mössbauer spectroscopy. XRD powder patterns were refined by the Rietveld analysis method which confirmed the formation of single phase magneto-plumbite structure and the substitution of La3+ and Bi3+ ions into the lattice of barium ferrite. These results show that both La3+ and Bi3+ ions completely enter into barium hexaferrite lattice without disturbing the hexagonal ferrite structure. The EDX spectra confirmed the presence of all the constituents in expected elemental percentage. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on Bi and La substitutions have been determined. Cation distribution in the presently investigated hexaferrite system was estimated using the relative area of Mössbauer spectroscopy.

To study the effect of Zn substitution on structural magnetic properties and hyperfine interactions of barium hexaferrite, BaFe12−x Zn x O19 (0.0≤x≤0.3) hexaferrites were synthesized via sol-gel auto-combustion technique. Rietveld analysis of XRD powder patterns confirmed the formation of single-phase hexaferrites for all products. Due to the larger ionic size of Zn2+ as compared with Fe3+, while x increases, the lattice constant parameters increase to a small degree. Nanoplate morphology of the products is presented by SEM analyses. It was observed that both saturation magnetization and coercivity decrease in almost the same manner with zinc concentration for all substitutions. Cation distribution calculations showed that Zn2+ occupies 12k, 4 f 2, 4 f 1, and 2b sites and at the same time pushes Fe3+ ions towards 2a and 12 k 1 sites. From57Fe Mossbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting, and hyperfine magnetic field values on Zn2+ substitution have been determined.

BaLa x Bi x Fe12−2xO19 (0.0 ≤ x ≤ 0.5) hexaferrites were produced by solid-state synthesis route, and the effect of Bi3+ and La3+ substitutions on electrical and dielectric properties of barium hexaferrite material were investigated. It is noticed that ac conductivity of barium (BaM) increases slightly with ionic substitutions of both La3+ and Bi3+ and then decreases. Ac conductivity is increased with increasing frequency at lower temperatures then remains constant for higher temperatures. This type of conductivity attitude could be originated from the indication of both electronics and polaron hopping mechanisms. The dielectric properties of BaLa x Bi x Fe12−2xO19 (0.0 ≤ x ≤ 0.5) hexaferrites represent a very interesting tunability as functions of frequency, temperature, and Bi3+ and La3+ ions.

Ba 1−x Zn x Fe 12 O 19 (0.0≤x≤0.3) hexaferrites were produced via sol-gel auto combustion technique. XRD patterns show that all the samples are single-phase M-type barium hexaferrite (BaM). Scanning electron microscopy (SEM) revealed that grains have a size range of 0.5–2 µm. The magnetic hysteresis (σ-H) loops revealed the ferromagnetic nature of NPs. The average crystallite sizes were calculated by applying Scherrer equation on the base of XRD powder patterns of all samples and found to be in the range of 16.78–48.34 nm. In particular, Ba 1−x Zn x Fe 12 O 19 (0.0≤x≤0.3) hexaferrites have suitable magnetic characteristics (saturation magnetization in a range of 63.00–67.70 emu/g and coercive field in a range of 822–1275 Oe) for magnetic recording and permanent magnets. Effective crystalline anisotropy constants ( K eff ) are between 4.20×10 5 and 4.84×10 5 Erg/g. Magnetic moment increased by the substitution of non-magnetic Zn 2+ ions. The anisotropy field ( H a ) or intrinsic coercivity values above 13255 Oe reveals that all samples are magnetically hard materials. Tauc plots were drawn to specify the direct optical energy band gap ( E g ) of NPs. The E g values are in a narrow range between 1.69 eV and 1.76 eV.

A simple sol-gel auto combustion process was used to synthesize La 3+ substituted M-type strontium hexaferrite, Sr 1-x La x Fe 12-x O 19 (0.0≤x≤ 0.5). Structural, magnetic, and optical behavior as a function of La 3+ substitutions were investigated by Fourier transformed infrared spectroscopy (FT-IR). X-ray powder diffraction (XRD). Scanning electron microscopy (SEM), Mossbauer spectroscopy, vibrating sample magnetometer (VSM), and Diffuse reflectance spectroscopy (DRS). XRD data showed single phase magnetoplumbite structure and Rietveld analysis confirmed P 6 3 / mmc space group for all the series. The average crystallite size was found to be in the range of 43.2–48.4 nm. The variation in line width, isomer shift, quadrupole splitting, relative area and hyperfine magnetic field values have been determined from 57 Fe Mossbauer spectroscopy data. The fittings accounted for the Fe 2+ /Fe 3+ charge compensation mechanism at the 2a site due to replacement of Sr 2+ by La 3+ . The saturation magnetization (σ s ) decreases from 57,21 to 63,23 emu/g and remnant magnetization (σ r ) decreases from 35.6 emu/g to 28.7 emu/g with increasing La substitution. The decrement is sharper at coercive field (H c ) from maximum value of 5325 to minimum 1825 Oe. Demagnetizing factor ( N ) is 3 times more for the x=0.3, 0.4, and 0.5. However all samples exhibit ferromagnetic behavior at room temperature. Magnetic anisotropy of Hexaferrites was detected as uniaxial and effective anisotropy constants ( K eff ) were between 5.93×10 5 and 4.76×10 5 Ergs/g. The high magnitudes of anisotropy fields ( H a ) in the range of 13863–15574 Oe reveal that all hexaferrites are magnetic hard materials. Tauc plots were applied to extrapolate the direct optical energy band gap ( E g ) of hexaferrites. The E g values decreased from 1.83 to 1.34 eV with increasing La content.

Single-phase M-type hexagonal ferrites, SrBi x Fe 12− x O 19 (0.0≤ x ≤1.0), were prepared by a co-precipitation assisted ceramic route. The influence of the Bi 3+ substitution on the crystallization of ferrite phase has been examined using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Mossbauer spectroscopy. The XRD data show that the nanoparticles crystallize in the single hexagonal magnetoplumbite phase with the crystallite size varying between 65 and 82 nm. A systematic change in the lattice constants, a = b and c , was observed because of the ionic radius of Bi 3+ (1.17 A) being larger than that of Fe 3+ ion (0.64 A). SEM analysis indicated the hexagonal shape morphology of products. From 57 Fe Mossbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on Bi substitutions have been determined.

In the present study, SrBixFe12-xO19 (0.0

WOS: 000380417600023 In this study, it was aimed to synthesize and to investigate the AC conductivity mechanism and dielectric properties of BaBixLaxYxFe12-3xO19 (0.0

SrBixLaxYxFe12-3xO19 (00.0≤x≤0.33) hexaferrites were produced via sol-gel auto combustion. XRD patterns show that all the samples are single-phase M-type strontium hexaferrite (SrM). The magnetic hysteresis (σ-H) loops revealed the ferromagnetic nature of nanoparticles (NPs). The coercive field decreases from 4740 Oe to 2720 Oe with increasing ion content. In particular, SrBixLaxYxFe12-3xO19 NPs with x = 0.0, 0.1, 0.2 have suitable magnetic characteristics (σs = 62.03-64.72 emu/g and Hc = 3105-4740 Oe) for magnetic recording. The intrinsic coercivity (Hci) above 15000 Oe reveals that all samples are magnetically hard materials. Tauc plots were used to specify the direct optical energy band gap (Eg) of NPs. The Eg values are between 1.76 eV and 1.85 eV. 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting, relative area and hyperfine magnetic field values on Bi3+ La3+ and Y3+ substitutions have been determined. © 2016 Elsevier Ltd. All rights reserved.