Role of vanadium ions substitution on spinel MnCo2O4 towards enhanced electrocatalytic activity for hydrogen generation.

Improving efficient electrocatalysts (ECs) for hydrogen generation through water splitting is of significant interest in tackling the upcoming energy crisis. Sustainable hydrogen generation is the primary prerequisite to realizing the future hydrogen economy. This work examines the electrocatalytic activity of hydrothermally prepared vanadium doped MnCo spinel oxide microspheres (MC), MnVxCo2-xO4 (Vx-MnCo MC, where x ≤ 0.4) in the HER (hydrogen evolution reaction) process. Magnetization measurements demonstrated a paramagnetic (at high temperatures) to a ferrimagnetic (at low temperatures) transition below the Curie temperature (Tc) in all the samples. The magnetization is found to intensify with the rising vanadium content of MCs. The optimized catalyst Vx-MnCo MCs (x = 0.3) outperformed other prepared ECs with a Tafel slope of 84 mV/dec, a low onset potential of 78.9 mV, and a low overpotential of 85.9 mV at a current density of 10 mA/cm2, respectively. The significantly improved HER performance of hydrothermally synthesized Vx-MnCo MCs (x = 0.3) is principally attributable to many exposed active sites, accelerated electron transport at the EC/electrolyte interface, and remarkable electron spectroscopy for chemical analysis (ECSA) value was found ~ 11.4 cm2. Moreover, the Vx-MnCo MCs (x = 0.3) electrode exhibited outstanding electrocatalytic stability after exposure to 1000 cyclic voltametric cycles and 36 h of chronoamperometric testing. Our results suggest a feasible route for developing earth-abundant transition metal oxide-based EC as a superior electrode for future water electrolysis applications.

Insights of Platinum Drug Interaction with Spinel Magnetic Nanocomposites for Targeted Anti-Cancer Effect.

In nanotherapeutics, gaining insight about the drug interaction with the pore architecture and surface functional groups of nanocarriers is crucial to aid in the development of targeted drug delivery. Manganese ferrite impregnated graphene oxide (MnFe2O4/GO) with a two-dimensional sheet and spherical silica with a three-dimensional interconnected porous structure (MnFe2O4/silica) were evaluated for cisplatin release and cytotoxic effects. Characterization studies revealed the presence of Mn2+ species with a variable spinel cubic phase and superparamagnetic effect. We used first principles calculations to study the physisorption of cisplatin on monodispersed silica and on single- and multi-layered GO. The binding energy of cisplatin on silica and single-layer GO was ~1.5 eV, while it was about double that value for the multilayer GO structure. Moreover, we treated MCF-7 (breast cancer cells) and HFF-1 (human foreskin fibroblast) with our nanocomposites and used the cell viability assay MTT. Both nanocomposites significantly reduced the cell viability. Pt4+ species of cisplatin on the spinel ferrite/silica nanocomposite had a better effect on the cytotoxic capability when compared to GO. The EC50 for MnFe2O4/silica/cisplatin and MnFe2O4/GO/cisplatin on MCF-7 was: 48.43 µg/mL and 85.36 µg/mL, respectively. The EC50 for the same conditions on HFF was: 102.92 µg/mL and 102.21 µg/mL, respectively. In addition, immunofluorescence images using c-caspase 3/7, and TEM analysis indicated that treating cells with these nanocomposites resulted in apoptosis as the major mechanism of cell death.

Preliminary results of blood growth differentiation factor-9 (GDF-9) measurement in cats: future aspects of GDF-9 on stage of the cycle and spaying history.

Growth differentiation factor-9 (GDF-9), an oocyte-derived member of the TGF-ß superfamily, plays an essential role in regulation of follicular development. This study aimed to determine the cyclic changes in serum GDF-9 concentration, compare its levels before and after ovariohysterectomy (OHE), and investigate its potential as a tool in ovarian remnant syndrome (ORS) diagnosis in cats. GDF-9 measurements were performed on 50 cats referred for routine OHE. The stage of the estrous cycle was determined by vaginal cytology and measurement of serum estradiol and progesterone levels was carried out to detect the cyclic changes in circulating GDF-9. One week after OHE, serum samples were collected again from 30 cats to reveal differences in GDF-9 levels. GDF-9 levels in the follicular phase were significantly higher than those in the interestrus (p⟨0.05). The postoperative analysis could be performed. GDF-9 levels slightly decreased one week after OHE (p=0.053). In conclusion, blood GDF-9 levels change during the estrous cycle, and may decrease with age in cats. However, further studies are needed to reveal the efficiency of GDF-9 in ORS diagnosis.

The anti-proliferative and apoptotic effects of curcumin on feline mammary gland tumor cells in vitro.

BACKGROUND: Feline mammary gland tumors (FMGTs) are the third most diagnosed tumors in cats. Feline mammary gland tumors have aggressive biological behavior and poor response to both surgical and medical treatments, thus, new therapeutic approaches are essential to improve. Curcumin (CUR) is a polyphenol component exhibiting anti-cancer effects and induces apoptosis through different mechanisms especially in human breast cancer. However, there is no study investigating the effects of CUR on FMGTs. AIMS: The aim of this study was to determine the anti-proliferative and apoptotic effects of CUR on primary cell lines from FMGT tissue samples of two cases classified as carcinoma-simple, tubular type (grade III). METHODS: The cytotoxic effect of CUR was determined by water-soluble tetrazolium salt-1 (WST-1) assay. Annexin V, cell cycle, and acridine orange (AO) analyses were performed to determine the apoptotic effect of CUR. RESULTS: Our results showed that CUR had an anti-proliferative and apoptotic effect through induction of apoptosis and cell cycle arrest (G0/G1) on FMGT cells. CONCLUSION: Therefore, this is the first study that shows the effects of CUR on FMGTs. However, further molecular studies are required to compare the effects of CUR on different histopathological phenotypes and to determine the further molecular mechanisms including the potential apoptotic and cellular pathways affected by CUR.

Features of structure, magnetic state and electrodynamic performance of SrFe12-xInxO19.

Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84-0.65 µm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the µ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.

Nasal secretory protein changes following intravenous choline administration in calves with experimentally induced endotoxaemia.

Nasal secretory fluid proteomes (NSPs) can provide valuable information about the physiopathology and prognosis of respiratory tract diseases. This study aimed to determine changes in NSP by using proteomics in calves treated with lipopolysaccharide (LPS) or LPS + choline. Healthy calves (n = 10) were treated with LPS (2 µg/kg/iv). Five minutes after LPS injection, the calves received a second iv injection with saline (n = 5, LPS + saline group) or saline containing 1 mg/kg choline (n = 5, LPS + choline group). Nasal secretions were collected before (baseline), at 1 h and 24 h after the treatments and analysed using label-free liquid chromatography-tandem mass spectrometry (LCMS/MS). Differentially expressed proteins (>1.2-fold-change) were identified at the different time points in each group. A total of 52 proteins were up- and 46 were downregulated at 1 h and 24 h in the LPS + saline group. The upregulated proteins that showed the highest changes after LPS administration were small ubiquitin-related modifier-3 (SUMO3) and glutathione peroxidase-1 (GPX1), whereas the most downregulated protein was E3 ubiquitin-protein ligase (TRIM17). Treatment with choline reduced the number of upregulated (32 proteins) and downregulated proteins (33 proteins) in the NSPs induced by LPS. It can be concluded that the proteome composition of nasal fluid in calves changes after LPS, reflecting different pathways, such as the activation of the immunological response, oxidative stress, ubiquitin pathway, and SUMOylation. Choline treatment alters the NSP response to LPS.

Synthesis of Ni0.5Co0.5-xCdxFe1.78Nd0.02O4 (x ≤ 0.25) nanofibers by using electrospinning technique induce anti-cancer and anti-bacterial activities.

Here we report the electrospinning synthesis of Cd-substituted Ni-Co ferrite Ni0.5Co0.5-xCdxFe1.78Nd0.02O4 (x ≤ 0.25) nanofiber (NFs) with a very low concentration of Nd as a dopant. The structure and surface morphology of the Ni0.5Co0.5-xCdxFe1.78Nd0.02O4 (x ≤ 0.25) NFs were analyzed by X-ray powder pattern (XRD), transmission and scanning electron microscopes (TEM) along with Energy-dispersive X-ray (EDX). We have examined the biological applications of the Ni0.5Co0.5-xCdxFe1.78Nd0.02O4 (x ≤ 0.25) NFs on both cancerous cells and bacterial cells. We have found that Ni0.5Co0.5-xCdxFe1.78Nd0.02O4 (x ≤ 0.25) NFs produced inhibitory action on the human colorectal carcinoma cells (HEK-293) and also showed inhibitory action on the bacterial strains (S. aureus and E. coli) respectively. Finally, this is the first report on the synthesis of Cd- substituted Co-Ni ferrite nanofibers using electrospinning technique exhibiting anti-cancer and anti-bacterial activities.Communicated by Ramaswamy H. Sarma.

Synthesis of niobium substituted cobalt-nickel nano-ferrite (Co0.5Ni0.5NbxFe2-xO4 (x ≤ 0.1) by hydrothermal approach show strong anti-colon cancer activities.

The combination of two or more nanoparticles found to be effective strategy to synthesize nanocomposites for better drug delivery and treatment. In the present study, we have combined cobalt (Co), nickel (Ni), niobium (Nb), and iron oxide (Fe2O4) and prepared niobium substituted cobalt-nickel nano-ferrite nanocomposites (Co0.5Ni0.5NbxFe2-xO4 (x ≤ 0.1) by using hydrothermal approach. We have characterized the structure and morphology of nanocomposites by using XRD, EDX, TEM and SEM methodologies. We have examined the impact of nanocomposites (Co0.5Ni0.5NbxFe2-xO4 (x ≤ 0.1) on cancerous cells (human colorectal carcinoma cells, HCT-116) by using MTT assay. We have also checked the impact of nanocomposites on normal and non-cancerous cells (human embryonic kidney cells, HEK-293) to confirm the specificity of their actions. Post- 48 h treatment of Co0.5Ni0.5NbxFe2-xO4 (x ≤ 0.1) led to dose-dependent inhibition of cancer cells growth and proliferation. However, no cytotoxic effect was observed on the normal cells (HEK-293). In addition, DAPI stained nuclear DNA staining analysis demonstrates that the Co0.5Ni0.5NbxFe2-xO4 (x ≤ 0.1) treatment also caused nuclear DNA disintegration which is the marker for programmed cell death. These results demonstrate that synthesized nanocomposites Co0.5Ni0.5NbxFe2-xO4 (x ≤ 0.1) selectively target the colon cancer cells and induce cancer cell death.Communicated by Ramaswamy H. Sarma.

Exploring the influence of varying pH on structural, electro-optical, magnetic and photo-Fenton properties of mesoporous ZnFe2O4 nanocrystals.

An economically viable and superficial technique was indorsed to yield ZnFe2O4 nanocrystals in the system to investigate the impact of pH variation on the optical, structural, electrical, and magnetic properties of as-prepared nanocrystals. The as-synthesized ZnFe2O4 nanocrystals were premeditated with the application protracted to degradation of Methylene blue organic dye. The results specify that the pH plays the utmost decisive facet in photo-Fenton recital. From XRD (X-Ray diffraction) analyses, it was confirmed that as-synthesized nanocrystals belong to a cubic Fd3m crystal phase. The crystallite size was also determined by the Scherrer formula and it was noticed that as the pH rises the crystallite size also increased. FT-IR (Fourier Transform Infrared) analysis depicts two absorption peaks âˆ¼ 500 and ∼600 cm-1 that represents tetrahedral (Td) and octahedral (Oh) sites. Using TEM (Transmission Electron Microscopy), the morphology was observed to be spherical particles with some agglomeration. Photoluminescence and UV-visible spectral studies were performed to investigate the optical properties. The bandgap energy was seen to decrease as the pH increased. Using BET analysis, the surface area for the as-synthesized samples was found to decrease on increasing the pH. The reaction results showed that the ZnFe2O4 has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe2O4 produced by the co-precipitation route exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 99.2% of decolorization at 100 min. Therefore, ZnFe2O4 particles rapidly prepared by the co-precipitation route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. With the help of VSM analysis, the coercivity and other magnetic properties were determined for the as-synthesized nanocrystal with plays a significant role in photocatalytic recyclability, which intends to premediate that the prepared nanocrystals can be used in industrial persistence.

Synthesis of Dy-Y co-substituted manganese­zinc spinel nanoferrites induced anti-bacterial and anti-cancer activities: Comparison between sonochemical and sol-gel auto-combustion methods.

This study described the beneficial properties of ultrasonic irradiation approach to synthesize the spinel-type Dy-Y co-substituted Mn-Zn nanospinel ferrites (NSFs). We have used two different approaches like citrate sol-gel combustion and ultrasonic irradiation routes to produced series of Mn0.5Zn0.5Fe2-2x(DyxYx)O4 (0.0 ≤ x ≤ 0.05) NSFs (DyY-MnZn NSFs). The structure and morphology of NSFs X-was examined by using XRD, EDX, SEM and TEM methods. We have found that spinel ferrites and hematite phase in DyY-MnZn NSFs produced by citrate sol-gel, while DyY-MnZn NSFs created by ultrasonic irradiation contain a pure phase of spinel ferrite. TEM analysis revealed the spherical nanoparticles with fairly uniform size. We have also analyzed the biological applications of DyY-MnZn NSFs prepared by both methods (ultrasonication and sol-gel) by examining their anti-cancer and anti-bacterial (Escherichia coli and Staphylococcus aureu) activities. We have found that both methods produced inhibitory actions on colon cancer cells (HCT-116) and bacterial cells, whereas, no inhibitory action was observed when examined on normal and non-cancerous cells (HEK-293).

Synthesis and biological characterization of Mn0.5Zn0.5EuxDyxFe1.8-2xO4 nanoparticles by sonochemical approach.

Metallic nanoparticles (NPs) possess unique properties which makes them attractive candidates for various applications especially in field of experimental medicine and drug delivery. Many approaches were developed to synthesize divers and customized metallic NPs that can be useful in many areas such as, experimental medicine, drug design, drug delivery, electrical and electronic engineering, electrochemical sensors, and biochemical sensors. Among different metallic nanoparticles, manganese (Mn) NPs are the most prominent materials, in the present study, we have synthetized unique Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs by using ultrasonication method (x ≤ 0.1). The structure, and surface morphology of Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs was characterized by XRD, SEM, TEM and EDX methods. We have examined the biological effects of Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs on both normal (HEK-293) and cancerous (HCT-116) cells. We have found that the treatment of Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs post 48 h, showed significant decline in cancer cells population as revealed by MTT assay. The IC50 value of Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs was ranged between (2.35 µg/mL to 2.33 µg/mL). To check the specificity of the actions, we found that the treatment of Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs did not produce any effects on the normal cells, which suggest that Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs selectively targeted the cancerous cells. The anti-bacterial properties of Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs were also evaluated by MIC and MBC assays. We suggest that Mn0.5Zn0.5DyxEuxFe1.8-2xO4 NPs produced by sonochemical method possess potential anti-cancer and anti-bacterial capabilities.

Peculiarities of the microwave properties of hard-soft functional composites SrTb0.01Tm0.01Fe11.98O19-AFe2O4 (A = Co, Ni, Zn, Cu, or Mn).

Herein, we investigated the correlation between the chemical composition, microstructure, and microwave properties of composites based on lightly Tb/Tm-doped Sr-hexaferrites (SrTb0.01Tm0.01Fe11.98O19) and spinel ferrites (AFe2O4, A = Co, Ni, Zn, Cu, or Mn), which were fabricated by a one-pot citrate sol-gel method. Powder XRD patterns of products confirmed the presence of pure hexaferrite and spinel phases. Microstructural analysis was performed based on SEM images. The average grain size for each phase in the prepared composites was calculated. Comprehensive investigations of dielectric properties (real (ε') and imaginary parts (ε'') of permittivity, dielectric loss tangent (tan(δ)), and AC conductivity) were performed in the 1-3 × 106 Hz frequency range at 20-120 °C. Frequency dependency of microwave properties were investigated using the coaxial method in frequency range of 2-18 GHz. The non-linear behavior of the main microwave properties with a change in composition may be due to the influence of the soft magnetic phase. It was found that Mn- and Ni-spinel ferrites achieved the strongest electromagnetic absorption. This may be due to differences in the structures of the electron shell and the radii of the A-site ions in the spinel phase. It was discovered that the ionic polarization transformed into the dipole polarization.

A study on the spectral, microstructural, and magnetic properties of Eu-Nd double-substituted Ba0.5Sr0.5Fe12O19 hexaferrites synthesized by an ultrasonic-assisted approach.

In this study, an examination on the spectral, microstructural, and magnetic characteristics of Eu-Nd double-substituted Ba0.5Sr0.5Fe12O19 hexaferrites (Ba0.5Sr0.5NdxEuxFe12-2xO19 (x = 0.00-0.05) HFs) fabricated by an ultrasonic-assisted approach has been presented. An UZ SONOPULS HD 2070 ultrasonic homogenizer with frequency of 20 kHz and power of 70 W was used. The chemical bonding, structure and the morphology of the products were evaluated by Fourier-Transform Infrared (FT-IR) Spectroscopy, XRD (X-ray diffraction), scanning and transmission electron microscopy and techniques. The textural properties of the prepared nanomaterials were examined by using the Brunauer-Emmett-Teller (BET) method. The magnetic properties were studied using a vibrating sample magnetometer (VSM) at room temperature (RT) and low temperature 10 K. The magnitudes of various magnetic parameters including Ms (saturation magnetization), Mr (remanence) and Hc (coercivity) were estimated and evaluated. The M-H loops revealed the hard ferrimagnetic nature for all products at both temperatures. The Ms and Mr values showed a decreasing tendency with increasing degree of Eu3+ and Nd3+ substitutions whereas Hc values displayed an increasing trend. At RT, Ms, Mr and Hc values lie in the ranges of 63.0-68.8 emu·g-1, 24.6-39.2 emu·g-1 and 2252.4-2782.1 Oe, respectively. At 10 K, the values of Ms, Mr and Hc lie between 87.5-97.1 emu·g-1, 33.5-40.1 emu·g-1 and 2060.6-2417.2 Oe, respectively. The observed magnetic properties make the prepared products promising candidates to be applied in the recording media.

Sonochemical synthesis of Dy3+ substituted Mn0.5Zn0.5Fe2-xO4 nanoparticles: Structural, magnetic and optical characterizations.

Mn0.5Zn0.5DyxFe2-xO4 (x ≤ 0.03) nanoparticles (NPs) were fabricated by using Ultrasonic irradiation using UZ SONOPULS HD 2070 ultrasonic homogenizer (frequency of 20 kHz and power of 70 W). Structural and morphological analyses were performed via XRD (X-ray powder diffractometer), TEM (Transmission electron microscopy) and SEM (Scanning electron microscopy). XRD presented the formation of Mn-Zn ferrite with average crystal size in 11 to 18 nm range. Direct optical energy band gaps (Eg) were specified applying diffuse reflectance investigations. Eg values are in a small band range of 1.61-1.67 eV. Low (10 K) and room temperature VSM data were recorded applying ±90 kOe external magnetic field. All samples exhibit superparamagnetic properties at RT. Magnetization parameters significantly increase due to coordination of Dy3+ rare earth ions. Magnetic moment per molecule (nB) increases from 0.952 µB to 1.137 µB and from 2.312 µB to 2.547 µB at RT and at 10 K data respectively. 10 K coercivity (Hc) values decrease from 260 Oe to 43 Oe. All samples have squareness ratios (SQR) of 0.231-0.400 range assigning the multi-domain structure at 10 K. ZFC-FC magnetization curves that were registered for two selected samples exhibit a divergence and a sharp drop below their Tpeak positions. This event is typically correlated to the collective freezing of system and spin-glass-like phase. Real part AC susceptibility data slightly shift toward high temperature regions with increasing frequencies. Critical Slowing Down (CSD) model explained the spin dynamics of interacting NPs consistently with literature and proved the spin-glass behavior of samples at low temperatures.

Ni0.4Cu0.2Zn0.4TbxFe2-xO4 nanospinel ferrites: Ultrasonic synthesis and physical properties.

The Fe3+ ions were replace with Tb3+ ions as highly paramagnetic rare earth element within the structure of Ni0.4Cu0.2Zn0.4Fe2O4 nano-spinel ferrites (NSFs). The structural, magnetic, spectroscopic and optic properties have been studied in details. All products have been synthesized via ultrasonic approach via Qsonica ultrasonic homogenizer, frequency: 20 kHz and power: 70 W for 60 min. No annealing or calcination process was applied for any product. The microstructural analysis of products has been done via X-ray powder diffractometry (XRD) which presented the cubic spinel structure with nanosized distribution of all. The cubic morphology of all products were confirmed by both HR-TEM and FE-SEM. Optical band gap (Eg) values were assessed by applying %DR (percent diffuse reflectance) analysis and Kubelka-Munk theory. The Tauc schemes showed that Eg values are in a narrow range (1.87-1.98 eV). The quadrupole splitting, line width, hyperfine magnetic field, isomer shift values and cation distribution have been determined from 57Fe Mossbauer analysis. The magnetic properties of various nanoparticles have been obtained from VSM (vibration sample magnetometer) measurements at 10 and 300 K (RT). The magnetic results revealed superparamagnetic and soft ferromagnetic traits at 10 and 300 K, respectively. Ms (saturation magnetization) and Mr (remanence) initially increase with increasing Tb3+ substituting level up to x = 0.06 then diminish for further x values. Hc (coercivity) shows an opposite variation tendency of Ms and Mr. The observed magnetic traits are deeply discussed in relation with the structure, morphology, magnetic moments and cation distributions.

Structural, magnetic, optical properties and cation distribution of nanosized Co0.7Zn0.3TmxFe2-xO4 (0.0 ≤ x ≤ 0.04) spinel ferrites synthesized by ultrasonic irradiation.

This study expressed the influence of Tm substitution on the structural, optical and magnetic properties of Co-Zn spinel ferrites (Co0.7Zn0.3TmxFe2-xO4 (0.0 ≤ x ≤ 0.04)). The different compositions were synthesized by sonochemical method using Qsonica ultrasonic homogenizer, frequency: 20 kHz and power: 70 W for 60 min. XRD patterns proved the presence of single-phase spinel ferrites with crystallites size in the 8-10 nm range. Cation distribution approved the occupancy of octahedral (B) site by Tm. The morphology and the elements stoichiometry are obtainable through FE-SEM, EDX and elemental mapping. Optical band gap (Eg) values were estimated via DR % (percent diffuse reflectance) investigations and Kubelka-Munk theory. Tauc plots revealed that direct Eg values are ranging between 1.49 and 1.68 eV. The analyses of magnetization versus magnetic field, M(H), were performed. The following magnetic parameters like saturation magnetization Ms, squareness ratio (SQR = Mr/Ms), magnetic moment nB, coercivity Hc and remanence Mr have been evaluated. M(H) curves revealed the superparamagnetic (SP) at RT and ferromagnetic property at 10 K. It was showed that the Tm3+ substitutions significantly affect the magnetic properties of host spinel ferrites. An increasing trend in the Ms, Mr, Hc, and nB values was noticed for lower Tm3+ substitution content.

Sonochemical synthesis and physical properties of Co0.3Ni0.5Mn0.2EuxFe2-xO4 nano-spinel ferrites.

Nanoparticles (NPs) of composition Co0.3Ni0.5Mn0.2EuxFe2-xO4, where 0.00 ≤ x ≤ 0.10 (hereafter called CNMEuF) were synthesized by sonochemical approach using UZ SONOPULS HD 2070 ultrasonic homogenizer (frequency of 20 kHz and power of 70 W). As-synthesized samples were characterized thoroughly to determine the effects of europium ions (Eu3+) substitution on their structure, morphology and magnetic traits. Structural analyses of the synthesized NPs confirmed their high purity and crystalline cubic phases. Percent diffuse reflectance (%DR) data and Kubelka-Munk theory were exploited to evaluate the optical band gap energies of the studied CNMEuF NPs. Values of optical band gap energies obtained from the Tauc plots were observed in the range of 1.47-1.58 eV. The hysteresis loops (at room temperature and 10 K) of synthesized NPs were analyzed to determine their magnetic properties. These NPs disclosed superparamagnetic and hard ferrimagnetic character at room temperature and 10 K, respectively. With exception, the sample with x = 0.10 revealed soft ferrimagnetic behavior at 10 K. Eu3+ doping was shown to have significant influence on the structure and magnetic attributes of the proposed CNMEuF NPs. Values of various magnetic parameters of proposed compositions were reduced with the increase in Eu3+ dopant contents.

Sonochemical synthesis of Eu3+ substituted CoFe2O4 nanoparticles and their structural, optical and magnetic properties.

Magnetic, optic and microstructural properties of ultrasonically synthesized CoEuxFe2-xO4 (x ≤ 0.1) nanoferrites (NFs) have been examined in this study. After sonochemical synthesis, XRD and FT-IR analyses confirmed the purity, the structure (cubic spinel structure and Fd3m space group) and the spectral properties of the spinel ferrite samples. The spherical morphology and chemical compositions of the products were observed via transmission and scanning electron microscopes along with EDX and elemental mapping. Percent diffuse reflectance (%DR) was used for optical investigation. Optical band gaps (Eg) were estimated utilizing Kubelka-Munk theory and Tauc equation. Eg values are in a narrow band of 1.34 to 1.44 eV. The magnetic parameters like Ms (saturation magnetization), SQR = Mr/Ms (squareness ratio), nB (magnetic moment), Hc (coercivity) and Mr (remanence) have been evaluated by analyzing measurements of magnetization versus magnetic field performed at room (RT; T = 300 K) and low (T = 10 K) temperatures. It is showed that the different produced CoEuxFe2-xO4 (0.00 ≤ x ≤ 0.10) nanospinel ferrites present superparamagnetic (SPM) nature at RT. At low temperature, the various produced CoEuxFe2-xO4 (x ≤ 0.08) nanospinel ferrites display ferrimagnetic (FM) nature. With exception, the x = 0.10 sample exhibit SPM behavior at T = 10 K. It is noticed that the Eu3+ substitutions alter in a significant way on the magnetic data. A decreasing trend in the Ms, Mr and nB values was noted with Eu3+ substitutions.

The Conductivity and Dielectric Properties of Neobium Substituted Sr-Hexaferrites.

The Nb3+ ion substituted Sr hexaferrites (SrNbxFe12-xO19 (x = 0.00-0.08) hexaferrites (HFs)) were fabricated via a citrate-assisted sol-gel approach. X-ray powder diffractometer analysis affirmed the pureness of all products. The crystallite sizes of the products which were estimated from Scherrer equation were in the 36-40 nm range. The chemical component of the samples was proved by Energy-dispersive X-ray spectroscopy (EDX) and Elemental mapping. The hexagonal morphology of all products was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM). The electrical conduction mechanisms and dielectric properties of a variety of Nb3+ions-substituted SrNbxFe12-xO19 HFs were investigated by a complex impedance system. Dielectric parameters such as conductivity, dielectric constant, dielectric loss, dielectric tangent loss and complex modulus, were studied at temperatures up to 120 °C in a frequency range varying from 1.0 Hz to 3.0 MHz for several Nb ratios. The frequency dependence of the conductivity was found to comply with the power law with diverse exponents at all frequencies studied here. Subsequently, incremental tendencies in dc conductivity with temperature indicate that the substituted Sr-HFs leads to a semiconductor-semimetal like behavior. This could be attributable to a feature of conduction mechanism which is based on the tunneling processes. Additionally, the dielectric dispersion pattern was also explained by Maxwell-Wagner polarization in accordance with the Koop's phenomenological theory.

Magnetic Attributes of NiFe2O4 Nanoparticles: Influence of Dysprosium Ions (Dy3+) Substitution.

This paper reports the influence of dysprosium ion (Dy3+) substitution on the structural and magnetic properties of NiDyxFe2-xO4 (0.0 ≤ x ≤ 0.1) nanoparticles (NPs) prepared using a hydrothermal method. The structure and morphology of the as-synthesized NPs were characterized via X-ray diffraction (XRD), scanning and transmission electron microscope (SEM, and TEM) analyses. 57Fe Mössbauer spectra were recorded to determine the Dy3+ content dependent variation in the line width, isomer shift, quadrupole splitting, and hyperfine magnetic fields. Furthermore, the magnetic properties of the prepared NPs were also investigated by zero-field cooled (ZFC) and field cooled (FC) magnetizations and AC susceptibility measurements. The MZFC (T) results showed a blocking temperature (TB). Below TB, the products behave as ferromagnetic (FM) and act superparamagnetic (SPM) above TB. The MFC (T) curves indicated the existence of super-spin glass (SSG) behavior below Ts (spin-glass freezing temperature). The AC susceptibility measurements confirmed the existence of the two transition temperatures (i.e., TB and Ts). Numerous models, e.g., Neel-Arrhenius (N-A), Vogel-Fulcher (V-F), and critical slowing down (CSD), were used to investigate the dynamics of the systems. It was found that the Dy substitution enhanced the magnetic interactions.