Search

Ba1-xPbxFe12O19 (x = 0.0 to 1.0) was synthesized by a co-precipitation method at room temperature. Parent compounds used were oxides of iron and lead, while barium was used in a carbonated form. Acids and Di-H2O were used as a solute. Na-Alkaline solution with molarity 5 was used for fertilization. Iron to barium ratio was kept 12. Washing played a vital role to minimize the impurities. It also improved the homogeneity. Semi-liquid-type material was obtained after overnight drying in an oven. It was further transformed into powder form which further processed, and pellets were formed for characterizations. These pellets were sintered for 3 h in a box furnace at 965 ± 5 °C. Growth along with its surface and dimensional modifications were analyzed by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). It showed almost 70% phase purity. Lead physical properties like higher mobility, ionic radii (Pb2+ = 1.76 Å & Ba = 1.37 Å), and occupancy preference were the important reasons for the investigation during heat treatment. Lead doping in R blocks was another big reason for these variations. SEM showed modification in all respect in each successive composition. Frequency-based analysis of whole composition from room temperature to 973 K with a step of 100 has discussed. Frequency precession analyzer was used from 20 Hz to 3 MHz for each sample. Obtained data was used to calculate dielectric constant, dielectric loss and dielectric loss factor, and AC conductivity. Determined parameters were further studied with respect to respective temperatures during whole applied frequency spectrum. The study contains almost different behaviors from each other. Prime factors were heat treatment, impurities, dopant (x), and variation of applied electric field. These behaviors and trends could be useful for today's modern IT applications and other related electrical and electronic components like capacitors. It could also be useful for high frequency microwave and related network applications. [ABSTRACT FROM AUTHOR]

The strong inter-planes coupling in cuprates is of immense importance in the field of high Tc superconductivity. For this purpose, Cu0.5Tl0.5Ba2Ca2Cu3O10−δ (CuTl-1223) superconducting phase was selected and Cu 3d9 was partially replaced with Zn 3d10 in CuO2 planes. The decrease in c-axis length and improvement in infield superconducting transport properties were observed after Zn doping at Cu sites in Cu0.5Tl0.5Ba2Ca2Cu3-xZnxO10−δ; x = 0, 1, and 2 superconducting phase. A continuous decrease in normal state resistivity and increase in Tc (0) values under applied magnetic field (i.e., from H = 0 to 5 T) was observed, which was an evidence of diminishing the anisotropic behavior, enhancement in coherence length, Fermi wave vector, and Fermi velocity of the carriers due to the improvement of inter-plane coupling associated with the reduction of Jahn-Teller distortions after Zn doping in CuO2 planes of CuTl-1223 system. The suppression of active Jahn-Teller distortions with Zn doping has reduced the volume of unit cell and enhanced the three dimensional (3D) superconducting properties of CuTl-1223 phase. The improvement in infield superconducting transport properties can also be attributed to the homogeneous and optimal charge distribution in conducting CuO2/ZnO2 planes of CuTl-1223 superconductor. [ABSTRACT FROM AUTHOR]

Sol-gel and solid-state reaction methods were used to synthesize diamond nanoparticles (DNPs) and (DNPs)x/CuTl-1223 (x = 0, 0.25, 0.50, and 1.00 wt.%) nanoparticle-superconductor composites, respectively. Effects of these DNPs on structural, morphological, compositional, and transport properties of CuTl-1223 superconducting phase were investigated by different experimental techniques such as X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and resistivity versus temperature (R-T) measurements. The unchanged crystal structure and stoichiometry of host CuTl-1223 superconducting matrix with addition of DNPs gave evidence about the dispersion of nanoparticles at the grain boundaries of the host matrix, which may heal up the inter-granular voids and pores resulting in enhanced inter-grain connectivity. Critical transition temperature Tc (0) and hole concentration of CuTl-1223 superconductor were observed to be increased with addition of DNPs up to a certain optimum value (i.e. x = 0.5 wt.%). [ABSTRACT FROM AUTHOR]

Magnesium ferrite was doped with Nd to get MgFeNd O ( x = 0 to 0.04). The samples were synthesized by a without water and surfactant (WOWS) sol-gel technique, and pellets were sintered at different temperatures. An inverse spinel structure was confirmed by the X-ray diffraction (XRD) pattern. Lattice constants increased with the increase in Nd doping. Microstructure analysis by SEM shows that particles are spherical in shape. AC electrical properties were studied at room temperature in the frequency range of 20 Hz-3 MHz. A minimum dielectric loss tangent value was achieved with x = 0.02 concentration of Nd, and it is suitable for high-frequency applications. [ABSTRACT FROM AUTHOR]

The synthesis of cerium oxide (CeO) nanoparticles through composite mediated hydrothermal approach is reported. A composite of sodium hydroxide and potassium hydroxide was used as precursor with cerium nitrate as the raw material. With the help of X-ray diffraction (XRD), we observed that the crystal structure of prepared ceria nanoparticles is cubic. Scanning electron microscopy (SEM) has been utilized to study the surface morphology of the material. Conductivity of synthesized cerium oxide was measured by standard two probes method. Cerium oxide is nonconductive at room temperature, but when we increase the temperature, it becomes conductive. It is observed that ionic conductivity depends on nature of nanoparticles and temperature. The oxygen ions conductivity was 2.32 ×10 S cm at 300 ± 5 C. In the region of 300 ± 5 to 400 ± 5 C, the conductivity increases slightly. Above 400 ± 5 C, it increases rapidly and gave a maximum value of 1.01 × 10 S cm at 700 ± 5 C. Also, the effect of applied frequency on the conductivity, dielectric constant, and dissipation factor was observed as a function of temperature. The studied material is a strong potential candidate for electrolyte material in intermediate temperature solid oxide fuel cells (ITSOFC). [ABSTRACT FROM AUTHOR]

With the development of synthesis of nanomaterials, magnetic ferrites and the traditional magnetic materials can be prepared by new methods, including top-down and bottom-up approaches. Ferrites are economic magnetic materials and are also being developed for new applications. Recent work on facile preparations and prospective applications for nanostructured ferrites will be discussed. Soft and hard ferrites are generally produced by ceramic routes in industry, but in present work, wet-chemical synthesis routes are utilized. Lithium ferrites were doped with Zn and Mg using co-precipitation method. They have shown promise in absorbers and sensors. Cobalt ferrite nanocrystals were prepared by a simplified sol-gel method namely the WOWS (without water and surfactants) sol-gel method. Cobalt ferrites with adjustable electrical properties have been obtained by doping a small amount of RE elements. Structural analysis of the prepared samples was done by X-ray diffraction (XRD). Lattice parameters and crystallite sizes were determined by using XRD data. Spinel structure was observed for all the prepared samples but with different space groups. DC electrical resistivity was measured as a function of temperature, and activation energies were determined from the Arrhenius plots for all the samples and their comparative study was done. Resistivity of all the samples was decreased with increase in temperature which indicated their semiconductor-like behavior. Polaron hopping was the major conducting mechanism as activation energies for all the samples were above 0.4 eV. The studied materials can be utilized in advanced electronics industries. [ABSTRACT FROM AUTHOR]

BaFePb O ( x = 0.0, 0.5, 0.75, and 1.0) was synthesized by a simplified sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for structural and morphological analyses, respectively. XRD patterns of the sintered samples showed maximum phase purity. XRD data were further analyzed for different structural parameters like crystallite size, lattice parameters, and volume of unit cell. It also showed that lead doping in place of iron was responsible of restricting the grain growth. For magnetic analysis, a magnetometer was used at room temperature and the obtained parameters were analyzed as a function of lead. Different DC parameters like resistivity and activation energy were determined and analyzed with respect to lead contents and as a function of temperature. A hopping model was used to explain variations in these parameters. The studied compositions are useful for smart data storage device applications. [ABSTRACT FROM AUTHOR]

In this paper, dielectric properties of Ni-Zn ferrite and carbon nanotube (CNT) composites were investigated at room temperature. Composites of CNTs and Nd-doped Ni-Zn ferrites were prepared with different CNT ratios by weight (0-1 %). Ferrite samples were prepared using a simplified sol-gel method with the composition NiZnFeNdO. Nd doping increased the resistivity of Ni-Zn ferrites than that of the un-doped sample. All the composite samples were sintered, and structural analysis was done through X-ray diffraction (XRD). Dielectric constant and dielectric loss increased and impedance decreased with an increase of CNT ratio, but both decreased with frequency. However, AC conductivity increased with CNT ratio as well as with frequency. The composite material with 1 % CNT ratio is suitable for high capacitive applications due to large dielectric constant. [ABSTRACT FROM AUTHOR]

Maghemite ( γ-FeO) nanoparticles and the (CuTl)BaCaCuO (CuTl-1223) superconducting phase were prepared separately by sol-gel and solid-state reactions, respectively. γ-FeO nanoparticles were added into the CuTl-1223 superconducting phase to get ( γ-FeO)/CuTl-1223, where x = 0 ∼ 1.25 wt.% nanoparticle-superconductor composites. The structural, morphological, and superconducting transport properties of these composites were investigated by using different experimental techniques. X-ray diffraction (XRD) of these composites revealed that γ-FeOnanoparticles have not changed the crystal structure of the host CuTl-1223 superconducting phase, which has indicated the occupancy of these nanoparticles at grain-boundaries. The grain morphology was improved due to change in reaction thermodynamics with addition of these magnetic nanoparticles. Superconducting transport parameters of the CuTl-1223 phase were enhanced up to a certain optimum level of γ-FeO nanoparticle content (i.e. x = 0.50 wt.%) followed by systematic suppression. Different microscopic superconducting parameters were deduced from resistivity versus temperature experimentaldata of ( γ-FeO)/CuTl-1223, where x = 0 ∼1.25 wt.% composites by using different theoretical models. [ABSTRACT FROM AUTHOR]

Spinel ferrites are an important class of compounds which have a variety of electrical, magnetic, and catalytic applications. Neodymium-doped cobalt ferrites with composition CoNdFeO where x is 0.00-0.20 were synthesized by a sol-gel method. A sol-gel method was preferred because it has good control over stoichiometry, crystallite size, and particle size distribution. An X-ray diffraction (XRD) technique was used for structural analysis, and a crystal structure was found to be spinel for all samples. Fourier transform infrared spectroscopy (FTIR) of the samples was also performed for structural information. DC resistivity has been studied, as a function of temperature, by using a two-probe method. It showed direct dependence on temperature and inverse dependence on the concentration of Nd dopant. I- V characteristics of samples at room temperature were analyzed. The non-linear I- V curves showed a non-ohmic behavior. When voltage was reversed, it did not follow the same values but showed a hysteresis loop-type trend. This confirms the presence of resistive switching effect in this voltage range at room temperature. The studied material is a potential candidate for resistive random access memory application. [ABSTRACT FROM AUTHOR]

Co-precipitated nanoparticles, with nominal composition SrFeCrO ( x = 0.0-0.3), were characterized for their structural and temperature-dependent electrical properties. X-ray diffraction (XRD) was used to analyze the crystallography of the samples. Structural parameters like crystal structure, phase purity, crystallite size, and lattice constants were estimated using XRD data. Scanning electron microscopy was used to analyze the surface morphology and particle size of the samples. Temperature-dependent ac electrical analysis was also done to study the effect of temperature and composition on the dielectric properties of the samples. Dielectric constant, dielectric loss tangent, and ac electrical conductivity increased with increase in temperature as well as with Cr doping content at 1-MHz frequency. [ABSTRACT FROM AUTHOR]

Rare earth doped strontium cobaltite (SrRCoO where R is rare earth element like cerium (Ce) ( x = 0.0, 0.025)) was synthesized by a composite-mediated hydrothermal method (CMHM). X-ray diffraction (XRD) was done to study the structural properties such as crystal structure, crystallite size, lattice constants and phase purity of the samples. Phase transformation from monoclinic to the hexagonal structure was observed with heat treatment. DC electrical conductivity was studied as a function of temperature in the range from room temperature to 430°C. It was observed that DC electrical conductivity increased with increase in temperature and was explained by a hopping model. Impedance was measured as a function of temperature (30-600°C) at the frequency of 1 MHz. Different parameters were correlated to study the conductivity mechanism. The prepared samples are one of the suitable candidates for the cathode of intermediate temperature solid oxide fuel cells (ITSOFCs). [ABSTRACT FROM AUTHOR]

Lithium ferrites have gained attention nowadays because of their unique structural and transport properties. These properties can further be enhanced by adding an appropriate dopant which makes them a potential candidate for various applications. In the present work, nanoparticles of Zn-substituted Li ferrites with the nominal composition LiZnFeO were prepared by a co-precipitation method. X-ray diffraction (XRD) was done to study the structural properties such as crystal structure, crystallite size, phase purity, and porosity of the samples. XRD revealed the spinel structure of the prepared samples. Scanning electron microscopy (SEM) was done to study the morphology, and it confirmed the particle-like morphology of the prepared sample. AC electrical properties (dielectric constant ( ε), dielectric loss tangent (tan δ), ac electrical conductivity ( σ ), and impedance ( Z)) in a frequency range of 20 Hz-3 MHz were studied at 25 to 600 °C. Dielectric constant and loss tangent decreased with frequency, but σ increased with increase in frequency. The magnitude of ε, tan δ, and σ was observed to be increasing with increase in temperature, while that for Z, it was decreasing. Maxwell-Wagner's model and Jonscher's power law were used to explain the electron hopping mechanism in frequency-dependent properties. [ABSTRACT FROM AUTHOR]

Zinc-doped lithium ferrite nanoparticles with general formula Li0.46Zn0.04Fe2.5O4 were prepared by Co-precipitation method and their thin films were grown by spin coating method. X-ray diffraction (XRD) confirmed the spinel structure of the synthesized samples. Fine morphology of the films was obtained by controlling the parameters. AC electrical properties including dielectric constant (έ), dielectric loss tangent (tanδ), AC electrical conductivity (σac), and impedance (Z) were studied as a function of frequency at different temperatures and at 1 MHz frequency in a temperature range of 40–500 °C. Dielectric constant, dielectric loss tangent, and ac electrical conductivity showed the decreasing trend with increase in temperature while opposite trend was observed for impedance. Zinc-doped Li-ferrite has better absorption properties in the studied frequency and temperature range as compared to that of Li-ferrites. [ABSTRACT FROM AUTHOR]

Metallic copper (Cu) nanoparticles were added in appropriate ratios into the CuTlBaCaCuO (CuTl-1223) superconducting phase to obtain (Cu)/CuTl-1223 ( x = 0 ∼ 4.0 wt%) nanoparticle-superconductor composites. Structural, morphological, compositional, and superconducting transport properties were investigated by using different experimental characterization techniques. The crystal structure of the host CuTl-1223 phase remained unaltered (i.e. tetragonal) after addition of Cu nanoparticles, which gave a clue about the occupancy of these nanoparticles at the inter-crystallite sites. Grain morphology and inter-grain connectivity were improved after addition of these Cu nanoparticles being metallic in nature were supposed to be the best candidate for improvement of inter-grain connectivity and superconducting properties. Calculation of the superconducting volume fraction showed the dominance of the CuTl-1223 phase along with the presence of some other superconducting phases and unknown impurities. The optimum content level of Cu nanoparticles in the CuTl-1223 phase for maximum improvement of superconducting properties was 1.0 wt%. [ABSTRACT FROM AUTHOR]

Nowadays it is the hot topic to analyze the behavior of different materials towards gasses so that they can be used for sensing purpose. Ferrites specifically lithium ferrites show very good response to gasses present in the environment. Lithium ferrite doped with Gd (LiFeGd O ) was selected for this purpose. Sample was synthesized by simplified sol-gel technique. After that, pellets were formed and sintered at different temperatures. Spinel cubic phase was observed in x-ray diffraction (XRD). It is noted that by increasing sintering temperature, results slightly decrease in lattice constant. Scanning electron microscopy (SEM) was used to study the surface morphology of the samples. It was observed that particles were spherical in shape. AC electrical properties were studied at room temperature in the frequency range of 20 Hz to 3 MHz. AC electrical conductivity and dielectric constant decreased with the increase in sintering temperature. The maximum conductivity was observed in the sample that was sintered at temperature of 700 C. Significant variation in electrical response with frequency made these samples suitable for sensing applications. [ABSTRACT FROM AUTHOR]

The conversion of waste heat into electrical energy plays a key role in our current challenge to develop alternative energy technologies to reduce our dependence on fossil fuels. Thermoelectric (TE) materials are the first choice to handle this subject. In TE materials, cobaltites are the material of interest, due to their nontoxic properties. Cobaltites exhibits large TE power, low resistivity, and relatively small thermal conductivity at room temperature. TE material (BiCaRCoO) where R is for rare earth like Nd, ( x = 0.0, 0.2) was synthesized in nanoregime by simplified sol-gel method. Simplified sol-gel method was chosen because it gives maximum phase purity and tunable parameters for desired properties. The mechanism used to enhance thermoelectric properties is to reduce thermal conductivity of the material and increase electrical conductivity of the material using nanostructures. Material characterizations were done for structural studies using X-ray diffraction (XRD). XRD revealed monoclinic crystal structure. Temperature-dependent electrical conductivity showed an increase with increase in temperature. Thermal conductivity was also measured. Both electrical resistivity and thermal conductivity decrease as a result of neodymium doping which enhanced its importance as thermoelectric material. The different parameters were correlated to understand the conduction mechanism. [ABSTRACT FROM AUTHOR]

Ferrites have become the source of attention for scientists due to their variety of physical properties. Their massive use in the electronics industry has made the study of their dielectric, thermal, and optical properties unavoidable. These materials have potential applications in high-frequency devices. The empirical formula for the synthesized nanoparticles is given by NiZnFeO. Nanoferrites were prepared by a simplified sol-gel method. The crystalline phase; crystallite size; surface morphology; dielectric properties such as AC conductivity ( σ), dielectric constant $(\epsilon ^{\prime })$, and dielectric loss (tan δ) as a function of frequency at different temperatures; and DC electrical resistivity as a function of temperature were studied. The Ni-Zn nanoferrite was sintered at 550 C. The X-ray diffraction (XRD) results showed a spinel cubic structure having a lattice constant a=8.383 Å and crystallite size of 12 nm for the (311) peak after sintering. Scanning electron microscopy showed the particle morphology of the samples. AC conductivity ( σ) increases with frequency as well as the temperature. DC resistivity decreased with increase in temperature. The observed behavior could be explained by the Maxwell-Wagner model. Parameters observed were correlated to understand the conduction mechanism. [ABSTRACT FROM AUTHOR]

Soft ferrites are useful for various applications due to their high resistivity and low eddy current losses. Nanoferrites of manganese (MnFeO) were prepared by chemical co-precipitation method. Synthesis conditions were optimized for phase purity. The prepared MnFeO were characterized by using X-ray diffraction (XRD) and AC and DC measurements for electrical conductivity and advantageous transient plane source (ATPS) method for thermal transport properties (thermal conductivity, thermal diffusivity, and volumetric heat capacity). The XRD results confirmed the spinel structure of as-prepared nanoferrites. Samples were sintered at 750°C for 2 h, and after sintering, the structure of the material changed from spinel to garnet. The sintering procedure was repeated for five times and its effect was observed on Mn ferrite nanoparticles. These materials are useful for various purposes of applications, e.g., as a core material to increase the efficiency of switch-mode power supply (SMPS). Using data of DC electrical resistivity as a function of temperature, activation energy was calculated. Thermal transport properties of the synthesized samples are reported and these are rarely found in literature. [ABSTRACT FROM AUTHOR]

Cerium oxide (CeO) nanoparticles were synthesized by using sol-gel methods and the Composite Mediated Hydrothermal Method (CMHM). Sol-gel synthesis was done for 0.6 M molarity of the precursor solution of cerium nitrate hexa hydrated [Ce(NO)⋅6HO] and the hydrothermal synthesis was done at 180 °C for 45 min. X-Ray diffraction (XRD) was used to measure the structural properties of the prepared ceria. Scherrer's formula was used to calculate the crystallite sizes of average and most intense peak. Temperature dependent (200 °C to 700 °C) dc conductivity was measured and found to be increasing with the increase in measuring temperature. The frequency dependent (20 Hz to 3 MHz) ac conductivity and dielectric properties were measured at different temperatures. The comparison of electric and dielectric properties was studied. Both synthesis techniques were further analyzed by the Raman spectrum at 514 nm excitation laser line for the different bands of cerium oxide and oxygen vacancies. [ABSTRACT FROM AUTHOR]

Superconductivity in bismuth-based high- T superconducting materials attracts the researchers for their unique properties. Bismuth-based superconductors commonly called BSCCO have great importance among the superconducting family. These are divided into three phases among them 2223 phase is highly studied in order to investigate its superconducting properties by substitution of different elements. We have studied the substitution of cerium (Ce) on the calcium site of bismuth-based Bi(Pb)Sr(Ba)-2223 high- T superconductor. The nominal compositions of BiPbSrBa(CaCe)CuO ceramic superconductor were prepared by the sol-gel method. X-ray diffraction (XRD) was done at room temperature for structural analysis and different parameters were calculated. Surface morphology was done by scanning electron microscopy (SEM). DC resistivity measurements for the transition temperature of synthesized superconducting samples were taken by the standard four-probe method, apparatus for which was developed in our laboratory. Current density measurements were also taken by the same apparatus. The synthesized superconducting samples were also characterized by thermogravimetric analysis (TG) and Fourier transformation infrared radiations (FTIR). It is observed that the substitution of cerium on the calcium site favors the formation of single high- T 2223 phase. [ABSTRACT FROM AUTHOR]

Spinel ferrites containing Nickel and Cobalt of composition with nominal formula NiCoFeO ( x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) prepared by the coprecipitation method are reported. The single phase spinel formation of ferrites was confirmed by X-ray diffraction techniques. The lattice constants ( a) were calculated based on the ionic radii of the constituents. The calculated lattice constants are smaller than the measured, because for calculations ideal ionic radii are used. The particle size calculated from the Scherrer formula varied within 15 to 33 nm. The dielectric constant and dielectric loss tangent measurement were carried out at room temperature as a function of frequency from 100 Hz to 3 MHz. Both the dielectric constant and dielectric loss tangent increased with increase in cobalt concentration. Ferrimagnetic transition temperature as a function of Co concentration was measured with the low field ac susceptibility apparatus. The ferrimagnetic transition ( T) was observed in the temperature range 573 to 720 K. The T decreased with the addition of Co concentration. The effect of Co concentration on the magnetic properties was investigated using a vibrating sample magnetometer (VSM). It was found that both magnetic saturation ( M) and coercivity ( H) increase with Co concentration. [ABSTRACT FROM AUTHOR]

series of NiCoFeO ( x=0.1, 0.2, 0.3, 0.4, 0.5) spinel ferrites have been synthesized successfully using the chemical co-precipitation route. The materials were characterized by X-rays powder diffractometry (XRD) and the electrical properties. The obtained crystallite size variation was within 15 to 33 nm using the Scherrer formula. The dc electrical resistivity was measured as a function of temperature. It is noticed that σ increases with a rise in temperature. The dielectric measurements were carried out at room temperature as a function of frequency and composition ( x). The dielectric constant ( ε′) and dielectric loss tangent (tan δ) showed a decreasing trend with increasing field frequency. The ac electrical conductivity is calculated from the dielectric measurements; it increases with the rise in frequency. [ABSTRACT FROM AUTHOR]

Bi-based layered cobalt oxide [Bi ACoO] with A = (Ca, Mg) nanoparticles were prepared by co-precipitation method. Coprecipitation method was used to improve homogeneity and phase purity of nanoparticles and is rarely reported for such type of materials. From X-ray diffraction (XRD) data, structural analysis was carried out for both samples BiCaCoO (BCCO) and BiMgCoO (BMCO). Crystallite size, lattice constants, and volume of unit cell were calculated using XRD data. Both compositions showed monoclinic crystal structure with space group C2/c. Crystallite sizes obtained were 52 and 50 nm for BCCO and BMCO samples, respectively. Scanning electron micrographs show the particle-like morphology with an average particle size of 54 and 68 nm for BCCO and BMCO samples, respectively. Thermogravimetric analysis-(TGA)-differential scanning calorimetery (DSC) technique was used to observe role of heat changes in both the samples with temperature variation up to 1000C. BCCO was found thermally more stable as compared to BMCO. Electrical resistivity decreased with increase in temperature, and BMCO showed high values as compared to BCCO. Thermal transport properties like thermal conductivity, thermal diffusivity, and volumetric heat capacity were determined. Both compositions are low thermally conducting materials. BCCO sample showed higher thermal conduction as compared to BMCO. BCCO sample could be a better candidate as thermoelectric material as compared to BMCO. [ABSTRACT FROM AUTHOR]

Phase pure multiferroic BiFeO (BFO) was prepared by the co-precipitation technique using diverse precursors at a temperature as low as 400 °C. The dependence of structural and dielectric properties was investigated with the variation of pH (8-13, with steps of 1). Uniaxially pressed powders were sintered in air at 500 °C for 2 h. X-ray diffraction analysis determined the amorphous nature of the as-synthesized samples and the perovskite nature of the sintered samples. The crystal structure obtained from the lattice parameters of the BFO specimens was R3c hexagonal. The fractional porosity of the pellets was determined from the measured and theoretical density of the samples. The crystallite size varies from 48-62 nm with the variation of the pH value. SEM micrographs exhibited a grain morphology and a wide size distribution. The dielectric constant, loss tangent, and ac conductivity of the pellets were measured as a function of frequency (20 Hz-3 MHz). A high dielectric constant and dissipation factor for the sample prepared with pH=10 was observed in the low frequency range. [ABSTRACT FROM AUTHOR]

Nanoparticles of cerium oxide were synthesized by the co-precipitation method. Synthesis conditions were optimized for phase purity, particularly the effect of pH (=14,13,11) of solutions during reaction, was studied. The phase analysis and structural properties of the prepared particles were determined by X-ray diffraction analysis. The average crystallite size decreased with the increase in pH of solution. The temperature-dependent DC conductivity was measured in the temperature range 300 °C to 700 °C and was found to be increasing with the increase in measurement temperature. AC conductivity and dielectric constants were measured in the frequency range of 1 kHz to 3 MHz and also at different temperatures. [ABSTRACT FROM AUTHOR]

Cobaltite of magnesium, embedded in polyvinylpyrrolidone (PVP) polymeric fibers forming nanocomposite were synthesized by combining conventional sol-gel method with electrospinning method. Ultrathin diameter polymer fibers containing nanoregime ceramic particles were obtained by varying various process parameters like voltage, concentration, feed rate, distance between nozzle tip and base plate on an indigenously assembled electrospinning unit. Polyvinylpyrrolidone (PVP) and polyvinylalcohol (PVA) polymeric fibers in nanoregime were also synthesized separately and the effect of the process parameters was observed on the fiber thickness and continuity. Characterization was done to verify the synthesis parameter effect on structural morphology of polymer based nanofiber composite. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were used as tools for study of structural morphology and its correlation with process parameters. [ABSTRACT FROM AUTHOR]

Mg-Co nano crystalline ferrites having the general formula MgCoFeO ( x=0, 0.05, 0.1, 0.15, 0.2, 0.25) were prepared by the sol-gel method. X-ray powder diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR) were carried out to investigate the structural properties of the samples. X-ray powder diffraction patterns indicated the formation of a spinel structure of the prepared compounds. Fourier Transform Infrared (FTIR) spectroscopy of the samples confirmed the XRD results. The crystallite size, lattice parameters and porosity of samples were calculated by XRD data analysis as a function of cobalt concentration. The dielectric constant ( ε), dielectric loss tangent (tan δ) and ac electrical conductivity ( σ) of nanocrystalline Mg-Co ferrites were investigated as a function of frequency and Co concentration. The frequency dependence of ε, tan δ and σ is in accordance with the Maxwell-Wagner model. The effect of Co doping on dielectric and electric properties was explained on the basis of cations distribution in the crystal structure. The saturation magnetization M, remanent magnetization M and coercivity H of all samples were explained as a function of cobalt concentration on the basis of Néel's two-lattice model. [ABSTRACT FROM AUTHOR]

Rare earth compounds are the subject of many recent experimental investigations because of the nature and variety of their physical properties. Cerium oxide (CeO) was the starting material for the fabrication of nanostructures. Ce(OH) was synthesised and structural characterisation was done. A hydrothermal method was used to prepare the nanostructures. The synthesised samples were examined by X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). The phase of the material was confirmed by the X-ray diffraction. Two solvents (nitric acid and sulphuric acid) were used to dissolve CeO. The phase and structural properties were studied as a function of the solvent. The sulphuric acid was found to be a better solvent to achieve the required phase of Ce(OH). Synthesised material has potential application in bio-labelling. [ABSTRACT FROM AUTHOR]

Soft ferrites are very useful for a wide variety of technological applications especially in high frequency devices due to high resistivity and low eddy current losses. Co nanoferrite particles were synthesized by co-precipitation method and characterized to understand the microstructure and electrical transport properties. The composition was varied by changing the ' A' concentration in Co AFeO ( A= Zn, Ni) nanoparticles with stoichiometric proportion ( x) varying from 0.0 to 1.0. X-ray diffraction was used for structural analysis. Then samples were sintered at 550 °C and 750 °C for 2 hours, characterized by X-ray diffraction at room temperature and DC electrical resistivity measurements were done as a function of temperature. The effects of sintering on structure were investigated. Activation energy was calculated from DC electrical resistivity data as a function of temperature. [ABSTRACT FROM AUTHOR]

Information on local crystal and electronic structure with elemental specificity is of paramount importance to understand many scientific problems. X-ray Absorption Spectroscopy (XAS) is particularly suited for this. Spinel structured ferrites exhibit a range of electrical and magnetic properties that make them particularly appealing for many technological applications such as permanent magnets, microwave absorbers, catalysts, and chemical sensors. Since the peculiar properties of ferrites are strictly related to the distribution of cations between octahedral and tetrahedral sites in the spinel structure, the control of cation distribution provides a means to tailor their properties. An EXAFS study of CoZnFeO nanoparticles is presented here. Using this technique, the information about the site distribution for Fe and Co/Zn is determined. The information obtained on the cation distribution is important to understand the microstructure of spinel ferrites which is useful to study their effects on structural, electrical, and magnetic properties. [ABSTRACT FROM AUTHOR]

Nanoengineered periodic array of holes on superconducting thin films have a great interest due to their excellence for the studies of the vortex pinning mechanisms in the type-II superconductors. Rectangular array of holes has been fabricated over a microbridge of Nb superconducting thin film by e-beam lithography. Rectangular array of holes have two type of scenario, at low magnetic fields matching effects are sharp and narrow while at high fields wide and shallower. In this work, we study the matching pinning effect by the artificial hole array in superconducting Nb thin films. We observed that as the inter distance between holes is decreased; the sharp matching effects become dominant and vice versa. [ABSTRACT FROM AUTHOR]

Patterned superconducting thin films having a periodic array of submicrometric pinning centers have been of great interest due to their excellence for the studies of the vortex pinning mechanisms in the type-II superconductors. Square hole array has been fabricated over a micro-bridge 60 mm×60 mm of NbN thin film by electron beam lithography. Previous works have been carried out in Nb, Pb and Al thin films where the vortex pinning effect is assumed to be small. In this work, we study the matching pinning effect by the artificial hole array in superconducting NbN thin films. We observed the interplay between the vortex quantization and the artificial hole array. Magneto-resistance minima at integer matching fields up to five times of H (the first matching field corresponding to one vortex inside each hole) and fractional matching fields at 1/2 H, 3/2 H and 5/2 H have been observed. [ABSTRACT FROM AUTHOR]

The calcination temperature effects on structural, magnetic, morphological, electrical, and dielectric properties for Mg0.6Co0.2Cu0.2FeCrO4 spinel ferrites have been investigated in this work. The samples (abbreviated as S900 and S1100) were prepared by the sol-gel route and calcined at two different temperatures (900 °C and 1100 °C). The thermogravimetric analysis was used to investigate the weight loss versus temperature and the formation of the spinel phases. The cation distributions were estimated for the samples using experimental XRD patterns based on the Rietveld refinement of the atomic occupancy values. With increasing calcination temperature, unit cell parameters and average crystallite size show an increasing trend. From the magnetic hysteresis loops, low coercive fields were obtained, making Mg0.6Co0.2Cu0.2FeCrO4 ferrites suitable candidates for soft magnetic devices. Nyquist-diagrams modeling shows that the conduction process in the samples is governed by the effect of grain and grain boundary contributions. Impedance and modulus curves show a dielectric relaxation phenomenon in the samples with non-Debye nature. The samples show electrical insulating (I)-semiconducting (S) transitions at TIS = 360 K for S900 and TIS = 400 K for S1100. Both NSPT and CBH models were used to explain the sample conduction process. Due to the increase in crystallite size with increasing calcination temperatures, activation energies decrease from 0.279 to 0.211 eV for S900 and S1100, respectively. In addition, the synthesized materials exhibit low dielectric constants and dielectric losses at higher frequencies as well as high electrical resistivity. These properties make Mg0.6Co0.2Cu0.2FeCrO4 samples suitable candidates for high-frequency applications and microwave absorption devices. [ABSTRACT FROM AUTHOR]

Nanoparticles of formula Co1-xZnxFe2O4 (x = 0.0, 0.3, and 0.5) were prepared successfully using a citrate-auto-combustion method. This work studies the substitution effect of the Zn2+ ion on the physical, chemical, and structural properties of CoFe2O4. The structure of the prepared samples was determined via X-ray diffraction (XRD) and Fourier transformed infrared spectrometer (FTIR). X-ray diffraction of the investigated samples ensures that all the prepared samples crystallite into single structure. There is a variation of crystallite size with change in Zn concentration as it is observed that the crystallite size increased from 16.01 to 30.56 nm by increasing Zn concentration. The Fourier transform infrared spectra (FTIR) in range (390:4000) Cm−1 were used for studying the elastic properties of the prepared spinel ferrites. It is observed that, by increasing Zn concentration, all elastic moduli increased. The morphological and surface study of the calcined samples was investigated by scanning electron microscopy (SEM) and Gwyddion 2.45 software respectively. The roughness average (Ra) was 35.20 nm at x = 0 and increased to 46.6 nm at x = 0.5. At the room temperature, magnetic behavior of the all studied samples was studied. It is observed that the maximum saturation magnetization was 67.611emu/gm and it was related to Co0.7Zn0.3Fe2O4 while the highest value of exchange bias (HEB) was 2.15 Oe for Co0.5Zn0.5Fe2O4. The antibacterial activity of CoFe2O4, Co0.7Zn0.3Fe2O4, and Co0.5Zn0.5Fe2O4 was successfully tested against Escherichia coli and Staphylococcus aureus bacteria. The highest inhibition zone of Co1-xZnxFe2O4 values was 8 and 7.5 mm for E. coli and S. aureus, respectively, and these values were observed for x = 0.5. Generally, these results exhibit a high possible of ferrites for using in antibacterial applications. [ABSTRACT FROM AUTHOR]

Al3+ and Cr3+ ions substituted ZnNiFe2O4 nanoparticles were successfully synthesized by sol-gel method followed by annealing treatment at 1000 °C. X-ray diffraction technique was used to determine the single phase cubic structure of nickel ferrite phase and its jumping length and average crystallite size of AlyCrxZn(0.4-y)Ni(0.6-x)Fe2O4 (N1–N6) nanoparticles. Ni2+ and Zn2+cations were decreased with the increase of Al3+ and Cr3+ ions in nickel ferrite crystalline nanoparticles and the combinations (x + y = 0 − 0.375) initiate considerable influence on the magnetic and electrical response of the nickel ferrite core materials. The vibrational modes and bond coordination of the atoms were investigated by Fourier transform infrared spectroscopy. Grain size and shape of the nanoparticles were examined by using field emission scanning electron microscopy technique. The broad uv–visible light absorbance and band gap values of the samples were obtained from UV-DRS. Raman spectroscopy shows that the surfaces of ZnNiFe2O4 material possess stretching vibrational peaks at 195, 331, 488, and 688 cm−1. The increase in permeability and soft magnetism were determined from the calculated magnetic parameters using vibrating sample magnetometer. The variations in complex impedance values of the samples were recorded from 8.2 × 106 Ω to 1.2 × 105 Ω and it confirms the possibility to develop the storage, charging and discharging of supercapacitor and battery materials. [ABSTRACT FROM AUTHOR]

The effect of bismuth ferrite (BiFeO3) nanoparticles (~ 20 nm) on Bi1.6Pb0.4Sr2Ca2Cu3O10 (Bi-2223) superconductor was studied. Bi-2223 powders with starting formula Bi1.6Pb0.4Sr2Ca2Cu3O10(BiFeO3)x for x = 0–0.20 wt.% were prepared using the co-precipitation method. The temperature dependent electrical resistance measurements showed the highest superconducting transition temperature for the x = 0.10 wt. % sample (Tc-onset = 118 K, Tc-zero = 106 K). The highest transport critical current density, Jct at 40 K was shown by the x = 0.02 wt. % sample (21.93 A cm−2). The peak temperature of imaginary part of susceptibility, Tp was much higher compared with the non-added sample, indicating BiFeO3 nanoparticles enhanced the flux pinning energy and intergranular coupling. The addition of a small amount of BiFeO3 nanoparticles (0.02–0.04% wt.%) increased the transport critical current density while further additions (0.06–0.20 wt.%) improved the superconducting transition temperatures. BiFeO3 nanoparticles slightly suppressed the formation of the Bi-2223 phase, but it increased the transport critical current density by more than eleven times demonstrating BFO could act as effective pinning centres and enhanced connectivity between grains. This work showed that BiFeO3 was better than other nanoparticles such as Ni0.5Zn0.5Fe2O4, Cr2O3, NiFe2O4, MgO, ZnO and Co3O4 in improving the transition temperatures and critical current density of the Bi-2223 phase superconductor. [ABSTRACT FROM AUTHOR]

Neutron irradiation is one of the methods to improve the transport properties of superconductors by creating defects for flux pinning centers. In this work, the effects of fast neutron irradiation on (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (Bi-2223) superconductor were studied. The samples were prepared using the co-precipitation technique and were exposed to fast neutron irradiation via pneumatic transfer system (PTS) with a neutron flux of 2.5 × 1012 n cm−2 s−1 from 60 to 660 s which are equivalent to neutron fluences of 1.55 × 1014 to 1.70 × 1015 n cm−2. The non-irradiated sample was dominantly Bi-2223 phase (85%) as shown by X-ray diffraction patterns. However, after irradiation, the volume fraction of the Bi-2223 was reduced and the (Bi1.6Pb0.4)Sr2CaCu2O8 (Bi-2212) phase increased, resulting in an almost 50:50 ratio of Bi-2223:Bi-2212. Energy-dispersive X-ray analysis indicated the presence of Zn and Po in some irradiated samples due to neutron activation. The onset transition temperature (Tc-onset) and zero transition temperature (Tc-zero) for the non-irradiated sample was 118 K and 105 K, respectively. The irradiated samples showed lower Tc-onset (112 to 115 K) and Tc-zero (100 to 104 K). AC susceptibility showed a transition temperature (Tcχ′) around 108 to 109 K. The imaginary part of the susceptibility showed intergranular loss peak temperature (Tp) from 89 to 96 K. Intermediate fluence of fast neutron irradiation did not affect the intergrain coupling and pinning strength of (Bi1.6Pb0.4)Sr2Ca2Cu3O10. However, higher fluence severely damaged the microstructure and degraded the flux pinning strength of (Bi1.6Pb0.4)Sr2Ca2Cu3O10. [ABSTRACT FROM AUTHOR]

The nanocrystalline Sr(1−x)CexFe12O19 (x = 0.00 < x < 0.09) strontium M-type hexaferrites (SrM-HFs) were prepared by self-propagation method using mixed fuels. The structure, morphology, and composition were analyzed by X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM) technique, and energy dispersive X-ray analysis (EDAX), respectively. Vibrating sample magnetometer (VSM) instrument was used for the determination of magnetic properties of each prepared sample. XRD peaks reveal nanocrystalline nature with a hexagonal single phase magnetoplumbite-like crystal structure. The FESEM micrograph shows accumulation of hexaferrite nanocompact magnetic aggregation. In addition, the size of the particles reduced with the increase in of Ce3+ ion content. The VSM analysis confirmed that SrM-HFs are hard magnetic in nature. Moreover, it is observed that the saturation magnetization and magnetic parameters of strontium ferrites decrease with the increase of the content of Ce3+ ion. In addition, Ce3+ substituted SrFe12O19 are most useful for magnetic recording and memory devices. [ABSTRACT FROM AUTHOR]

In order to investigate the size dependence of magnetic properties in the single-domain and superparamagnetic regimes, zinc ferrite ZnFe 2 O 4 nanoparticles were synthesized with sizes around 15 nm by the hydrothermal method. The zinc ferrite nanoparticles were characterized by XRD, TEM, FT-IR, and VSM. According to the Rietveld refinement results, the nanoparticles exhibited a cubic single-phase spinel-type structure. The TEM observations indicated that the nanoparticles were spherical in shape. The FT-IR analysis revealed two dominant absorption bands, confirming the formation of a single-phase spinel structure with two sub-lattices: tetrahedral and octahedral. Magnetic measurements conducted over a wide range of temperatures and magnetic fields revealed that the ferrite nanoparticles were ferrimagnetic dressed with spin-glass behavior below the blocking temperature ( T B ) and superparamagnetic above T B . The saturation magnetization and the first anisotropy constant of the nanoparticles were found to increase with decreasing temperature. The superparamagnetic critical size, D SP , of the nanoparticles was found to be about 13 nm, suggesting that the prepared ferrite nanoparticles were within the superparamagnetic regime, and thus by implication within the single domain regime. [ABSTRACT FROM AUTHOR]

Barium hexaferrite is an essential, prudent, and promising material for the permanent magnet, ceramic, and modernized magnet industry. In the present study, the sol–gel auto-combustion technique was adopted for the synthesis process to get the particles of comparatively lesser size, and the morphological analysis of the sample supports the same. The magnetic studies at room temperature disclosed a good maximum energy product value (BHmax) and uniaxial anisotropy with a single domain arrangement of the particles. Furthermore, the space charge polarization and Maxwell- Wagner relaxation was detected in the system during dielectric studies. The influences of structural properties on magnetic and dielectric properties are the impressive outcomes of the present research work. [ABSTRACT FROM AUTHOR]

The nanoparticle spinel ferrites Mg0.5Zn0.5CexLaxFe2-2xO4 (x = 0.0, 0.0125, 0.025, 0.0375, 0.05) were synthesized by mean of co-precipitation method. These magnetic nanoparticles were sintered at 750 °C for 8 h. XRD patterns confirmed the formation of the cubic spinel structure of prepared nanoparticles. The lattice constant of nanoparticle ferrites increased, while crystallite size decreased with doping content (x). Pure ferrite sample has an optical bandgap of 2.61 eV, and it increases from 1.73 to 2.17 eV as concentration (x) is changed from 0.0125 to 0.05. The electrical dc resistivity is of the order of 1010 Ω cm for doping content (x) from 0 to 0.0375 and has a maximum value of 5.48617 × 1012 Ω cm for content x = 0.05. The Curie temperature (Tc) decreased 433–373 K as concentration (x) was increased. The dielectric constant, dielectric loss, and impedance are reduced with the increase of frequency. The dielectric constant, as well as the dielectric loss diminished while impedance increased as doping of cerium and lanthanum, was increased. [ABSTRACT FROM AUTHOR]

Two-step solid-state reaction method was used to synthesize (Cu0.5Tl0.5) Ba2Ca2Cu3O10-δ (CuTl-1223) superconducting phase, and sol–gel method was used to prepare copper (Cu) nanoparticles. These Cu nanoparticles (NPs) were mixed with CuTl-1223 superconducting phase to get (Cu)x/CuTl-1223 (x = 0, 1.0, and 2.0 wt%) nanoparticle-superconductor composites. These composites were prepared at high pelletize pressure of 0.202 GPa. The crystal structure and phase purity of (Cu)x/CuTl-1223 composites were determined by X-ray diffraction (XRD). The morphology was examined by scanning electron microscopy (SEM), and elemental analysis was carried out via energy-dispersive X-ray spectroscopy (EDS). Different vibrational modes of oxygen in these samples were studied with the help of Fourier transform infrared (FTIR) spectroscopy. The four-point probe technique was used to study the resistivity versus temperature measurements, and Arrhenius law was used for the calculation of activation energy. The critical transition temperature width and hole concentration were calculated for different contents of Cu nanoparticles in (Cu)x/CuTl-1223 composites. All the findings were elaborated in comparison with (Cu)x/CuTl-1223 composites prepared at relatively low hydraulic pressure. [ABSTRACT FROM AUTHOR]

This paper reports a potential and easy method to prepare nickel ferrite nanoparticles with improved dielectric and magnetic properties by doping with zinc. The structural studies and Rietveld refinement of the XRD pattern confirm the cubic spinel structure of the ferrite phase belonging to the Fd3m space group. Morphological and elemental composition analyses of the prepared samples are carried out using scanning electron microscopy and energy dispersive spectroscopy (EDAX). The frequency variation of the dielectric constant and ac conductivity have been studied. The dependence of dielectric constant and ac conductivity on the frequency of the alternating applied electric field is explained by the Maxwell–Wagner model. The zinc doping in nickel ferrite nanoparticles is helpful in modifying the dielectric properties and thereby designing materials matching the application requirements. Magnetic measurements were carried out at 300 K and 5 K points toward an enhanced magnetic property in zinc-doped samples. The saturation magnetization value for zinc ferrite nanoparticles is around 23 emu/g at 300 K and 56 emu/g at 5 K which clearly indicates the superparamagnetic behavior of the samples. The maximum value for Ms is obtained for the Ni0.5Zn0.5Fe2O4 sample which is 74 emu/g and 101 emu/g at 300 and 5 K, respectively. The enhanced dielectric and magnetic properties inherited by Zn doping in nickel ferrite (NFO) nanoparticles suggest the improved potential of these superparamagnetic NZFO nanoparticles for various applications. [ABSTRACT FROM AUTHOR]

Sol–gel technique was adopted to synthesize Sr2−xCoxNi2Fe28−yBiyO46 (x = 0.00, 0.01, 0.02, 0.03, 0.04; y = 0.00, 0.05, 0.10, 0.15, 0.20) X-type hexa-ferrites. The lattice parameters were altered ("a" from 5.886 to 5.851 Å and "b" from 84.637 to 84.672 Å). The force constant was found to decrease with the substitution of Bi3+–Co2+. The dielectric constant decreased from 62.8 to 47.5, while the tangent loss increased from 0.06 to 0.13 within the frequency range of 1–1.5 GHz. The Cole–Cole plots symbolize the predominance of grains and grain-boundary resistance. The saturation magnetization was optimized, whereas coercivity was declined by the substitution of Bi3+–Co2+. The high values of the dielectric constant, high tangent loss, high saturation magnetization, and small values of coercivity revealed prospects of Bi3+–Co2+-substituted SrNi-based X-type hexa-ferrites as effective microwave absorbing materials or shielding materials for high frequency and multi-layer chip inductor materials. [ABSTRACT FROM AUTHOR]

The magnetic properties of nickel ferrite (NiFe2O4) nanoparticles (NPs) and its composite with titanium oxide (TiO2) have been studied in detail. The average crystallite size was found to be ~ 32 nm for NiFe2O4 NPs with and without presence of TiO2 and confirmed that TiO2 did not affect the crystalline growth of NiFe2O4 NPs. The transmission electron microscopy confirmed the spherical morphology of NPs, whereas the selected area electron diffraction patterns confirmed the polycrystalline nature of these NPs. The zero-field cooled and field cooled magnetization curves confirmed that the blocking temperature lies above the room temperature for both the samples. The gradual increase of magnetization in field cooled curve at low temperatures for NiFe2O4/TiO2 nanocomposites (NCs) indicates the reduced inter-particle magnetic interactions. The value of saturation magnetization was found to be same for both NiFe2O4 NPs and NiFe2O4/TiO2 NCs after subtracting the mass contribution of TiO2 which is non-magnetic in nature. The higher value of fitting parameter B in Bloch's law fit for NiFe2O4/TiO2 NCs indicates the weak exchange coupling constant (J). As the average crystallite size of NiFe2O4 NPs is same with and without presence of TiO2, the lower value of blocking temperature for NiFe2O4/TiO2 NCs indicates the lower value of effective anisotropy constant and reduced surface effects caused by TiO2. In summary, NiFe2O4/TiO2 NCs showed reduced inter-particle interactions and reduced surface effects. [ABSTRACT FROM AUTHOR]

NixZn1-xFe2O4 (x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) nanoferrites were synthesized using the citrate precursor method with high-purity metal nitrates and citric acid as synthesis precursors. For a detailed analysis of the structural, optical and magnetic properties of these nanoferrites sintered at 700 °C for 3 h, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM) tests were done. The analysis of XRD patterns of the powdered samples revealed that the nanoferrites have a spinel structure, and the crystallite size of the nanoferrites ranged from 23 to 31 nm. The nanoferrite samples were found with a maximum porosity of 57% at x = 0.5 which indicated the higher adsorption capacity of the materials. The density of these nanoferrites varied from 2.318 to 2.590 g/cm3 with the change in their crystallite size and lattice parameter. FTIR spectroscopy also revealed two prominent peaks between 542–582 and 402–415 cm−1, representing the tetrahedral and octahedral site occupancies, occupied by Ni2+, Zn2+ and Fe3+ ions. These peaks indicated the spinel structure of the nanoferrites. The magnetic behaviour of the nanoferrites was analysed from the hysteresis loop obtained from VSM data. It was observed that the nanoferrites are highly magnetic as the value of specific saturation magnetization varied from 1.31 to 63.31 emu/g with the variation in concentration of Ni2+ metal ions ranging from x = 0.0 to x = 1.0. High values of anisotropic constant were observed, which varied from 0.00147 × 105 to 0.16218 × 105 erg/g. [ABSTRACT FROM AUTHOR]

Cobalt ferrites have attracted extraordinary attention due to their high coercivity, chemical stability, and mechanical hardness. Lanthanum doped-cobalt ferrites having chemical formula CoLaxFe2-xO4 with composition x = (0.00, 0.015, 0.045, 0.060) were synthesized by chemical co-precipitation method. The prepared samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and current-voltage (I-V) technique. The structure of the crystal was analyzed by X-ray diffraction. The crystallite size of nanoparticles was examined in the range of 21–25 nm, and a fluctuating trend was found with the inclusion of La3+ cations. The X-ray diffraction patterns verify the contraction of lattice constant and unit cell volume with the substitution of La3+ cations except for the concentration of x = 0.060. Lattice constant was in the range of 8.34 Å–8.41 Å while unit volume cell was in the range of 580 Å3–596 Å3. The resistivity of all samples was calculated by the application of two probes I-V technique. The maximum resistivity of the order of 81.129 × 105 Ω cm was found for the concentration of x = 0.060 at 723 K which makes it useful for high-frequency gimmicks applications. The resistivity and drift mobility were found inversely related to each other. The inverse relation low-frequency absorption band and high-frequency absorption bands were analyzed by Fourier-transform infrared spectroscopy technique. [ABSTRACT FROM AUTHOR]

Advances in magnetoelectric BiFeO3 open the opportunity to commercialize innovative memory devices. Spin-based technology was employed to fabricate the magnetic random access memory (MRAM). The ferroelectric random access memory (FeRAM) based on ferroelectricity was also realized. Both memories have great properties, but unfortunately with some flaws. A new vision was hypothesized to combine both memories to create unlimited memory device. Combination of MRAM and FeRAM means coupling of ferromagnetic-ferroelectric properties in single material. Studies on magnetoelectric BiFeO3 might hold the future for memory devices with thousands of published papers in last years. In this review, we tried to show a comprehensive picture of the large number of studies on multiferroic BiFeO3 including techniques to enhance the properties and remove obstacles. Here, we begin with an overview of spintronics memory devices and multiferroic materials. An organized classification of studies depended on occupation site in BiFeO3 and type of dopant was presented. [ABSTRACT FROM AUTHOR]

In present work, we investigated the structural, magnetic, and electrical properties of Bi1.6Pb0.4Sr2Ca2Cu3O10+x superconductor prepared by using four different techniques: (i) solid-state (A), (ii) sol-gel (B), (iii) chemical wet (C), and (iv) melt-quench (D). From x-ray diffraction (XRD) and transmission electron microscopy (TEM) results, it is observed that the sintering process does not influence final crystallite size of compounds, but final crystallite sizes of the compounds were nearly the same after sintering process, while initial crystallite sizes were found to be different after the preparation process. From the XRD results, it is seen that the main phase in the compound is low-Tc Bi-(2212) phase and all samples contain a small amount of high-Tc Bi-(2223) phase. From scanning electron microscopy (SEM), two different types of surface crystallization of the compounds have been observed. The low-temperature resistivity, R(T), measurements show that all compounds have low zero resistivity, Tc,offset, value. Samples A, B, and C show the high-Tc and low-Tc transition at 110 and 75 K, respectively, while sample D displays only low-Tc transition at 75 K. These results have been supported by magnetization versus temperature measurement, M(T). In order to calculate critical current, Jc, values for the samples, magnetic hysteresis curves were taken at temperatures 10, 20, 30, 40, 50, and 60 K between the fields of ± 9 T. The hysteresis and the Jc calculation results show that sample D, when compared with other samples, has the best superconducting properties and has the highest Jc value. The best superconductivity properties between the studied samples have been obtained for sample A, while the best magnetic properties and the highest Jc value have been observed for sample D. According to the results obtained in this study, the structural and superconducting properties change with sample preparation method. [ABSTRACT FROM AUTHOR]