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Soft ferrimagnetic spinel lithium based oxides were prepared with additives like V2O5 and Na2SiO3 and sintered with the efficient microwave sintering technique. Tetravalent metal ions substituents like Mn+4, Ti+4 were used to enhance the important properties like D. C. resistivity, saturation magnetization, permeability, hysteresis and dielectric behavior. The ferrites were sintered at different sintering temperatures viz., 900, 950 and 1000 °C for 10 min by microwave technique and by conventional technique at 1050 °C for 4h. X-ray diffraction (XRD) studied the structural behavior which confirmed the spinel characteristics, Scanning electron microscopy (SEM) and EDAX revealed the microstructural and elemental compositions respectively of the ferrites. The use of additives and the microwave sintering significantly influencing the microstructural behavior and subsequently on the electromagnetic properties could be observed. Studies of initial permeability and initial permeability loss found to remain nearly constant with change in frequency until at certain frequency they showed resonance behavior. The resonance frequency's dependence on the microstructures of the ferrites could be observed. Temperature dependence behavior of the dielectric parameters and the B-H loop traced from torroidal samples of the ferrites were studied. [ABSTRACT FROM AUTHOR]

Rare earth yttrium substituted lithium ferrites Li0.5Zn0.1Ti0.1YxFe2.3–xO4 with nominal composition x = 0.00 to 0.10 in steps of 0.02 was prepared by the conventional ceramic method. The samples were sintered at 1050 °C for 6 h using resistive conventional heating. X-ray diffraction (XRD) patterns confirmed the formation of a single phase with a spinel structure. FTIR studies also confirmed the tetrahedral and octahedral metal-oxygen bonding of the spinel structure. Structural parameters like density, lattice constant, and crystallite size, site distances, bond length distances were measured from XRD data. The crystallite size reduces while the density increased with the progressive substitution of Y3+ ions. The Fe3+ ions at the A and the B sites mainly contributes to the electromagnetic properties of ferrites. Y3+ ions preferably entering the B sites can significantly interfere with the conduction mechanism of lithium ferrites. The objective of the present work is to find out the effect of Y3+ substitution on the structural and electrical conduction response Li-Zn-Ti ferrites. The DC resistivity initially is found to increase for concentration x = 0.04 and then decrease with further substitution. The study of the temperature dependence of DC resistivity depicts two types of conduction mechanisms in the range studied. The results obtained are analyzed and presented in the paper. [ABSTRACT FROM AUTHOR]

Through a typical solid-state reaction followed by planetary ball milling, ABO3 structured perovskite Bi0.5Na0.5ZrO3 (BNZ) was employed as an additive to create the lead-free piezoceramic composite having compositional formula K0.47Na0.47Li0.06NbO3+(x)Bi0.5Na0.5ZrO3 where x = 0.0 wt% to 0.5 wt%. The prepared composites were characterized with the help of XRD, SEM, and FTIR. The XRD results indicated manifestation of morphotropic phase boundary (MPB), i.e. orthorhombic-tetragonal (O-T) phase boundary, for 0.4 wt% and 0.5 wt%. The SEM pictures revealed the microstructural properties of grain-grain size distribution and the average grain size of the composites. The elemental composition examination using EDAX revealed no foreign element contamination. The FTIR examination verified the development of perovskite, indicating that the BNZ has correctly fused into the KNLN matrix. The DC resistivity (ρdc) behavior was determined from IV and IR curves measured at room temperature together with varied temperature line up from 30 °C to 150 °C and a high dc resistivity ρdc of order ≈ 109 Ω cm was obtained for all the ceramics. The results have been analyzed and the mechanism pertaining to the results has been discussed in the paper. Thus the main idea was to develop a lead-free piezoceramic composite by incorporating Bi0.5Na0.5ZrO3 as an additive and investigating its effect on the above mentioned properties of the composite material. [ABSTRACT FROM AUTHOR]

Lead-free K0.47Na0.47Li0.06NbO3 added with different oxides such as ZnO, Na2SiO3, Bi2O3, NiO, and CoO were prepared with conventional two steps sintering ceramic method where the samples were sintered at 1050 °C(5 min) and 950 °C(4h). The phase structures and crystallite sizes were studied using X-ray diffraction analysis. A dispersive behavior is observed when dielectric constant and dielectric loss were studied with variation in frequency in the range from 20 Hz to 5 MHz at room temperature. It is seen that addition of oxides improved the dielectric properties. The a. c. conductivity and impedance characteristics for the samples were also measured for a wide range of frequencies using an impedance analyzer. The Nyquist impedance plot for these samples studied for the conduction mechanism. The results were analyzed and presented in the paper. [ABSTRACT FROM AUTHOR]

Tetravalent titanium substituted lithium zinc manganese ferrite having chemical formula Li0.35+x/2Zn0.1Mn0.1TixFe2.35 − 3x/2O4 where x = 0.00, 0.15, 0.30, 0.45, 0.60, 0.75 were prepared by using the solid-state ceramic technique. Using additives V2O5 and Na2SiO3 as sintering aids, the samples were calcined and sintered at 900 °C and 950 °C, respectively for 1 h each, at a regulated heating rate of 10 °C/min. The X-ray diffraction (XRD) studies showed a single-phase spinel structure. XRD data were used to assess the structural information including density, lattice constant, and crystallite size. The additives reduced the sintering temperature and time and an increase in porosity has been observed with the increase of Ti4+ substitution. Scanning electron microscopy (SEM) was used to analyze the samples' microstructure, while Energy-dispersive X-ray (EDAX) analysis was used to identify the different elemental makeup. The fluctuation of the initial permeability and permeability loss at room temperature with a change in frequency was investigated using an impedance analyzer and found that higher substitution reduced the resonance frequency. The magnetic hysteresis studies showed that saturation magnetization reduced with an increase of Ti4+ substitution. The results obtained were analyzed and discussed systematically in the paper. [ABSTRACT FROM AUTHOR]

Different types of ferrimagnetic spinel nanoferrites having the general formula Li0.5Fe2.5O4, NiFe2O4, ZnFe2O4 and MnFe2O4 were synthesized by chemical sol-gel method. The synthesized nanoferrites were milled using high energy ball milling to get fine and homogenous nanoferrite particles. The nanoferrites were characterized using X Ray Diffraction (XRD) Technique and Fourier Transform Infrared (FTIR) Spectroscopy. XRD patterns confirmed the spinel structure of the samples. FTIR studies show the metal oxygen bond of the tetrahedral and octahedral sites. These nanoferrite particles were used to prepare ferrite nanofluids using different solvents. The optical property of these fluids was studied using a UV spectroscopy. The results of all the measurements were analyzed and reported in this paper. [ABSTRACT FROM AUTHOR]

Lithium ferrites-yttrium manganite composites were prepared by adding varying amount of yttrium manganite to lithium ferrite. The composites prepared have the general formula Li0.5Fe2.5O4+(x) YMnO3where x=(0, 10, 15, 20, 25, 30)wt%. They were studied for their structural properties by using X-Ray Diffraction (XRD) Technique. The XRD patterns revealed that in addition to the reflection peaks corresponding to cubic spinel structure of the ferrite components, few peaks which are reflections from planes of hexagonal yttrium manganite have been observed confirming the formation of composites. From the XRD data various structural parameters were evaluated and it is found that lattice constant and density increased slightly with addition of yttrium manganite while the crystallite size is decreased. The initial permeability and permeability loss of the samples showed resonance in the range 20-40MHz. The magnetic hysteresis properties were obtained from M-H loop measurements and it is found that the hysteresis parameters such as remanence and coercivity of lithium ferrites were improved with yttrium manganite additions. The results and the mechanism pertaining to the results have been discussed in the paper. [ABSTRACT FROM AUTHOR]

Lithium zinc cadmium ferrite nanocrystallites having the compositional formula Li1+0.4-x/2Zn2+0.2Cd2+xFe3+2.4-x/2O2−4 where x = 0.02, 0.03 and 0.04 were prepared by microwave process heating at 1050ºC for 25 min. X Ray Diffraction (XRD) technique confirmed the formation of single phase with spinel structure in all the samples and compared with samples of same composition prepared by conventional process heating at 1050ºC for 6 h. Scanning Electron Microscopy (SEM) photomicrograph revealed the microstructures of the samples and showed finer microstructures in the microwave processed samples. The B-H loop traced from the samples showed significant improvements in the various hysteresis parameters such as coercivity and remanance ratio for the microwave processed samples. The Curie temperature and saturation magnetization also increased for these samples. The microstructural properties such as grain, grain boundaries, pores, and their distribution due to microwave processing contributed to the observed hysteresis properties. The results of the various measurements are discussed in the paper. [ABSTRACT FROM AUTHOR]

Hexagonal yttrium manganites, YMnO3, exhibit multiferroic behavior and doping suitable cations at the either Y-site or Mn-sites can significantly influence the structural and electrical properties. Nanocrystalline Fe3+-doped YMnO3 manganites substituting at the Y-sites having the general formula Y1-xFexMnO3 with x = 0, 0.1, 0.15, 0.20, 0.25 were synthesized by sol–gel method and were sintered at 1100 °C for 1 h. X-ray diffraction (XRD) studies confirmed the hexagonal phase of the samples and various structural parameters viz. lattice constant, crystallite size, X-ray density were evaluated from the XRD data. The crystallite size of the nanocrystalite manganites ranges from 39 to 63 nm. Investigation on the dielectric properties such as dielectric constant and dielectric loss of the samples was done using an impedance analyzer. The studies showed large increase in dielectric constant and dielectric loss for higher Fe3+-doped manganites i.e. for x ≥ 0.20. Temperature variation of dielectric properties revealed a ferroelectric phase transitions which shift to lower temperature with the increase of Fe3+ ion substitution. [ABSTRACT FROM AUTHOR]

Li-Ni-Co ferrite samples with compositional formula LiNiCoFeO4 with ranging from 0.00 to 0.1 in steps of 0.02 were prepared by sol-gel method. X-ray diffraction (XRD) analysis confirmed the formation of single phase with spinel structure in all the samples. The lattice constant evaluated from XRD data was found to increase with increase of Co substitution and crystallite size was observed in the range of 30-59 nm. The microstructure of the samples was studied by using scanning electron microscopy (SEM). Nanocrystalline nature of ferrites was also confirmed by transmission electron microscopy (TEM). - measurements were made using a vibrating sample magnetometer and hysteresis parameters such as saturation magnetization and coercivity were obtained for all compositions. The frequency variations of initial permeability and permeability loss showed a dispersive behavior for all compositions and an increase in initial permeability is observed with increase of Co substitution. The results obtained and mechanisms involved are discussed in the paper. [ABSTRACT FROM AUTHOR]

In this paper, V2O5 added Li–Mn–Ti ferrites were prepared by the conventional double sintering ceramic technique having the compositional formula Li+0.6Mn4+0.1Ti 4+0.1Fe3+2.20O2–4+(x) where "x" is the amount of V2O5 added and x = (0.0, 0.1, 0.2 and 0.3) wt.%. The samples were pre-sintered at 650°C for 2 h and then finally sintered at 950°C for 1 h. Single phase cubic spinel structures of the samples were confirmed by XRD studies. Various structural and electrical properties were studied and compared with those measured from sample of same composition but prepared with 0.5 wt.% of Bi2O3. This sample was pre-sintered at 850°C for 4 h and sintered at 1050°C for 4 h. Adding V2O5 in Li-ferrites was found to reduce the sintering temperature and obtained products with reduced porosity and crystallite size but with enhanced DC resistivity. From the studies of dielectric properties, it is found that V2O5 added ferrites have lower dielectric constant and dielectric loss. Temperature dependence of dielectric properties was also studied and temperature dependence of dielectric constant and dielectric loss were less significant in the V2O5 added Li-ferrites. [ABSTRACT FROM AUTHOR]

Abstract: Substituted Li-ferrites with compositional formula Li0.45−x/2Ni0.1Mn0.1Co x Fe2.35−x/2O4 with ranging from 0 to 0.1 in steps of 0.02 were prepared by the conventional ceramic technique. The single-phase spinel structure of the samples was confirmed by XRD analysis. The lattice constant was observed to increase with the increase of the Co2+ substitution. The dielectric constant, and dielectric loss tangent, tan was studied as a function of frequency in the range 100 Hz to 1 MHz. A decrease is observed in the value of with substitution at lower frequencies. showed a dispersive behavior with frequency for all the samples. The frequency dependence of tan showed a resonance peak. The magnetic properties viz initial permeability and magnetic loss were also studied as a function of frequency. The possible mechanisms contributing to the results have been discussed. [Copyright &y& Elsevier]

The article reports on the improvements that arise in the electrical and structural properties of Li-Mn-Ti ferrite with the formula Li0.60Mn0.1Ti0.1Fe2.20O4 using novel microwave (MW) processing. It says that the formation of single phase spinel structure in both samples was confirmed by X-ray diffraction. It adds that the studies of dielectric properties as temperature function show the stability of dielectric properties with temperature.

Li–Zn–Ti ferrite substituted with vanadium having the general formula Li0.5+tZn0.2Ti0.2VtFe2.1-2tO4 with 0.00≤t≤0.25 in steps of 0.05 were synthesized by the standard ceramic technique. X-ray diffraction (XRD) analysis showed all the samples to be single-phase with spinel structure. The variation of the lattice parameter with vanadium concentration is reported. The density of the samples has been studied as a function of composition. Magnetic properties such as Curie temperature (Tc), saturation magnetization (4πMs) were measured and were found to decrease with compositional parameter x. The mechanisms involved are discussed. [Copyright &y& Elsevier]