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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]

Potassium sodium niobate (KNN) is an environmentally compatible piezoelectric material for substituting harmful lead-based ceramics. KNN-based ceramics have excellent piezoelectric properties with high Curie temperature. But, KNN faces difficulties during the processing like volatilization of alkali elements, chemical inhomogeneity, low densification, etc. The objective of this research is to investigate the impact of certain metal oxides additions like ZnO and MnO2 as sintering aids to solve the problems of the preparation and hence study the structural and electric properties of K0.5N0.5NbO3 (KNN) ceramics. ZnO and MnO2 added potassium sodium niobate, K0.5N0.5NbO3 was prepared by using the ceramic method. The prepared samples were sintered at 1000 °C for 2h conventionally. The structural properties of the ceramics have been analyzed by using X-Ray Diffractometer. The study demonstrates the formation of the orthorhombic-symmetric perovskite phase in all the prepared samples. The microstructural behavior of the ceramics has been characterized by techniques such as scanning electron microscopy (SEM) and compositional properties were studied by energy dispersive x-ray (EDAX). The effects of metal oxide additions on the electronic properties such as dielectric constant, dielectric loss, impedance properties, Nyquist plot, etc., were studied. The results have been analyzed and discussed 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]

MnO2 added potassium sodium niobate (KNN) electroceramics were prepared by conventional double sintering ceramic route. The samples prepared have the compositional formula K0.5Na0.5NbO3+ (x)MnO2 where x = 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% and 25 wt% is the amount of MnO2 added. The sintering of the samples was done using the microwave sintering technique. Pre-sintering was done at 850 °C for 20 min. Different sintering conditions may results in KNNs with varied properties. The studies of the structural properties of the prepared samples were done by X-ray diffraction (XRD) technique. It has been found that addition of MnO2 to KNNs and sintering at 1000 °C for 20 min and at 1050 °C for 10 min showed all the KNNs crystallization in tetragonal phase with nearly similar structural parameters. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the prepared samples were investigated using an impedance analyzer. The room temperature frequency variation of electrical properties showed a dispersive behavior for all the samples. The temperature variation of the dielectric properties showed an increase with the increase of temperature. The results of the various measurements are discussed in the paper. [ABSTRACT FROM AUTHOR]

Li- Co-Y ferrites having the general formula Li0.495Co0.01YxFe2.485-xO4 where x ranges from 0.00 to 0.25 in steps of 0.05 were synthesized by chemical sol-gel auto combustion method. The sol-gel derived nanoferrite powders were initially heated at 300 °C for 1 h. The powders were then processed, shapped and heated at 1000 °C for 1 h using conventional furnace. The structural properties were studied using X-ray diffraction (XRD) technique and Fourier Transform Infrared (FTIR) Spectroscopy. The studies confirmed the formation of single phase with spinel structure in all the sol-gel synthesized ferrites. Scanning Electron Microscopy (SEM) studied the microstructure of the samples and found the formation of well defined grains. Vibrating Sample Magnetometer (VSM) measured the magnetic hysteresis properties of the prepared ferrites and found that saturation magnetization decreased but coercivity increased with Y3+ substitution. The results of the measurements obtained have been discussed 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]

Nanocrystallite piezoceramics sodium potassium niobates commonly known as KNN having compositional formula Na0.50K0.50NbO3 were synthesized by ceramic technique using high energy ball milling. The sample was calcined at 850 °C by conventional heating technique for 3 h. The calcined composition powders were pelleted and sintered by microwave heating technique at 1050 °C for different durations viz 10 min, 15 min, 20 min and 25 min. X-ray diffraction (XRD) technique studied the structure of the prepared samples and confirmed the formation of an orthorhombic phase in all the samples. The crystallite size evaluated from the XRD data revealed the formation of nanocrystallites of sizes in the range 32–37 nm. Scanning electron microscopy (SEM) revealed the microstructure of the samples. Electrical properties such as dielectric constant, dielectric loss, a. c. conductivity were measured in the frequency range of 10 kHz to 2 MHz by using an impedance analyzer. The frequency variation of these parameters showed the general dispersion behavior. The effect of microwave sintering for different durations on the structural and electrical properties and the results 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]

Lead-free lithium doped sodium potassium niobate piezoceramics having the compositional formula Na.47K.47Li.06NbO3 were synthesized by ceramic technique using high energy ball milling. The compounds were calcined at 850 °C for 3h and sintered at different temperatures viz. 900 °C, 950 °C, 1000 °C, 1050 °C and 1100 °C for 2h. The calcined compositions showed an orthorhombic perovskite phase and on sintering, the phase transformed to tetragonal phase and this tetragonal structure has been observed for sintering temperature up to 1050 °C. Effect of various sintering temperatures on the electrical properties like dielectric constant, dielectric loss and a.c. conductivity were also studied. The results obtained were analyzed and discussed in the paper. [ABSTRACT FROM AUTHOR]

Spinel lithium ferrite ceramics inherently possess useful properties like high resistivity, saturation magnetization and Curie temperature, rectangular hysteresis loop and low dielectric and magnetic losses. They find widespread applications in high frequency electronic devices. Attempting an enhancement in the properties of interest, lithium ferrites were prepared by adding V2O5 and Na2SiO3 additives. Samples having Li0.5 Fe2.5O4 + (0.1) V2O5 + (x) Na2SiO3 as representative formula where x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25 were prepared by the ceramic technique using high energy ball milling. The prepared samples were calcined at 650 °C for 1h and sintered at 950 °C for 1h. XRD was done on the sintered samples and it is found that the samples possessed single phase with spinel structure. From the XRD data various structural parameters were evaluated. The microstructure of these samples was studied from the SEM micrograph. The room temperature frequency variation of initial permeability and permeability loss were measured in the range 5MHz to 40MHz using an impedance Analyzer. The results of these measurements are discussed in the paper. [ABSTRACT FROM AUTHOR]

A series of nickel doped yttrium manganites having the representative formula Y1-xNixMnO3 with x = 0.0-0.1 in steps of 0.02 were prepared by conventional ceramic method. Analysis of the XRD pattern clearly showed the structural phase transformation from hexagonal to orthorhombic perovskite phase with nickel substitution. Variation of structural parameters such as lattice constant, crystallite size, theoretical density, etc. with nickel concentration was studied. Frequency variation of electrical properties such as dielectric constant, dielectric loss and ac conductivity were studied at room temperature in the range 3kHz-2MHz. The variation showed a dispersive behaviour for all the samples. [ABSTRACT FROM AUTHOR]

Lithium ferrites were prepared by adding different amount of Na2SiO3with representative formula Li0.5Fe2.5O4+ yV2O5+ xNa2Sio3where y = 0.1 wt% and x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25 wt% by the ceramic technique and using high energy ball milling. XRD confirmed the samples with single phase spinel structure. The lattice constant and the X-ray density are found to be of the order of 8.3 Å and 4.8 g/cc respectively. The Curie temperature of these samples ranged from 642–637°C. The frequency variation of the dielectric constant and dielectric loss showed dispersive behavior. The magnetization behavior of these samples was studied from the M-H curve. [ABSTRACT FROM AUTHOR]

Polycrystalline yttrium iron manganites – YMn1-xFexO3(with x = 0.0, 0.1, 0.15, 0.20) were synthesized by ceramic method and sol-gel auto-combustion method. XRD confirmed the formation of hexagonal phase in all samples. The hexagonal a– and c- parameters for the samples prepared by the sol-gel method are found to be closer to the stoichiometric values. The room temperature frequency variation of electrical properties such as dielectric constant, dielectric loss and ac conductivity showed a dispersive behavior for all the samples. The values of dielectric constant and dielectric loss are found to be lower for the sol-gel prepared samples. [ABSTRACT FROM AUTHOR]

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.