Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

Nanocomposites, a high performance material exhibit unusual property combinations and unique design possibilities. With an estimated annual growth rate of about 25% and fastest demand to be in engineering plastics and elastomers, their potential is so striking that they are useful in several areas ranging from packaging to biomedical applications. In this unified overview the three types of matrix nanocomposites are presented underlining the need for these materials, their processing methods and some recent results on structure, properties and potential applications, perspectives including need for such materials in future space mission and other interesting applications together with market and safety aspects. Possible uses of natural materials such as clay based minerals, chrysotile and lignocellulosic fibers are highlighted. Being environmentally friendly, applications of nanocomposites offer new technology and business opportunities for several sectors of the aerospace, automotive, electronics and biotechnology industries.

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Nanocomposites: synthesis, structure, properties and new application opportunities

Transition-metal activated phosphors are an important family of luminescent materials that can produce white light with an outstanding color rendering index and correlated color temperature for use in light-emitting diodes. In recent years, work in this quite “hot” research field has focused on the development of Mn2+ and Mn4+ activated red phosphors. In this review article, we provide an overview of recent studies on Mn2+ and Mn4+ doped phosphors, including detailed synthesis routes (solid-state reaction and wet-chemical synthesis) and description of luminescence mechanisms and phosphors’ behaviors; discuss their promising applications in white light-emitting diodes; and present an extensive list of references to representative works in this field.

Mn2+ and Mn4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review

Multiferroic bismuth ferrite-based materials for multifunctional applications: Ceramic bulks, thin films and nanostructures

A conceptual review on polymer electrolytes and ion transport models

Polycrystalline samples of Bi0.90La0.10(Fe1−xMnx)O3 (x=0, 0.05, 0.10, 0.15, and 0.20) were prepared using a novel mechanical activation followed by a conventional solid-state reaction technique. The formation of the desired materials was confirmed using x-ray diffraction. The electrical and magnetic properties of the materials were investigated at different Mn concentrations as a function of temperature. Both dielectric constant and loss tangent increased with the increase in Mn content in the system. The grain and grain boundary contributions have been estimated using impedance spectroscopy analysis. Both grain and grain boundary conductivity increased with a rise in temperature for all Mn concentrations. The value of activation energy for both grain and grain boundary is nearly the same, and decreased with an increase in Mn concentration. There is a systematic increase in the value of magnetization on increasing Mn concentration.

Effect of Mn substitution on electrical and magnetic properties of Bi0.9La0.1FeO3

Yttrium (Y) modified nanocrystalline samples of BiFeO3 (BFO) were prepared by a metal ion ligand complex-based precursor-solution evaporation method. Partial substitution of Y (0–15%) at the Bi site results in structural change (rhombohedral to tetragonal) and single phase formation. With increasing Y concentration, enhancement in dielectric ordering, reduction in loss tangent and improvement in magnetic ordering in BFO were observed. Diffuse peaks in both permittivity and loss tangent were observed at 207 °C and 222 °C, respectively, for 15% substitution of Y. In all the Y substituted BFO samples, a switching behavior in low fields was observed in the field dependence of magnetization, even at room temperature, and this behavior was found to be improved with increasing Y concentration.

http://iopscience.iop.org/article/10.1088/0953-8984/20/04/045218/pdf

Effect of yttrium on improvement of dielectric properties and magnetic switching behavior in BiFeO3

A perovskite ceramic oxide having the general formula Pb0.97Ca0.03Zr0.05Ti0.95O3 (PCZT) was prepared using precursor solution method. The compound belongs to the tetragonal system. TEM micrographs show that the particles are more or less spherical in shape. Complex impedance analysis indicates the presence of grains separated by grain boundaries, which are also evident from the SEM micrographs. The sample impedance behavior has been explained in terms of the bricklayer model. The relaxation process taking place is short range. The conductivity variation shows a typical Arrhenius-type behavior having linear dependence on logarithm of conductivity.

Structural and electrical properties of Ca2+-modified PZT electroceramics

Structural, thermal and electrical behavior of polymer-clay nanocomposite electrolytes consisting of polymer (polyethylene oxide (PEO)) and NaI as salt with different concentrations of organically modified Na + montmorillonite (DMMT) filler have been investigated. The formation of nanocomposites and changes in the structural properties of the materials were investigated by X-ray diffraction (XRD) analysis. Complex impedance analysis shows the existence of bulk and material-electrode interface properties of the composites. The relative dielectric constant (er) decreases with increase in frequency in the low frequency region whereas frequency independent behavior is observed in the high frequency region. The electrical modulus representation shows a loss feature in the imaginary component. The relaxation associated with this feature shows a stretched exponential decay. Studies of frequency dependence of dielectric and modulus formalism suggest that the ionic and polymer segmental motion are strongly coupled manifeasting as peak in the modulus (M") spectra with no corresponding feature in dielectric spectra. The frequency dependence of ac (alternating current) conductivity obeys Jon- scher power law feature in the high frequency region, where as the low frequency dispersion indicating the presence of electrode polarization effect in the materials.

http://www.expresspolymlett.com/letolt.php?file=EPL-0000708&mi=c

R. N. P. Choudhary

Papers

Effect of Mn substitution on electrical and magnetic properties of Bi0.9La0.1FeO3

Effect of yttrium on improvement of dielectric properties and magnetic switching behavior in BiFeO3

Structural and electrical properties of Ca2+-modified PZT electroceramics

Studies of structural, thermal and electrical behavior of polymer nanocomposite electrolytes

Characterization of electrical properties of Pb-modified BaSnO3 using impedance spectroscopy