There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

3d-transition-metal-doped ZnO films (n-type Zn1−xMxO (x=005–025): M=Co, Mn, Cr, Ni) are formed on sapphire substrates using a pulsed-laser deposition technique, and their magnetic and electric properties are examined The Co-doped ZnO films showed the maximum solubility limit Some of the Co-doped ZnO films exhibit ferromagnetic behaviors with the Curie temperature higher than room temperature The magnetic properties of Co-doped ZnO films depend on the concentration of Co ions and carriers

Magnetic and electric properties of transition-metal-doped ZnO films

Recent advances in the theory and experimental realization of ferromagnetic semiconductors give hope that a new generation of microelectronic devices based on the spin degree of freedom of the electron can be developed. This review focuses primarily on promising candidate materials (such as GaN, GaP and ZnO) in which there is already a technology base and a fairly good understanding of the basic electrical and optical properties. The introduction of Mn into these and other materials under the right conditions is found to produce ferromagnetism near or above room temperature. There are a number of other potential dopant ions that could be employed (such as Fe, Ni, Co, Cr) as suggested by theory [see, for example, Sato and Katayama-Yoshida, Jpn. J. Appl. Phys., Part 2 39, L555 (2000)]. Growth of these ferromagnetic materials by thin film techniques, such as molecular beam epitaxy or pulsed laser deposition, provides excellent control of the dopant concentration and the ability to grow single-phase layers. T...

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Wide band gap ferromagnetic semiconductors and oxides

The applicability of the modfied Lippincott δ-function model method is tested for binary mesophase mixtures. Using this method, the polarizabilities, polarizability anisotropies and order parameters of binary mesophase mixtures containing N-(ρ-propoxy-benzylidene)-p-pentylaniline are evaluated and compared with the reported values. Α close agreement is observed between the estimated values and reported values. PACS numbers: 61.30.—v, 35.20.My

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PHYSICAL STUDIES OF BINARY MESOPHASE MIXTURES CONTAINING N-(p-PROPOXY- -BENZYLIDENE)-.p-PENTYLANILINE

The procedure for measuring ac conductivity at microwave frequencies is outlined. The Tc of typical 123 oxide superconductors obtained by ac measurement is lower than that obtained by dc measurement. Possible reasons for this observation are also considered.

Conductivity measurements of some high-Tc superconducting materials at microwave frequencies

Dielectric spectra of propylene glycol, aniline and their binary mixtures with different concentrations were studied at 303K-323K by using Coaxial cable method in the microwave frequency range 20 MHz-20 GHz. The relaxational response of the propylene glycol, aniline and their binary liquid mixtures over the entire composition range is analysed by using Cole-Cole relaxation model. Dipole moments obtained from the Higasi’s method are compared with the quantum mechanical HF and DFT calculations. From the experimental datadipole moment, Bruggeman parameter, Kirkwood g factor, excess dielectric and thermodynamic parameters have been calculated. The obtained data have been analysed in terms of the parallel and anti parallel orientation of the dipoles, chain length and hydrogen bond interaction in the mixture composition. Keywords--Relaxation Time, Dipole Moment, Excess Dielectric And Thermodynamic Parameters

/pdf/dielectric-spectroscopic-studies-of-propylene-glycol-aniline-3w3mzboyoc.pdf

Dielectric Spectroscopic Studies of Propylene Glycol/Aniline Mixtures at Temperatures Between 303K to 323K

The molecular interaction between the polar systems of isobutanol and methyl benzoate for various mole fractions at different temperatures were studied by determining the frequency dependent complex dielectric permittivity by using the open-ended coaxial probe technique method in the microwave frequency range from 20MHz-20 GHz. The geometries are optimized at HF, B3LYP with 6-311G and 6-311G+ basis sets. Dipole moments of the binary mixtures are calculated from the dielectric data using Higasi’s method and compared with the theoretical results. Conformational analysis of the formation of hydrogen bond between isobutanol and methyl benzoate is supported by the FT-IR, 1NMR and molecular polarizability calculations. The average relaxation times are calculated from their respective Debye and Cole-Cole plots. The activation entropy, activation enthalpy, Gibbs free energy of activation and Kirkwood correlation ‘g’ factor, excess permittivity (ε), excess inverse relaxation time (1/τ) , Bruggeman parameter (fB) have also been determined for isobutanol and methyl benzoate and the results were correlated. Keywords— Complex dielectric permittivity; relaxation time; excess dielectric and thermodynamic parameters; ab-initio calculations.

/pdf/investigation-of-intermolecular-interaction-between-4qa5ycwpak.pdf

Investigation of Intermolecular Interaction Between Isobutanol and Methyl Benzoate using Excess Dielectric and Thermodynamic Parameters

Structure analysis of polycrystalline BaMg1/3Ta1/3Nb1/3O3 ceramics has been carried out using the Rietveld technique, wherein the B cations (Mg, Ta, and Nb) have the same occupancy with a size difference and charge imbalance. The compound has an ordered trigonal structure as well as a disordered cubic phase depending on the preparation temperature. The weight percentage of the ordered phase is found to increase with a rise in the calcination temperature.

V. R. K. Murthy

Papers

PHYSICAL STUDIES OF BINARY MESOPHASE MIXTURES CONTAINING N-(p-PROPOXY- -BENZYLIDENE)-.p-PENTYLANILINE

Conductivity measurements of some high-Tc superconducting materials at microwave frequencies

Dielectric Spectroscopic Studies of Propylene Glycol/Aniline Mixtures at Temperatures Between 303K to 323K

Investigation of Intermolecular Interaction Between Isobutanol and Methyl Benzoate using Excess Dielectric and Thermodynamic Parameters

Ordering in BaMg1/3Ta1/3Nb1/3O3 ceramics: An X-ray Rietveld analysis