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

Dielectric, magnetic and enhanced magnetoelectric response in high energy ball milling assisted BST-NZF particulate composite

The application of microwave cavity perturbation technique for the study of transients in semiconductors is becoming popular due to its simplicity in measurement procedure and high sensitivity. This paper discusses the effects of quality factor, sample size, and coupling factor on the sensitivity of the measurement. Also, it deals with a measurement approach for the study of triplet state transitions and excited state studies in organic solvents. Finally, a comparison between the cavity perturbation technique and the currently used reflection technique is made.

Sensitivity analysis of transient measurements using the microwave cavity perturbation technique

Microwave dielectric properties of Li2SrTa2(1−x)Nb2xO7 ceramics investigated by Raman spectroscopy

Nanocrystalline powders of the composition Pb(Zr0.52Ti0.48)O3 were obtained by Mechanical alloying (high-energy ball milling). X-ray diffraction studies show that these compounds are completely into the perovskite phase. Detailed studies of electrical and mechanical properties of PZT as a function of temperature (and frequency) showed the high permittivity of 20653 at Curie transition temperature. Temperature variation of longitudinal modulus and internal friction of these ceramics at 104 kHz frequency were studied in the wide temperature range of 30°C-420°C. The internal friction measurements showed sharp stress induced relaxation peaks in the present composition corresponding to those temperatures where the minima were noticed in temperature variation of longitudinal modulus behavior. This dielectric and internal friction behaviour was explained in the light of polaron hopping mechanism and structural phase transitions in the present piezoelectric compositions.

https://downloads.hindawi.com/journals/jnm/2010/783043.pdf

Nanocrystalline Pb(Zr 0.52 Ti 0.48 )O 3 ferroelectric ceramics: mechanical and electrical properties

The dielectric behaviour of the polar liquids like propionaldehyde, isopropyl amine and their equimolar binary mixture in nonpolar solvent benzene is studied in the microwave frequency range using the cavity perturbation technique at 6.218 GHz (J band), 9.880 GHz (X band), 16.331 GHz (P band) and 24.951 GHz (K band). Hamiltonian quantum mechanical calculations such as AM1, PM3, and MNDO optimized converged geometry operation is performed by using Argus lab chemical modelling software 2004 for both pure and binary systems of propionaldehyde and isopropyl amine. 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 a hydrogen bond between the propionaldehyde and isopropyl amine is supported by FT-IR, proton NMR spectra and molecular polarizability calculations. The average relaxation times are calculated from their respective Cole–Cole plots.

V. R. K. Murthy

Papers

Dielectric, magnetic and enhanced magnetoelectric response in high energy ball milling assisted BST-NZF particulate composite

Sensitivity analysis of transient measurements using the microwave cavity perturbation technique

Microwave dielectric properties of Li2SrTa2(1−x)Nb2xO7 ceramics investigated by Raman spectroscopy

Nanocrystalline Pb(Zr 0.52 Ti 0.48 )O 3 ferroelectric ceramics: mechanical and electrical properties

Conformational and microwave dielectric relaxation studies of hydrogen bonded polar binary mixtures of propionaldehyde with isopropyl amine