Enhanced magnetization with unusual low temperature magnetic ordering behaviour and spin reorientation in holmium-modified multiferroic BiFeO3 perovskite ceramics , Singh, Hemant; Yadav, K. Electrical, magnetic and magnetodielectric properties in ferrite-ferroelectric particulate composites , Rawat, Meera; Yadav, K. Dielectric and magnetic properties of xCoFe 2 O 4 - 1-x [0.

Compositional effects on structural, dielectric, ferroelectric and transport properties of Ba1-x Bi0. Structural, dielectric and optical properties of sol-gel synthesized 0.

## Solid-State Physics, Fluidics, and Analytical Techniques in Micro- and Nanotechnology

Study of barrier layer capacitance effect in lead free Ba0. Effect of BaTiO3 addition on structural, multiferroic and magneto-dielectric properties of 0. Enhanced magnetodielectric effect and optical property of lead-free multiferroic 1-x Bi0.

Dielectric, ferroelectric and magnetoelectric response in Ba Structural, dielectric, magnetic, and optical properties of Ni0. Effect of yttrium on microstructure, dielectric, ferroelectric and optical properties of BaZr0. Study of structural, electrical, magnetic and optical properties of 0. Origin of giant dielectric constant and magnetodielectric study in Ba Fe0. Multiferroic Properties of Bi0. Synthesis and study of structural, dielectric, magnetic and magnetoelectric characterization of BiFeO3-NiFe2O4 nanocomposites prepared by chemical solution method ; Singh, Hemant; Yadav, K.

Reduced dielectric loss in Ba0. Enhanced dielectric, ferroelectric and optical properties of lead free K0.

Structural, dielectric and ferroelectric properties of Ba1-x Bi0. Giant dielectric permittivity and room temperature magnetodielectric study of BaTi0. Enhanced magnetodielectric properties of single-phase Bi0. Title: Enhanced magnetoelectric sensitivity in Co0. A model is presented in which the magnetic field induces a transition from transport in a conduction band to an impurity band, in the impurity band the activation energy appears due to the separation of the two Hubbard bands.

Describes a method for combining a quantum mechanical treatment of a cluster of ions near a point defect in an ionic crystal with self-consistent polarisation in the surrounding perfect lattice, which is described by a shell model. They show that lattice polarisation effects are important in accurate calculations of the optical absorption and emission.

The authors calculations give some support to suggestions that charge transfer from second-neighbour O 2- ions is important. They discuss ways of improving the method for example the use of pseudopotential in the light of their results. The general behaviour of deep-level wavefunctions induced by the short-range defect potential is investigated quantitatively when the energy difference epsilon between the defect state and the band edge is very small.

The configurations of A 1 deep wavefunctions in Si and GaAs are reported for the first time. For Si, when epsilon is less than 2 meV, the wavefunctions tend to correct significantly in k-space. For GaAs, the wavefunctions do not contract explicitly in k-space even for epsilon as small as 0. The multiple-scattering X alpha molecular cluster model is used to carry out self-consistent calculations of the electronic states of an isolated P vacancy in GaP. A fully occupied singly degenerate a 1 level and a threefold-degenerate t 2 level occupied by one electron are found within the band gap.

This configuration indicates that the centre is unstable with respect to Jahn-Teller distortions. The vacancy states a 1 and t 2 are quite extended showing an appreciable charge distribution in the next-nearest neighbours of the vacancy P atoms. The role played by these results in the explanation of the properties of the GaP:O centre is discussed. To assess the effect of random coordination percolation properties of the three-dimensional 3D Voronoi network and the body-centred cubic with second-nearest-neighbour bonding BCC2 are calculated by Monte Carlo simulation and compared.

The accessible fraction, backbone fraction and effective conductivity of the Voronoi network and regular networks are qualitatively the same. Moreover, when enough bonds are removed from the Voronoi network to make the average coordination match that of the BCC2 network the difference between the conductivities of the two networks is less than 0.

Finite-size scaling theory is used to estimate percolation thresholds and critical exponents. The bond percolation thresholds of the Voronoi and BCC2 networks are 0. The effective conductivity of the network derived from a crude finite-element approximation to the Voronoi tessellation is only slightly different from that of the same network with the conductances redistributed at random.

A long-standing paradox concerning reduction factors in excited states of an E X epsilon Jahn-Teller system is resolved.

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Leung and Kleiner defined reduction factors p, q for each excited vibronic doublet, while Gauthier and Walker defined p, q from a Green function formalism at finite temperatures. However, the thermal averages of the Leung and Kleiner factors disagree with the Gauthier and Walker expressions.

It is shown here that the two schemes use different assignments of excited states into doublets, and that the resulting p, q factors are relevant to different features in the E X epsilon spectrum. In this notation Gamma corresponds to the irreducible representation labelling the degenerate electronic state and epsilon is the doubly degenerate representation labelling the vibrations in the point group of the physical system.

The method is shown to be straightforward to apply to other point groups as well, involving the multiplication of three terms, a phase factor, a reduced matrix element and a 6j symbol, all of which can be tabulated. The form of the matrix elements and symmetrised electron phonon bases are very simple and this allows one to calculate matrix elements involving high phonon numbers by following a recipe to combine the three tabulated terms.

Another advantage of this method is that it can be extended to include spin-orbit, higher-order and anharmonic terms within the same framework. The low-temperature breakdown characteristics of n-Ge are investigated theoretically using various models for the recombination process of the non-equilibrium carriers. The energy distribution of the carriers at the onset of the breakdown is assumed to be Maxwellian and effective electron temperature is used.

The calculations are carried out for a parabolic law of dispersion and a scalar effective mass. The theoretical results for some of the models of the recombination process are found to be in good agreement with the available experimental data. The authors derive the thermodynamics and the static correlation functions for the classical Heisenberg chain with the anisotropies within a low-temperature steepest-descent approach.

As regards the thermodynamics, they find agreement with transfer matrix and 'ideal-gas' phenomenological results. For the longitudinal correlation function the authors find an antiferromagnetic-type behaviour with a correlation length inversely proportional to the domain wall density. The transverse in-plane correlation function exhibits a damped oscillatory behaviour due to domain-wall-spin interference.

The transverse out-of-plane correlations, on the other hand, are exponentially damped with the correlation length increasing as the easy-axis limit is approached. The intensity and linewidth sets of data each suggest considerable short-range order above T N. An equation describing the effect of temperature on the isothermal piezo-optic coefficient under normal pressure has been established for water, at AA wavelength and for temperatures below 65 degrees C.

This along with other optical data allowed the author to test various refringency laws. It is shown that the so-called 'invariants of refraction' given in literature are not satisfactory. The theoretical formula given by Lucas leads to results that disagree with the experimental data. The semi-empirical formula of Eisenberg only give correct values for the refractive index and thermo-optical coefficient of water; in the case of the piezo-optic coefficient there is, however, a discrepancy with reference values at the highest temperatures.

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## Solid State Physics. Advances in Research and Applications. : Zeitschrift für Physikalische Chemie

I see ibid. Expressing the elasto-optical coefficient of a fluid through its refractive index, one obtains relations between the refractive index, its derivatives relative to temperature and pressure, and various thermodynamic parameters of the liquid. Study of the particular case of water allows the author to express these various relationships in a more convenient way.

One is then close to the Eisenberg formulae with the Gladstone-Dale refringence function instead of the Lorentz-Lorenz function. The addition of one more term in the equation of the isothermal piezo-optical coefficient gives a very good agreement with experimental data. The equations obtained may be extended to the case of any liquid.