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Titanium oxide ceramics doped with niobium is synthesized in reduced atmosphere at 1200 ℃ by conventional solid-state reaction technique. From their crystal structures determined by the powder X-ray diffraction(XRD), the samples have multiple-phase with low Nb concentration, but they have single tetragonal rutile phase when Nb content is larger than 0.02. The electrical conductivities, the Seebeck coefficients and the thermal conductivities of the samples with single phase are measured at a temperature range between room temperature and 900 K. The electrical conductivity and the Seebeck coefficient show non-metallic behaviors. According to the fitting, it is found that the samples show thermal-activation mechanism at low temperatures and small-polaron hopping conduction mechanism at high temperatures. Moreover, the analyses of XRD, electrical conductivity and Seebeck coefficient show that the concentration of oxygen vacancy decreases with Nb content increasing. Thermal conductivity decreases with temperature increasing, dominating by lattice thermal conductivity. In the measurement region, the figure of merit (ZT) reaches a highest value of 0.19 at 873 K in the Ti0.98Nb0.02O2- sample.

Perovskite La0.9Sr0.1FeO3 ceramics have been synthesized at 1250℃，1300℃ and 1350℃ by the conventional solid-state reaction technique. From their crystal structures determined by powder X-ray diffraction，we found that the lattice volume decreases with increasing sintering temperature. The scanning electronic microscope (SEM) images of surface microstructures of the samples show that the average grain size increases with increasing sintering temperature. The electrical resistivity and Seebeck coefficient have been measured between room temperature and 800℃. At low temperatures，the electrical resistivity shows a semiconductivity-like behavior. With further increasing of temperature，the electrical resistivity slightly increases. An adiabatic hopping conduction mechanism of small-polarons is suggested from the temperature dependence of the electrical resistivity，which has different activation energies at low and high temperatures. The Seebeck coefficient rapidly decreases with increasing temperature，and reaches a saturation value about 600℃. With further increasing of temperature，the Seebeck coefficient slightly increases. With the increase of sintering temperature，the electrical resistivity decreases，while the Seebeck coefficient increases. Therefore，the power factor increases with increasing sintering temperature. The highest power factor of 90 μW/K2m was obtained at 727℃ for sample sintered at 1350℃.

The possibility of forming cascading energy levels in SrTiO3 by doping Bi and Cu as an example is analyzed by using the density-functional-theory based first principles calculations of the electronic structure. The results show that both Bi doping and Cu doping can introduce a defect level in the forbidden band，and Co-doping of Bi and Cu can introduce two defect levels in the forbidden band. Electrons at the top of valence band can transit to the bottom of conduction band through a cascade transition process. Using the nonradiative transition model，we point out that the probability of electronic transition from the valence band to the conduction band through a cascade transition is much higher than that of direct transition from the valence band to the conduction band. The cascade transitions can effectively increase the carrier concentration in the conduction band.

There are important applications of metal in metamaterials. Three methods for dealing with metal in FDTD are analyzed and compared. ADE(auxiliary differential equation method) and PLRC(piecewise linear recursive convolution) have the same numerical result. However, there is a little difference between Sakoda's method and ADE. It is due to the error in calculation of convolution integral with Sakoda's method. Improving the convolution integral with the method used in PLRC, these three methods give the same results.

The Xα method is applied to study the spin-polarized electronic structures and atomic magnetic moments of clusters La8-xBaxCuO6 in the compound La2-yBayCuO4.This paper shows that Cu magnetic moment in La2CuO4 is 0.37μB, which is in better agreement with the experimental value(0.48±0.15μB). Ba substitution lowers the structure symmetry, removes molecular orbital degeneracy, and hence strengthens orbital hybridization and weakens quasi-two-dimensional feature, which enhance the coupling between Cu-O layer and the neighbormg layers and influence the charge transfer. These changes strongly affect the properties of carriers. Holes are introduced due to Ba substitution and they mainly enter into O sites, a few d-electronic holes enter into Cu sites, which causes important effects on the density of states, atomic magnetic moment and valence states of Cu and O in Cu-O layers. The results confirm that the holes are not always beneficial to the superconductivity. At the beginning the holes are beneficial to the superconductivity; they can decrease the superconductivity when more holes are introduced. This paper can explain that the transition temperature of high-temperature superconductive oxides changes with the variation of the doping level.

La0.67Ca0.33MnO3 films with thickness between 25 and 400nm were fabricated on (001) SrTiO3 and (001) LaAlO3 substrates, using pulsed laser deposition. The magnetization and resistivity p of the films were studied as functions of thickness. The reduction of t causes the decrease of the Curie temperature T-C in addition to the increase of p of the films. Compared with the compressive strain in the La0.67Ca0.33MnO3/LaAlO3 films I the tensile strain in the La0.67Ca0.33MnO3/SrTiO3 films causes a faster reduction of T-C with t, and a larger value of rho(0). The low-temperature rho is found to follow well rho = rho(0) + Bomega(s)/sinh(2) (homega(s)/2k(B)T) + CTn, with rho(0) being the residual resistivity. The second term arises from the scattering by a soft optical phonon mode, and the third term denotes the other possible transport mechanisms. B, omega(s) ( the frequency of a soft optical mode) and C are fitting parameters. At temperatures higher than T-C, rho of all the films show activated conduction with rho = DTexp(E-a/k(B) T). Here, E-a is the activation energy. Based on the investigation of rho(0), omega(s) and E-a,E- the thickness and strain effects in the films are discussed, separately. Further study shows that the variation of T-C is mainly associated with E-a and omega(a), confirming the crucial role of the electron-phonon coupling in the strain effects on T-C.

We present the results of the Austin-Model 1 (AM1) geometry optimizations aimed at determining the charged geometry properties of -(PA)4-(PPP)m-(PA)4- triblock copolymers that have the well-barrier-well structure. The distributions of the doped charges depend upon the density of doped charges and the length of the barrier.

Polarons and bipolarons in mixed halide MX compounds were studied in the frame work of the two-band extended Peierls-Hubbard model.Different from the isolated MX chains,it was found that the segments tend to select impurities in mixed halide compounds.Then the charge confinement and the effect of electron-electron interactions were investigated.Finally the properties of impurities in mixed halide compounds with spontaneous charge transfer were also discussed.

We present a model calculation,using the tight-binding approach,of a one-dimensional heterostructure consisting of regular alternation of two different halogen-bridged transition-metal compounds (MX compounds).Superlattice and multi-quantum-well properties can be detected depending on the well-barrier alternation sequence.We prove the possibility of developing new multi-quantum-well devices based upon MX compounds.

In our calculations of lattice vibration, one acoustic and three optical branche s were found to compose the phonon vibrating spectrum. Some isolated modes with frequencies lying outside the continuum branches aise under the defect states. These localized modes result in the sharp peaks in the infrared absorption and Raman spectra.

Intrinsic charge transfer in mixed halide compounds PtXxX′1-x was studied in the framework of the two-band extended Pielerls-Hubbard model. It was found that the number of transferred charges can be a fraction times of the electronic charge. The maximum amount of transferred charges occurs at a certain x for a given mixed compound.

Magnetic properties and giant magneto-impedance (GMI) effects of Fe73.5Cu1Nb3Si13.5B9 single layered films and sandwiched fimls using Cu or Ag as the central layer prepared by radio frequency sputtering are investigated. The as-deposited single layered films are in amorphous state. The domain structures of single layered films annealed as 380℃ show that the films are in nanocrystalline state with homogeneous magnetization. The samples possess excellent soft magnetic properties and have the maxiumum values of GMI effects, the maxiumum GMI ratios are 18% and 14% in longitudinal and transverse fields, respectively, at 13MHz. Sandwiched films in the as-deposited state possess large GMI effects, the maximum GMI ratios of sandwiched films with a Cu central layer are 32% and 11% for longitudinal and transverse cases, respectively, and those of sandwiched films with a Ag central layer are 47% and 57% for longitudinal and transverse cases, respectively. Sandwiched films using Cu as the inner layer annealed at 250℃ exhibit large magneto-inductance effect at low frequencies. The maximum magneto-inductance ratio is 1733% at 100kHz.

Spin density wave in organic ferromagnets with open ends was studied and the results were compared with that in a closed organic ferromagnet ring. It was found that an end-open chain structure is unfavorable for the formation of the ferromagnetic ground. The competition of electron-electron interactions and the π-electron-radical spin couplings and their different effect on the SDW in the main chain were discussed.

A tight-binding model for conducting polymer poly(phenylene vinylene) (PPV) has been suggested in the framework of one-dimensional chains. The calculations showed that this model is effective to describe the ground state, polaron and bipolaron excitations in PPV. The stability of polarons and bipolarons was discussed by considering the effect of the dimensions, e-ph and e-e interactions.

The stabilities of one-dimensional conducting polymer chains with finte lengths have been studied in the frame work of the SSH tight-binding model.Three kinds of boundary conditions have been proposed to stabilize the dimerized structure of the chains.It was found that the natural boundary condition or the end-fixed boundary condition is applicable for getting a result to fit the observed photo-absorption of polyacetylene with short (N

Two series of [Pd/Co-Nb/Pd/Si] multilayer films were prepared by rf sputtering. The measurements of structure and magnetism were made by X-ray diffraction and magnetometer, respectively. As the thickness of Pd layers increases, the structure of Pd layers transfers from an amorphous state to a polycrystalline state. The polycrystalline state of the Pd layers shows two adjacent Pd fcc(111) peaks, which originate from the differences of lattice-mismatching degree and polarization of Pd atoms between the interfaces of Co-Nb layers and Pd layers and the interfaces of Pd layers and Si layers. As the thickness of Pd layers increases, the saturation magnetization monotonously increases from a value which is smaller than that of the bulk Co-Nb alloy with the same compositions to another value which is larger, then takes a constant value. This is contributed to the effects of polarization of Pd layers, dimension of Co-Nb magnetic layers and interdiffusion of atoms in the interfaces. The amorphous Co-Nb layers can influence the polarization of Pd atoms in the range of 2.5nm from the interfaces of Co-Nb layers and Pd layers. The is related to the strong interdiffusion of atoms in the interfaces and the large change of the Pd lattice constant in the film normal.

Based on the phenomenological theory of Camley and Barnas and coworkers (C-B), the dependence of magnetoresistance in Fe/Cr multilayers on the applied magne-tic field is calculated. In these multilayers an antiferromagnetic coupling exists between any two adjacent Fe-layers. The applied magnetic field is either parallel or perpendicular to the layers. Good agreement of the calculated results with the experimental ones is found. The symmetry implicitly involved in the C-B theory is disclosed and is used to simplify the original C-B formalism, this leads to the closed expressions for the distribution function of conducting electrons and for magnetore-sistance.

With a local potential of site-impurity in the frame work of the SSH model, the Coulomb effect of the dopant ions on the vibrational modes around the charged-soliton in doped poly-acetylene has been studied. The calculated results showed that the Goldstone theorem will be destroyed and the translation mode g1 will be pined by the dopant potential. At the same time, a new even-parity mode g′ 1 has been found. The appearance of g1 and g′1 interpret well the broad peak at 930 cm-1. In addition, other localized modes have also been discussed.

The stability of soliton pairs and the electronic energy level structures in a doped poly-acetylene chain have been studied under natural boundary conditiono. In the Itamiltanian usel an end point potential was added to the SHH model, and the screened Coulomb potential of impurities and e-e interaetion on the tattice points were also indndelincluded. The caleulated results Show that, as the range of coulomb interaction is long enongh, stable soliton pairs are formel in the chain, and the stability is enlanced by the influce of the ends the gap width becomes narrow with the increase of chain length. But the deplndence of transition energg from soliton level to band bottom on chain length is not very signicant.

Based on the fact of the existance of a small amount itinerant electrons, a new theoretical model giving rise to magneto-crystalline anisotropy in compound Nd2Fe14B is presented in this paper. It is proposed that a combined effect on Nd-ion coming from both the crystal field of ligands and the electric field of itinerant electrons results in the anisotropy in the compound. An approach of calculating the interaction between itinerant electrons and central Nd-ion is given. The magneto-crystalline anisotropy of Nd-ion and its temperature dependences are calculated based on the model. The results are in good agreement with the experiments, and also give explanation to the spin reorientation phenomenon in the compound.

The structural and magnetic properties of the two sources deposited Fe/Pd superlattices were studied. The samples were prepared by keeping the thickness of Pd layers dpd at 30? and varying dFe from 56 to 5.7?. The reduced saturation magnetization of Fe/Pd superlatti-ces, σt increased with the decrease of dFe this was due to the polarization effect of Pd. The effective thickness of polarization effect dpd was found as about 10? at 0K. The temperature dependence of magnetization followed Bloch T3/2 law in the range of 7-300K. and the spin-wave stiffness constant B increased with the decrease of dFe The Curie temperature, Tc decreased with dFe The 57Fe conversion electron M?ssbauer spectrum illustrated that the polarization effect existed among the layers, and there were no magnetic enhancing effect and "dead layer effect" on the Fe atoms at the interfaces.

The electron correlation and soliton in polyacetylene have been studied with the CBF method. By considering the complete electron-electron interaction, we concluded that the stable static configuration of a PA chain with odd atoms and a single electric charge is a soliton. With the increase of e-e interaction strength U and interaction range α/β the localization of soliton is enhanced, and the soliton creation energy is reduced, so although the e-e interaction is considered, the conclusion that soliton is main charged carrier in high conducting polymers is still tenable.

The compositionally modulated FeBSi/Si amorphous films were prepared by rf sputtering. The saturation magnetization of modulated films decreases exponentially with increase of the thickness of Si layers. This is caused by the dead layers. The M?ssbauer spectra measurements showed that the dead layers are the paramagnetic phase formed by the interdiffusion of Fe and Si atoms at the interfaces. The size effect was observed in the FeBSi/Si films. The size effect depends only on the thickness of FeBSi layers, and the dead layer effect depends on both the FeBSi layer thickness and Si layer thickness.

The compositionally modulated amorphous films FeSi/Si have been prepared successfully. Systematically varying the thickness dm of the FeSi layers with fixed thickness of Si layers, it is shown that the saturation magnetization Ms decreases monotonously with decreasing dm. This basically is the contribution from the dead layer effect. The thickness of dead layer at OK is about 5.8?. With decreasing dm, the modulated films transit from three dimensional magnetism to two dimensional one gradually. The expressions of this transition are the appearances of low magnetic and nonmagnetic hysteresis effect, the linear Ms(T)-T relations and the monotonous decreasing of Curie temperature Tc. Tc satisfies the equation: △Tc∝dm-1, where λ=1.6.

A calculation of magnetic single-ion anisotropy in hematite (α-Fe2O3) has been made, based on point-charge model in crystalline field. The nearest-neighbor O2- ions and the nexi-nearest-neighbor Fe3+ ions were chosen as ligands and the effect of electrostatic shield provided by the O2- ions was taken into account. Considering the sixth order perturbation, we ob-tained an equivalent single-ion anisotropy field Hsi=102.3×102 Oe. Making use of this results in conjunction with the computed equivalent dipolar anisotropy field by Artmen et al,. the Morin transition temperature in hematite TM=261 K was obtained, which is in good agreement with the experimental value. Based on the linear approximation principle, we got the TM-n relation for low n value in α-(Fe-1nAln)2O3. With this relation the dependence of the-Morin transition temperature, TM, on n in low n value range could be explained quite well.

Production of amorphous alloy layer in pure polycrystalline iron thin film by boron ion implantatiom has been studied and interesting phenomena have been observed such as the magnetic coercive field of the film decreases non-monotonously with increasing ion dose, etc. The possible mechanisms of the phenomena have been discussed.

The permeability of polycrystalline iron thin films implanted with different doses of boron ions rises nonmonotonously with increasing dose, while the 57Fe conversion electron Mossbauer spectra of the films have shown the formation of amorphous metallic alloy. The results favour the critical defect density model of amorphous state formation.

We have proposed a simple Hamiltonian for poly(p-phenylene) in the framework of SSH tight binding model. The calculations presented to the ground state, polaron and bipolaron show that the formation of doubly charged bipolaron is energetically more favorable than the-formation of two polarons with single, charge. Because the period of the chain is 4a, the CB and VB band will split in two, and when there is a polaron (or bipolaron) in the chain, shallow energe levels will emerge near each band edge besides the polaron (or bipolaron) energe levels, all the corresponding electronic states are localized.

The electronic structures of Si (111) surface have been studied by means of molecular orbital theory of SCF-CNDO with the cluster model treatment. The calculated results show that: (1) The distribution and transfer of net charges in thesurface have localized characters at the atomic orbitals. Also, the T30, T3+ and T3-defect forms do not exist easily in practical system. (2) The electronic structures can be discribed with the stoohastic potential, from which one can find out the adsorption site and learn the adsorption dynamic process of ion and ionic molecules adsorbed on the Si (111) surface. (3) The surface states mainly appear in the region from the top of valence band to the centre of gap, and is strongly localized at the atomic orbitals. The above-mentioned results are consistent with some experimental discoveries.