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The properties of potassium natrium tantalite niobate (KNTN) surfaces are discussed, A-site substitution with potassium tantalite niobate (KTN) and the use of Na cations to replace K ones. After geometrical structure optimization, band structure and density of states (DOS) are analyzed for KNTN [1 0 0] surface. Furthermore, we evaluate the optical and physical properties of KNTN surfaces using first-principles calculations such as dielectric function, refractive index, and energy-loss function and compare the results with KNTN bulk and KTN surfaces; there are some similar and different properties with these materials.

The electronic structures and magnetic properties of SmCo7-xMx (M = Ti, Si, Zr, Hf, Cu, B, Ag, Ga, Mn) compounds are investigated by using a spin-polarized MS-X.α method. The results show that the long-range ferromagnetic order is determined by a stronger 3d_5d interaction, rather than the traditional RKKY interaction, and the effects of doping element M on 3d_5d coupling are negligible in Sm-Co-based compounds. The nonmagnetic dopant Si atoms have a larger effect on the moments of 2e site although they preferably occupy the Co 3g sites, which results in the stronger uniaxial anisotropy of this compound. Analysis of the formation energies indicates that 5d-element doped compounds are more stable than other dopants, and furthermore, they have a higher Curie temperature above room temperature, which will be in favor of their potential application as high-temperature permanent magnets.

In the presence of an applied uniform magnetic field B0, the properties of 2-dimensional (2D) magnetosonic solitary waves of relativistic amplitude in the plasma containing electron, light ions He+, and heavy ions O+ are presented. In the weakly relativistic limit, a Kadomtsev–Petviashvili (KP) equation is derived by reductive perturbation method. We give the N-soliton solution of the KP equation and find dromion solutions of a potential of the physical field. The interaction law of the dromions is obtained, which shows there is no exchange of energy, momentum, and angular momentum before and after interaction of the dromions except for phase shifts.

Two-dimensional (2D) relativistic magnetosonic solitons in the negative-ion-rich plasma consisting of positive ions Ar+, negative ions SF6- and electrons are investigated in the presence of an applied magnetic field B0 and can be described by a Kadomtsev–Petviashvili (KP) equation in the weakly relativistic limit. The ratio of positive ion density to negative ion density has a marked influence on the amplitudeΦm and width W of the steady-state KP soliton. The interaction law of the nontrivial solitons with rich web structure is studied by the Wronskian determinant method.

Considering the limiting weak nonlinearity, we obtained the solution of the coupled equations describing the interaction of ultraintense laser with cold transparent multicomponent plasma. It was indicated that the ions tend to accumulate at the center of the soliton and have large velocity when we consider the mobile ions in the multicomponent plasma, which shows that the result is different from that of the Berezhiani's analysis. The change of proportion of ions in the plasma has effects on the amplitude of vector potential and the maximum velocity of the soliton.

In the presence of an applied static and uniform magnetic field, a cylindrical Kadomtsev–Petviashivili equation is derived for a relativistic electromagnetic solitary wave propagating in collisionless plasma consisting electrons, positrons, and ions in the case of weak relativistic limit. This equation is solved in a stationary frame to obtain explicit expression for the velocity, amplitude and width of solitons. The amplitude of the solitary wave has a maximum value at a critical αc of the ratio of the ion equilibrium density to the electron one, and it increases as the applied magnetic field becomes larger.

The coupling between two mutually incoherent optical beams that propagate collinearly in open-circuit photovoltaic photorefractive media is investigated. It is shown that an incoherently coupled bright–dark spatial soliton pair can be formed due to photovoltaic effect. The physical properties of such a soliton pair are also discussed.

We show that incoherently coupled grey–grey spatial soliton pairs can be established in guest–host photorefractive polymers under steady-state conditions, provided that their carrier beams have the same polarization, wavelength and are mutually incoherent. The properties of these soliton pairs, such as their width and polarization, are discussed in detail.

We have proven theoretically that there are sublinear, linear and superlinear relations between the response rates and total incident intensity for different cases of traps in photorefractive polymer materials. These relations were observed in inorganic photorefractive crystals many years ago. Also, the steady-state space-charge field is a function of the total incident intensity, which has also been found in inorganic photorefractive crystals. We have measured the relations of the steady-state diffraction efficiency and the response rate with respect to the total incident intensity in the photorefractive composite consisting of the polymer (N-vinylcarbazole) (PVK) doped with 4,4'-n-pentylcyanobiphenyl (5CB) and C60. The results obtained show that the composite belongs to the case of low trap density.

The S-wave Klein-Gordon equation with vector and scalar Wood-Saxon potentials is solved, and the energy levels are given through an equation.

The temporal behavior of the bidirectional phase-conjugate outputs from a coherently induced phase conjugator has been observed on a Cu-doped barium strontium potassium sodium niobate crystal. In our experiment, the phase-conjugate outputs of two incident beams vary smoothly with time if the beam ratio is large. When the beam ratio is reduced, however, each phase-conjugate output will experience a temporal fluctuation. The phase-conjugate output characteristic is found to be dependent on the beam ratio of the two input beams, their positions, their beam-path-length difference and sometimes the input order of the two beams. We present a model of multi-region-interaction to explain the operation of the device and the experimental results in this paper.

The transmission of rapidly phase modulated signal beams in photorefractive two-wave mixing is studied theoretically. The analytical expressions of output intensities are given both in diffusion regime and in drift regime.

A new scheme of coherent mutually pumped phase conjugate (MPPC) reflection that depends on the formation of self-pumped phase conjugate reflection of another beam has been demonstrated in a Cu:KNSBN crystal. The dependences of the MPPC reflectivity on the intensity ratio of the two incident beams and on the incident position of the signal beam were measured. We obtain phase conjugate reflectivities of greater than 90% at 488 nm.

The coupled wave equations and their analytic solutions in photorefractive crystals are presented for the case of two-beam writing, while the light-induced scattering is considered. Using this result, the diffraction efficiency for each writing beam is discussed in doped KNSBN crystals with unidirectional fan, which is explained theoretically and verified experimentally.

We investigate the luminescence properties of erbium-doped and erbium-ytterbium-codoped potassium lithium tantalate niobate ceramics prepared by the solid phase syntheses method. The crystalline structure and surface morphology of these ceramics are tested by x-ray diffraction and scanning electron microscopy. The green, red, and near-infrared upconversion photoluminescence properties are analyzed by the steady-state spectra under 975 nm and 800 nm excitations. These ceramics are well sintered and tetragonal tungsten type crystalline structure with the 4mm point group and the P4bm space group. The Er3+ upconversion emission integrated intensities increase with the increase in Er3+ ion concentration, while the green emission decreases with the increase in Yb3+ ion concentration under the 800 nm excitation. An effective energy back transfer process from the Er3+ 4S3/2 state to Yb3+ ground state plays an important role in enhancing the red emission and weakening the green emission.

The crystal surface properties of potassium tantalite niobate, KTa0.5Nb0.5O3 (KTN), are studied with first-principles calculation based on the density functional theory (DFT). Generalized gradient approximation (GGA) functional analysis is also employed by using CASTEP software. The explanations for the differences of the ferroelectric and piezoelectric properties between the bulk and surface of the material are provided. The DFT with GGA is used to determine the structure and to calculate the electronic and optical properties of the chemically ordered KTa0.5Nb0.5O3 crystal (100), (110) and (111) surfaces. The results show that the surface properties are different from the bulk properties. The data obtained agree with the expected values and can serve as guidance for future experimental studies in the fields of photorefraction and nonlinear optics.

The damage model and the rate equation of quartz glass were set up under charged particles irradiation, and the concentration of ions and electrons produced by ionization were also given. The mathematical fitted results of the change in optical density are in accordance with the experimental results. The model was also applied to optical Al film reflector, and the mathematical fitted results of the integral reflectance of Al film reflector were given. The proposed damage model can be used to describe quantitatively the change in optical property of quartz glass with increasing absorption dose under charged particles irradiation.

The general formulas for radial matrix elements p|n′l′> and q|n′m′> of three-dimensional and two-dimensional isotropic harmonic oscillators are derived

The s-wave bound states solutions of Klein-Gordon equation and Dirac equation with scalar and vector Morse-type potentials are obtained.