Polynomial reconstruction of electric charge distribution on the conductive plate caused by external electric field

The paper proposes an original method of calculating the charge distribution on the surface of the conductive plate introduced into the external electrostatic field. The authors managed to obtain the polynomials which allow to solve the integral equation that establishes the relationship between charge distribution of the conductive plate and the potential distribution of the external field and the potential on the surface of the plate. The proposed algorithms solutions are valid in the presence of axial symmetry of the field and the plate. Examples of calculation of conductor charge distribution in the presence of external field by using a polynomial expansion have been presented. The comparisons of results calculated by the polynomial method and by known analytical solutions have been given

Anisotropic conductivity of Nd_{1.85}Ce_{0.15}CuO_{4-\delta} films at submillimeter wavelengths

The anisotropic conductivity of thin Nd$_{1.85}$Ce$_{0.15}$CuO$_{4-\delta}$ films was measured in the frequency range 8 cm$^{-1}<\nu <$ 40 cm$^{-1}$ and for temperatures 4 K $<T<300$ K. A tilted sample geometry allowed to extract both, in-plane and c-axis properties. The in-plane quasiparticle scattering rate remains unchanged as the sample becomes superconducting. The temperature dependence of the in-plane conductivity is reasonably well described using the Born limit for a d-wave superconductor. Below T_{{\rm C}%} the c-axis dielectric constant $\epsilon_{1c}$ changes sign at the screened c-axis plasma frequency. The temperature dependence of the c-axis conductivity closely follows the linear in T behavior within the plane.Comment: 4 pages, 4 figure

Broadband Dielectric Spectroscopy on Glass-Forming Propylene Carbonate

Dielectric spectroscopy covering more than 18 decades of frequency has been performed on propylene carbonate in its liquid and supercooled-liquid state. Using quasi-optic submillimeter and far-infrared spectroscopy the dielectric response was investigated up to frequencies well into the microscopic regime. We discuss the alpha-process whose characteristic timescale is observed over 14 decades of frequency and the excess wing showing up at frequencies some three decades above the peak frequency. Special attention is given to the high-frequency response of the dielectric loss in the crossover regime between alpha-peak and boson-peak. Similar to our previous results in other glass forming materials we find evidence for additional processes in the crossover regime. However, significant differences concerning the spectral form at high frequencies are found. We compare our results to the susceptibilities obtained from light scattering and to the predictions of various models of the glass transition.Comment: 13 pages, 9 figures, submitted to Phys. Rev.

Colossal dielectric constants in transition-metal oxides

Many transition-metal oxides show very large ("colossal") magnitudes of the dielectric constant and thus have immense potential for applications in modern microelectronics and for the development of new capacitance-based energy-storage devices. In the present work, we thoroughly discuss the mechanisms that can lead to colossal values of the dielectric constant, especially emphasising effects generated by external and internal interfaces, including electronic phase separation. In addition, we provide a detailed overview and discussion of the dielectric properties of CaCu3Ti4O12 and related systems, which is today's most investigated material with colossal dielectric constant. Also a variety of further transition-metal oxides with large dielectric constants are treated in detail, among them the system La2-xSrxNiO4 where electronic phase separation may play a role in the generation of a colossal dielectric constant.Comment: 31 pages, 18 figures, submitted to Eur. Phys. J. for publication in the Special Topics volume "Cooperative Phenomena in Solids: Metal-Insulator Transitions and Ordering of Microscopic Degrees of Freedom

Luminescence Study of Structural-Changes Induced by Laser Cutting in Diamond Films

The effect of laser cutting on the structure of a chemical vapor deposited diamond film has been investigated by cathodoluminescence (CL) in the scanning electron microscope. The variation of particle morphology and CL spectra as a function of the distance to the cutting edge is described and possible laser induced structural changes are discussed. At the damaged region total CL emission increases and nitrogen-vacancy centers are detected

Surface and bulk processes in materials induced by pulsed ion and plasma beams at Dense Plasma Focus devices

A review of results and new data on the interaction of pulsed ion and dense plasma beams with metals in different Dense Plasma Focus (DPF) devices are presented. Different irradiation conditions with microsecond pulses of the power density in the range of 105 109 W/cm2 were applied. The most interesting thermal and radiation effects observed in both surface and bulk of the material positioned at the cathode part of the DPF device have been considered. Advanced directions of DPF use for scientific and applied problems of radiation material science were determined

Damage and modification of materials produced by pulsed ion and plasma streams in Dense Plasma Focus device

The Dense Plasma Focus (DPF) devices PF-1000, PF-6 and PF-5M working with different gases and in dissimilar irradiation modes were used to carry out experimental investigations of irradiation of a number of materials by powerful pulsed ion and high-temperature plasma streams. The materials under test were designed for application in structural and functional components of thermonuclear fusion devices with magnetic (MPC) and inertial (IPC) plasma confinement, as well as for working chambers of plasma and accelerator devices. The main features of the materials are low-activation and radiation-resistant properties. On the basis of the investigations a significant progress was achieved in understanding of dynamics of high-energy nano- and micro-second pulsed streams in DPF from one side as well as on the mechanisms of their influence upon materials under irradiation from the other one. We demonstrated that this approach can be useful for certain tests of plasma-facing materials (e.g. W for MPC and stainless steels for IPC) and of structural (construction) elements of the above-mentioned devices subjected to pulsed high-energy radiation streams. The results obtained suggest also that DPF devices can be used in new pulse technologies for material treatment by means of powerful nanosecond and microsecond pulses of plasma and ion streams