Features of the photoconductivity of the quasi-one-dimensional compound TiS3

Problem formulating. The features of linear and nonlinear conductivity, magnetic conductivity, thermopower, and the Hall effect observed on TiS3 whiskers indicate phase transitions to a state of CDW in this compound, but there is no direct evidence yet. The study of photoconductivity would allow us to learn more about the nature of these phase transitions. Goal. Study of the effect of radiation in the range from near-IR to near-UV on the conductivity of single-crystal TiS3 whiskers at 4.2 <T<300 K and search for features of photoconductivity in the temperature range of the suggested phase transitions. Result. Features of the photoconductivity of TiS3 at temperatures of 50 K and 15 K, at which the −dlnσ/d(1/T) maxima were previously observed, are found. A decrease in photoconductivity at these temperatures indicates a change in the electronic spectrum, which may be associated with the formation of CDW. Practical meaning. In the case of developing TiS3-based photosensors, it is important to study the photoconductivity in a wide temperature range.

Análisis de capas PML en una región de campo electromagnético utilizando el Método de Diferencias Finitas en el Dominio del Tiempo

The Finite Difference in Time Domain (FDTD) method is currently one of the most used electromagnetism methods in electromagnetic field simulation, however, in order to obtain reliable results from this simulation it is necessary to have optimal boundary conditions. Perfectly Coupled Layers (PML) is characterized by the decomposition of the transversal field to the direction of propagation in its rectangular projections, and the use of both electrical and magnetic conductivity in the numerical layers for the absorption of electromagnetic fields. The PML layers are characterized by values of permittivity, permeability and conductivity that are assigned to each of the equations according to their position in the region. Because it is the same set of equations there is no need to use connection conditions at the junction of the analysis region with the PML absorption region, which provides a natural transition throughout the region. This paper presents the study of the difference between the calculation region with and without PML layers.

Dielectric and Magnetic Properties of Nanocomposites Based on Opal Matrixes, Phosphates and Vanadates of Metals

Opal matrix is a regular 3D-packing of spherical particles of amorphous SiO2, forming an ordered system of voids. Opal matrixes with spherical particles of SiO2 diameter d ≈ 260 nm (Δd ≈ 2 %) were synthesized. The frequency dependences of the conductivity, real and imaginary components of the dielectric and magnetic conductivity of nanocomposites containing crystallites 16–65 nm in size of magnetic materials ‒ double phosphates (LiNiPO4, LiCoPO4) and vanadates (GdVO4 and DyVO4) were measured. The dielectric losses of nanocomposites remain low (at a level of ~ 0.06) in the frequency range 107–1010 Hz for nanocomposites with DyVO4 and LiCoPO4. The dielectric loss increases both in the direction of low frequencies (< 106 Hz) and in the direction of THz frequencies.

Quantum Effects of Non-Ballistic Transport in Films Based on Compound PbSnAgTe

Based on the theory of weak localization, taking into account the mechanism of spin-orbit scattering, the patterns of change in the magnetic conductivity of films PbSnAgTe are considered. The dependences of the magnetoresistance of PbSnAgTe films in a magnetic field perpendicular to the surface of the film are studied. It is shown that for polycrystalline films on mica-muscovite substrates, the time of spin-orbital interaction depends on the composition and may change the sign of the magnetoresistance.

AJUSTMENT OF THE POSITION SENSOR OF THE ROTOR OF THE SYNCHRONOUS RELUCTANCE MOTOR WITH ANISOTROPIC MAGNETIC CONDUCTIVITY OF THE ROTOR

The article is devoted to the development of the algorithm for adaptation the rotor position sensor of a synchronous reluctance electric machine with anisotropic magnetic conductivity of the rotor. The main advantages and disadvantages of synchronous electric machines are considered in the construction of ship propulsion systems. The advantages of reluctance motor with anisotropic magnetic conductivity of the rotor are given in the construction of propulsion systems. The essence of the method of adaptation of the rotor position sensor is given. The differential equation of adaptation of the rotor position angle sensor is obtained, its stability is investigated. A model of a reluctance machine with anisotropic magnetic conductivity of a rotor is given, which makes it possible to determine its parameters.