Vol 2, No S3 (2014)
- Year: 2014
- Published: 30.12.2014
- Articles: 10
- URL: https://ogarev-online.ru/2311-2468/issue/view/24152
Full Issue
Spectroscopy of UV active medium LiCa1-xSrxF6:Ce3+
Abstract
The aim of this work is growing of new materials based on fluoride crystals with the colquiriite structure LiSr0,8Ca0,2F6, as well as studying of their phase composition. The experiments demonstrate that for a series of crystals LiSr0,8Ca0,2F6 distribution of reflections observed corresponds to the colquiriite structure, and the dependence of the lattice constant in the transition from LiCaAlF6 crystal to LiSrAlF6 crystal is linear. Also it was found that the absorption coefficient in mixed samples is much larger than in the unmixed ones.
2-9
Optical and physical properties of fluorite crystals CaF2: Ce3 +, Yb3 +, Lu3 +
Abstract
The aim of the study is to investigate the optical properties of crystals as well as the parameters of thermal expansion, thermal conductivity, and the temperature coefficient of the refractive index. The data are very important in the development of optical laser systems. The parameters of thermal expansion and temperature coefficient of the refractive index were obtained by Jamin and Michelson interferometrs.
10-15
An analysis of FPCM DUROSTON microstructure by scanning electron microscopy and X-ray microtomography
Abstract
The article presents the results of an analysis of the microstructure of the FPCM "Duroston" by scanning electron microscopy and X-ray microtomography. The material is used for manufacturing of support-fixing elements in power electronics. The analysis showed that the structure of the polymer matrix composite has spherical inclusions with the X-ray density less than the density of the ray matrix and sheath compacted. These inclusions are identified as gas formations arising in the making of FPCM. At the interface "matrix-fiber" micropores, which may be associated with the low wettability regions on fiberglass surfaces, were found.
16-22
An analysis of interface "fiber-matrix" effect on the strengh properties of FPCM DUROSTON
Abstract
The paper presents the results of an analysis of the mechanical properties of FPCM "Duroston" used in power electronics for manufacturing of support-fixing elements. The tests were conducted to determine the effects of interfaces "fiber-matrix" on the strength properties of FPCM. Mechanical tests were done in the temperature range from 20 °C to 200 °C on tensile and compression of the specimen. Using scanning electron microscopy, the authors studied the microstructure of FPCM in the areas of destruction. The analysis showed that the compressive deformation delaminates FPCM by cracking, which will determine the nature of the layered swarm structure of the fiberglass. It has been established that at room temperature the predominant mechanism of cracking is adhesive fiber peeling from the polymer matrix, and at high temperatures in the given interval, along with the mechanism of adhesion, separation occurs as a cohesive rupture of the matrix polymer.
23-30
A study of the mechanisms of anti-stokes luminescence of Er3+ ions in YSZ:Er crystal under excitation of 4i13/2 level
Abstract
The mechanisms of anti-Stokes luminescence of YSZ:Er crystal corresponding to 4S3/2—4I15/2, 4F9/2—4I15/2 transitions upon excitation of the 4Ib/2 level of Er3+ ions were studied. Ionion interaction between Er3+ ions populate 4S3/2, 4F9/2 levels upon excitation of the 4Ib/2. Keywords: ions Er3+, crystal YSZ, anti-Stokes luminescence.
31-36
A study of optical and nonlinear properties of langasite crystal
Abstract
The edge of fundamental absorption in langasite crystal was studied. The energy gap was measured to be 6,5 eV. Using the technique of the second harmonic generation in powdered samples, the value of the quadratic nonlinear susceptibility in langasite crystal was estimated to be 7 times higher than that in quartz.
37-42
A study of thermomechanical and thermophysical properties of FPCM Durostone
Abstract
The paper presents the results of measurements of the thermomechanical and thermal characteristics of the fibrous polymer composite (FPCM) Durostone used in power electronics for manufacturing of support-fixing elements. The coefficient of thermal expansion and thermal diffusivity of the samples were measured in the temperature range from 30 °C to 200 °C. A differential thermal analysis and thermogravimetry were done in the temperature range from 30 °C to 400 °C. When measuring thermal diffusivity by laser flash, a waveguide effect of the FPCM Durostone reinforcing filler was revealed.
43-49
Dependence of spin pinning degree on microwave field frequency in two-layer magnetic films
Abstract
The study showed that the increase of microwave field frequency makes significant changes in the spectrum of spin-wave resonance. In particular, the disagreement of dispersion curves is decreasing when magnetic field has perpendicular and parallel orientation in the film plane. This fact is due to increasing of the spin pinning degree at interlayer border. Keywords: spin-wave resonance, two-layer magnetic film.
50-57
Stability criterion for semiconductor superlattice
Abstract
The paper considers the stability criterion of the gain of high-frequency electromagnetic radiation in semiconductor superlattice with miniband transport mode in the standard gaining scheme. The study shows that the Ohmic boundary condition gives the criterion different from the one connected with the negative different conductivity (NDC). It gives hope to get the stable gain in some region of NDC under certain system parameters.
58-63
Stabilization gain of high-frequency radiation in superlattice in tilted magnetic field
Abstract
In this paper we demonstrate that the differential conductivity of superlattice in a tilted magnetic field may be represented in the form of a difference derivative that is convenient for analysis. It allows determining the possibility of gaining of the high-frequency radiation and the gain coefficient.
64-68