Thermal Raman study of Li4Ti5O12 and discussion about the number of its characteristic bands

Lithium battery industry is booming, and this fast growth should be supported by developing industry friendly tools to control the quality of positive and negative electrode materials. Raman spectroscopy was shown to be a cost effective and sensitive instrument to study defects and heterogeneities in lithium titanate, popular negative electrode material for high power applications, but there are still some points to be clarified. This work presents a detailed thermal Raman study for lithium titanate and discusses the difference of the number of predicted and experimentally observed Raman-active bands. The low temperature study and the analysis of thermal shifts of bands positions during heating let us to conclude about advantages of the proposed approach with surplus bands and recommend using shifts of major band to estimate the sample heating

Transport Construction Cost Management by Rational Organizational and Technological Solutions

Special conditions of implementation of construction projects of transport facilities show that cost management requires appropriate optimization of organizational and technological solutions. The computer model and method for selecting optimal management by the criterion of construction cost minimization are developed. The model shows the organizational and technological variability of the enterprise, characteristic of transport construction. The method allows to carry out variant modeling, according to which the patterns of changes in the construction cost, the ratio of direct and general production costs are compiled under the influence of the following factors: average complexity of the project totality, average relocation distance, attribution of resources, industrialization of applied solutions.The numerical experimental studies quantitatively proved that organizational and technological solutions characteristic of the enterprise as a whole affect the solutions of individual construction projects of transport facilities. In particular, it was found that with a decrease in the average complexity of the project totality, the influence of industrialization of applied solutions is reversed and begins to increase the cost of works.The lowest value of cost change (–13.6 %) was found, characterized by the most effective organizational and technological solutions: the average complexity of the project totality X1=2.2 thousand hours, the average relocation distance Х2=100 km, using only own equipment and labor resources (Х3=0 %), minimal industrialization of applied solutions (Х4=0 %).It was revealed that contracting organizations building relatively small transport facilities should use traditional methods of work. The cost efficiency of solutions, according to which enterprises constructing geographically dispersed facilities should use contracted resources with local material and technical base was also determined

Morphology, structure, and optical properties of semiconductor films with GeSiSn nanoislands and strained layers

The dependences of the two-dimensional to three-dimensional growth (2D-3D) critical transition thickness on the composition for GeSiSn films with a fixed Ge content and Sn content from 0 to 16% at the growth temperature of 150 °С have been obtained. The phase diagrams of the superstructure change during the epitaxial growth of Sn on Si and on Ge(100) have been built. Using the phase diagram data, it becomes possible to identify the Sn cover on the Si surface and to control the Sn segregation on the superstructure observed on the reflection high-energy electron diffraction (RHEED) pattern. The multilayer structures with the GeSiSn pseudomorphic layers and island array of a density up to 1.8 × 1012 cm−2 have been grown with the considering of the Sn segregation suppression by the decrease of GeSiSn and Si growth temperature. The double-domain (10 × 1) superstructure related to the presence of Sn on the surface was first observed in the multilayer periodic structures during Si growth on the GeSiSn layer. The periodical GeSiSn/Si structures demonstrated the photoluminescence in the range of 0.6–0.85 eV corresponding to the wavelength range of 1.45–2 μm. The calculation of the band diagram for the structure with the pseudomorphic Ge0.315Si0.65Sn0.035 layers allows assuming that photoluminescence peaks correspond to the interband transitions between the X valley in Si or the Δ4-valley in GeSiSn and the subband of heavy holes in the GeSiSn layer