Formation of metallic magnetic clusters in a Kondo-lattice metal: Evidence from an optical study

Magnetic materials are usually divided into two classes: those with localised magnetic moments, and those with itinerant charge carriers. We present a comprehensive experimental (spectroscopic ellipsomerty) and theoretical study to demonstrate that these two types of magnetism do not only coexist but complement each other in the Kondo-lattice metal, Tb2PdSi3. In this material the itinerant charge carriers interact with large localised magnetic moments of Tb(4f) states, forming complex magnetic lattices at low temperatures, which we associate with self-organisation of magnetic clusters. The formation of magnetic clusters results in low-energy optical spectral weight shifts, which correspond to opening of the pseudogap in the conduction band of the itinerant charge carriers and development of the low- and high-spin intersite electronic transitions. This phenomenon, driven by self-trapping of electrons by magnetic fluctuations, could be common in correlated metals, including besides Kondo-lattice metals, Fe-based and cuprate superconductors.Comment: 30 pages, 6 Figure

Rationale for priority factors of effective cluster development of regional economy

The article discusses the importance of creating a favorable environment to grow regional clusters spanning multiple socio-economic, institutional, natural resource conditions for regional economic development. The aim of the study is to identify factors that have a positive impact on strengthening the strategic positions of the clusters in the regional economy (the cases of 17 emerging clusters in the Perm region serving as an example). Theoretical and applied scientific substantiation of conditions for effective development of the area cluster space is a scientific novelty. The empirical analysis is based on the assessment of clusters weight in the region economy in the years 2002-2014, obtained in the course of processing regional statistics data on employment in different economic activities including the ranking of investment attractiveness compiled by “Expert RA” agency. Using the tools of economic and mathematical modeling with respect to each cluster that are characterized by unique industry specialization, the article identifies the priority development factors, institutional, innovation, labor and natural resources being important factors for most of the analyzed clusters. In terms of the four priority factors directions of cluster development of the Perm region economy are proposed, including proposals for the institutional design of cluster management structures, support of education and research institutions in the region, development of innovative entrepreneurship and strengthening of private initiative in clusters, the conservation of natural resources, and greening of local production. It is shown that the instruments used in the research and results of the factor analysis are of interest to representatives of public authorities who design cluster policies, as well as to experts in the field of cluster analysis; the results can be used to further elaborate programs of cluster development of the region and for the study of cluster initiatives.Статья посвящена обсуждению значимости формирования благоприятной среды выращивания территориальных кластеров, охватывающей многообразные социально-экономические, институциональные, природно-ресурсные условия развития региональной экономики. Целью исследования является идентификация факторов, оказывающих положительное воздействие на укрепление стратегических позиций кластеров в экономике региона (на примере семнадцати формирующихся в Пермском крае кластеров). Научную новизну исследования составляет теоретическое и научно-прикладное обоснование условий эффективного развития кластерного пространства территории. Эмпирический анализ базируется на оценке веса кластеров в экономике региона за 2002-2014 гг., полученной в ходе обработки данных региональной статистики занятости населения по видам экономической деятельности с привлечением экспертных данных рейтинга инвестиционной привлекательности агентства «Эксперт РА». При помощи инструментария экономико-математического моделирования по отношению к каждому кластеру, характеризующемуся уникальной отраслевой специализацией, в статье установлены приоритетные факторы развития, среди которых институциональный, инновационный, трудовой и природно-ресурсный факторы оказались значимыми для большинства анализируемых кластеров. В разрезе четырех приоритетных факторов предложены направления кластерного развития экономики Пермского края, включающие предложения по институциональному оформлению структуры управления кластерами, поддержке образовательных и научно-исследовательских учреждений региона, развитию инновационного предпринимательства и укреплению частной инициативы в кластерах, сбережению природно-ресурсной среды, экологизации местного производства. Показано, что используемый в исследовании инструментарий и результаты факторного анализа представляют интерес для представителей органов государственной власти, разрабатывающих кластерную политику, а также специалистов в области кластерного анализа и могут быть использованы для детализации программ кластерного развития территории и проработки кластерных инициатив.Публикация подготовлена в рамках поддержанного РГНФ научного проекта №16-12-59011

The corrosion resistant coating with halloysite nanoparticles

The process of application of coating on metal surfaces is described in this article. The composition with 100 % corrosion preventing substance + 42,5 % acetone + 10 % halloysite was recognized as the most appropriate for coating, and it provides the best corrosion resistance of hydraulic pump details. The impellers of circulation pumps for water delivery in heating system fail after 5 - 6 months because of the galling of work flutes, as water doesn’t pass through the chemical purification. After applying corrosion resistant coating with halloysite the lifetime of impellers increases. The essence of which is dipping the impeller into hydrochloric acid with 24 hour keeping in it, then it is dried in dryer up to 4 hours. The lifetime of this impeller increases 1,8 fold and it was approximately 9 months

The corrosion resistant coating with halloysite nanoparticles

The process of application of coating on metal surfaces is described in this article. The composition with 100 % corrosion preventing substance + 42,5 % acetone + 10 % halloysite was recognized as the most appropriate for coating, and it provides the best corrosion resistance of hydraulic pump details. The impellers of circulation pumps for water delivery in heating system fail after 5 - 6 months because of the galling of work flutes, as water doesn’t pass through the chemical purification. After applying corrosion resistant coating with halloysite the lifetime of impellers increases. The essence of which is dipping the impeller into hydrochloric acid with 24 hour keeping in it, then it is dried in dryer up to 4 hours. The lifetime of this impeller increases 1,8 fold and it was approximately 9 months

The corrosion resistant coating with halloysite nanoparticles

The process of application of coating on metal surfaces is described in this article. The composition with 100 % corrosion preventing substance + 42,5 % acetone + 10 % halloysite was recognized as the most appropriate for coating, and it provides the best corrosion resistance of hydraulic pump details. The impellers of circulation pumps for water delivery in heating system fail after 5 - 6 months because of the galling of work flutes, as water doesn’t pass through the chemical purification. After applying corrosion resistant coating with halloysite the lifetime of impellers increases. The essence of which is dipping the impeller into hydrochloric acid with 24 hour keeping in it, then it is dried in dryer up to 4 hours. The lifetime of this impeller increases 1,8 fold and it was approximately 9 months

Practical recommendations for the teachers on optimization process of the students majoring in Tourism

© 2015, Canadian Center of Science and Education. The problem under study is urgent as there is the lack of research by the Russian scientists concerning training and retraining of the teachers to implement professionally motivational training of the students majoring in "Tourism". This article presents guidelines for the teachers to optimize professionally motivational training of the students majoring in "Tourism", which are one of the most important conditions for the effective formation of the students’ motivational sphere in continuous professional education. The article provisions are practically significant for the administration and teaching staff of the vocational education institutions in the course of organizing professionally motivational training of the students and also for the centers that provide training and professional retraining of the college and university teachers

Effect of Na content and hydration on the excitation spectrum of the cobaltite Na_xCoO_2 yH_2O

We report on a Raman scattering study on the superconducting cobaltite $Na_xCoO_2\cdot yH_2O$ as function of Na content and hydration (x$\approx$1/3, 3/4 and y$\approx$0, 2/3, 4/3). The observed phonon scattering and scattering continua are analyzed in terms of lattice strain due to the structural misfit and disorder. Hydration, due to the intercalation of one or two $H_2O$ layers, releases a part of this strain. Our Raman data suggest a connection between disorder on the partly occupied Na sites, the split off of the $a_{1g}$ level from the other $t_{2g}$ states of $Co^{4+}$ and superconductivity.Comment: 10 pages, 4 figures, for further information see http://www.peter-lemmens.d

Lattice Relaxation and Charge-Transfer Optical Transitions Due to Self-Trapped Holes in Non-Stoichiometric LaMnO3_3 Crystal

We use the Mott-Littleton approach to evaluate polarisation energies in LaMnO$_3$ lattice associated with holes localized on both Mn$^{3+}$ cation and O$^{2-}$ anion. The full (electronic and ionic) lattice relaxation energy for a hole localized at the O-site is estimated as 2.4 eV which is appreciably greater than that of 0.8 eV for a hole localized at the Mn-site, indicating on the strong electron-phonon interaction in the former case. Using a Born-Haber cycle we examine thermal and optical energies of the hole formation associated with electron ionization from Mn$^{3+}$, O$^{2-}$ and La$^{3+}$ ions in LaMnO$_3$ lattice. For these calculations we derive a phenomenological value for the second electron affinity of oxygen in LaMnO$_3$ lattice by matching the optical energies of La$^{4+}$ and O$^-$ hole formation with maxima of binding energies in the experimental photoemission spectra. The calculated thermal energies predict that the electronic hole is marginally more stable in the Mn$^{4+}$ state in LaMnO$_3$ host lattice, but the energy of a hole in the O$^-$ state is only higher by a small amount, 0.75 eV, rather suggesting that both possibilities should be treated seriously. We examine the energies of a number of fundamental optical transitions, as well as those involving self-trapped holes of Mn$^{4+}$ and O$^-$ in LaMnO$_3$ lattice. The reasonable agreement with experiment of our predicted energies, linewidths and oscillator strengths leads us to plausible assignments of the optical bands observed. We deduce that the optical band near 5 eV is associated with O(2p) - Mn(3d) transition of charge-transfer character, whereas the band near 2.3 eV is rather associated with the presence of Mn$^{4+}$ and/or O$^-$ self-trapped holes in non-stoichiometric LaMnO$_3$ compound.Comment: 18 pages, 6 figures, it was presented partially at SCES-2001 conference in Ann Arbor, Michiga

C-axis lattice dynamics in Bi-based cuprate superconductors

We present results of a systematic study of the c axis lattice dynamics in single layer Bi2Sr2CuO6 (Bi2201), bilayer Bi2Sr2CaCu2O8 (Bi2212) and trilayer Bi2Sr2Ca2Cu3O10 (Bi2223) cuprate superconductors. Our study is based on both experimental data obtained by spectral ellipsometry on single crystals and theoretical calculations. The calculations are carried out within the framework of a classical shell model, which includes long-range Coulomb interactions and short-range interactions of the Buckingham form in a system of polarizable ions. Using the same set of the shell model parameters for Bi2201, Bi2212 and Bi2223, we calculate the frequencies of the Brillouin-zone center phonon modes of A2u symmetry and suggest the phonon mode eigenvector patterns. We achieve good agreement between the calculated A2u eigenfrequencies and the experimental values of the c axis TO phonon frequencies which allows us to make a reliable phonon mode assignment for all three Bi-based cuprate superconductors. We also present the results of our shell model calculations for the Gamma-point A1g symmetry modes in Bi2201, Bi2212 and Bi2223 and suggest an assignment that is based on the published experimental Raman spectra. The superconductivity-induced phonon anomalies recently observed in the c axis infrared and resonant Raman scattering spectra in trilayer Bi2223 are consistently explained with the suggested assignment.Comment: 29 pages, 13 figure