Search

The waste thermal/heat energy harvesting can contribute to more sustainable and efficient energy systems. The high energy harvesting and storage are indispensable with considering ferroelectric/antiferroelectric materials. In this work, Pb0.99Nb0.02[(Zr0.57Sn0.43)0.92Ti0.08]0.98O3 (PNZST) is studied for high energy density (harvesting and storage). The Olsen cycle is performed on the materials for direct thermal/waste heat to electrical energy conversion. A large energy harvesting density of 1.0 MJ/m3 per cycle was obtained at temperatures of 303 and 403 K, cycling the electric field between 1 and 9 kV/mm. An estimated high energy harvesting is a result of the polarization change due to the ferroelectric (rhombohedral) to antiferroelectric (tetragonal) phase transition. The high energy storage of 0.9 J/m3 and energy efficiency of 81% were obtained at 403 K under an electric field of 9 kV/mm. The results will enrich our understanding of PNZST materials that offer high-performance energy harvesting and storage-based applications. This work can also be helpful in improving energy harvesting density via phase transition behaviors.

In this study, non-stoichiometric solid solution, Sr1–1.5(x+y)CexPryTiO3 abbreviated as (Sr, Ce, Pr)TiO3 (with 0.05 ≤ x ≤ 0.35 and y = 0.05, sintered in N2/H2 with 99% N2 and 1% H2) were prepared via a conventional solid-state method. By introducing (Ce0.25Pr0.05)3+/4+ on the A-site, the structure symmetry of the ceramic could be reduced, confirming cubic to tetragonal phase transition. Using Rietveld refinement and electron diffraction (TEM), the tetragonal phase was assigned to P4/mmm space group which posses a center of symmetry (centrosymmetric tetragonal unit cell). A small opening of hysteresis loop at higher Ce doping is assumed to be a caused by defect dipoles and conductivity. The dielectric anomalies were observed in all compositions, therefore, we assume that they are not related to structural phase transition but rather to some conductivity processes.

Induced relaxor-like behavior is reported by addition of a sintering additive to the (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 solid solution. The effect of Bi2O3 sinter additive on microstructure is determined. The phase transition behavior is highlighted by dielectric permittivity measurements. The electrocaloric temperature change is directly measured and comparison with literature data is provided on basis of the material related cooling power. Addition of Bi2O3 drastically increases the temperature stability and an ultra-wide temperature range of over 100 K is achieved. The findings path a way to tune electrocaloric materials for optimization of properties for solid-state coolers based on the electrocaloric effect.

The piezoelectric coefficient is a measure to quantify the potential use of a material in energy harvesting and sensor applications. High concentration of free charge carriers in piezoelectric materials can significantly impede the use of generated piezoelectric charge. In this study, undoped semiconducting ZnO single crystals with both Ohmic and Schottky contacts were prepared to quantify the effective piezoelectric response at temperatures from 20 °C to −140 °C and frequencies of mechanical loading from 0.5 Hz to 160 Hz. It was demonstrated that the formation of an electrostatic potential barrier at the metal-semiconductor interface increases the overall resistance, which provides access to unbiased piezoelectric coefficients of ZnO single crystals even at room temperature. These findings were verified using semiconducting ZnO for energy harvesting at room temperature and relatively low loading frequency.

ZnO is considered as one of the most promising semiconductor materials for future applications based on the piezotronic effect. Intense studies on ZnO nanowires had been carried out to understand the modulation of the Schottky barrier height at the metal ZnO interface via piezoelectricity. However, an experimental investigation on bulk ZnO single crystals and a fundamental comparison of the modification of the barrier height determined experimentally and theoretically are still missing. Therefore, an adjustment of the electrostatic potential barrier height at metal-ZnO single crystal interfaces due to stress induced piezoelectric charges was conducted, using both O- and Zn-terminated surfaces. In-situ stress dependent impedance and current-voltage measurements were utilized to extract the electrical properties of the potential barrier and to determine the reduction of the barrier height. The decrease of the interface resistance and increase of the capacitance reveal the presence of stress induced piezoelectric charges. The experimentally evaluated reduction of the barrier height reveals a moderate change of about 9 meV at 70 MPa and supports prior work on metal-ZnO nanowires. This change was found to be in good agreement with theoretical calculations based on the imperfect screening model if a thickness of the interface layer is assumed to be ~2 ��.

This article implies that cinematic narratives project practical geopolitical discourses by using the example of Marvel Cinematic Universe’s success – The Avengers film franchise. The conceptualisation of imaginary threats in the films that follow the main storyline of the Avengers assembly, determined by the time and the geographic space, give those threats a symbolical manifestation that tends to overlap with the practical geopolitical notions of American foreign policy, as well as contemporary international politics. The interpretative textual analysis of the films’ narratives and their relations to world politics, hence, presents the central methodology of this article. The relation between those two has a capacity to transmit a subconscious message to blockbusters’ consumers about preferable practical geopolitical visions in contemporary world politics. Simply, the paper shows how cinematic narratives form an identity that is deeply securitised and able to capture the Zeitgeist of world’s politics. info:eu-repo/semantics/publishedVersion

Relaxor ferroelectrics have drawn attention for possible applications in solid-state cooling and thermal energy harvesting, owing to their electrothermal energy conversion properties. Here, we have synthesized and characterized the structure-property correlations of a new Sn- and Nb-doped (Ba,Ca)TiO3 relaxor ferroelectric with large pyroelectric and electrocaloric effects over a broad temperature range. We observed two peaks for the temperature-dependent pyroelectric coefficient: (i) -(partial derivative P/partial derivative T) similar to 563 mu C/(m(2) K) at T similar to 270 K and (ii) -(partial derivative P/partial derivative T) similar to 1021 mu C/(m(2) K) at T similar to 320 K. In addition, a broad peak for electrocaloric temperature change is observed near 320 K with a relative cooling power of similar to 17 J/kg. These properties could be correlated to structural changes observed using X-ray diffraction at two different temperature ranges in the material. Analysis of high-energy X-ray scattering and specific heat capacity data revealed a transition from the cubic to tetragonal phase near T-m similar to 320 K, whereas an additional increase in the tetragonality (c/a) of the polar phase is observed below T-s similar to 270 K. CityUCity University of Hong Kong [7200514, 7004967, 9610377]; Danish National Research FoundationDanmarks Grundforskningsfond [DNRF93]; Danish Research Council for Nature and Universe (Danscatt); European UnionEuropean Union (EU) [778072]; Slovenian Research AgencySlovenian Research Agency - Slovenia [P1-0125]; DOE Office of ScienceUnited States Department of Energy (DOE) [DE-AC02-06CH11357] A.P. gratefully acknowledges funding support from CityU (Project Nos. 7200514, 7004967, and 9610377). M.R.V.J. is grateful for the support by the Danish National Research Foundation (DNRF93), and the Danish Research Council for Nature and Universe (Danscatt). N.N. acknowledges the European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie grant agreement No 778072 and the Slovenian Research Agency under program P1-0125. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. A.P. gratefully acknowledges technical assistance from Mr. Daniel Yau.

International audience; The effects of 2% Zr introduction in Ba0.8Ca0.2TiO3 (BCT) system on its electrical and electrocaloric properties was investigated. BCT and Ba0.8Ca0.2Zr0.02Ti0.98O3 (BCZT) ceramics synthesized by solid-state processing were crystallized in a pure perovskite phase with a group space P4mm. After Zr insertion, the enhanced dielectric constant was obtained around the Curie temperature (Tc) in BCZT ceramic (εr = 6330 at Tc = 388 K) compared to BCT ceramic (εr = 5080 at Tc = 388.6 K). Moreover, the large-signal piezoelectric coefficient (d∗33) was improved from 270 to 310 pm/V in BCT and BCZT ceramics, respectively, under a moderate electric field of 25 kV/cm. The electrocaloric effect was determined via indirect and direct methods. In the indirect approach, the electrocaloric temperature change (ΔT) was calculated via Maxwell relation, and the measured ferroelectric polarization P (E, T) extracted from the P–E curves recorded at 24 kV/cm. The maximum values of ΔT = 0.68 K and the electrocaloric responsivity ζ = 0.283 K mm/kV obtained at 385 K in BCZT ceramic were found to be higher than those observed in BCT ceramic (ΔT = 0.37 K and ζ = 0.154 K mm/kV at 387 K). In the direct approach, ΔT was measured utilizing a modified high-resolution calorimeter at 14 kV/cm. As the direct method is more sensitive to the latent heat, it provided larger values for smaller applied field, i.e., ΔT = 0.474 and 0.668 K for BCT and BCZT ceramics, respectively. A significant ζ of 0.477 K mm/kV was obtained in BCZT at 385 K and 14 kV/cm that matches the values found in lead-based materials. These results suggest that BCZT lead-free ceramics could have an excellent potential to be used in solid-state refrigeration applications.

This paper seeks to answer to what extent the city of Vukovar is divided and in which way this division is geographically imagined and embedded in everyday life. Since each case of divided cities is driven by different factors and consists of different manifestations, case study design is the most appropriate one for researching micro-divisions in this post-conflict area. The case study of Vukovar is interesting because war legacy influenced new local policies and politics; open border issues affect bilateral relations on State level; and micro-regional frictions show deep identity-based divisions. Regardless of the lack of physical obstacles in the urban structure of the city, the research presents multilevel divisions that are visible in a form of imagined boundaries. Although Vukovar is an ethnically divided city we presume that division(s) lacks any strong geographical (or territorial) aspect. That is why the method of mental mapping on a random based sample of local population is used to compare imagined divisions in everyday life with administrative, ethnical and political ones. Cette étude vise à établir dans quelle mesure la ville de Vukovar est divisée et comment cette division est représentée d’un point de vue géographique et intégrée dans la vie quotidienne. Les études de cas s’avèrent la méthode la plus appropriée pour étudier les micro-divisions présentes dans cette zone post-conflit. Le cas de Vukovar est particulièrement intéressant dans la mesure où l’héritage de la guerre a pesé sur les politiques mises en œuvre, mais aussi parce que les questions de frontières ouvertes affectent les relations bilatérales au niveau de l’Etat et que les frictions à l’échelle micro-régionale recèlent de profondes divisions basées sur l’identité. Nonobstant l’absence d’obstacles physiques dans la structure urbaine de Vukovar, notre recherche montre des divisions à différents niveaux, sous la forme de frontières mentales. En dépit de la division de la ville en termes d’ethnicité, la (les) division(s) ne présente(nt) pas d’aspect géographique (ou territorial) très marqué. C’est pourquoi la cartographie mentale est utilisée ici sur un échantillon aléatoire de la population locale afin de mettre en parallèle les divisions fantasmées dans la vie quotidienne et les divisions administratives, ethniques et politiques.

The sensitivity toward mechanical stress of barium titanate-based positive temperature coefficient resistor material was investigated by determining the resistance change with application of uniaxial stress from room temperature to 200 °C, which is well above the Curie temperature TC. Using the Landau–Ginsburg–Devonshire theory the resistance increases in the paraelectric state, the negligible impact of stress close to TC and the observed increase in TC with increasing stress could be rationalized. For the ferroelectric state, the stress-related resistance increase was attributed to ferroelasticity, a change in bulk permittivity and interfacial stress inducing a piezoelectric potential. The obtained results are also discussed with respect to recent endeavors to tune properties of potential barriers in piezoelectric semiconductors by mechanical stress.

The electric field–temperature phase diagrams of three bismuth sodium titanate-based relaxor ferroelectrics are reported, namely 0.94(Na1/2Bi1/2TiO3)–0.06(BaTiO3), 0.80(Na1/2Bi1/2TiO3)–0.20(K1/2Bi1/2TiO3) and 0.75(Na1/2Bi1/2TiO3)–0.25(SrTiO3). Relaxor behavior is demonstrated by temperature-dependent dielectric permittivity measurements in the unpoled and poled states, as well as by the field-induced phase transition into a ferroelectric phase from the relaxor phase. From temperature-dependent thermometry measurements, we identified the threshold electric field to induce the ferroelectric phase and obtained the released latent heat of the phase transition. We determined the nonergodic and ergodic relaxor phase temperature range based on the absence or presence of reversibility of the relaxor to ferroelectric transition. For all three compositions, the electric field–temperature phase diagram was constructed and a critical point was identified. The constructed electric field–temperature phase diagrams are useful to find optimum operational ranges of ferroelectrics and relaxors for electromechanical and electrocaloric applications.

The fracture toughness in the lead-free relaxor ferroelectric (1-x)(Na1/2Bi1/2)TiO3-xBaTiO3 was investigated utilizing the surface crack in flexure method. To allow a comprehensive assessment, unpoled and poled samples from the rhombohedral, the tetragonal, and the morphotropic phase regime were considered. It was found that the fracture toughness is up to 23% higher for the poled state. In order to cover the transition from ferroelectric to relaxor phase, the temperature dependence of 0.97(Na1/2Bi1/2)TiO3-0.03BaTiO3 was studied as well. Fracture toughness values of up to 2 MPam1/2 were determined, which are considerably above data for lead zirconate titanate materials. The results are rationalized using a simple transformation toughening-type model in conjunction with investigations into the ferroelastic behavior. The presented model can be applied without fitting parameters but utilizes measurements of the coercive stress and remanent strain as well as the elastic modulus. This article is protected by copyright. All rights reserved.

Electrocaloric device structures have been developed as multilayer ceramics (MLCs) based on fundamental research carried out on PMN-8PT bulk ceramics. Two different MLC structures were prepared with nine layers each and layer thicknesses of 86 μm and 39 μm. The influence of the device design on its properties has been characterized by microstructural, dielectric, ferroelectric, and direct electrocaloric measurement. For direct characterization two different methods, ie temperature reading (thermistor and thermocouple) and heat flow measurement (differential scanning calorimetry), were used. A comparison of results revealed a highly satisfactory agreement between the different methods. This study confirms that MLCs are promising candidates for implementation into energy-efficient electrocaloric cooling systems providing large refrigerant volume and high electrocaloric effect. Due to their micron-sized active layers, they allow for the application of high electric fields under low operation voltages. We measured a maximum electrocaloric temperature change of ΔT=2.67 K under application/withdrawal of an electric field of ΔE=16 kV mm−1, which corresponds to operation voltages below 1.5 kV.

Antiferroelectric materials exhibit electric field-induced phase transitions between antiferroelectric and ferroelectric states, which enable their use in energy storage and other applications. However, the mechanisms of these transitions are insufficiently understood. Here, we considered the electric field-induced phase transition in the lead-free antiferroelectric NaNbO$_3$. Macroscopic measurements of polarization and longitudinal, transverse, and volumetric strain were complemented with simultaneous structural investigations using high-energy x-ray radiation, yielding crystallographic strain and unit cell volume changes. The field-induced behavior can be divided into the structural antiferroelectric–ferroelectric phase transition at about 8 kV/mm and the clearly decoupled polarization switching process at about 12 kV/mm, which is associated with a large increase in polarization and strain. Decoupling of the field-induced phase transition and polarization switching is related to the randomly oriented grains and mechanical stress present at the phase boundary.

Electrostatic potential barriers at doped ZnO‐ZnO interfaces can be modified bystress‐induced polarization charges. This concept was enhanced by preparingZnO‐based single crystal‐polycrystal‐single crystal structures by diffusion bond-ing. Increasing time for epitaxial solid‐state transformation results in structureswith a decreasing thickness of residual polycrystalline material in between twowell‐oriented single crystals. Microstructural and electrical analysis quantifies theinfluence of high‐temperature treatment during epitaxial growth on the stress sen-sitivity of the prepared structures. The orientation of the single crystals is definedto maximize the interaction between stress‐induced polarization charges and thepotential barriers at doped ZnO‐ZnO interfaces. With decreasing thickness ofresidual polycrystalline material, the percentage of grain boundaries with favor-ably aligned polarization vectors is increased resulting in a higher stress sensitiv-ity. This effect is compensated by an adverse effect of the high‐temperaturetreatment on the initial potential barrier height. Hence, a maximum in stress sensi-tivity can be observed for intermediate times of epitaxial growth. The preparedstructures close the gap between the varistor piezotronics based on bulk ceramicswith random orientation of the polarization vector and the bicrystal piezotronicswith perfect orientation of the polarization vector, demonstrating the capability ofmicrostructural engineering for varistor‐based piezotronic devices.

The electrocaloric effect in ferroics is considered a powerful solid-state cooling technology. Its potential is enhanced by correlation to the inverse electrocaloric effect and leads into mechanisms of decreasing or increasing dipolar entropy under applied electric field. Nevertheless, the mechanism underlying the increase of the dipolar entropy with applied electric field remains unclear and controversial. This study investigates the electrocaloric response of the antiferroelectric Pb0.99Nb0.02[(Zr0.58Sn0.43)0.92 Ti0.08]0.98O3 in which the critical electric field is low enough to induce the ferroelectric phase over a broad temperature range. Utilizing temperature- and electric-field-dependent dielectric measurements, direct electrocaloric measurements, and in situ transmission electron microscopy, a crossover from conventional to inverse electrocaloric response is demonstrated. The origin of the inverse electrocaloric effect is rationalized by investigating the field-induced phase transition between antiferroelectric and ferroelectric phases. The disappearance of the latent heat at field-induced transition coincides with the crossover of the electrocaloric effect and demonstrates that the overall electrocaloric response is an interplay of different entropy contributions. This opens new opportunities for highly efficient, environmentally friendly cooling devices based on ferroic materials.

The formation of polar nanoregions through solid-solution additions is known to enhance significantly the functional properties of ferroelectric materials. Despite considerable progress in characterizing the microscopic behavior of polar nanoregions (PNR), understanding their real-space atomic structure and dynamics of their formation remains a considerable challenge. Here, using the method of dynamic pair distribution function, we provide direct insights into the role of solid-solution additions towards the stabilization of polar nanoregions in the Pb-free ferroelectric of Ba(Zr,Ti)O3. It is shown that for an optimum level of substitution of Ti by larger Zr ions, the dynamics of atomic displacements for ferroelectric polarization are slowed sufficiently below THz frequencies, which leads to increased local correlation among dipoles within PNRs. The dynamic pair distribution function technique demonstrates a unique capability to obtain insights into locally correlated atomic dynamics in disordered materials, including new Pb-free ferroelectrics, which is necessary to understand and control their functional properties. (Less)

The paper defines Mostar as a divided city on three levels according to authors. The research included method of mental maps drawing and bordering of division. Micro-scale borders phenomenon on the case study of Mostar is elaborated.

The Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 system was synthesized in a wide compositional range in order to study the relationship between its phase diagram and electromechanical properties. Phase transitions were marked using peaks in temperature-dependent permittivity, providing up to three transitions from the rhombohedral phase to an orthorhombic, tetragonal and finally cubic phase, which meet in a region that is termed the phase convergence region in this work. In situ small and large signal electromechanical properties were studied as a function of temperature with specific emphasis on these transitions. A small signal piezoelectric coefficient, d33, presents maximized values at the transition from the orthorhombic to the tetragonal phase, while a large signal piezoelectric coefficient, d 33 ∗ , does so at both rhombohedral to orthorhombic and to tetragonal phase transitions. Maximum polarization Pmax was the only quantity determined that had a clear maximum at the phase convergence region.

An improved thermodynamic cycle is validated in ferroelectric single crystals, where the cooling effect of an electrocaloric refrigerant is enhanced by applying a reversed electric field. In contrast to the conventional adiabatic heating or cooling by on-off cycles of the external electric field, applying a reversed field is significantly improving the cooling efficiency, since the variation in configurational entropy is increased. By comparing results from computer simulations using Monte Carlo algorithms and experiments using direct electrocaloric measurements, we show that the electrocaloric cooling efficiency can be enhanced by more than 20% in standard ferroelectrics and also relaxor ferroelectrics, like $\mathrm{Pb}({\mathrm{Mg}}_{1/3}$/${\mathrm{Nb}}_{2/3}$)${}_{0.71}{\mathrm{Ti}}_{0.29}{\mathrm{O}}_{3}$.

We present a critical review that encompasses the fundamentals and state-of-the-art knowledge of barium titanate-based piezoelectrics. First, the essential crystallography, thermodynamic relations, and concepts necessary to understand piezoelectricity and ferroelectricity in barium titanate are discussed. Strategies to optimize piezoelectric properties through microstructure control and chemical modification are also introduced. Thereafter, we systematically review the synthesis, microstructure, and phase diagrams of barium titanate-based piezoelectrics and provide a detailed compilation of their functional and mechanical properties. The most salient materials treated include the (Ba,Ca)(Zr,Ti)O3, (Ba,Ca)(Sn,Ti)O3, and (Ba,Ca)(Hf,Ti)O3 solid solution systems. The technological relevance of barium titanate-based piezoelectrics is also discussed and some potential market indicators are outlined. Finally, perspectives on productive lines of future research and promising areas for the applications of these ma...

Application of a negative field on a positively poled ferroelectric sample can enhance the electrocaloric cooling and appears as a promising method to optimize the electrocaloric cycle. Experimental measurements show that the maximal cooling does not appear at the zero-polarization point, but around the shoulder of the P-E loop. This phenomenon cannot be explained by the theory based on the constant total entropy assumption under adiabatic condition. In fact, adiabatic condition does not imply constant total entropy when irreversibility is involved. A direct entropy analysis approach based on work loss is proposed in this work, which takes the entropy contribution of the irreversible process into account. The optimal reversed field determined by this approach agrees with the experimental observations. This study signifies the importance of considering the irreversible process in the electrocaloric cycles.

The interactions between the dielectric polarization and the fluctuations of the strain (stress) tensor in relaxor ferroelectrics are shown to give rise to the anisotropy of the anharmonic P4-term in the Landau-type free energy, however, the harmonic P2-term is still properly described by the rigid spherical random bond--random field model. These are the essential features of the compressible spherical dipolar glass model, which is used to calculate the singularities of the specific heat near field-induced critical points. The results agree with recent high-resolution calorimetric experiments in PMN [110]., Comment: 5 pdf pages, 4 figures

O período após a Grande Guerra teve implicações profundas no panorama geopolítico Europeu. O colapsar de diversos impérios, o pós-colonialismo, a ascensão do comunismo e de outros movimentos extremistas, opuseram-se às conceções liberais de livre mercado, à democracia e à autodeterminação nacional. No Sudeste Europeu, a ideia de um estado eslavo uniu nações anteriormente em lados opostos na guerra. A luta pelo domínio político e nacional, pela hegemonia, o confronto de diferentes ideias e as constantes mudanças de alianças e fronteiras internas dos diversos estados estiveram na origem de um conjunto de novas divisões micro-geopolíticas nesta região. A tentativa de implementação do ideal jugo-eslavo implicou um conjunto de processos de reterritorialização e desterritorialização na região da ex-Jugoslávia, sendo que a última tentativa que procurou a criação de soluções para as nações jugoslavas culminou em guerra. A Guerra Civil na Bósnia e Herzegovina, a Guerra da independência da Croácia e a Guerra do Kosovo, constituem-se como os últimos conflitos armados que tiveram lugar no continente Europeu no século XX. Embora estes Estados se constituam nos dias de hoje como países independentes e reconhecidos internacionalmente, a gestão do pós-crise nestes países teve um impacto reduzido. As fronteiras nacionais hoje reconhecidas não respeitaram as divisões a nível local nem a micro-geopolítica das mesmas. As regiões divididas, as cidades e fronteiras percecionadas são assim, nos dias de hoje, uma parte crucial da geografia humana e das conceções geopolíticas nesta região. Esta investigação parte do estudo de caso das divisões micro-geopolíticas da antiga Jugoslávia, com especial destaque na temática das cidades divididas. A principal unidade de análise são as micro-entidades presentes na região, nomeadamente as cidades divididas cujos territórios foram afetados pela guerras jugoslavas - Bósnia e Herzegovina, Croácia e Kosovo. A pesquisa combina análise sincrónica e diacrónica, diacrónica - dada a componente histórica e o estudo dos processos de reterritorialização e desterritorialização na região, sincrónica - visto que a análise incide sobre três estudos de caso semelhantes de cidades divididas e que emergiram destes processos. Os três estudos de caso incidem sobre as cidades de Mostar, Vukovar e Kosovska Mitrovica. The period after the Great War marked significant geopolitical perturbances in Europe. The collapse of empires, (post)colonialism and the rise of communism and other extremist movements, opposed the liberal understandings of free market, democracy and national self-determination. In Southeastern Europe, the idea of shared South Slavic state brought together nations previously engaged on opposite sides in the War. Battles for political and national dominance, hegemony, clashes of different ideas and constant changes of alliances and internal borders of several shared states led towards further micro-geopolitical divisions in this part of the world. Attempts to make the idea of Yugo-Slavism work fostered the processes of reterritorialization and deterritorialization in the region of former Yugoslavia. The ultimate attempt that sought solutions for Yugoslav nations ended up in wars. The last armed conflicts that happened in the European continent in the 20th century were the Civil War in Bosnia and Herzegovina, the Croatian Homeland War and the Kosovo War. Even though these states are now independent and internationally recognized countries, post-crisis management had little success. Recognized national borders did not prevent further divisions on local levels and microscale geopolitics. Divided regions, cities and immaterial ethnic micro-borders still burden lived realities and geopolitical visions in this region. This research is designed as a case study of the micro-geopolitical divisions in the former Yugoslavia with a special focus on divided cities. The primary unit of analysis is microscale entities in the region, but within-case cases are divided cities in states which territories were affected by the Yugoslav Wars - Bosnia and Herzegovina, Croatia and Kosovo. The research combines synchronic and diachronic analysis, as it has historical components and it studies the processes of reterritorialization and deterritorialization in the region - diachronic approach, while, at the same time, it focuses on three similar case studies of the divided cities that were an outcome of those processes - synchronic approach. Those three case studies are Mostar, Vukovar and Kosovska Mitrovica.

The aim of the paper is to explore whether contemporary Russian Federation has imaginations of its power in the region of the Central and Eastern Europe. Using a theoretical framework based on instruments, notions and tools of critical geopolitics, this paper discusses four discourses that define the territory which is the focus of the research, as well as stressing the most important concepts of contemporary foreign policy of the Russian Federation. Due to the strong influence of NATO’s (and the EU’s) enlargement policies in this region, the Russian administration tries to preserve its traditional geopolitical sphere of interest in the European continent. Therefore, three sub-regional case studies— annexation of Crimea in the Eastern Europe, the Three Seas Initiative in the Central Europe, and Western Balkan’s case study of Montenegro’s path to full NATO membership—will be explored to examine this hypothesis. Finally, adequate conclusion, regarding the main hypothesis, is brought. info:eu-repo/semantics/publishedVersion