Self-organization approach for THz polaritonic metamaterials

In this paper we discuss the fabrication and the electromagnetic (EM) characterization of anisotropic eutectic metamaterials, consisting of cylindrical polaritonic LiF rods embedded in either KCl or NaCl polaritonic host. The fabrication was performed using the eutectics directional solidification self-organization approach. For the EM characterization the specular reflectance at far infrared, between 3 THz and 11 THz, was measured and also calculated by numerically solving Maxwell equations, obtaining good agreement between experimental and calculated spectra. Applying an effective medium approach to describe the response of our samples, we predicted a range of frequencies in which most of our systems behave as homogeneous anisotropic media with a hyperbolic dispersion relation, opening thus possibilities for using them in negative refractive index and imaging applications at THz range

Sinterització assistida per camp elèctric: flash sintering

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2020, Tutora: Lourdes Mestres VilaFlash sintering is a novel technique used for ceramics densification by means of heating and applying an electric field. Its advantages over conventional sintering have been discussed in the present work, amongst which, the following advantages are displayed: energy savings, shorter sintering times and preparation of ceramic materials with complex compositions by controlling abnormal grain growth and stoichiometry, as the loss of volatile compounds is avoided. The setup for flash sintering has been constantly developing since the introduction of the technique and sophisticated setups have been designed in order to collect all the required data during the same analysis. Moreover, the electrical response has been reviewed during this process where power, applied field and current are controlled. Flash sintering mechanisms have also been discussed as various authors proposed different mechanisms to explain this phenomenon such as Joule heating, nucleation of Frenkel pairs and electrochemical reduction. Furthermore, an extensive list of parameters controlling flash sintering have been studied and its optimization have been discussed; for instance, applied electric field, current density, initial particle size, green density, addition of sintering aids and the atmosphere. In this work, a comprehensive study of different prediction models have been made. These models have been created to predict sample temperature from furnace temperature, and onset temperature depending on the applied field. The last bibliographic section exhibit new materials sintering by flash sintering. Dwelling time and temperature are compared with the conventional sintering of the same materials. Useful information can be extracted from this analysis in order to prepare dense ceramics as a few studies about materials’ properties show similar results to conventionally sintered materials. However, flash sintering have been shown to substantially reduce onset temperatures and dwelling times.Concerning the experimental part, conventional sintering and flash sintering experiments of a commercial sample of BaTiO3 have been performed but relative densities and characterization methods have not been carried out due to the pandemic. Regarding the study of a previously prepared Nd2Zr2O7, conventional sintering was performed and the resulting relative density was calculated. X-ray diffraction analysis was carried out and the resulting diffractometer was analyzed. Impedance spectroscopy was carried out, but results were not analyzed as a full set of measurements was not performed

The Thirteenth Annual Conference YUCOMAT 2011: Programme and the Book of Abstracts

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)

Solidification and Gravity VII

International audienc

Sintering Applications

Sintering is one of the final stages of ceramics fabrication and is used to increase the strength of the compacted material. In the Sintering of Ceramics section, the fabrication of electronic ceramics and glass-ceramics were presented. Especially dielectric properties were focused on. In other chapters, sintering behaviour of ceramic tiles and nano-alumina were investigated. Apart from oxides, the sintering of non-oxide ceramics was examined. Sintering the metals in a controlled atmosphere furnace aims to bond the particles together metallurgically. In the Sintering of Metals section, two sections dealt with copper containing structures. The sintering of titanium alloys is another topic focused in this section. The chapter on lead and zinc covers the sintering in the field of extractive metallurgy. Finally two more chapter focus on the basics of sintering,i.e viscous flow and spark plasma sintering

Ferroelectrics

Ferroelectric materials exhibit a wide spectrum of functional properties, including switchable polarization, piezoelectricity, high non-linear optical activity, pyroelectricity, and non-linear dielectric behaviour. These properties are crucial for application in electronic devices such as sensors, microactuators, infrared detectors, microwave phase filters and, non-volatile memories. This unique combination of properties of ferroelectric materials has attracted researchers and engineers for a long time. This book reviews a wide range of diverse topics related to the phenomenon of ferroelectricity (in the bulk as well as thin film form) and provides a forum for scientists, engineers, and students working in this field. The present book containing 24 chapters is a result of contributions of experts from international scientific community working in different aspects of ferroelectricity related to experimental and theoretical work aimed at the understanding of ferroelectricity and their utilization in devices. It provides an up-to-date insightful coverage to the recent advances in the synthesis, characterization, functional properties and potential device applications in specialized areas

Development of Novel Nano - Single Si Phase Cast Hypereutectic Al-Si Alloys

The research presented in this PhD dissertation renders a novel nano and ultra-fine structured cast industrial grade hypereutectic Al-Si-Cu engineering material and processing technologies capable of maximizing its functional characteristics. This development will allow for further engineering of exceptionally lightweight and near net-shape components for aerospace and transportation applications. The research outcomes offer the design and casting communities with new capabilities enabling gains in component properties, productivity, rapid component design and manufacturing procedures. These procedures include industrial melt chemical and physical treatments and an ultra rapid Solution and Artificial Aging Heat Treatments. These approaches were not feasible due to problems such as the lack of scientific knowledge on industrial grades of nano Al-Si-X alloys, limited solid solubility of elements, inadequate wear resistance in extreme environments and the lack of physical simulation engineering tools. The patented Universal Metallurgical Simulator and Analyzer (UMSA) Technology Platforms’ capabilities were further developed to expedite Squeeze Casting (SC), Liquid and Semi-Solid melt processing using various pressure profiles for rapid physical simulations of these complex experimental industrial alloys. SC/HPDC UMSA experiments address: liquid and semi-solid chemical and dynamic physical treatments for structure control and elimination of solidification issues; neutralization of impurity elements; high temperature Solution Treatment and Artificial Aging; and elimination of the grain boundary precipitate-free zone that contributes to corrosion. The novel melt’s physical treatments include impact pressure, monotonic pressure and cyclic pressure loading profiles. Several novel as-cast and heat treated structures were developed and comprehensively characterized. Extensive UMSA Platform(s) processing and Thermal Analysis capabilities were enhanced, allowing for significant gains in understanding the link between processing parameters, Thermal Analysis data, and as-cast and heat treated material characteristics. The project utilized leading edge scientific methodologies for development of new cost effective nano and ultra-fine structured cast aluminum materials that will satisfy future fuel economy and emission targets

Glassy Materials Based Microdevices

Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries. The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome