Studium mikrostruktury a vlastností M-Al-(Si-)N

In this work, microstructure and properties of M-Al-(Si-)N nanocrystalline hard coatings and thin film nanocomposites deposited by cathodic arc evaporation (CAE) process at different positions of substrates in the deposition apparatus were investigated using the combination of electron probe microanalysis, X-ray diffraction, transmission electron microscopy with high resolution and hardness measurement. Six series of specimens that differed in the transition metal type (Cr, Ti and Zr) and in the amount of Si and Al were deposited using the CAE process in the deposition apparatus π-80 produced by Platit AG. The essential microstructural parameters; the chemical and phase composition, the residual stress, preferred orientation of crystallites, crystallite size and mutual disorientation of crystallites were determined in all coatings under study. The derived microstructural parameters were correlated with the hardness of coatings. Finally, the microstructural model of the nanocrystalline hard coatings and thin film nanocomposites formation was developed. Depending on the sample chemical composition, three regions with different phase compositions exist in the coatings. In the transition metal richest samples, a single fcc M1-x- yAlxSiyN phase exists in the coating. With increasing Al content,...Tato práce je věnována studiu mikrostruktury a vlastností M-Al-(Si-)N nanokrystalických tvrdých povlaků a nanokompozitních tenkých vrstev, deponovaných napařováním v katodovém oblouku (CAE), kombinací metod elektronové mikroanalýzy, difrakce rentgenového záření, transmisní elektronové mikroskopie s vysokým rozlišením (TEM / HRTEM) a měřením mikrotvrdosti. Šest sérií vzorků, lišících se typem přechodového kovu (Cr, Ti and Zr) a množstvím Al a Si v závislosti na pozici substrátu vzhledem ke katodám, bylo deponováno CAE procesem v depozičním přístroji π-80 vyrobeném firmou Platit AG. Ve všech studovaných povlacích byly určeny základní mikrostrukturní parametry, jmenovitě chemické a fázové složení, zbytková napětí, preferenční orientace krystalitů, velikost koherentně difraktujících domén a vzájemná desorientace krystalitů. Odvozené mikrostrukturní parametry byly korelovány s mechanickými vlastnostmi vrstev - mikrotvrdostí. Následně byl vytvořen mikrostrukturní model vývoje nanokrystalických tvrdých povlaků a nanokompozitních tenkých vrstev. V závislosti na chemickém složení vzorků existují ve studovaných vrstvách tři oblasti lišící se fázovým složením. Ve vzorcích s nejvyšší koncentrací přechodového kovu existuje pouze jediná - kubická plošně centrovaná (kpc) M1-x-yAlxSiyN fáze. Se vzrůstající...Katedra fyziky kondenzovaných látekDepartment of Condensed Matter PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Mechanical Properties and Microstructure Development in Ultrafine‐grained Materials Processed by Equal‐channel Angular Pressing

In this chapter, the detailed characterization of processes of grain fragmentation and refinement resulting from gradual imposition of strain by individual equal‐channel angular pressing (ECAP) passes is reported. A great emphasis is placed on the processing of materials with different crystal structure, particularly the face‐centred cubic (FCC), the body‐centred cubic (BCC) and the hexagonal close‐packed (HCP). Advanced techniques of electron microscopy, electron and X‐ray diffraction and positron annihilation spectroscopy have been employed to characterize microstructure, texture and defect evolution in the material as a function of strain imposed by ECAP. Microstructure development was correlated with mechanical properties obtained by both mechanical tests and microhardness measurements. Processes controlling the microstructure refinement and texture development were identified and discussed in detail

Synthesis of gold ring-shape nanoparticles using co-sputtering over liquids

Abstract The energy flow, dE/dη, is studied at large pseudorapidities in proton-proton collisions at the LHC, for centre-of-mass energies of 0.9 and 7 TeV. The measurements are made using the CMS detector in the pseudorapidity range 3.15 < |η| < 4.9, for both minimum-bias events and events with at least two high-momentum jets. The data are compared to various pp Monte Carlo event generators whose theoretical models and input parameter values are sensitive to the energy-flow measurements. Inclusion of multiple-parton interactions in the Monte Carlo event generators is found to improve the description of the energy-flow measurements

Kondo volume collapse in frustrated antiferromagnet: The case of Ce2Pd2In. Supplementary information [Dataset]

The Supplementary file contains a detailed description of experimental and computational techniques together with a part of results, not necessarily included in the main text for proper understanding.Peer reviewe

Insights into the growth of nanoparticles in liquid polyol by thermal annealing

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Co-sputtering of gold and copper onto liquids: a route towards the production of porous gold nanoparticles

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Co-sputtering of gold and copper onto liquids: a route towards the production of porous gold nanoparticles

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Antiferroelectric negative capacitance from a structural phase transition in zirconia

Crystalline materials with broken inversion symmetry can exhibit a spontaneous electric polarization, which originates from a microscopic electric dipole moment. Long-range polar or anti-polar order of such permanent dipoles gives rise to ferroelectricity or antiferroelectricity, respectively. However, the recently discovered antiferroelectrics of fluorite structure (HfO$_2$ and ZrO$_2$) are different: A non-polar phase transforms into a polar phase by spontaneous inversion symmetry breaking upon the application of an electric field. Here, we show that this structural transition in antiferroelectric ZrO$_2$ gives rise to a negative capacitance, which is promising for overcoming the fundamental limits of energy efficiency in electronics. Our findings provide insight into the thermodynamically 'forbidden' region of the antiferroelectric transition in ZrO$_2$ and extend the concept of negative capacitance beyond ferroelectricity. This shows that negative capacitance is a more general phenomenon than previously thought and can be expected in a much broader range of materials exhibiting structural phase transitions