Reactive High-Power Impulse Magnetron Sputtering of Oxides and Oxynitrides Thin Films

Oxidy a oxynitridy přechodových kovů jsou třídou materiálů s ještě neprozkoumanými fyzikálními, chemickými a funkčními vlastnostmi a s velkým potenciálem pro průmyslové aplikace. Tato disertační práce se zabývá přípravou a charakterizací multifunkčních oxidových a oxynitridových vrstev. Pro přípravu vrstev bylo použito vysokovýkonové pulzní reaktivní magnetronové naprašování se zpětnovazebním pulzním řízením průtoku reaktivního plynu. Práce je rozdělena do šesti kapitol. Kapitola I je věnována stručnému všeobecnému úvodu do problematiky. V kapitole II jsou definovány cíle disertační práce. Kapitola III je nejrozsáhlejší a je věnována výsledkům dosaženým v této práci. Tato kapitola je rozdělena do pěti částí prezentovaných v podobě vědeckých prací publikovaných (AC) nebo předložených k publikaci (DE) v prestižních mezinárodních časopisech. V části A je prezentována depozice hustých, tvrdých (1518 GPa), vysoce opticky transparentních (index lomu 2,072,12 a extinkční koeficient mezi 0,1103 a 0,6103; obě veličiny při vlnové délce 550 nm), stechiometrických vrstv HfO2 na křemíkové substráty na plovoucím potenciálu. Je diskutován vliv depozičních podmínek (délka pulzu 50200 ?s a průměrná hustota výkonu na terč 2954 Wcm-2) na depoziční rychlost (až 345 a 460 nm/min pro HfO2 a Hf v uvedeném pořadí) a na vlastnosti vrstev. Je představen zjednodušený vztah pro depoziční rychlost. V části B je diskutována mikrostruktura hustých, tvrdých (1718 GPa), vysoce opticky transparentních (index lomu 2,022,11 a extinkční koeficient mezi 0,1103 a 1103; obě veličiny při vlnové délce 550 nm), hladkých (maximální průměrná střední drsnost asi 1 nm) HfO2 vrstev, připravených na křemíkových substrátech na plovoucím potenciálu. Byl zkoumán vliv délky pulzu (50200 ?s) a průměrné hustoty výkonu na terč (7,354 Wcm-2) na jejich mikrostrukturu. Bylo zjištěno, že všechny vrstvy se skládají z přechodové mezivrstvy na substrátu následované vrstvou vykazující nanosloupcovou strukturu. V jedné vrstvě byla zjištěna vysokoteplotní ortorombická fáze HfO2. V části C je zkoumána závislost smáčivosti a volné povrchové energie HfO2 vrstev na jejich tloušťce. V rozmezí 50250 nm je pozorována nejsilnější závislost (zvýšení kontaktního úhlu kapky vody až na 120°) díky dominanci elektrostatické Lifshitzovy van der Waalsovy složky povrchové volné energie. Zároveň povrchová volná energie roste od přibližně 25 mJ/m2 při tloušťce 50 nm do přibližně 33 mJ/m2 při tloušťce 2300 nm. Byla navržena dvě vysvětlení pro závislost smáčivosti na tloušťce vrstev: vliv nedominantní textury a/nebo nemonotónní závislost povrchové energie na velikosti zrn. V části D jsou ukázány vztahy mezi prvkovým složením, fázovou strukturou a optickými, elektrickými, mechanickými a hydrofobními vlastnostmi Hf-O-N vrstev. Vrstvy byly připraveny při podílu dusíku v průměrném průtoku reaktivního plynu: 0, 0,9, 2,6, 5, 25, 50 a 100 %. Je ukázána plynule řízená příprava vrstev z hlediska plynule laditelných vlastností materiálu při přechodu z oxidu do nitridu. Jedná se například o změnu extinkčního koeficientu při vlnové délce 550 nm z 5104 na 1,77, elektrického odporu z >108 m na 3,2106 m, tvrdosti z 18 GPa na 25 GPa nebo kontaktního úhlu kapky vody ze 101° na 107°. V části E jsou uvedeny a diskutovány základní principy jednoduché (bez použití předpětí a externího ohřevu substrátu během celého procesu reaktivní depozice) třístupňové (předčištění substrátu, depozice gradientních mezivrstev ZrOx a depozice stechiometrických vrstev ZrO2) HiPIMS techniky pro rychlou depozici stechiometrických hustých vrstev ZrO2 se zvýšenou adhezí k povrchu ocelových substrátů. Kapitola IV je věnována závěrům disertační práce. V kapitole V jsou uvedeny další publikace kandidátaNeobhájenoTransition metal oxides and oxynitrides are a class of materials with yet unexplored physical, chemical and functional properties, and a great potential for industrial applications. This Ph.D. thesis deals with preparation and characterization of multifunctional oxide and oxynitride films. They were prepared using high-power impulse magnetron sputtering with a feedback pulsed reactive gas flow control. Chapter I is devoted to a short general introduction into problematics. In Chapter II, the aims are defined. Chapter III is the most extensive and is devoted to the results achieved in this thesis. This chapter is divided in five parts presented in a form of scientific papers published (A-C) or submitted for publication (D-E) in prestigious international journals. In Part A, the deposition of densified, hard (15-18 GPa), highly optically transparent (refractive index of 2.07-2.12 and extinction coefficient between 0.110-3 and 0.6x10-3; both quantities at the wavelength of 550 nm), stoichiometric HfO2 films onto floating silicon substrates is reported. Influence of the deposition conditions (pulse duration of 50-200 ?s and deposition-averaged target power density of 29-54 Wcm-2) on deposition rates (up to 345 and 460 nm/min for HfO2 and pure Hf, respectively) and on film properties was discussed. A simplified relation for the deposition rate was presented. In Part B, microstructure of densified, hard (17-18 GPa), highly optically transparent (refractive index of 2.02-2.11 and extinction coefficient between 0.110-3 and 110-3; both quantities at the wavelength of 550 nm), smooth (maximum average mean roughness of about 1 nm) HfO2 films onto floating silicon substrates was presented. The effect of the voltage pulse duration (50-200 ?s) and the deposition-averaged target power density (7.3-54 Wcm-2) on their microstructure was investigated. All films were found to be composed of an interlayer next to the substrate interface followed by a nano-columnar structure layer. In one film, high temperature orthorhombic HfO2 phase was found. In Part C, the dependence of wetting properties and surface free energy of HfO2 films on their thickness is investigated. In the range of 50250 nm, the strongest dependence (increase of the water droplet contact angle up to 120°) due to the dominance of the electrostatic Lifshitz-van der Waals component of the surface free energy was found. At the same time, the surface free energy grows from about 25 mJ/m2 for the thickness of 50 nm to about 33 mJ/m2 for the thickness of 2300 nm. It was proposed two explanations for the observed thickness dependence of the wetting properties: influence of the non-dominant texture and/or non-monotonic size dependence of the particle surface energy. In Part D, the relationships between elemental composition, phase structure, and optical, electrical, mechanical and hydrophobic properties of the Hf-O-N films are shown. The films were prepared at nitrogen fractions in the average reactive gas flow of 0, 0.9, 2.6, 5, 25, 50 and 100%. The smoothly controlled composition is shown in terms of smoothly controlled material properties along the transition from an oxide to a nitride including, for example, extinction coefficient at 550 nm from 5x10-4 to 1.77, electrical resistivity from >108 m to 3.2x10-6 m, hardness from 18 GPa to 25 GPa or water droplet contact angle from 101° to 107°. In Part E, the basic principles of a simple (no substrate bias voltage during reactive sputter depositions and no external heating during the whole process) three-step HiPIMS technique (substrate pretreatment, deposition of gradient ZrOx interlayers and deposition of stoichiometric ZrO2 films) for a fast deposition of densified stoichiometric ZrO2 films with enhanced adhesion to steel substrates are presented and discussed. Chapter IV is devoted to the conclusions of the Ph.D. thesis. In Chapter V, further publications of the candidate are given

Spiders (Aranei) of the Lower Volga Region (Astrakhan and Volgograd areas of Russia) with the description of new taxa

Based on the original material and literature data the annotated species list of spiders is presented for the Lower Volga Region (the Astrakhan and Volgograd areas of Russia). At present 254 species from 23 families are recorded in the region. Of them in the Astrakhan area — 177 species from 22 families, in Volgograd area — 149 species from 19 families are revealed. The genus Bogdocosa Ponomarev et Belosludtsev gen. n. (Lycosidae) with type species Bogdocosa baskuntchakensis Ponomarev et Belosludtsev sp. n. is described from the Astrakhan area of Russia. The new species Haplodrassus caspius Ponomarev et Belosludtsev sp. n. (Gnaphosidae) from the Astrakhan area of Russia and Atyrau areas of Kazakhstan is descrab

The Short-Term Opening of Cyclosporin A-Independent Palmitate/Sr2+-Induced Pore Can Underlie Ion Efflux in the Oscillatory Mode of Functioning of Rat Liver Mitochondria

Mitochondria are capable of synchronized oscillations in many variables, but the underlying mechanisms are still unclear. In this study, we demonstrated that rat liver mitochondria, when exposed to a pulse of Sr2+ ions in the presence of valinomycin (a potassium ionophore) and cyclosporin A (a specific inhibitor of the permeability transition pore complex) under hypotonia, showed prolonged oscillations in K+ and Sr2+ fluxes, membrane potential, pH, matrix volume, rates of oxygen consumption and H2O2 formation. The dynamic changes in the rate of H2O2 production were in a reciprocal relationship with the respiration rate and in a direct relationship with the mitochondrial membrane potential and other indicators studied. The pre-incubation of mitochondria with Ca2+(Sr2+)-dependent phospholipase A(2) inhibitors considerably suppressed the accumulation of free fatty acids, including palmitic and stearic acids, and all spontaneous Sr2+-induced cyclic changes. These data suggest that the mechanism of ion efflux from mitochondria is related to the opening of short-living pores, which can be caused by the formation of complexes between Sr2+(Ca2+) and endogenous long-chain saturated fatty acids (mainly, palmitic acid) that accumulate due to the activation of phospholipase A(2) by the ions. A possible role for transient palmitate/Ca2+(Sr2+)-induced pores in the maintenance of ion homeostasis and the prevention of calcium overload in mitochondria under pathophysiological conditions is discussed.Peer reviewe

PROBLEM ISSUES OF SCHOOL MATHEMATICS EDUCATION

В статье рассматриваются проблемы подготовки школьников к Государственной Итоговой Аттестации по математике. Представлен анализ возникающих проблем и пути их преодоленияThe article deals with the problems of teaching schoolchildren to the State Final Certification in Mathematics. There is the analysis of emerging problems and ways to overcome the

The Short-Term Opening of Cyclosporin A-Independent Palmitate/Sr2+-Induced Pore Can Underlie Ion Efflux in the Oscillatory Mode of Functioning of Rat Liver Mitochondria

Mitochondria are capable of synchronized oscillations in many variables, but the underlying mechanisms are still unclear. In this study, we demonstrated that rat liver mitochondria, when exposed to a pulse of Sr2+ ions in the presence of valinomycin (a potassium ionophore) and cyclosporin A (a specific inhibitor of the permeability transition pore complex) under hypotonia, showed prolonged oscillations in K+ and Sr2+ fluxes, membrane potential, pH, matrix volume, rates of oxygen consumption and H2O2 formation. The dynamic changes in the rate of H2O2 production were in a reciprocal relationship with the respiration rate and in a direct relationship with the mitochondrial membrane potential and other indicators studied. The pre-incubation of mitochondria with Ca2+(Sr2+)-dependent phospholipase A2 inhibitors considerably suppressed the accumulation of free fatty acids, including palmitic and stearic acids, and all spontaneous Sr2+-induced cyclic changes. These data suggest that the mechanism of ion efflux from mitochondria is related to the opening of short-living pores, which can be caused by the formation of complexes between Sr2+(Ca2+) and endogenous long-chain saturated fatty acids (mainly, palmitic acid) that accumulate due to the activation of phospholipase A2 by the ions. A possible role for transient palmitate/Ca2+(Sr2+)-induced pores in the maintenance of ion homeostasis and the prevention of calcium overload in mitochondria under pathophysiological conditions is discussed

Real-time DNA microarray analysis

We present a quantification method for affinity-based DNA microarrays which is based on the real-time measurements of hybridization kinetics. This method, i.e. real-time DNA microarrays, enhances the detection dynamic range of conventional systems by being impervious to probe saturation in the capturing spots, washing artifacts, microarray spot-to-spot variations, and other signal amplitude-affecting non-idealities. We demonstrate in both theory and practice that the time-constant of target capturing in microarrays, similar to all affinity-based biosensors, is inversely proportional to the concentration of the target analyte, which we subsequently use as the fundamental parameter to estimate the concentration of the analytes. Furthermore, to empirically validate the capabilities of this method in practical applications, we present a FRET-based assay which enables the real-time detection in gene expression DNA microarrays

Влияние микроструктуры сплавов на основе магния на катодное выделение водорода

Solubility of several transition metal chlorides (NiCl2, CrCl2, MoCl3, FeCl2) was measured in KCl-AlCl3 based melts. It was found that the solubility of studied metal chlorides depends on K : Al mole ratio. MoCl3 solubility decreases with increasing AlCl3 content. Solubility of CrCl2 and FeCl2 reaches maximum at K : Al ratio of 1 and decreases when this ratio either de-creases or increases. The dependence of NiCl2 solubility on K : Al mole ratio is V-shaped with the maximum near 0.9–0.95. The effect of temperature on solubility of transition metal chlorides in KCl-AlCl3 melts was also investigated. Increasing temperature does not  alter the character of «solubility – K : Al mole ratio» dependences.Исследована эволюция зеренной структуры магниевых сплавов в процессе равноканального углового прессования (РКУП) при 200 ºС. Показано, что РКУП приводит к формированию сильно неоднородной структуры. Установлено, что деформация не оказывает влияния на кинетику реакции выделения водорода (РВВ), но оказывает воздействие на скорость катодного процесса. Сплав AZ31 является более эффективным катодным материалам в щелочных средах по сравнению с магнием и сплавом ZK60