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In this work, the phase behavior of cryoprotective mixtures based on dimethyl sulfoxide (DMSO) mixed with a lipid bilayer consisting of dimyristoyl phosphatidylcholine (DMPC) was studied. This system represented a model of a biological cell and its membrane. The aim of the work was to clarify the origin of the cryoprotective action of low-concentrated mixtures (1-10 vol%) DMSO in water, representing mixtures used in cryopreservation in cell therapy. The combination of experimental techniques of differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy (PALS) allowed a study of crystallization behavior of water confined in liposomes imitating the intracellular environment. The ability of liposomes to show the fundamental aspects of water phase behavior seen during freezing of biological cells was proved. The presence of an amorphous freeze-concentrated phase of DMSO in the frozen state was confirmed and its possible crystallization into the DMSO trihydrate and ice during thawing was demonstrated. Correlation between the critical temperature range for the loss of cell viability during slow thawing and the temperatures of freeze-concentrated phase crystallization was found. Based on this finding, possible mechanisms of DMSO cryoprotection are discussed with support brought by results for the studied model system. Quantification of the ice phase fraction in the frozen mixtures revealed that even low concentrations of DMSO can induce a considerable decrease in the amount of ice present.

Thick InAlN layers (In-molar fraction >0.37) on GaN buffer layers were prepared using a close-coupled showerhead metalorganic chemical vapor deposition (MOCVD) reactor. This work provides a discussion of the dependence of reactor parameters (pressure, ammonia flow and temperature) and unintentional Ga-incorporation on structural, optical and chemical properties of those layers down to the nanoscale. Rutherford back-scattering spectrometry, Auger electron spectroscopy, and transmission electron microscopy with the energy dispersive X-ray analysis were used for in-depth chemical analysis of layers. A diminishing Ga-auto-incorporation in thick InAlN layer creates a chemically graded InAl(Ga)N interlayer that assists in releasing of interfacial strain and paves the way toward In-rich InAlN layer. The rate of unintentional Ga-auto-incorporation in InAlN layers increases with decreasing of growth temperature, and increasing of reactor pressure and ammonia flow during growth. Raman and photoluminescence spectroscopy were used to get the crystal structural fingerprint influenced by Ga-incorporation. We suggested that Ga could incorporate at nitrogen vacancies at high reactor pressures (≥200 mbar). Screw dislocations and/or N-vacancies in InAl(Ga)N layers may be energetically favorable sites for In-incorporation and lead to compositional fluctuation and local In-rich InAl(Ga)N phase.

Study of the interlayer interactions and hysteresis processes was performed for the nano/microcrystalline bilayer ribbon composed of soft magnetic Fe73.5Cu1Nb3Si13.5B9 layer and semihard magnetic Co72.5Si12.5B15 layer. Precursor amorphous ribbons were prepared by modified double-nozzle planar flow casting method. Measurement of the First Order Reversal Curves (FORCs) was utilized for detailed characterization of its magnetic hysteresis behaviour. Calculated switching field distribution (SFD) consists of two distinct peaks, each representing specific magnetic phase. With decreasing reversal field value, SFD peak of the microcrystalline, semihard magnetic Co-based layer is shifted to the higher field values, indicating presence of strong positive exchange interaction. On the other hand, SFD peak of the soft magnetic nanocrystalline Fe-based layer is shifted to lower and even negative field values. Such behaviour was associated with the presence of magnetostatic bias field originating in the semihard magnetic layer.

Microporous carbon fibers prepared by controlled carbonization of cellulose proved promising carrier of nano- and microparticles of solid active substances. The average pore size of the carbon fibers ranges from 0.5 to 0.6 nm and, therefore, molecules of many low- molecular substances are excluded. Consequently, the nano- and microparticles formed by precipitation of a solution in the presence of fibers are deposited exclusively on their outer surface. In this way, composite materials with favorable macro-structure can be created because large surface of appropriate active substance remains easily accessible for the desired action. Technical problems connected with the direct application of nano- and microparticles are avoided. The practical advantages of the microporous carbon fibers prepared from cellulose comprise feasibility of their preparation, as well as general availability and low price of the raw material. Moreover, compared to particulate carriers with identical diameter, fibrous carriers exhibit reduced resistance against flow of liquids and gases. The pertinence of carriers based on the microporous carbon fibers prepared from delignified cellulose has been tested with the deposition of nano- and microparticles of hydrated ferric hydroxide, Fe(OH)3·(H2O)n. Compared with particulate ferric hydroxide, the resulting heterogeneous composite showed increased efficiency in adsorptive removal of harmful arsenic from water.

A series of porous carbon microfibers has been prepared by controlled carbonization of cellulose precursors. Their surface area determined by the BET method from argon absorption ranges from about 1 to almost 1500 m2 g−1. The pore sizes of fibers determined with help of positron annihilation lifetime spectroscopy are in the range below 1 nm. Dried samples of the resulting material were imbued with water in order to characterize their water sorption abilities. Amount of absorbed water was precisely determined by thermogravimetry. Carbon fibers filled with water were analyzed with differential scanning calorimetry and positron annihilation lifetime spectroscopy. It has been shown that water sorption abilities of fibers are not simply proportional to their surface area; there exists a significant impact of other factors.

A joint investigation of n-undecane (n-UND) in the bulk and confined states in irregular silica gel (SG) matrices differing in their surface composition via two extrinsic probes using positron annihilation lifetime spectroscopy (PALS) and electron spin resonance (ESR) as well as DSC technique is presented. Ortho-positronium (o-Ps) exhibits a pronounced change in the annihilation behavior as detected by the o-Ps lifetime,τ3, as a function of temperature due to the enhanced amorphization of the n-UND after confinement with respect to the bulk solid n-UND. In addition, with an exception of the low-T region it exhibits rather small alterations in the confined state in the unmodified (virgin) SG100A-SIL compared to modified (silanized) SG100A - C4. On the other side, the stable free radical of nitroxide type 2,2,6,6-tetramethylpiperidinyl-1-oxy(TEMPO) shows the essential differences in the spectral properties with temperature not only in the confined n-UND with respect to the bulk sample, but especially in the confined state in the modified SG-C4 matrix compared to the unmodified SG100A-SIL one. These differences are attributed to the presence and absence of the preferential interaction of the polar spin probe TEMPO with the polar surface of the virgin SG matrix or the apolar surface of the silanized SG100A-C4 one, respectively. The coinciding relationships between the characteristic PALS and ESR temperatures reflecting the changes in annihilation and rotation dynamics of the respective extrinsic probes are related to the dynamic and phase transitions as found by wide-T DSC.

Micro-Raman spectroscopy, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were used to study the effect of cutting speed and cutting depth on the mode of the single-point diamond fly cutting of Ge(110) surface via crystallinity of the chips. Reducing the cutting depth from 15 to 2 μm and concurrently cutting speed from 10 to 2 mm/min at 2000 rpm, the content of amorphous phase in the chips increased at the expense of the crystalline one from 28 to 46%. Simultaneously, the chip morphology visible by SEM suggested transition from a brittle to a mixed brittle-ductile mode of nanomachining. The damage transition line indicates 1/3 portion of the ductile component at 2-μm cutting depth that produced twisted lamellae of a width of 18–20 μm without any signs of a fracture. As the feed rate here was 1 μm/rev, the tool made 18–20 revolutions while passing the same point of the nanomachined surface that was enough to gradually remove the surface region damaged by the brittle cutting component along with the entire amorphous region beneath, both being delaminated by the chips. This explains the dislocation-free single-crystal lattice beneath the Ge(110) surface machined under these conditions. A close relationship between the brittle mode of nanomachining and crystallinity of the chips observed by micro-Raman spectroscopy and SEM was confirmed by HR-TEM showing dense occurrence of nanocrystals in the chips coming from the nanomachinings with 5-μm and 15-μm cutting depths. These results demonstrate potential of the single-point diamond machining for the preparation of high-quality X-ray surfaces with undistorted single-crystal lattice beneath for next-generation X-ray crystal optics.

Undoped and BaZrO3 nanopowder-doped MgB2/Nb/Cu single filament wires were prepared by modified internal magnesium diffusion (IMD) process using 0, 2 and 5 wt% BaZrO3 addition in amorphous B powder. Superconducting MgB2 phase was formed during heat treatment at temperatures from 650 to 670 °C. The wire microstructure was analysed using XRD, SEM, TEM and EDS to study BaZrO3 dopant interaction with Mg and B precursors during the heat treatment and effect of dopant on MgB2 superconductor. The BaZrO3 nanopowder decomposed and its products reacted with Mg and B producing relatively large BaB6 grains and nanograins of ZrB2 and MgO phases which were not detected by conventional XRD measurements due to their low grain size. Measured MgB2 lattice parameters varied with the dopant addition and heat treatment temperature. Different possible origins of MgB2 lattice deformation were discussed, and it was shown that Zr substitution in MgB2 lattice could not cause this deformation.

The biosorbent used in this study was prepared from wood-decay fungus Fomes fomentarius. The chemical modification of biosorbent with potassium–copper hexacyanoferrate (KCuHCF) for cesium sorption in aqueous solutions studies was used. It was found that the biosorbent has a high 137Cs absorbability in the wide range of pH, even in the solutions with high ionic strength. The developed method for 137Cs determination by using modified bio-sorbent was applied to various types of water delivered by the Water Research Institute in Bratislava. 137Cs was measured on HPGe detector and 137Cs activity was less than the minimum detectable activity (5mBq L−1). The tested modified bio-sorbent is suitable for pre-concentration of 137Cs from water.

The presented work describes an effective method for 226Ra determination using laboratory- prepared MnO2-SiO2 composite resin. Samples were traced with 133Ba for radium radiochemical recoveries monitoring which were in the range of (77 – 100%). MnO2- SiO2 composite resin was used to collect for 226Ra from water samples (pH = 6.5–7.0). Radium was eluted from the column with 50 mL of 4 mol L−1 HNO3 at a flow rate of 1.5 mL min−1. Alpha-spectrometric counting of Ba(Ra)SO4 microprecipitate was used for 226Ra determination. The new developed method was used to the 226Ra determination in samples of natural mineral, mountain spring, drinking and natural healing waters from Slovakia and Czech Republic.

The well-known method of planar flow casting has been used for preparation single- and tri-layered ribbons of the same composition to attain ribbon thickness significantly different. The aim was to suppress potentially undesired surface effects of chemical or topological differences between ribbon surfaces/volume. The prepared ribbons’ composition was Co47Fe21Mo6.5B21Si4.5 and the samples were investigated for structural, chemical and magnetic properties in amorphous (as-cast) and crystalline state. The average thickness was ∼55 µm for the trilayer and ∼14.5 µm for the monolayer, thus the thickness ratio was somewhat more than 3:1. The composition chosen targeted low saturation magnetostriction and nanocrystallization improved soft magnetic properties more namely for trilayer. The reduction of large surface/volume ratio, that enables shrinking surfaces to squeeze efficiently the small volume of single ribbon, proved effective indeed.

Local atomic structure of liquid and amorphous Al80 − xTxSi20 (where T = Fe, Co, Ni and x = 10, 15) alloys has been studied by X-ray diffraction (XRD) and molecular dynamics simulations. Chemical short-range order in the liquid and amorphous alloys has been found to be similar to that in the corresponding crystalline counterparts. Formation and evolution of crystalline phases during heat-treatment of the as-quenched ternary alloys up to liquid state were shown using in-situ XRD. Analysis of the morphology of the as-quenched and annealed Al-T-Si ribbons has been performed by transmission electron microscopy.

The aim of this study is to characterize adsorbed liquid in montmorillonite structure for different levels of adsorption by both thermoanalytical and microstructural methods. Montmorillonite of Ca type is used for the analysis. Water desorption process occurring typically between 50 and 180 °C is analysed in details by thermogravimetric analysis. Thermal response of adsorbed water for the selected steps of desorption process is studied by differential scanning calorimetry. Corresponding characterization of free volume is performed by positron annihilation lifetime spectroscopy. An attempt to determine a correlation of characterization method results is provided.

Surface nanomachining based on single-point diamond turning is a viable technology for the preparation of high-quality surfaces. It found its first extensive use in infrared optics, but it is also attractive for X-ray optics. The challenge is that the X-rays used in laboratories have wavelengths 4 orders of magnitude shorter than infrared radiation. Though recent studies have shown promising results, periodic surface ripples as a footprint of the regular cutting tool scanning proved to be an unavoidable feature, producing unwanted effects in reciprocal space. Hence, the presented paper addresses the problem of finishing Ge monocrystalline X-ray surfaces while keeping all benefits of nanomachining. To do so, chemomechanical polishing, Ar+ ion beam bombardment, and UV laser irradiation were tested separately. Chemomechanical polishing proved to be rather time consuming, whereas ion beam bombardment was not sufficient to suppress the ripples even at the highest available energies. In contrast, UV laser irradiation turned out to be a suitable and time-efficient finishing tool to fully suppress the ripples while keeping the local rms surface roughness around 1 nm.

Combination of mechanical alloying and friction stir processing was used for the fabrication of Al/(Al13Fe4 + Al2O3) nano-composites. Pre-milled hematite + Al powder mixture was introduced into the stir zone generated on 1050 aluminum alloy sheet by friction stir processing. Uniform and active milled powder mixture reacted with plasticized aluminum to produced Al13Fe4 + Al2O3 particles. Al13Fe4 intermetallic showed elliptical shape with a typical size of ~ 100 nm, while nano-sized Al2O3 exhibited irregular floc-shaped particles that formed clusters with the remnant of iron oxide particles in the fine recrystallized aluminum matrix. As the milling time (1-3 h) of the introduced powder mixture increased, the volume fraction of Al13Fe4 + Al2O3 particles increased in the fabricated composite. The hardness and ultimate tensile strength of the fabricated nano-composites varied from 54.5 to 75 HV and 139 to 159 MPa, respectively; these are much higher than those of the friction stir processed base alloy (33 HV and 97 UTS). The highest hardness and strength were achieved for the nano-composite fabricated using the 3-h milled powder mixture; hard nano-sized reaction products and fine recrystallized grains of Al matrix had major and minor roles on enhancing these properties, respectively.

Alloys of composition (Fe-Co)83(Sn-P)5B12 have been prepared by planar flow casting method in air with substitution Co = 0; 5; 10 at. % for Fe and substitution P = 2 at. % for Sn. All as-cast ribbons were amorphous and submitted to chemical and thermal analyses, scanning and transmission electron microscopy and magnetic measurements. Hysteresis loops of strips after nanocrystallization at 380 and 400 °C for 30 min changed their shape – the saturation magnetization increased for Co containing alloys Js = 1.74–1.80 T. The off-axis component of magnetic anisotropy decreased significantly due to the annealing. Coercivity in this case considerably increased due to the growth of grain size and crystalline volume fraction. The samples annealed at 350 °C disclosed a relaxed state with changes in microstructure and achieved very good soft-magnetic properties namely for P substituted alloys.

Si-poor Fe 74 Nb 3 Cu 1 Si 8 B 14− x P x , ( x =0, 3) nanocrystalline ribbon-form alloys often form surfaces, which exert in-plane force on underlying ribbon interior when nanocrystallized in even modest presence of oxygen. Mostly unwanted hard-ribbon-axis magnetic anisotropy is standard result. Essential sources of the surface-caused stress have been sought and influence of P instead of B substitution on this effect was studied too. Preferred surface crystallization (PSC) was found to be the major reason. However P substitution suppresses PSC and promotes Fe-oxide formation, which eases the stress, softens the surfaces and provides different annealing evolution of surface properties.

This work investigates the free-volume properties of the dimethyl sulfoxide (DMSO)–water mixtures by positron annihilation lifetime spectroscopy over a wide temperature range of 20–320 K. The processes of melting and solidification of the water, DMSO and the DMSO–water mixtures at 1.8, 2.0 and 10% vol. DMSO respectively were studied. It was found that the recrystallization during heating of the water–DMSO cryoprotective mixtures above 160 K at low DMSO concentrations is affected by the amount of DMSO in the mixture. The amount of amorphous phase formed during cooling influences the hysteresis between cooling and heating cycles which could be crucial for cell survival. Experiments also show the time dependence of crystallization which indicates that rapid heating can suppress this secondary crystallization which is undesirable during the cell thawing process. Similar concentrations of DMSO (1.8% and 2% vol. DMSO in water) where a 2% vol. DMSO mixture secures cell survival but 1.8 vol% does not, showed differences in structural and dynamic properties that are key factors in cell survival. These results were supported by differential scanning calorimetry and low frequency dielectric spectroscopy measurements. The obtained data are in strong agreement with the observed cryoprotective efficacy of the DMSO–water mixtures on living cells.

The system of FeCoSn(P)B in the ribbon form has been successfully prepared by planar flow casting on air, studied for the thermal analysis and magnetic properties. After annealing at 400 °C during two times the soft-magnetic properties result for shorter time significantly better - Hc decreased by ∼ 30 %. Substitution of 2 at % P for Sn has a positive effect on the formation of stable magnetic anisotropy oriented along the ribbon axis and a slight increase in magnetic saturation (up to 1.80 T).

The properties of Fe-Co-Sn / P-B ribbons prepared by planar flow casting of the melt were investigated by various methods in as-cast and nanocrystallized state. To examine the influence of surfaces on ribbon’s magnetic properties was the major aim. As the surfaces and the ribbon interior possess slightly different properties, mutual macroscopic force is generated and it can affect the magnetic properties. The ribbon with P 2 at % and P-free one was annealed at two different temperatures to achieve partially nanocrystalline structure. P-free ribbon shows tilted hysteresis loop after annealing, what indicates a possible surface squeeze effect. The increase of coercivity after higher temperature annealing at 380 °C is due to the formation of a bcc-Fe phase with a larger grain size and higher crystallinity contents. Oxides, mainly Fe2O3 have been confirmed on surfaces of both the lower temperature (350 °C) annealed ribbons. P substitution appears to reduce the mutual force by impeding the formation of crystalline phase during 350 °C annealing.

The aim of the work is to study interface formation between Al2O3 particles and Al(Ca) matrix in dependence of Ca content. Aluminium matrix composites (AMC) subjected to investigation were prepared by gas pressure assisted infiltration of alumina beds with aluminium-calcium alloys. It is shown that alumina particles in the AMC are covered with a monocalcium aluminates layer whose coherence increases with increasing amounts of Ca in the aluminium-calcium alloys. Moreover, Al4Ca intermetallic phases are formed with increasing Ca content and interconnect alumina particles. XRD confirms the presence of both CaAl2O4 and CaAl4O7 ternary phases. However, HRTEM analysis confirmed CaAl2O4 with a rather complex structure containing a high density of stacking faults. It appeared that annealing at 735 °C does improve consistency of interface for Al 2 wt.%Ca/Al2O3 AMC, but do not affect the thickness of the interface in dependence on annealing time. Keywords: Al2O3 particles, AlCa alloy, Gas pressure infiltration, Interface, Aluminium matrix composites

Permanent magnets used in most electronic devices still rely on a certain content of rare-earth elements while the newest trend is a total reduction or substitution of those. A comfortable and simple solution is conveniently offered by magnetic Mn compounds. Magnetic properties of Mn55Bi45 alloy are determined by the presence of ferromagnetic MnBi phase. This metastable low temperature phase prepared by planar flow casting and followed by specific annealing process, has been studied by several techniques. The controlled heat treatment helps to scale up the magnetic properties resulting from the structural transformation. We have investigated the dependence of magnetic phase content with respect to primary chemical composition in master alloy, the structure evolution from as cast state to the required one after processing and the gradual decay of magnetic phase in time and temperature. The formation and evolution of magnetic crystalline phases were monitored by the structure analysis using X-ray diffraction. Phase transformations and their degradation in temperature and time were directly characterized by thermal analysis techniques (differential scanning calorimetry and thermogravimetry). Crystal structure of ribbons in as-quenched state was investigated by X-ray diffraction. Long-term time evolution of stability of structure and properties was studied at different lower temperatures on samples after the original aging process.

The method of planar flow casting has been used for preparation of single-, bi- and tri-layered ribbons of the two different or the same composition to attain multi-layered ribbons suitable for an application. Prepared bilayer was composed of positively and negatively magnetostrictive layers Fe77.5Si7.5B15/Co72.5Si12.5B15. Other aim was to suppress potentially undesired surface effects of differences between ribbon surfaces and volume. We prepared the ribbons with composition Co47Fe21Mo6.5B21Si4.5 as single layer and trilayer with the thickness ratio more than 3:1. Structural, chemical and magnetic properties in amorphous (as-cast) and crystalline state were investigated. The composition was chosen to obtain low saturation magnetostriction. Nanocrystallization improved soft magnetic properties namely for trilayer. Work proved that reduction of large surface/volume ratio enables to reduce undesired effects of shrinking surfaces that squeeze the small volume of a single ribbon more efficiently.

In addition to surface roughness and shape precision, the subsurface damage (SSD) generated by single point diamond turning (SPDT) of Ge and Si crystal optics is of increasing importance with decreasing wavelength from infrared through visible, UV, and x-ray. There are various components of SSD, e.g., microcracks, dislocations, strain, and a near-surface amorphous layer, and there are also several techniques to evaluate various components of SSD. Cross-sectional transmission electron microscopy (XTEM) is expensive and not often directly used in the optics laboratory. However, because of its very high sensitivity to SSD and down to atomic resolution, it is often used as an external service for developing SPDT technology and other surface processing techniques. It is shown in the paper that improper sample preparation can generate near-surface amorphization. Measures to avoid this artifact and a test of reliability of XTEM sample preparation are proposed. (C) 2018 Optical Society of America

The solidification/melting of water confined in controlled pore glass CPG126 has been studied by differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy. Samples with variable coefficient of filling of water were prepared and analysed. DSC measurements revealed, besides effects related to the melting or freezing point depression of the confined liquid, a shift of freezing peaks towards lower temperatures with decreasing water content and due to the heat treatment. An attempt of interpretation of this effect based on microstructural properties has been made, which is supported also by detected freezing of confined water by homogenous nucleation. Positron annihilation lifetime spectroscopy shows the difference between the bulk and confined water in the global trends of temperature dependence of the ortho-positronium lifetime and also confirms some results of calorimetric measurements connected with the phase transitions.

The presented work describes an effective method for

Amorphous Fe78Sn5B17 ribbons were prepared by planar flow casting. The thermodynamic stability and the kinetics of observed phase transformations were monitored by thermal analysis. The structure and morphology of phases forming upon the thermally activated crystallization is studied by X-ray diffraction and transmission electron microscopy. The crystallization begins by nucleation-and-growth of specific nanocrystalline bcc-Fe(Sn) phase, its structure is explored more in details and the role of Sn in its formation is discussed. In the next step of the crystallization a transformation of remaining amorphous matrix to iron borides runs via rather complex process, which is inspected more in details as well.

The less silicon, the more pronounced is the diversity between surfaces and ribbon interior of non-vacuum annealed Fe–Nb–Cu–B–Si nanocrystalline Finemets. The diversity significantly impacts material's magnetic properties particularly by engaging surface-created macroscopic forces in magnetoelastic interaction. A medium-Si Finemet (10 at%) was investigated using several surface analysis methods and compared to standard Si-rich Finemet. Oxides were detected on the surfaces after non-vacuum annealing. No explicit contiguous oxide layer was revealed. Surface crystallization is considered to be the direct source of the macroscopic forces.

Silica gel with extremely small pores of 3 nm diameter was filled with liquid cetane. Samples with various coefficients of filling k of cetane were prepared. After the solidification of confined cetane, its free volume has been investigated. The positron annihilation lifetime spectroscopy at 24–300 K and differential scanning calorimetry (DSC) at 233–303 K measurements have been performed. Decreasing the temperature, only small changes in dimensions of silica gel matrix and pronounced contraction of confined cetane have been indicated. In the case of k

The solidification/melting of cetane confined in nine silica glasses with specific controlled pores (CPG) with different pore sizes (r p ranging from 3.7–72 nm) has been studied. Samples with variable coefficient of filling of cetane were prepared and analyzed. Combining the indication of the evolving solidification heats (via differential scanning calorimetry, DSC) with the lifetime spectra of positron annihilation, the mechanism of filling of cetane molecules in the pores of the hosting silica glass matrices has been searched. Three independent solidification effects—three independent DSC peaks—were observed in each measuring cycle, namely one crystallization exotherm Rb of the bulk-cetane (if present) and two crystallization sub-peaks Rc1 and Rc2 of the confined cetane in the case of continuous cooling. The temperatures of both Rc1 and Rc2 effects decrease on decreasing the r p of the CPG matrix. The mutual relation between Rc1 and Rc2 has been analyzed. The kinetics of all three steps of the solidification in the continuous-cooling as well as isothermal regimes have been specified.

We present our recent technological achievements in development of the nano-machining of active X-ray crystal optics surfaces. This technique uses a single crystal diamond tool with extremely precise and temperature stabilized positioning system. We can prepare various simple (flat, spherical, cylindrical) as well as more complex free-form surfaces (including aspherical ones). The objective is to prepare high-quality surfaces of the desired shape with sub-nanometer surface roughness and low sub-surface damage of the crystal lattice. The final surface roughness of a flat Ge surface below 0.4 nm (RMS) was achieved for a very slow regime of the processing using feed rates

The eventual competition between the dehydrogenation and oxidation of TiH2 powder in the argon, oxygen, and static air atmospheres has been examined in the regime of linear heating using differential thermal analysis (DTA), X-ray diffraction, transmission and scanning electron microscopy coupled to energy dispersive spectroscopy techniques. Three stages of dehydrogenation, R1, R2, and R3, and two different oxidation reactions, O1 and O2, have been identified. The kinetics of individual reactions has been investigated by the Kissinger and Surinach curve fitting procedures. While the kinetics of O1, O2, and R1 reactions depends on the diffusivities of the external reagent gas, being oxygen, and internal product gas, being hydrogen, the main dehydrogenation stage R2 is controlled by the combined nucleation-and-growth and coalescence kinetics. The effect of pre-annealing of TiH2 on its subsequent degradation has also been studied. Due to the huge overheating accompanying both oxidation reactions in the DTA set-up, substantial thermal losses have been demonstrated and the method to obtain the true heat of oxidation reactions in metals has been described.

Readers should note that there is a phrase missing in the Acknowledgment Section of this article as published

The crystallization process in Fes6(Cu~)ZrTB6 and FesvZr7B6 is .investigated using the methods of transmission electron microscopy, electron and X-ray diffraction and resistrometry. Two crystallization reactions take place during thermal annealing of amorphous Fe86(Cul)ZrvBe and Fes7Zr7B6 alloys. In both alloys the first crystallization begins with the formation of nanocrystalline c~-Fe at temperature to approximately 800 K. The second crystallization starts above 1000 K; the nanocrystalline phase dissolves and together with the remaining amorphous matrix form rough grains of a-Fe and dispersed Fe23Zr6 phases. From M6ssbauer spectroscopy it seems that there exist two neighbourhoods of Fe atoms in the amorphous structure. One of them is characterized by low Zr content and is responsible for the high-field component of the hyperfine field distribution p(H). The second one is rich in Zr and B and is responsible for the low-field component of p(H). This is in accord with the observation of two crystallization steps separated by a large interval of temperatures due to the existence of two chemically different regions or clusters.

Using the methods of X-ray diffraction, transmission electron microscopy and selected area electron diffraction, five finement alloys have been investigated with different chemical compositions: Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 , Fe 72 Cu 1 Nb 4.5 Si 13.5 B 9 , Fe 70.5 Cu 1 Nb 4.5 Si 16 B 8 , Fe 76 Cu 1 Si 13.5 B 9.5 and Fe 74 Nb 3 Si 13.5 B 9.5 . The formation of the crystalline phases has been studied and an attempt has been made to explain the influences of Cu on the crystallization of the nanocrystalline phase.

The kinetics and mechanism of formation of nanocrystalline phase by heat treatment have been studied in amorphous NiP and NiPNb systems with low Nb-content by resistometry, transmision electron microscopy, electron and X-ray diffraction. In NiP alloys no orientation relationship between the forming nanocrystalline Ni3P and γ-Ni has been observed. The addition of niobium into NiP system results in the refinement of the nanocrystalline phase, which, however, is less stable and exhibits a tendency to precrystalization. In systems with 10 at.% Nb-content a major change of the crystallization kinetics is observed and phases containing NbP and NiP are formed.

Structural changes taking place in the course of crystallization in nanocrystalline Fe 73 Cu 1 Nb 3 Si 13.5 B 9.5 and their influence on the initial permeability of the material have been studied as a function of ribbon thickness and thermal treatment. To obtain good magnetic properties it is necessary, as well as keeping the α(FeSi) grains to a suitable size, to ensure the appropriate Cu and Nb content. Inhomogeneous Cu distribution and eventual decrease in its content has been found to cause formation of borides or silicides in regions of Cu depletion, influencing the magnetic properties of the Finemets. It has further been determined that the content of Si in α-Fe is of great importance for the permeability of the Finemets.