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Herein, we investigate silicate-phosphate glasses from the SiO2–P2O5–K2O–MgO–SO3 system enriched with various amounts of sulfur, as a nutrient indispensable for the proper development of plants, in order to gain a profound understanding of the structure of such materials. An inherent capability of glasses from the studied system to incorporate sulfate groups into the vitreous matrix was discussed on the basics of the results from XRF, XRD and internal Al2O3 standard techniques. It has been found, that as much as 3 mol.% of SO3 can be loaded into the glass batches to obtain fully amorphous material, while beyond this limit K2SO4 crystallizes within the matrix. Comprehensive spectroscopic investigation, comprising Raman, Middle Infrared (MIR), 29Si and 31P MAS-NMR, X-ray absorption spectroscopy (XANES and XAS) techniques, has been implemented in order to determine an impact of sulfur on silicate-phosphate glass framework. On this basics, it has been concluded, that sulfur exists in the vitreous matrix in the form of specific domains, in which [SO4]2- anions are surrounded by the shell of charge-compensating K+ cations. Such sulfate groupings maintain their individuality without direct bonding to silico-oxygen or phospho-oxygen subnetwork. Spectroscopic results revealed also, that the presence of sulfur affects silico-oxygen subnetwork to a significantly greater extent than the phospho-oxygen one. It has been demonstrated, that along with SO3 addition, the more polymerized Q S i 3 units increase in abundance at the expense of less polymerized Q S i 2 groups. Results of the present study are believed to contribute to a greater understanding of the nature of sulfur-bearing oxide glasses.

The spectroscopy using synchrotron radiation is the advanced tool for materials characterization. In the current work we are reporting recent activity in this research field implemented at the 04BM (PEEM/XAS) beamline of the National Synchrotron Radiation Centre SOLARIS in Krakow, Poland. The beamline is designed to cover wide energy range of soft X-rays, which is well suited for a broad range of applications, including surface physics, material science and magnetism. The comparison of the experimental parameters and selected examples of the results achieved on the PEEM and XAS end stations is demonstrated.

A new X-ray absorption spectroscopy (XAS) beamline is currently under construction at a bending magnet of the National Synchrotron Radiation Centre SOLARIS. The front end of this beamline was installed in April 2020. This beamline has a few outstanding characteristic features: The monochromator is a fixed exit beam Lemmonier type monochromator allowing to cover the pursued energy range (1 keV to ~15 keV) with 3 sets of crystals: KAP (100) + multilayer, InSb (111) and Ge (220). The monochromator is a high vacuum system allowing the change of crystals in less than an hour. In order to minimize absorption of photons no windows will be installed in the beamline down to the monochromator, and just one thin polypropylene window will be used for separating the vacuum of the monochromator from the ionization chambers and the sample chamber. A special differential ion pump will be installed to maintain the pressure difference of four orders of magnitude between the storage ring and the monochromator. As SOLARIS is a low energy machine, the beamline can be built without any radiation safety hutches without exceeding the strict low radiation safety levels. The straightforward design of the beamline without additional optical elements, its compact overall dimensions and an easy to handle monochromator make this beamline especially user friendly. In combination with the characteristics of the 1.5 GeV SOLARIS storage ring this beamline will be specifically attractive for the tender X-ray range, i.e. the K-edges of important elements such as P, S, Si, Al and Mg.

Virgin and Yb-implanted epitaxial ZnO films grown using atomic layer deposition (ALD) were investigated by X-ray absorption spectroscopy (XAS). XAS study revealed a strong polarization dependence of films determined by the orientation of the polarization vector of the synchrotron radiation to the sample surface. It also indicated that the implantation and subsequent annealing have an important influence on the native point defect complexes in the ZnO. Comparison of experimental spectra with the modelled ones, which are computed based on the linear combination of model spectra corresponding to the selected point defects and their complexes, confirmed the presence of donor-acceptor complexes (mVZn - nVO, m = 1,4; n = 1,2) in the samples under study. The mechanism of vacancy complexes formation is unclear as it takes place under non-equilibrium conditions, for which any theoretical method has not been well established. Exploring the 3 d → 4 f absorption, it was found that oxidation state of Yb in ZnO is 3+, which is consistent with the XPS findings and previously conducted Resonant Photoemission Spectroscopy (RPES) investigations. The inversion of the polarization dependence for samples with different Yb fluences visible in Yb M5 spectra can be associated with a tilt of the oxygen pseudo octahedra or/and with their distortion. The analysis of the presented data suggests that the donor-acceptor complexes are present both in as grown and implanted films and may influence their electrical properties. This suggestion was confirmed by previous Hall measurements showing that the resistivity of annealed ZnO:Yb film with a fluence of 5e15 ions/cm2 decreases by about one order compared to the one with a fluence of 5e14 ions/cm2.

We report on exchange bias and interfacial antiferromagnetic spin orientation in epitaxial CoO(111)/Fe(110) bilayers. Our X-ray magnetic linear dichroism and magneto-optic Kerr effect results show that exchange bias sets on in the zero-field-cooled system and is governed by in-plane magnetic state Fe(110) sublayer above Neel temperature of CoO. Uniaxial magnetic anisotropy of Fe layer determines the direction of interfacial frozen antiferromagnetic CoO spins within CoO(111)//Fe(110) sample plane. Choice of the particular magnetic state of Fe sublayer, when passing Neel temperature of CoO, determines both the axis and direction of interfacial antiferromagnetic spins after the sample is cooled and allows for imprinting their +/- 90° and 0/180° alignment within the sample plane.

An attempt is undertaken to chemically modify YMnO3+δ by the partial substitution of Y with larger Nd and Sm, aiming to boost the oxygen storage performance in the temperature swing process. Single-phase (P63cm) Y0.95Nd0.05MnO3+δ and Y0.95Sm0.05MnO3+δ compounds are obtained in a sol-gel auto-combustion process followed by the annealing at 1000 °C in Ar. Both materials show improved oxygen storage capacity, however, doping with Nd3+ enables the effective operation in air – capacity reached 1453 μmol-O g−1, which is over 86% of the capacity in O2. As documented for the Nd-containing sample, oxygen absorption is accompanied by oxidation of Mn3+ to Mn4+, and no changes in the valence of neodymium occur. The reversible oxygen intake and release occur at exceptionally low temperatures for Y0.95Nd0.05MnO3+δ, as low as in the 201–240 °C range. This enables utilization of the recovery of low- and medium-temperature waste heat. In addition, the paper presents the impact of the preparation route of the material on the oxygen storage-related performance. It is shown that lowering of the annealing temperature allows to further increase the rate of O2 absorption, making the material a promising candidate for practical application, however, it results also in the presence of the secondary phases. © 2021 The Authors

Solaris is a third generation light source built and commissioned at the Jagiellonian University in Krakow. It is a replica of the MAX IV 1.5 GeV storage ring and part of its injector. The commissioning of the storage ring started in May 2015. First light at the bending magnet beamline front end was observed after two weeks of optimisation. After one year of commissioning excellent performance of the Solaris synchrotron has been achieved. Injection into the storage ring occurs at the designed electron energy of 525 MeV, next the beam is ramped to the final energy of 1.5 GeV. Beam optics has been adjusted to be close to the design one. Solaris is operating at a working point of (11.22, 3.15) and with a corrected chromaticity of (+0.93, +0.91). Recently over 600 mA of beam current was stored for injection energy. The vacuum system of the storage ring is still being conditioned. After about 90 A.h of beam cleaning dose the total beam lifetime at 100 mA is approaching 11 h at 1.5 GeV. So far two beamlines have been constructed. The UV angle-resolved photoemission spectroscopy (UARPES) beamline with a photon energy range from 8 eV to 100 eV, is in commissioning since April 2016 and the soft X-ray spectroscopy dedicated PEEM/XAS beamline from a bending magnet source, which is at the end of its installation phase. This paper reports on the current status of the Solaris facility and the commissioning results.

Suppressed immune status facilitates immune escape mechanisms that allow chronic lymphocytic leukemia cells to proliferate and expand. The expression of HLA-G could effectively inhibit the immune response. In immune response inhibitory signals follow activation of immune system which might be occur during bacterial or viral infection in CLL patients. In the current study we characterized two components of immune system, inhibitory molecule HLA-G with its receptor - CD85j and Toll-like receptor 9. The material was obtained from 41 CLL patients and 41 HV with similar median age. In CLL patients expression of intracellular and surface HLA-G and soluble HLA-G levels were significantly higher than in HV. We found higher expression of CD85j compared to HV and the positive correlation between expression of HLA-G and CD85j. All the CLL cells expressed TLR-9, and the level of expression positively correlated with expression of HLA-G and CD85j. Patients with higher expression of intracellular expression of TLR-9 have significantly longer treatment-free survival than patients with low expression of TLR-9 (57 months vs. 8 months, respectively). Summarizing in CLL we characterized activatory and inhibitory components of immune system that might be connected functionally. Analysis of TLR-9 expression might have additional prognostic value for CLL patients.

The first Polish synchrotron radiation facility Solaris is being built at the Jagiellonian University in Krakow. The project was approved for construction in February 2010 using European Union structural funds. The Solaris synchrotron is based on the 1.5 GeV facility being built for the MAX IV project at Lund University in Sweden. A general description of the facility is given together with a status of its implementation. The specific Solaris solutions taken for the linear accelerator, beamlines and civil engineering infrastructure are outlined.

GaN epilayers were grown by metalorganic chemical vapor deposition (MOCVD) on c -, m -, a -, and (20.1)-plane GaN substrates obtained by the ammonothermal method. The influence of (i) the surface preparation of substrates, (ii) MOCVD growth parameters, and (iii) the crystallographic orientation of substrates on the structural and optical properties of GaN epilayers was investigated and carefully analyzed. It was observed that the polishing of substrates and their misorientation have strong impact on the quality of GaN epilayers grown on these substrates. The MOCVD growth process was optimized for epilayers grown on m -plane GaN substrates. The best structural and optical properties were achieved for epilayers deposited at 1075 °C and the total reactor pressure of 50 mbar. These conditions were applied to grow GaN epilayers on substrates with other ( c -, a -, and (20.1)-plane) crystallographic orientations in the same MOCVD process. Particularly good optical properties were obtained for GaN epilayers deposited on polar and non-polar ( m - and a -plane) substrates, whereas slightly worse optical properties were observed for epilayers deposited on the semi-polar substrate. It therefore means that MOCVD growth conditions optimized for a given crystallographic direction ( m -plane direction in this case) work rather well also for other crystallographic directions.

The electronic and magnetic properties of epitaxial Fe 3 O 4 (001) films on MgO(100) substrates were studied throughout the 2.5- to 30-nm thickness range using conversion electron Mossbauer spectroscopy. Despite the superparamagnetism that was observed for film thickness below 5 nm, the Verwey transition persisted even for the thinnest film. Temperature-dependent Mossbauer measurements between 80 K and 400 K revealed that the activation energy for the magnetic moment fluctuations in the 3-nm magnetite film is higher than the magnetic anisotropy energy by an order of magnitude.

In this paper we present progress made recently in the development of the growth of truly bulk GaN crystals by the ammonothermal method in basic environment. High quality 2-in c-plane GaN seeds are shown. Non-polar wafers can also be cut out from thick GaN crystals grown by ammonothermal method. Perfect crystallinity manifests in very narrow peaks in X-ray rocking curves (the full width at half maximum equals about 15 arcsec). GaN epilayers deposited on these substrates exhibit intrinsic narrow exciton lines, which are very sensitive to the optical selection rules typical for hexagonal symmetry, proving the truly non-polar character of such AMMONO-GaN substrates. Other challenges like homogenous insulating properties or high p-type conductivity have been also accomplished by means of ammonothermal method. Semi-insulating crystals of resistivity up to 1011 Ω cm and p-type conductivity within hole concentration up to 1018 cm−3 are already available in diameters up to 1.5-in.

We have applied positron annihilation spectroscopy to study in-grown vacancy defects in bulk GaN crystals grown by the ammonothermal method. We observe a high concentration of Ga vacancy related defects in n-type samples in spite of the low growth temperature, suggesting that oxygen impurities promote the formation of vacancies also through other mechanisms than a mere reduction of thermodynamical formation enthalpy. On the other hand, no positron trapping at vacancy defects is observed in Mg-doped p-type samples, as expected when the Fermi level is close to the valence band and intrinsic defects are dominantly positively charged. Annealing of the samples at temperatures well above the growth temperature is found to change significantly the defect structure of the material.

We used nuclear hyperfine spectroscopies and a 57 Fe probe layer approach to study the depth-dependent magnetic properties of ultrathin Fe films on NiO(0 0 1), a system exhibiting exchange bias. Conversion electron Mossbauer spectroscopy and nuclear resonance scattering of synchrotron radiation were employed. The samples were two Fe films with a thickness (8–10 ML) slightly above the critical thickness for the onset of ferromagnetism at room temperature, in which a 2 ML-thick probe layer, enriched in the 57 Fe Mossbauer isotope, was embedded at different depths from the Fe/NiO interface. Both techniques indicate that inside the film Fe has a metallic character, while at the interface with NiO different Fe phases are present. The main conclusion is that already a few monolayers from the interface with NiO the magnetic properties of Fe are bulk-like.

Epitaxial Fe3O4(0 0 1) thin films (with a thickness in the range of 10–20 nm) grown on MgO substrates were characterized using low-energy electron diffraction (LEED), conversion electron Mossbauer spectroscopy (CEMS) and investigated using Rutherford backscattering spectrometry (RBS), channeling (RBS-C) experiments and X-ray reflectometry (XRR). The Mg out-diffusion from the MgO substrate into the film was observed for the directly-deposited Fe3O4/MgO(0 0 1) films. For the Fe3O4/Fe/MgO(0 0 1) films, the Mg diffusion was prevented by the Fe layer and the surface layer is always a pure Fe3O4 layer. Annealing and ion beam mixing induced a very large interface zone having a spinel and/or wustite formula in the Fe3O4-on-Fe film system.

The interface reactions in an epitaxial 10 nm-thick Fe3O4/MgO(0 0 1) film were investigated by using Rutherford Backscattering spectrometry (RBS), channeling (RBS-C) and X-ray reflectometry (XRR). The as-grown film had a good crystallinity indicated by the minimum yield and the half-angle value for Fe, respectively, χmin(Fe) = 22% and ψ1/2(Fe) = 0.62°. Annealing the films under partial argon pressure up to 600 °C led to a large enhancement of Mg out-diffusion into the film forming a wustite-type phase, but the total layer thickness did not change much. Ion irradiation of the film by 1 MeV Ar ion beam caused a strong Fe ion mixing resulting in a large interfacial zone with a thickness of 23 nm.

Epitaxially-grown Fe3O4(0 0 1) thin films by reactive deposition on MgO(1 0 0) substrates were studied using low-energy electron diffraction (LEED), conversion electron Mossbauer spectroscopy (CEMS), Rutherford backscattering spectrometry (RBS), channeling (RBS-C) experiments and X-ray reflectometry (XRR). No visible influence from the ion irradiation of the samples on the CEMS spectra was found, while surface oxidation of the samples was observed after exposure to the atmospheric pressure. RBS analysis indicated the presence of magnesium with an average amount of 3% in the films. RBS-C experiments yielded a value of 22% for the minimum yield of Fe and a value of 0.62° for the half-angle for Fe in the film indicating a good crystal quality of the films. The value for film-thickness obtained from XRR is in a good agreement with that from RBS and the nominal value.

The initial growth and influence of annealing on structural and magnetic properties of 5 monolayers epitaxial Fe films on cleaved and polished MgO(0 0 1) substrates was studied using conversion electron Mossbauer spectroscopy (CEMS). Broadening of LEED spots indi- cated a granular structure of the films grown at room temperature. The CEMS analysis showed that the film on the cleaved substrate is flat and consists of a 2 ML interfacial layer with the electronic structure affected by the oxidic substrate, while the remaining 3 ML are metallic with the Curie temperature below RT. Annealing changes the film structure, as seen by CEMS, but only for temperatures above 550 K. In the annealing process the continuous film breaks into 3-dimensional islands and oxidation takes place at the Fe/cleaved-MgO interface. On the polished substrate, the as-prepared film consists of small superparamagnetic metallic iron particles. Contrary to the cleaved substrate, no oxidation is observed at the interface upon annealing. � 2007 Elsevier B.V. All rights reserved.

We investigated changes in the magnetic properties of a single Fe monolayer on Au(0 0 1) induced by the interlayer exchange coupling (IEC) to FeAu monoatomic superlattices. The grazing incidence nuclear resonant scattering of X-rays (GI-NRS) combined with the 57 Fe probe layer concept allowed us to selectively monitor the local structure and magnetism of the Fe(0 0 1) monolayer in a coupled state. The dependence of the monolayer hyperfine parameters on temperature and spacer thickness was determined from the fitted GI-NRS time spectra, collected for the selected thickness of the stepped Au spacer. The influence of the coupling on the hyperfine magnetic field B HF was negligible at temperatures much lower than T C of the uncoupled Fe monolayer ( T C = 210 K as checked by MOKE). The analysis of the time-spectra accumulated at 200 K showed a non-monotonous dependence of the average B HF as a function of the spacer thickness, related to IEC oscillations. The maximum influence of IEC on B HF (13 T) was found for the 4 ML Au spacer.

The valence band photoemission spectra of epitaxially grown 300 Ǻ single crystalline magnetite films were measured by the angle-resolved ultraviolet photoemission spectroscopy (ARUPS) at 300 K. The samples were grown either on MgO(0 0 1) (B termination) or on (0 0 1) Fe (iron-rich A termination), thus intentionally presenting different surface stoichiometry, i.e. also different surface electronic states. Four main features of the electron photoemission at about −1.0, −3.0, −5.5 and −10.0 eV below a chemical potential show systematic differences for two terminations; this difference depends on the electron outgoing angle. Our studies confirm sensitivity of angle resolved PES technique on subtleties of surface states.