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In this work we present the optical and structural characteristics of ZnO/MgO short period superlattices grown on c-plane ZnO. The structures were composed on 80 pairs of ZnO/MgO thin layers. Rutherford backscattering allowed to estimate the real thickness of the structures and compare them with the intended one. The thicknesses differed from growth to growth and they were on the order of 1 nm ZnO to 1-1.5 nm MgO. The thickness of MgO layers was crucial for the growth mode and resulting quality of the structures. Channeling measurement revealed that in the case of the thinnest MgO layers the growth of superlattices was coherent, as χmin of the backscattering yield for the superlattice is the same as for ZnO substrate. This very good crystalline quality was also reflected in photoluminescence (PL) measurements, which revealed PL typical of superlattice. However, the PL of some structures showed that ZnMgO alloy was formed instead of the superlattice. PL excitation spectra allowed to determine the band gap values of the ZnO/MgO structures by observation of the PL from the ZnO substrate. Reasons for it are discussed. Transmission Electron Microscope imaging allows to compare both types of structures. Acknowledgements. The work was supported by the NCN project DEC-2014/15/B/ST3/04105 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE).

High-quality ZnO epitaxial layers deposited by Atomic Layer Deposition were implanted at room temperature with 150 keV Pr3+ions to fluence of 1x1015 and 2x1015. Two different types of annealing on as implanted samples were performed: rapid thermal annealing (RTA) and flash lamp annealing (FLA). Crystalline quality, damage recovery and Yb lattice site location were evaluated by the Channeling Rutherford Backscattering Spectrometry (RBS/c). The optical properties were studied by photoluminescence (PL). Upon annealing defects recovery has been observed. After RTA the return of Zn atoms to their substitutional sites produces displacement RE atoms into interstitial positions. The increase of RTA temperature and time leads to enhanced out-diffusion of RE atoms. Consequently, better recovery of the crystal structure is accompanied by lower photoluminescence (PL) efficiency. The FLA precludes the RE-atom surface segregation. The substitutional fraction of Pr ions is higher than after RTA with the same structure recovery, but PL intensity from Pr3+ is lower. This suggests that the substitutional RE atoms are preferentially in the 2+ state. Acknowledgments: The work was supported by the NCBiR (Poland) project PBS2/A5/34/2013 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE), by the Polish Ministry of Science and Higher Education (3418/SPIRIT/2015/0) and by the Helmholtz Zentrum Dresden-Rossendorf (HZDR) in a frame of the program Access to Infrastructure (15100222-ST and 16000696-ST).

ZnO epitaxial layers deposited by Atomic Layer Deposition were implanted with Yb ions to a fluence of 1x1016 at./cm2 at energy of 150 keV. Different types of annealing (in oxygen or ambient atmosphere) of ZnO:Yb samples have been performed: millisecond range flash lamp annealing (FLA), rapid thermal annealing (RTA) up to 30 min. and tube furnace annealing (TFA) up to 1 h at 800oC. It was found that the optical properties of ZnO:Yb films are strongly affected by the annealing time. According to Rutherford Backscattering and channeling (RBS/c) the annealing of implanted films leads to a partial recovery of the crystal lattice. The photoluminescence (PL) spectra in combination with RBS/c reveal that the worse reconstruction of lattice and reduction of the fraction of substitutional Yb ions results in more intense emission around 0.98 µm in case of RTA and TFA annealing. Surprisingly, the FLA annealing has shown very good result in terms of PL intensity at RT as a thermal quenching effect is much weaker in this case. The RBS/c and PL results lead to a conclusion that RTA and FTA annealing promotes cluster formation and outdiffusion of Yb while FLA suppresses it. Acknowledgements. The work was supported by the NCBiR (Poland) through the project PBS2/A5/34/2013 and by the EU 7th FP project REGPOT-CT-2013-316014 (EAgLE). It was also co-financed by Helmholtz Zentrum Dresden-Rossendorf (HZDR) in the frame of the program Access to Infrastructure (15100222-ST).

This work presents the results of investigation of microwave heating on hardening process of water glass molding sands. Essential influence of this heating process on basic properties such as: compression, bending and tensile strength as well as permeability and abrasion resistance has been found. It has been proved, that all investigated sorts of sodium water glass with a module between 2.0 and 3.3 can be used as a binder of molding sands in microwave curing process. It has been found during analysis of research results of sands with 2.5 % water glass addition that they are practically the same as in case of identical molding sands dried for 120 minutes at the temperature of 110°C, used for comparative purposes. Application of microwave curing of molding sands with water glass, however, guarantees reduction of hardening time (from 120 to 4 minutes) as well as significant reduction of energy consumption. Attempts of two stage hardening of the investigated water glass molding sands have also been carried out, that is after an initial hardening during a classical CO2 process (identical sands have also been tested for comparison after CO2 blowing process) and additional microwave heating. It has been found that application of this kind of treatment for curing sands with 2.5 % sodium water glass content and module from 2.0 up to 3.3 results in the improvement of properties in comparison to classical CO2 process.

The subject-matter of the paper covers a very topical problem of possible restriction of shortcomings like poor knocking-out properties of castings and hard reclaimability of this type sandmixes by proper selecting their components and using innovative microwave heating. It was proved that the sandmixes subject to quick dielectric process of drying/hardening show significantly lower residual strength, which gives this method priority over traditional energy-consuming processes of casting core manufacture.

Complex systems, simulating natural conditions like in groundwater, have rarely been studied, since measuring and in particular, modeling of such systems is very challenging. In this paper, the adsorption of the oxyanions of As(III) and As(V) on goethite has been studied in presence of various inorganic macro-elements (Mg2+, Ca2+, PO3¿4, CO2¿3). We have used `single-,¿ `dual-,¿ and `triple-ion¿ systems. The presence of Ca2+ and Mg2+ has no significant effect on As(III) oxyanion (arsenite) adsorption in the pH range relevant for natural groundwater (pH 5¿9). In contrast, both Ca2+ and Mg2+ promote the adsorption of PO3¿4. A similar (electrostatic) effect is expected for the Ca2+ and Mg2+ interaction with As(V) oxyanions (arsenate). Phosphate is a major competitor for arsenate as well as arsenite. Although carbonate may act as competitor for both types of As oxyanions, the presence of significant concentrations of phosphate makes the interaction of (bi)carbonate insignificant. The data have been modeled with the charge distribution (CD) model in combination with the extended Stern model option. In the modeling, independently calculated CD values were used for the oxyanions. The CD values for these complexes have been obtained from a bond valence interpretation of MO/DFT (molecular orbital/density functional theory) optimized geometries. The affinity constants (logK) have been found by calibrating the model on data from `single-ion¿ systems. The parameters are used to predict the ion adsorption behavior in the multi-component systems. The thus calibrated model is able to predict successfully the ion concentrations in the mixed 2- and 3-component systems as a function of pH and loading. From a practical perspective, data as well as calculations show the dominance of phosphate in regulating the As concentrations. Arsenite (As(OH)3) is often less strongly bound than arsenate (AsO3¿4) but arsenite responses less strongly to changes in the phosphate concentration compared to arsenate, i.e., ¿logcAs(III)/¿logc(PO4)¿0.4 and ¿logcAs(V)/¿logc(PO4)¿0.9 at pH 7. Therefore, the response of As in a sediment on a change in redox conditions will be variable and will depend on the phosphate concentration level.

Arsenic in groundwater has generated one of the most important problems with respect to the quality of drinking water in the modern world. The aim of this thesis has been to assess, as good as possible for the present state of the art, the factors and processes that govern the arsenic behavior in contaminated aquifers. The research tactics have included 3 sequential steps: (1) obtaining adsorption datasets for systems simulating relevant groundwater field situations; (2) interpretation of these data with a molecular based adsorption model and the model application to predict the adsorption behavior of arsenic for a range of compositions relevant in the field; (3) providing quantitative understanding of the behavior of arsenic in natural waters. This knowledge may contribute to a better understanding of the problem, the long-term solutions, such as an optimization of treatment techniques for drinking water as well as a methodology to guide the positioning of new arsenic-free wells