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1
Content available remote Electron paramagnetic resonance study of impurities and point defects in oxide crystals
Stefaniuk I.
Opto-Electronics Review
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2018
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Vol. 26, No. 2
81--91
EN
In this topic review the results of the X-band electron paramagnetic resonance (EPR) measurements of Mn, Co, Cr, Fe ions in YAlO₃ (YAP) crystals and Fe ions in LiNbO₃ (LNO) crystals and of chromium doped Bi₁₂GeO₂₀ (BGO) and Ca₄GdO(BO₃)₃ single crystals, are presented. It is well known that the oxide crystals (for example:YAP, LNO, BGO) are one of the most widely used host materials for different optoelectronic applications. The nature of point defect of impurities and produced in the oxide crystal after irradiation by bismuth ions and after irradiation by the ²³⁵U ions with energy 9.47 MeV/u and fluency 5 × 10¹¹ cm⁻¹ is discussed. The latter is important for applications of these oxide crystal as laser materials.
2
Content available remote Magnetic properties of ZnO:Co layers obtained by pulsed laser deposition method
Stefaniuk I., Cieniek B., Rogalska I., Virt I. S., Kościak A.
Materials Science Poland
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2018
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Vol. 36, No. 3
439--444
EN
We have studied magnetic properties of zinc oxide (ZnO) composite doped with Co ions. The samples were obtained by pulsed laser deposition (PLD) method. Electron magnetic resonance (EMR) measurements were carried out and temperature dependence of EMR spectra was obtained. Analysis of temperature dependence of the integral intensity of EMR spectra was carried out using Curie-Weiss law. Reciprocal of susceptibility of an antiferromagnetic (AFM) material shows a discontinuity at the Néel temperature and extrapolation of the linear portion to negative Curie temperature. The results of temperature dependence of EMR spectra for the ZnO:Co sample and linear extrapolation to the Curie-Weiss law indicated the AFM interaction between Co ions characterized by the Néel temperatures TN = 50 K and TN = 160 K for various samples. The obtained g-factor is similar to g-factors of nanocrystals presented in literature, and the results confirm that in the core of these nanocrystals Co was incorporated as Co2+, occupying Zn2+ sites in wurtzite structure of ZnO.
3
Content available Magnetic transformation in Ni-Mn-In Heusler alloy
Kuzma M., Maziarz W, Stefaniuk I.
Nukleonika
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2015
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Vol. 60, No. 3, part 1
435--438
EN
Magnetic properties of a Ni50Mn35.5In14.5 Heusler ribbon were studied by ferromagnetic resonance (FMR) in the temperature range of 335–100 K. In the temperature region of 265–170 K, the FMR signal disappeared, in spite of the fact that this region comprised the main crystal transformation temperatures: Ms, Mf, As, Af. In the austenite crystal state, a weak antiferromagnetic interaction was observed, whereas ferromagnetism was detected in the low temperature martensitic state.
4
Content available EMR study and superposition model analysis of Cr3+ and Fe3+ impurity ions in mullite powders used in aerospace industry
Stefaniuk I., Rogalska I..
Nukleonika
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2015
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Vol. 60, No. 3, part 1
399--403
EN
In this work, the electron magnetic resonance (EMR) spectra of the mullites powders were measured for different grain sizes (0.07 and 0.12 mm). We have used EMR spectroscopy at X-band, combined with superposition model (SPM) calculations to reveal electronic structure and establish correlations between structure, and surroundings of these complexes.
5
Content available Dyson line and modified Dyson line in the EPR measurements
Popovych V., Bester M., Stefaniuk I., Kuzma M.
Nukleonika
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2015
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Vol. 60, No. 3, part 1
385--388
EN
The difficulty in determining the electron paramagnetic resonance (EPR) line parameters of ferromagnetic semiconductors has been addressed. For these materials, the resonance line is very broad and lies at low resonance fi eld, so that only a part of the line can be detected experimentally. Moreover, the line is of asymmetric (Dysonian) shape as described by the line shape parameter α. We have compared values of line parameters derived by computer fi tting of the whole experimental EPR line to the Dyson function (or modified Dyson function) with the values obtained by applying this procedure to the left and the right half of the line.
6
Content available Electron paramagnetic resonance studies of manganese and cobalt ions in YAlO3 crystals
Stefaniuk I., Rogalska I, Suchocki A, Berkowski M., Cieniek B., Potera P.
Optica Applicata
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2014
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Vol. 44, nr 1
113--121
EN
The results of X-band electron paramagnetic resonance measurements of Mn2+ and Mn4+ ions in YAlO3 (YAP) crystals in the temperature range 100–300 K are presented. Additionally, we observe electron paramagnetic resonance spectra of unintentional impurities Fe3+ and Cr3+ in YAP crystals. The angular dependence for Mn ions in YAP crystals can be presented. We aim at obtaining a better insight into the spectroscopic properties of paramagnetic Mn centers and structural information about their nearest environment in YAP host and at determining the valence of manganese ion. In this paper we compare electron paramagnetic resonance spectra for Co and Mn ions in YAP crystals.
7
Content available EPR study of ZnO:Co thin films grown by the PLD method
Cieniek B., Stefaniuk I., Virt I.
Nukleonika
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2013
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Vol. 58, No. 3
359--363
EN
We have studied magnetic properties of zinc-oxide composite doped with a relatively high concentration (4%) of Co ions. Samples were obtained by the pulsed laser deposition (PLD) method with different parameters of the laser ablation. For various samples, the power of laser was changed as well as the temperature of sample heating. Electron paramagnetic resonance (EPR) measurements were carried out and temperature dependence of the EPR spectra was obtained. Analysis of the temperature dependences of the integral intensity of EPR spectra was carried out using the Curie-Weiss law. Fitting yields the following values θCW = 150 K and C = 1.6710, where C is the Curie constant, and θCW is the paramagnetic Curie temperature.
8
Content available EPR measurements of ceramic cores used in the aircraft industry
Stefaniuk I., Rogalska I.., Potera P., Wróbel D.
Nukleonika
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2013
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Vol. 58, No. 3
391--395
EN
In this work the electron paramagnetic resonance (EPR) spectra of Al2O3 and ZrO2 powders were measured for different size of grains (0.074, 0.044 mm) as well as the mullites (0.07 and 0.12 mm). Also were investigated the ceramic cores. The measurements were performed at room temperature and in the temperature range from 140 up to 380 K. The main purpose of this work was to investigate the possible relationships between the EPR spectra and the size of powder grains as well as the identification of EPR spectra in view of the potential application of EPR technique as a fingerprinting method.
9
Content available Computer program superposition model - Monte Carlo (SPM-MC) and its applications in EMR studies of transition ions at low symmetry sites Fe3+ doped YAP crystals
Stefaniuk I., Rudowicz Cz.
Nukleonika
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2013
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Vol. 58, No. 3
397--400
EN
An extension of the computer program superposition model-Monte Carlo (SPM-MC), designed for modelling of the spectroscopic and structural properties of transition ions at low symmetry sites in crystals, is presented. Special focus is put on two aspects. The first aspect concerns the effects of variation of the superposition model (SPM) parameters, i.e. the intrinsic parameters (b2, b4) and power low exponents (t2, t4), on the quality of fittings of experimental data and theoretical predictions. This enables to increase the reliability of the modelling results. The second aspect concerns the implications of low site symmetry on modelling of the pertinent properties. Applications of the program SPM-MC to Fe3+ ions at the triclinic (Ci) symmetry sites in YAlO3 (YAP) crystals are considered.
10
Content available Antioxidant properties of wines produced in the Podkarpacie region
Szterk A., Stefaniuk I., Cieniek B., Kuźma M.
Nukleonika
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2013
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Vol. 58, No. 3
447--450
EN
The wine is famous and popular drink having properties of reactive oxygen species scavenging. In this paper we study the antioxidant activity of the selected wines produced in the south-east region of Poland, in Subcarpathian Voivodeship, in the Podkarpacie region. We have concentrated our studies on the superoxide radical anion O2 •–. We have used electron spin resonance spectroscopy (ESR) as it is the best method for radical detection. The nitrone spin trap α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) has been used in the experiment. The radical scavenging ability of wines were determined from the changing intensity of the spectrum in time.
11
Content available Dependence of the ESR spectra intesity of POBN : O2 adduct on the concentrtions components in non-fenton reaction
Stefaniuk I., Cieniek B., Szterk A., Kuźma M.
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
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2012
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nr 2
34-36
EN
In the paper the trapping of the O2 radical by the nitrone a-(4-pyridyl1-oxide)-N-tert-butylnitrone (POBN) compound was investigated. The O2 radicals were generated by the nonFenton reaction of water solutions of KOH and H2O2 reagents. The ESR spectrum of POBN : O2 adduct can be recorded under carefully selected concentration of components. The best spectra were obtained for 6% KOH and 6% H2O2.
PL
W pracy badano pułapkowanie rodnika O2 przez a-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN). Rodnik O2 generowano w reakcji niefentonowskiej z KOH i H2O2. Widmo ESR adduktu POBN : O2 powstaje po starannym dobraniu stężeń substratów. Najlepsze widmo otrzymuje się dla stężeń 6% KOH i 6% H202.
12
Wielofunkcyjny system komputerowy do współpracy ze spektrometrem EPR
Stefaniuk I., Cieniek B.
Elektronika : konstrukcje, technologie, zastosowania
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2012
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Vol. 53, nr 2
96-99
PL
W pracy opisano wykonanie nowatorskiego sprzęgnięcia komputera ze spektrometrem EPR. Polega ono na bezkonfliktowej pracy systemu z zapisem analogowym na rejestratorze XY, lub z zapisem cyfrowym na komputerze. Możliwy jest także równoczesny zapis na obu systemach. Do zaprogramowania i cyfrowej obróbki sygnału użyto środowisko LabVIEW, które standardowo zawiera wiele procedur poprawiających stosunek sygnału do szumów. Ta modernizacja pozwala na uzyskiwanie znacznie lepszych wyników niż tradycyjne metody, w krótszym czasie, co jest ważne w pomiarach szczególnie w funkcji temperatury. Pomiar temperatury dokonywany jest za pomocą dwóch różnych układów termopar. Wszystkie mierzone wartości są rejestrowane w czasie rzeczywistym z równoczesną wizualizacją widma na ekranie monitorze. System umożliwia cyfrową obróbkę sygnałów już w trakcie trwania pomiarów. Na zmodernizowanym spektrometrze wykonano dużo wartościowych pomiarów, z których część została przedstawiona na międzynarodowych konferencjach i opublikowana.
EN
This paper describes an innovative implementation of a computer connection with an EPR spectrometer. It's a conflict-free system for recording to an analog XY recorder, or with digital recording on a computer. There is also a possibility to simultaneously record on both systems. Lab VIEW environment was used in the area of programming and digital signal processing, which typically includes many procedures to improve the signal-to-noise ratio. This upgrade allows obtaining much better results than traditional methods in less time, which is especially important in measurements as a function of temperature. Measurements of temperature were performed using two different thermocouple. AU measured values are recorded in real time with simultaneous visualization of the spectrum on the screen. The system enables digital signal processing during the measurements. Using a modernised spectrometer, a lot of valuable measurements were made, some of which were been presented at international conferences and already published.
13
Content available remote Modelowanie pola temperaturowego w stali SW7M podczas laserowego hartowania
Kuźma M., Wasińska T., Stefaniuk I., Bylica A.
Krzepnięcie Metali i Stopów
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1998
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nr 36
201--207
PL
W oparciu o liniowy model źródła ciepła obliczono przestrzenne i czasowe rozkłady temperatur w stali SW7M hartowanej z przetopieniem laserem CO2 o pracy ciągłej.
14
Content available remote Badania rentgenograficzne stali SK5MC po obróbce laserowej
Polit J., Stefaniuk I., Bylica A.
Krzepnięcie Metali i Stopów
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1998
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nr 36
295--300
PL
W pracy przedstawiono wyniki analizy rentgenowskiej stali SK5MC poddanej obróbce laserowej oraz odpuszczaniu. Stwierdzono występowanie węglików typu M6C, M7C3, MC, faz typu FeCrMo, CoMoSi, a także węglików chromu Cr7C3.
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