Wyniki wyszukiwania - Biblioteka Nauki

1

Interaction of the Components in Li-V-Sn System at 470 K

100%

Azarska O. , Pavlyuk V.

Polish Journal of Chemistry

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2003

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tom Vol. 77 / nr 8

1027-1031

EN

The isothermal section of the Li-V-Sn system at 470 K has been investigated by X-ray phase analysis. There is an unmixing region, which extends at ternary system to about 12 at. % of Sn. Two ternary phases Li11V3Sn4 and ~LiV2Sn and solid solutions based on the binary compounds were obtained. Crystal structures were determined for both ternary phases: Li11V3Sn4 is a superstructure to Li13Sn5 binary compound, and LiV2Sn crystallizes in a BiF3 structure type. The solubility of the third component in the binary compounds is less than 10 at. %.

2

Determination of hyperfine fields and atomic ordering in NiMnFeGe exhibiting martensitic transformation

80%

Satuła D. , Szymański D. , Rećko K. , Olszewski W. , Kalska-Szostko B.

Nukleonika

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2015

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tom Vol. 60, No. 1

127--131

EN

The hyperfi ne fi elds and atomic ordering in Ni1−xFexMnGe (x = 0.1, 0.2, 0.3) alloys were investigated using X-ray diffraction and Mössbauer spectroscopy at room temperature. The X-ray diffraction measurements show that the samples with x = 0.2, 0.3 crystallized in the hexagonal Ni2In-type of structure, whereas in the sample with x = 0.1, the coexistence of two phases, Ni2In- and orthorhombic TiNiSi-type of structures, were found. The Mössbauer spectra measured with x = 0.2, 0.3 show three doublets with different values of isomer shift (IS) and quadrupole splitting (QS) related to three different local surroundings of Fe atoms in the hexagonal Ni2In-type structure. It was shown that Fe atoms in the hexagonal Ni2In-type structure of as-cast Ni1−xFexMnGe alloys are preferentially located in Ni sites and small amount of Fe is located in Mn and probably in Ge sites. The spectrum for x = 0.1 shows the doublets in the central part of spectrum and a broad sextet. The doublets originate from the Fe atoms in the paramagnetic state of hexagonal Ni2In-type structure, whereas the sextet results from the Fe atoms in orthorhombic TiNiSi-type structure.

3

PbS nanopowder – synthesis, characterization and antimicrobial activity

80%

Suganya M. , Balu A. R.

Materials Science Poland

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2017

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tom Vol. 35, No. 2

322--328

EN

Lead sulphide (PbS) nanopowder was synthesized by a simple soft chemical route using lead nitrate and thiourea as precursor salts. The as-synthesized nanopowder was characterized by XRD, SEM, EDX, FT-IR, PL, Raman and magnetic measurements. XRD studies reveal the polycrystalline nature of the powder. The powder exhibits face-centered cubic structure with a strong (2 0 0) preferential orientation. The presence of Pb and S in the powder is confirmed by energy dispersive X-ray analysis. The peaks observed at 1112 cm-1 and at 606 cm-1 in the FT-IR spectrum are related to heteropolar diatomic molecules of PbS. The Raman peak shift at 173 cm-1 might have originated from the combination of longitudinal and transverse acoustic phonon modes associated with PbS crystal. The M-H loop confirms the paramagnetic nature of the as-synthesized PbS nanopowder. The nanopowder has significant antimicrobial activity against certain bacteria and fungi strains which make it suitable as antimicrobial agent against pathogenic microorganisms.

4

Intermetallic phase identification on the cast and heat treated 6082 aluminium alloy

80%

Mrówka-Nowotnik G. , Sieniawski J. , Nowotnik A.

Archives of Metallurgy and Materials

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2006

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tom Vol. 51, iss. 4

599-603

EN

In the technical 6xxx Al alloys besides the intentional additions Mg and Si transition metals and impurities (Fe and Mn) are always present. Even not large amount of these impurities causes the formation a new phase components: Al-Fe, Al-Fe-Si and Al-Fe-Mn-Si. During casting of 6xxx alloys, a wide variety of Fe-containing complex intermetallic phases, i.e.: Β-Al5FeSi, α-Al15(FeMn)3Si), Al9Mn3Si and Mg2Si, are formed among the dendrite arms of α-Al solid solution. These intermetallics have different unit cell structures, morphologies, stabilities and physical properties depending on chemical composition and cooling conditions. Thus, these affects very much the mechanical properties of an alloy. In this study, several methods were used such as: optical light microscopy (LOM), transmission (TEM) and scanning (SEM) electron microscopy in combination with electron dispersive X-ray (EDX) using polished sample, and X-ray diffraction (XRD) to identify chemical composition and morphologies of the phase components in both as-cast and heat treated 6082 alloy.

PL

W technicznych stopach aluminium grupy 6xxx obok podstawowych pierwiastków stopowych Mg i Si występują zawsze metale przejściowe oraz zanieczyszczenia przede wszystkim Fe i Mn. Mała ich zawartość powoduje już powstanie odrębnych faz międzymetalicznych Al-Fe, Al-Fe-Si oraz Al-Fe-Mn-Si. Ustalono, że podczas krzepnięcia stopów 6xxx tworzą się, w przestrzeniach międzydendrytycznych roztworu stałego α-Al, wydzielenia złożonych faz międzymetalicznych: Β-Al5FeSi, α-Al15(FeMn)3Si), Al9Mn3Si i Mg2Si. W zależności od składu chemicznego oraz warunków chłodzenia zmienia się ich struktura, morfologia a także właściwości fizyczne, a to z kolei silnie wpływa na właściwosci mechaniczne stopów. W pracy podjęto próbę identyfikacji faz międzymetalicznych występujących w stopie aluminium 6082. Zastosowano różne techniki badawcze (mikroskopia świetlna, transmisyjna mikroskopia elektronowa (TEM), elektronowa mikroskopia skaningowa z dyspersją energii promieniowania rentgenowskiego (SEM/EDX) oraz rentgenografia XRD), które umożliwiły określenie zmiany składu chemicznego i morfologii składników fazowych stopu w stanie lanym oraz po obróbce cieplnej.

5

The Structure and Magnetocaloric Effect of MnCoGe Alloy Modified by Nb

80%

Kutynia K. , Gębara P. , Przybył A.

Archives of Metallurgy and Materials

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2022

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tom Vol. 67, iss. 3

879--883

EN

The aim of this work was to investigate the effect of partial substitution of Mn by Nb on structure and thermomagnetic properties in the (Mn, Nb)-Co-Ge alloy. The master alloys were prepared by arc-melting in an arc furnace with high purity of constituent elements under a low pressure of Ar. The prepared specimens were studied in as-cast state. The X-ray was performed by BRUKER D8 Advance diffractrometer with Cu Kα radiation. The analysis of the XRD pattern revealed coexistence of two orthorhombic phases with different lattice constants. The analysis of the temperature dependence of magnetizaton confirmed the XRD results and showed that produced material manifested two magnetic phase transitions corresponding to detected phases. The values of the Curie temperature were 275 and 325 K. The values of magnetic entropy change ∆SM equaled 3.30 and 2.13 J/(kg K), respectively for recognized phases. Biphase structure of produced material allowed to reach relatively high refigeration capacity 307 J/(kg). Moreover, the analysis of field dependences of magnetic entropy change (∆SM = CBn) allowed to construct temperature dependence of exponent n. The analysis of elaborated n vs. T curve confirmed biphasic structure of produced material.

6

Structural and dielectric properties of La substituted polycrystalline Ca(Ti0.5Fe0.5)O3

80%

Shah M. R. , Akther Hossain A. K. M.

Materials Science Poland

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2013

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tom Vol. 31, No. 1

80-87

EN

Polycrystalline Ca1xLax(Ti0:5Fe0:5)O3 were prepared by the standard solid state reaction technique. Pellet shaped samples prepared from each composition were sintered at 1573 K for 5 h. The X-ray diffraction analysis indicated the formation of a single-phase orthorhombic structure. The lattice parameters as well as densities increased but the average grain sizes decreased with the increase of La content. The dielectric measurements were carried out at room temperature as a function of frequency and composition. The experimental results revealed that dielectric constant (e0) decreased but dielectric loss (tand) and ac electrical conductivity (sac) increased as frequency increased. The composition dependence of e0 and tand indicated that they decreased with the increase of La content. The sac was derived from the dielectric measurements and it is concluded that the conduction in the present samples is due to mixed polarons hopping.

7

57Fe Mössbauer spectroscopy and X-ray diffraction study of gadolinites REE2Fe2+Be2Si2O10 from Lower Silesia (Poland) and Ytterby (Sweden)

80%

Malczewski D.

Nukleonika

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2003

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tom Vol. 48,suppl.1

41-44

EN

This paper reports the results of 57Fe Mössbauer spectroscopy, X-ray diffraction (XRD) and gamma-ray spectroscopy studies of partially metamict gadolinites from Szklarska Poręba and Zimnik (Lower Silesia, Poland), a fully metamict gadolinite sample from Ytterby (Sweden) and a crystalline sample obtained after annealing of a fragment of the sample from Ytterby at 1373 K in an argon atmosphere. Both fully metamict and crystalline gadolinite show divalent iron exclusively in octahedral coordination. Changes of the amplitudes ratio of high energy to low energy absorption peaks from Fe2+ quadrupole doublets are strictly correlated with calculated absorbed alpha-dose and the metamictization stages of the gadolinite specimens. In this respect, one of the samples is in conflict with the estimated radiation dose based on age and radionuclide concentrations. In this case, Mössbauer spectroscopy shows that the sample had to be naturally annealed over geologic time.

8

Influence of L-threonine on the growth, structural, optical, mechanical and nonlinear optical properties of tartaric acid single crystal

80%

Thilakavathi G. , Arun Kumar R. , Gunasekaran V.

Materials Science Poland

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2018

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tom Vol. 36, No. 4

630--637

EN

Single crystals of pure and L-threonine added tartaric acid (LT/TA), organic nonlinear optical (NLO) materials were grown from their respective aqueous solution by slow evaporation method. The crystalline nature of the grown crystals was confirmed by powder X-ray diffraction analysis (XRD). UV-Vis-NIR absorption and transmission spectra revealed that the lower cut-off wavelength was around 281 nm and the crystals exhibited high transmission over visible and near IR region. The presence of the functional groups such as O–H, C–H, C–O, C=O in the grown crystals was confirmed by FT-IR analysis. CHN analysis was carried out to confirm the presence of L-threonine in the grown crystals. Microhardness study on the crystals revealed that the hardness number Hv increased with the applied load. The growth pattern of the crystals were analyzed through etching analysis from which the etch patterns in the shape of 'step-triangle' were observed. The second harmonic generation (SHG) properties of pure and L-threonine doped tartaric acid crystals were confirmed by Kurtz-Perry powder technique.

9

Dielectric and spectroscopic analysis of cobalt doped potassium hexatitanate (K2Ti6O13) ceramics

80%

Siddiqui M. A. , Chandel V. , Shariq M. , Azam A.

Materials Science Poland

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2013

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tom Vol. 31, No. 4

555--560

EN

Pure and cobalt doped (x = 0.05, 0.10, 0.15 mol %) polycrystalline potassium hexatitanate (K2Ti6O13) ceramics were synthesized using conventional solid state reaction route. XRD result conﬁrmed the successful doping of Co in the K2Ti6O13 matrix, as no additional peak was observed in the pattern. Dielectric permittivity was found to decrease with the increase in frequency while it increased with the increase in doping. The dielectric loss decreased with small doping whereas excessive doping caused its augmentation. Ac conductivity (s ac ) has also been studied as a function of frequency at room temperature for all the samples. Scanning Electron Microscope (SEM) inspection of the synthesized samples showed the formation of rod like shapes. FTIR analysis was carried out to identify the chemical bonds present in the system.

10

Dielectric and impedance analysis of Li0.5La0.5Ti1-xZrxO3(x = 0.05 and 0.1) ceramics as improved electrolyte material for lithium-ion batteries

80%

Babu K. V. , Veeraiah V.

Materials Science Poland

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2016

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tom Vol. 34, No. 3

605--616

EN

The most attractive property of Li0.5La0.5 TiO3 (LLTO) electrolytes is their high ionic conductivity. Studies have shown that LLTO is capable of existing in a state with an ionic conductivity of 10-3 S/cm, which is comparable to liquid electrolytes. In addition to the high ionic conductivity of the material, LLTO is electrochemically stable and able to withstand hundreds of cycles. So, the studies of the solid electrolyte material are very important for the development of lithium-ion batteries. In the present paper, Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1) have been prepared by a solid-state reaction method at 1300 °C for 6 hours to improve electrolyte materials for lithium-ion batteries. The phase identified by X-ray diffractometry and crystal structure corresponds to pm3m (2 2 1) space group (Z = 1). The frequency and temperature dependence of impedance, dielectric permittivity, dielectric loss and electric modulus of the Li0.5La0.5Ti1-xZrxO3 (x = 0.05 and 0.1) have been investigated. The dielectric and impedance properties have been studied over a range of frequency (42 Hz to 5 MHz) and temperatures (30 °C to 100 °C). The frequency dependent plot of modulus shows that the conductivity relaxation is of non-Debye type.

11

Crystal structures of ErGe2 and TmGe2 compounds

80%

Matvijishyn R. , Pavlyuk V. , Shpyrka Z. , Serkiz R.

Chemistry, Environment, Biotechnology

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2010

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tom Vol. 14

35-40

EN

Crystal structures of ErGe2 and TmGe2 compounds were determined by X-ray single crystal diffraction. Both TmGe2 and ErGe2 crystallized with the ZrSi2 structure type (space group Cmcm).

12

Crystal structure of nitromethane solvated (-)-2(3,4-dimethoxyphenyl)-4-phenyl-5-phthalimido-1,3-dithiane

80%

Ratajczak-Sitarz M. , Rozwadowska M. D. , Katrusiak A.

Polish Journal of Chemistry

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1998

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tom Vol. 72, nr 11

2493-2499

EN

The crystal structure of the title solvate has been determined by X-ray diffraction with R=0.065. The 1,3-dithiane ring presents a chair conformation, the substituents at C(2), C(4) and C(5) are all in equatorial positions and the molecular ratio of the solvate is 1:1.

13

Fast method of identification of crystal powder mixture by X-ray diffraction technique

80%

Kulczycki A.

Chemia Analityczna

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2000

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tom Vol. 45, No. 2

305-310

EN

A simple method for qualitative analysis of crystalline phases based on X-ray characteristic diffraction patterns generated by pure substance is reported. Exact values of scattering intensity both of sample and standard substances are not required owing to originally constructed algorithm for computer program. Very high accuracy of analysis was achieved even for components that appear in low concentrations in the mixture. It is also shown how accuracy of measurement of diffraction angle influences the quality of analysis.

PL

Przedstawiono prostą metodę jakościowej analizy faz krystalicznych opartą na położeniu charakterystycznych refleksów dyfrakcyjnych czystych substancji. Dzięki specyficznie skonstruowanemu algorytmowi nie są potrzebne dokładne wartości intensywności rozpraszania zarówno dla próbki jak i dla substancji wzorcowych. Bardzo wysoką dokładność analizy osiągnięto nawet w przypadku niskich stężeń składników w mieszaninie. Pokazany został wpływ dokładności pomiaru kąta rozpraszania na jakość analizy.

14

Application of Laboratory Diffraction Methods in Characterization of Elements Made By Additive SLM Methods - State of the Art

80%

Gadalińska E. , Pawliszak Ł. , Moneta G.

Fatigue of Aircraft Structures

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2021

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tom Iss. 13

72--80

EN

The greatest challenge of widely developed incremental manufacturing methods today is to obtain, as a result of the manufacturing process, such components that will have acceptable strength properties from the point of view of a given application. These properties are indirectly determined by three key characteristics: the level of surface residual stress, the roughness of the component and its porosity. Currently, the efforts of many research groups are focused on the problem of optimizing the parameters of incremental manufacturing so as to achieve the appropriate level of compressive residual stress, the lowest possible porosity and the lowest possible roughness of parts obtained by 3D methods. It is now recognized that determining the level of these three parameters is potentially possible using experimental X-ray diffraction methods. The use of this type of radiation, admittedly, is only used to characterize the surface layer of elements, but its undoubted advantage is its easy availability and relatively low cost compared to experiments carried out using synchrotron or neutron radiation.

15

Investigation Of Intermetallic Compounds In Sn-Cu-Ni Lead-Free Solders

80%

Nagy E. , Kristaly F. , Gyenes A. , Gacsi Z.

Archives of Metallurgy and Materials

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2015

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tom Vol. 60, iss. 2B

1511--1515

EN

Interfacial intermetallic compounds (IMC) play an important role in Sn-Cu lead-free soldering. The size and morphology of the intermetallic compounds formed between the lead-free solder and the Cu substrate have a significant effect on the mechanical strength of the solder joint. In the soldering process of Sn-Cu alloys, Cu6Sn5 intermetallic compounds are formed. The complex structural behaviour of Cu6Sn5 IMC is temperature- and composition-dependent and it is long since subject to scientific research. The Cu6Sn5 phase basically exists in two crystal structures: hexagonal η-Cu6Sn5 (at temperatures above 186°C) and monoclinic η’-Cu6Sn5 (at lower temperatures). In the presence of Ni in the solder, the η-η’ transformation does not occur, therefore, the η-Cu6Sn5 phase remains stable. In this study the role of Ni in the (Cu,Ni)6Sn5 intermetallic compound in Sn-Cu lead-free solders was examined. Sn-Cu alloys with different Cu content (0.5 to 1 mass%) were modified through Ni addition. The morphology of the intermetallic compounds of the modified Sn-Cu alloys was investigated by optical microscopy (OM) and scanning electron microscopy (SEM), the IMC phases were examined with X-ray diffraction method (XRD).

16

Dielectric and structural characteristics of Sm doped Ba4La9.33Ti18O54 microwave ceramics

80%

Bahel S. , Narang B.

Materials Science Poland

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2008

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tom Vol. 26, No. 3

555--561

EN

The microwave dielectric properties and structural variation of Sm doped Ba4La9.33Ti18O54 have been investigated. Ba4(La(1-y)Smy)9.33Ti18O54, y = 0.0.0.7 ceramics were prepared by conventional solid state route. The electric permittivity and loss tangent were measured using a network analyzer in the frequency range of 0.3.3.0 GHz at room temperature. The loss tangent decreases significantly upon increasing Sm contents, along with a slight reduction in electric permittivity. A relatively good combination of dielectric properties was obtained for y = 0.5 (ε = 83.3 and tanδ = 0.021 at 3.0 GHz). X-ray diffraction and scanning electron microscopy were applied to investigate the microstructure and correlate it with microwave dielectric properties.

17

Otrzymywanie i właściwości modyfikowanych nanoporowatych adorbentów krzemionkowych

80%

Choma J. , Jaroniec M.

Ochrona Środowiska

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2003

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tom R. 25, nr 1

3-8

PL

Otrzymano uporządkowane, nanoporowate adsorbenty krzemionkowe (MCM-41) z merkaptopropylowymi oraz aminopropylowymi grupami. W procesie syntezy tych materiałów wykorzystano metodę hydrotermiczną z zastosowaniem bromku cetylotrimetyloamoniowego, jako surfaktantu, i tertaetoksysilanu, jako źródła krzemionki. Po wytrąceniu się białego osadu uporządkowanego materiału krzemionkowego dodawano 3-merkaptopropylotrietoksysilan lub 3-aminopropylotrietoksysilan, jako modyfikatory. Właściwości tak otrzymanych modyfikowanych merkaptopropylowych i aminopropylowych materiałów porównano z właściwościami niemodyfikowanego MCM-41. Otrzymane materiały badano za pomocą metody rozpraszania promieniowania rentgenowskiego (XRD), wysokorozdzielczej termograwimetrii (HRTG) i niskotemperaturowej (77 K) adsorpcji azotu. Stwierdzono, że w wyniku tak przeprowadzonej syntezy udało się wprowadzić około 12% wag. grup merkaptopropylowych oraz około 6% wag. grup aminopropylowych. Tak otrzymane modyfikowane materiały charakteryzują się uporządkowaną strukturą mezoporowatą o małej dyspersji porów a ich średnica wynosi około 3,6 - 3,8 nm. Inne parametry struktury mezoporowatej takie jak całkowita powierzchnia właściwa Sc, powierzchnia właściwa SBET, objętości pierwotnych mezoporów Vme i całkowita objętość porów Vc są wysokie i niewiele mniejsze od odpowiednich parametrów dla niemodyfikowanego MCM-41 C16. Badane modyfikowane adsorbenty MCM-41 mogą być wykorzystywane do usuwania jonów metali ciężkich z wody.

EN

Ordered nanoporous siliceous adsorbents (MCM-41) with mercaptopropyl and aminopropyl groups were synthesized. Cetyltrimethylammonium bromide as the templating surfactant and tetraethoxysilane as the silica source were used to synthesize these materials hydrothermally. After precipitation of a white powder of ordered silica, 3-mercaptopropyltriethoxysilane and 3-aminopropyltriethoxysiliane were added as modifiers. The properties of mercaptopropyl- and aminopropyl-modified materials were compared with those for the unmodified MCM-41. The resulting materials were studied by powder X-ray diffraction (XRD), high resolution thermogravimetry (HRTG) and low temperature (77 K) nitrogen adsorption. With the method of synthesis used we were able to introduce 12% of mercaptopropyl groups and 6% of aminopropyl groups. The resulting modified materials possess on ordered mesoporous structure of a small dispersion of pores, with a pore diameter ranging between 3.6 and 3.8 nm. The other structural parameters such as the total specific surface area (Sc), the BET surface area (SBET), the volume of primary mesopores (Vme) and the total pore volume (Vc) are high and not very much smaller than the corresponding parameters for the unmodified MCM-41. The modified MCM-41 adsorbents can be used for the removal of heavy metal ions from water.

18

Impedance and modulus spectroscopy studies of Ba4SrSmTi3V7O30 ceramics

80%

Sahoo P. S. , Panigrahi A. , Patri S. K. , Choudhary R. N. P.

Materials Science Poland

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2010

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tom Vol. 28, No. 4

764--772

EN

Modulus and impedance spectroscopy studies on barium strontium samarium vanadate (Ba4SrSmTi3V7O30) were carried out, as functions of frequency (1 kHz-1 MHz) and temperature (31-500 °C). XRD analysis of Ba4SrSmTi3V7O30 ceramic revealed the formation of single phase compound in an orthorhombic structure. The Cole-Cole plots showed a non-Debye type of dielectric relaxation. The dc and ac analyses of Ba4SrSmTi3V7O30 reveal typical negative temperature coefficient of resistance (NTCR) behaviour. The electric modulus, which describes the dielectric relaxation of the compound, is fitted to the Kohlrausch exponential function. Modulus analysis suggests the existence of a hopping mechanism for the electrical transport processes of the material.

19

Structure irregularities detected by X-ray diffraction effects

80%

Tarkowski L. , Schafler E.

Archives of Metallurgy and Materials

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2005

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tom Vol. 50, iss. 2

457-461

EN

Polycrystalline materials are solids which properties depend on such quantities as chemical and phase composition, crystallographic texture, residual stresses, grain size, etc. Applied technological processes lead usually to change the values of the parameters describing the quantities as well as modify the structure characteristics in macro- and micro-scale. In the result, both the global and local irregularities of material structure appear. When the irregularities become significant, numerous material properties reveal dierentials from point to point in a prepared constructing element. Spatial distribution of the irregularities can show a continuous character (gradient of the properties) or a non-continuous one, like in a layered structure. Moreover, the mentioned structure heterogeneity can be an intended effect like in a functionally graded materials or a quite non-favorable result of technological process (e.g. non controlled grain growth in the heat affected zone of welded elements). Among the most provocative challenge for the researchers are the structure inhomogeneities appeared under exploitation conditions (e.g. fatigue wear of the near-surface areas). In spite of the origin of the above structure irregularities, great research problem is recognizing its spatial distribution in the material. One of the most effective and non-destructive tool in this range is the X-ray diffraction technique assisted by appropriate experimental method and data processing procedures. The work presents the changes of the diffraction peak parameters of structure irregularities of a welded constructing element analyzed by the X-ray technique applied to investigation.

PL

Materiały polikrystaliczne są ciałami stałymi, których własności zależą od takich własności jak skład chemiczny i fazowy, tekstura krystalograficzna, naprężenia własne, rozmiar ziarna itp. Zastosowane procesy technologiczne prowadzą zwykle do zmiany wartości parametrów opisujących te własności, jak również modyfikują strukturę materiału w makro- i mikro-skali. W rezultacie w materiale pojawiają się globalne i lokalne niejednorodności. Kiedy nieregularności stają się znaczące, wiele cech materiału zmienia sie od punku do punktu w tak przygotowanym elemencie konstrukcyjnym. Przestrzenny rozkład tych niejednorodności może mieć charakter ciągły (gradient własności) lub nieciągły, jak w strukturze warstwowej. Co wiecej ta niejednorodność może być zamierzonym efektem, czego przykładem są funkcjonalne materiały gradientowe, lub niechcianym rezultatem technologicznego procesu (np. niekontrolowany wzrost ziaren w strefie wpływu ciepła w elementach spawanych). Wyzwaniem dla badaczy są niejednorodności powstałe w warunkach eksploatacyjnych (np. zmęczenie materiału w warstwach powierzchniowych). Niezależnie od pochodzenia tych nieregularności, problemem badawczym jest poznanie przestrzennego rozkładu tych efektów w materiale. Jedną z najbardziej efektywnych i nieniszczących metod jest dyfrakcja rentgenowska, przy wsparciu odpowiednich technik eksperymentalnych i przetwarzania uzyskanych danych. Przedstawiona praca poświęcona jest zmianom w parametrach pików dyfrakcyjnych uzyskanych przy użyciu dyfrakcji rentgenowskiej w konstrukcyjnym elemencie spawanym.

20

The sorption of copper ions by gyrolite in alkaline solution

80%

Bankauskaite A. , Baltakys K.

Materials Science Poland

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2009

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tom Vol. 27, No. 3

899--908

EN

Sorption of copper ions by synthetic pure gyrolite (CaO/SiO2 = 0.66; 96 h; 200 °C) in alkaline solutions was examined. When the initial concentration of Cu2+ ions is 1 g/dm3, the cation exchange capacity of the gyrolite is 100 mg Cu2+/g after 360 min of sorption at 25 °C. It has been proved that the cation exchange capacity of gyrolite depends on the concentration of copper ions in the Cu(NO3)2 solution, because a fivefold increase of the concentration (from 1.0 to 5.0 g/dm3) reduces the duration of the ion exchange reaction by a factor of three (from 15 min to 5 min). In solutions with higher initial concentrations of Cu2+ ions (10.0 and 20.0 g/dm3), the sorption proceeds more intensively and all the copper ions are adsorbed in 1 min. It should be noted that the cation exchange reactions are reversible in alkaline solution, because nearly 90% of the copper ions are adsorbed in a physical process, while the remaining part of the cation exchange process takes place in a chemical reaction. Furthermore, the crystal structure of gyrolite is stable in alkaline solution. The products of sorption were characterized by X-ray diffraction, thermogravimetry-differential scanning calorimetry and Fourier-transform infrared spectroscopy methods.