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1
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The Effect of Synthesis Pressure on Properties of Eu-Doped ZnO Nanopowders Prepared by Microwave Hydrothermal Method

100%
Rosowska J., Kaszewski J., Witkowski B., Wachnicki Ł., Godlewski M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 5
1205-1208
EN
In the current research, europium doped ZnO nanopowders prepared by a microwave hydrothermal method are investigated. The effects of synthesis pressure on the morphologies, crystal structures, and optical properties of Eu-doped ZnO were analyzed by scanning electron microscopy, X-ray diffraction, cathodo- and photoluminescence. From our investigations it can be concluded that the synthesis pressure strongly influences the surface morphology. With the increase of the synthesis pressure from 2 MPa to 10 MPa significant changes can be observed. An increase of the mean crystallites sizes and change of the intensity ratio between the near band edge and defect related deep level emission band of ZnO were observed.
2
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Gradual and Self-Sustaining Processes in the Sn-Zn-Se System

100%
Takacs L.
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vol. 126
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issue 4
1032-1039
EN
Ball milling induces self-sustaining reaction in binary Sn-Se and Zn-Se powder mixtures. But if such mixtures are blended, the ignition time increases at either end of the concentration scale and the suppression of ignition can take place in an intermediate concentration interval. This phenomenon was investigated in (1-x)(Sn+Se)+x(Zn+Se) and (1-x)(Sn+2Se)+x(Zn+Se) mixtures, by measuring the ignition time as a function of both composition and milling conditions and investigating activated and reacted mixtures using X-ray diffraction and scanning electron microscopy. At the Sn-rich compositions of the first system, ignition happened as soon as the mill was started, in spite of the rather low adiabatic temperature of the reaction. Simultaneous local melting of Sn and Se is suggested as a possible explanation for immediate ignition. It can also explain the asymmetry of the properties of the binary reactions, namely that Sn+Se is less exothermic but easy to ignite, while Zn-Se is more exothermic but difficult to ignite. Similar asymmetry is considered as the reason for the increase of the ignition time and the loss of ignition in other mixed metal-chalcogen systems.
3
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Preparation and Characterization of High Purity Silica Obtained from Rice Husks

100%
Şımşek Y.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
1002-1005
EN
Although SiO₂ is produced mostly from mineral sources like quartz, it has recently been obtained from lignocellulosic natural resources, such as rice husk (hull). Several methods for extracting silica (SiO₂) from rice husks are available in the literature. These methods are based essentially on heat treatment and/or extraction. This study represents a thorough account of heat treatment and acid-base extraction, to obtain silica from rice husks with a high purity and to eliminate other inorganic impurities. Rice husks, considered to be a potential silica source, were pretreated with various acids, base and water and then thermally degraded in a fixed bed reactor under an inert gas atmosphere (N₂). The materials produced in these conditions were characterized by Brauner-Emmett-Teller analysis, for surface area and pore volume, by Fourier transform infrared spectroscopy, powder X-ray diffraction, X-ray fluorescence, and scanning electron microscopy.
4
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Mechanochemical Synthesis and Characterization of II-VI Nanocrystals: Challenge for Cytotoxicity Issues

100%
Baláž P., Jardin R., Dutková E., Sayagués M., Baláž M., Mojžišová G., Mojžiš J., Turianicová E., Fabián M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 1
224-229
EN
CdSe@ZnS nanocrystals have been prepared by a two-step solid state mechanochemical synthesis. CdSe prepared from elements in the first step is mixed with ZnS synthesized from zinc acetate and sodium sulfide in the second step. The crystallite size of the new type CdSe@ZnS nanocrystals determined by X-ray diffraction Rietveld refined method was 35 nm and 10 nm for CdSe and ZnS, respectively. Energy dispersive/transmission electron microscopy/energy dispersive spectroscopy methods show good crystallinity of the nanoparticles and scanning electron microscopy elemental mapping illustrate consistent distribution of Cd, Se, Zn and S elements in the bulk of samples. UV-VIS spectra show an onset at 320 nm with calculated bandgap 3.85 eV. This absorption arises from the vibration modes of Zn-S bonds. The nanocrystals show the blue shift from the bandgap of bulk ZnS (3.66 eV). The synthesized CdSe@ZnS nanocrystals have been tested for dissolution, cytotoxicity and L-cysteine conjugation. The dissolution of Cd was less than 0.05 μg mL^{-1} (in comparison with 0.8 μg mL^{-1} which was evidenced for CdSe alone). The very low cytotoxic activity for selected cancer cell lines has been evidenced. CdSe@ZnS nanocrystals coated with L-cysteine are water-soluble and have a great potential in biomedical engineering as fluorescent labels.
5
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Structural Analysis of Ce Doped La_{1-x}Sr_xCo_{1-y}Fe_yO_{3-δ} Nanopowders Synthesized by Glycine-Nitrate Gel Combustion

100%
Yildiz Ö., Soydan A., Ata A., İpçızade E., Akin D., Uçak Ö.
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vol. 125
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issue 2
669-672
EN
Ce doped La_{1-x}Sr_xCo_{1-y}Fe_yO_3 (LCSCF) is a widely used cathode material due to its high catalytic activity for oxygen reduction and high oxygen exchange coefficient. LCSCF is also known with its high ionic and electronic conductivities and low electrode polarization losses which are highly critical properties for low temperature solid oxide fuel cell applications. In this study, structural properties of the LCSCF cathode nanopowder materials synthesized by glycine-nitrate gel combustion have been investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and nanosizer. Synthesized nanopowders represent volcanic ash like structures and morphologies. Ce, Sr, Co, and Fe are found to have significant effects on the structural properties of powders in terms of powders morphology, agglomerate structure, crystallite size and also lattice parameter of perovskite crystal. All synthesized ash powders have particle sizes around 50-600 nm, varying crystalline structures of perovskite and fluorite depending on molar ratio of Ce in the composition. Increasing molar Ce ratio over 0.4 is found to lead to the formation of a separate nano ceria phase in fluorite crystal structure on the surface of the synthesized powder.
6
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Properties of ZnO Nanopowders Synthesized by Glycine-Nitrate Gel Combustion

100%
Yıldız Ö., Soydan A., Ipçizade E., Akın D., Uçak Ö.
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vol. 125
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issue 2
664-666
EN
The morphology and other physical properties of ZnO nanopowders synthesized by glycine-nitrate gel combustion process were investigated and characterized by scanning electron microscopy, transmission electron microscopy, nanosizer and X-ray diffraction. Glycine, NH_2CH_2COOH, and zinc nitrate Zn(NO_3)_2·6H_2O were dissolved in distilled water and the solution was coagulated by mixing at 90°C. The viscous gel prepared during glycine-nitrate mixing was heated at ≈220C to initiate the exothermic reactions by self-combustion where the temperature reached up to 1200°C. The glycine-nitrate ratio had a significant effect on the reaction temperature and final particle morphology. Therefore the synthesized powders have a different morphology like formless and spherical tufa ash. The particle size distribution was 50-1200 nm as measured using a nanosizer.
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Electromagnetic Properties of Substituted Barium Hexaferrites

100%
Sláma J., Grusková A., Jančárik V., Štofka M., González-Angeles A.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
609-612
EN
Substituted M-type ferrite BaFe_{12-2x}(Me_1Me_2)_xO_{19}, 0≤x≤0.6 was prepared by both mechanical alloying and precursor method, where Me_1 = Co, Ni, Zn, Sn and Me_2 =Ru, Ti, Zr, Sn. Magnetic phase purity, change of saturation polarization, Curie temperature, coercivity and magnetic susceptibility was studied as function of x. Attention was focused to results obtained for (NiRu)_x, (ZnRu)_x, and (SnRu)_x mixtures with low doping ratio x.
8
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Silicon Carbide Nanowires Synthesis and Preliminary Investigations

100%
Patyk J., Rich R., Wieligór M., Żerda T.
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issue 3
480-482
EN
As the field of biotechnology expands and the semiconductor industry approaches the limit of size reduction with conventional materials, these and other fields will increasingly rely on nanomaterials with novel properties. Silicon carbide (SiC) possesses many properties that make it appealing to research and industry: a large band gap, high hardness, high strength, low thermal expansion, chemical inertness, etc. It is known that silicon carbide nanowires can be synthesized through a reaction between silicon vapor and multiwalled carbon nanotubes. This process was refined to produce smaller, straighter nanowires. This was done by analyzing the dependence of the reaction rate on the partial vapor pressure of silicon. The reaction rate was studied by comparison of SiC and multiwalled carbon nanotubes peak intensities in X-ray diffractograms, which produced an estimate of the respective reactions' SiC yields. The particle morphologies were then analyzed with transmission electron microscopy. Finally, Fourier transform infrared spectroscopy was utilized to study the intensities and frequencies of the SiC infrared absorption bands. This data was analyzed with respect to the previously determined yield and particle sizes of the respective SiC nanowire samples.
9
Content available remote

Synthesis, Characterization of Novel Dinuclear Co(II)-Cu(II) Complexes and Investigation of Their Catecholase and Catalase-Like Activities

100%
Dede B., Cicek E., Karipcin F.
Acta Physica Polonica A
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2016
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vol. 129
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issue 2
203-207
EN
The purpose of this study is synthesis, characterization and enzyme activity functions of novel dinuclear metal complexes. Therefore two new dinuclear heterometallic cobat(II)-copper(II) complexes have been synthesized and structurally characterized by using Fourier transform infrared method, elemental analysis, inductively coupled plasma optical emission spectrometry, molar conductivity, magnetic moment measurements and thermal analysis. Spectroscopic and stoichiometric data of the metal complexes indicated that the metal:ligand ratio of the complexes were found to be 2:1. Both of the complexes are 1:2 electrolytes as shown by their molar conductivities and paramagnetism. The subnormal magnetic moment values of the dinuclear complexes were explained by an antiferromagnetic interaction. Additionally complexes were each tested both for their ability to oxidation reaction of 3,5-di-tert-butylcatechol to the 3,5-di-tert-butyl-o-benzoquinone presence of O₂ and catalyse the disproportionation of hydrogen peroxide in the presence of the added base imidazole. It was found that both of the complexes exhibited good catecholase and catalase-like enzyme activity.
10
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Novel Metal(II) Complexes with Bidentate Schiff Base Ligand: Synthesis, Spectroscopic Properties and Dye Decolorization Functions

100%
Karakaya C., Dede B., Cicek E.
Acta Physica Polonica A
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2016
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vol. 129
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issue 2
208-212
EN
The bidentate Schiff base ligand 4-chloro-2-[1-(4-phenylphenyl)ethylideneamino]phenol and its mononuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized. Ligand and metal complexes were characterized by elemental analyses, magnetic susceptibility, molar conductivity, ¹H- and ¹³C-NMR, the Fourier transform infrared, UV-Vis, inductively coupled plasma optical emission spectrometry, and thermogravimetric-differential thermogravimetric studies. The results suggest that the mononuclear complexes have a metal to ligand mole ratio of 1:2 and the metal(II) ions are coordinated with the phenolic oxygen and imine nitrogen atoms. Octahedral structures are proposed for the complexes of the Schiff base ligand. Furthermore, the complexes were checked for their efficiency to decolorize the dye methylene blue. In our experiments we found that metal(II) complexes had an acceptable decolorization efficiency against the dye methylene blue.
11
Content available remote

Cast Intermetallic Alloys by SHS Under High Gravity

100%
Sanin V., Andreev D., Ikornikov D., Yukhvid V.
Acta Physica Polonica A
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2011
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vol. 120
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issue 2
331-335
EN
Pilot-scale series of cast Ti-Al, Ti-Al-Nb, (Ni, Co, Mn)Al_x, Ni-Cr-Al-Si-C, and Co-V-Al-Si-C alloys were produced by thermit-type SHS under high gravity for their potential use as heat-resistant materials, master alloys, precursors for catalysts, etc.
12
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LaYO_{3}:Sm^{3+} Nanocrystalline Phosphor: Preparation and Emission Properties

100%
Đorđević V., Nikolić M., Antić Ž., Mitrić M., Dramićanin M.
Acta Physica Polonica A
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2011
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vol. 120
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issue 2
303-305
EN
Samarium doped LaYO_{3} nanocrystalline phosphor powders are obtained by polymer complex solution method. Stoichiometric quantities of La_{2}O_{3}, Y_{2}O_{3} and for dopant ions Sm_{2}O_{3} were dissolved in hot nitric acid. Polyethylene glycol was added in solutions in 1:1 mass ratio to corresponding metal nitrates to form gel. The gel is combusted and annealed at 800°C for two hours to form nanopowder samples. Crystalline structure and phase purity is checked by X-ray diffraction and show that this material is synthesized in cubic bixbyite type structure for the first time. Luminescence properties of Sm^{3+} doped LaYO_{3} exhibited characteristic orange-red emission coming from the intra-4f-shell ^{4}G_{5/2}→^{6}H_{J} electron transitions with emission decay of 1.5 ms. Energy level positions are derived from emission and excitation spectra.
13
Content available remote

Hydrothermal Synthesis of Hydroxyapatite on Titanium after Anodic Oxidation

88%
Strzała A., Simka W., Marszałek M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 2
561-564
EN
Hydrothermal synthesis of hydroxyapatite (HA) is a method which is relatively easy to apply and enables HA precipitation on substrates of various shapes, which is vital to endoprostheses fabrication. Anodic oxidation facilitates HA precipitation, making the coating thicker and more uniform. In this paper the influence of anodic oxidation of titanium substrates on HA precipitation in hydrothermal synthesis is discussed. To determine chemical composition and coating uniformity of anodised and polished Ti substrates the Raman microspectroscopy was employed. The composition was also confirmed using X-ray diffraction method. HA coatings on Ti after anodic oxidation exhibit higher uniformity in comparison to untreated Ti. The X-ray diffraction patterns showed that the HA coating was partly amorphous. Also influence of additional treatment (soaking in NaOH and/or HBSS) after anodic oxidation is discussed in the present paper. It seems that pretreatment may be favourable in some cases, but if the anodic oxidation was conducted in the presence of calcium phosphates the pretreatment seems to prevent the HA precipitation.
14
Content available remote

La-doped and La/Mn-co-doped Barium Titanate Ceramics

88%
Vijatović Petrović M., Bobić J., Grigalaitis R., Stojanović B., Banys J.
Acta Physica Polonica A
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2013
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vol. 124
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issue 1
155-160
EN
Barium titanate ceramics doped with 0.3 mol.% lanthanum and co-doped with 0.3 mol.% lanthanum and 0.05 mol.% manganese were investigated. The powders were prepared by a modified polymeric precursor method based on the Pechini process. The ceramics were obtained by sintering at 1300C for 8 h. The influence of dopants on structural changes and grain size reduction was analyzed. The presence of dopants influenced the tetragonality of the barium titanate crystal structure. Reduction of polygonal grain size with dopant addition was noticed. In the doped ceramics, characteristic phase transitions were shifted to lower temperatures in comparison with pure barium titanate. The dielectric permittivity value showed the tendency of a slight increase with lanthanum addition and further increase with adding of manganese. La as a single dopant increased the diffuseness of phase transitions indicating the formation of a diffuse ferroelectric material but in the co-doped ceramics the phase transition diffuseness decreased. The resistivity of the co-doped ceramics was higher than for lanthanum doped ceramics, indicating possible segregation of manganese at grain boundaries that influenced the total resistivity of the material.
15
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Properties of Ceria Based Novel Anode Nanopowders Synthesized by Glycine-Nitrate Process

75%
Yıldız Ö., Soydan A., Ata A., Tunaboylu B., Akın D., İpcizade E.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
432-435
EN
Novel anode nanopowder materials consisting of ceria-based components synthesized by glycine-nitrate process were investigated for solid oxide fuel cells. Glycine-nitrate process involves a self-combustion reaction at 220C of water-based nitrate and glycine solutions which subsequently can reach up to 1200°C. The resulting morphology, the size of particles and the formation of crystalline phases were characterized by differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, the Brunauer-Emmett-Teller method and Nanosizer. It was determined that dopants in ceria such as Co, Ni, Cu, V and Fe had significant effect on the morphology and size. The size distribution measured by Nanosizer was 50-600 nm, transmission electron microscopy, 5-200 nm and the Brunauer-Emmett-Teller method 100-120 nm and specific surface area of powders in the range 67.45-72.05 m^2 g^{-1} as measured by the Brunauer-Emmett-Teller method. Particles were observed to have spherical structures for Cu and Fe doped powders and rod-shaped in a porous tuff microstructure for those doped with Co and Ni. Vanadium doping helped to decrease the porosity and initiated the process of spheroidization of particles.
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