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Thermal characterization of polymer composites with nanocrystalline maghemite

Maryniak M., Guskos N., Typek J., Petridis D., Szymczyk A., Guskos A., Goracy K., Rosłaniec Z., Kwiatkowska M.

Polimery

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2009

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T. 54, nr 7-8

546-551

EN

Samples of multiblock poly(ether-ester) copolymer doped with magnetic ?-Fe2O3 nanoparticles (at small concentrations of 0.1 wt. % and 0.3 wt. %) have been investigated by DSC method to study the melting and crystallization behavior. Two forms of magnetic ?-Fe2O3 nanoparticle filler were used: solid-state grains and a suspension of ?-Fe2O3 with palmitic acid in toluene. Application of the solid filler caused formation of agglomerates of size of about 20?m while in the suspension form separate nanoparticles were in the range 10-20nm. The thermal and thermo-oxidative stability of composites was analyzed by conventional TGA analysis. The DSC results showed that crystallization and, to a smaller extent, melting, were considerably affected by the introduction of magnetic nanoparticles. The main influence is a shift in the crystallisation temperature up to 20° and melting/glass transition shift up to 6°. Thermogravimetric analysis showed significant enhancement of thermal and thermo- oxidative stability of the composites with respect to pure PEE. The dependence of thermal parameters on the concentration of magnetic filler has shown that the largest agglomerates produced the biggest change in all thermal parameters.

PL

Próbki multiblokowego kopolimeru eterowo-estrowego (PEE) domieszkowano magnetycznymi nanocząstkami ?-Fe2O3 (w ilości 0,1 % mas. lub 0,3 % mas.). Zastosowano dwie postacie napełniacza, mianowicie ziarna polikrystaliczne (tworzące aglomeraty o wymiarze ok. 20?m) lub zawiesiny nanocząstek ?-Fe2O3 w otoczce kwasu palmitynowego w toluenie (wymiar ok. 20nm). Metodą DSC zbadano wpływ tego nanonapełniacza na zjawiska topnienia i krystalizacji uzyskanych kompozytów (tabela 1, rys. 1) a do oceny stabilności termicznej i termooksydacyjnej wykorzystano analizę termograwimetryczną TGA (tabela 2, rys. 2, 3). Stwierdzono, że proces krystalizacji i, w mniejszym stopniu, także topnienia zostały znacznie zmodyfikowane przez obecne w kompozycie nanocząstki magnetyczne. Głównym efektem domieszkowania było podwyższenie temperatury krystalizacji aż o 20° i przesunięcie temperatury przemiany topnienia/zeszklenia o 6°. Analiza TGA wykazała istotniejszy wzrost stabilności termicznej i termooksydacyjnej kompozytów niż niemodyfikowanego PEE, przy czym wzrost ten jest tym wyraźniejszy im większe są aglomeraty.

2

FMR study of nanocarbon materials obtained by carburisation of nanocrystalline iron

Narkiewicz U., Arabczyk W., Pełech I., Guskos N., Typek J., Maryniak M., Woźniak M. J., Matysiak H., Kurzydłowski K. J.

Materials Science Poland

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2006

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Vol. 24, No. 4

1067--1075

EN

Samples of nanocrystalline iron were carburised with ethylene and next reduced with hydrogen. Both carburisation and reduction were monitored by the thermogravimetry. The obtained samples were characterised using X-ray diffraction, high-resolution transmission electron microscopy and ferromagnetic resonance. The samples after carburisation contained cementite (Fe3C) and carbon deposit (nanofibres and nanotubes). As the result of reduction with hydrogen at 450 or 500 °C cementite was reduced to iron. A major part of carbon was also hydrogenated, only thin carbon nanotubes remained. The FMR spectra of the prepared samples were recorded at room temperature. The sample after carburisation has shown a wide FMR line with weak intensity while the resonance field has been shifted to lower magnetic field. This spectrum has been attributed to the presence of cementite. The FMR lines corresponding to samples after reduction are more intense and are connected with the presence of alfa-Fe nanoparticle conglomerates.

3

Effect of calcination and structural additives on EPR spectra of nanocrystalline cobalt oxides

Guskos N., Typek J., Maryniak M., Żołnierkiewicz G., Podsiadły M., Arabczyk W., Lendzion-Bieluń Z., Narkiewicz U.

Materials Science Poland

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2006

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Vol. 24, No. 4

1095--1102

EN

Samples of nanocrystalline Co3O4 were prepared at various calcination temperatures and with various amounts of structural additives (CaO and Al2O3). The samples were characterized by X-ray diffraction. The average size and size distribution of nanoparticles have been calculated. Electron paramagnetic resonance (EPR) spectra of the samples were recorded at room temperature. The spectra have been attributed to divalent cobalt ions. Samples calcinated at higher temperatures showed an almost symmetrical, intensive EPR line. Temperature of calcination determined the character of the EPR spectra. The intensities of EPR spectra depended on the presence of CaO and Al2O3 additives

4

The linewidths and pintegrated intensities of the d-d transitions in photoacoustic spectra of polyamine copper(II) complexes

Guskos N., Typek J., Papadopoulos G. J., Maryniak M., Aidinis K.

Materials Science Poland

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2005

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Vol. 23, No. 4

955--960

EN

Photoacoustic spectra of the d-d transitions for three different series of copper(II) complexes of spermidines Spn (Spn323, Spn333, Spn343), Spm (Spm323, Spm333, Spm343) and Spc (Spc323, Spc333) have been investigated. Replacements of distant atoms, the presence or absence of water molecule in the structure, the kind of ligands surrounding the metal(II) ions have a strong influence on the crystal field splitting and the intensities of the non-radiative transitions. Non-radiative processes are involved in important mechanisms of the dynamic interactions between the electrons and the lattice. Studies of the intensities of the non-radiative transitions provide a very important data for the thermodynamic states of these systems. Photoacoustic absorption band of the d-d transitions could be decomposed into three lines (due to the crystal field splitting) with different intensities, positions and linewidths. The integrated intensities may yield information about the number of non-radiative processes, while the linewidths about the mechanisms of the relaxation processes.

5

Temperature dependence of the FMR spectra of Fe3O4 and Fe3C nanoparticle magnetic systems in copolymer matrices

Guskos N., Typek J., Roslaniec Z., Narkiewicz U., Kwiatkowska M., Maryniak M.

Materials Science Poland

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2005

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Vol. 23, No. 4

1055--1063

EN

A binary magnetic nanoparticle system, consisting of Fe3O4 (35 wt. %), Fe3C (29 wt. %), and C (36 wt. %) filling in a PTMO-block-PET polymer at low concentration (0.3 %), has been synthesized. X-ray and SEM analyses have been carried out. The temperature dependence of the FMR spectrum of this system has been investigated. At higher temperatures resonance from Fe3O4 nanoparticles dominates the FMR spectrum, while at lower temperatures a more intense line from Fe3C is recorded. The temperature dependence of the FMR spectrum confirms that the nanoparticles of Fe3O4 reach the ordered state faster than Fe3C nanoparticles. In both cases, the spin-glass state is observed below 50 K.

6

Photoacoustic study of a new neodymium(III) hydrazone complex

Guskos N., Paschalidis D. G., Majszczyk J., Typek J., Maryniak M.

Materials Science Poland

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2005

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Vol. 23, No. 4

1029--1034

EN

The neodymium(III) hydrazone complex [Nd(DBH)2(NO3)3] has been synthesized and characterized using microanalysis and IR spectroscopy. High-resolution photoacoustic spectrometry has been applied for studying the complex. The obtained photoacoustic spectrum has been analysed and compared to a similar [Nd(PicBH)2(NO3)2]NO3 complex. The intensities of the f-f transitions in the photoacoustic spectrum of Nd(DBH)2(NO3)3 were two times greater than for the [Nd(PicBH)2(NO3)2]NO3 complex.

7

Magnetic resonance study of SbVO5 thermal decomposition products

Typek J., Filipek E., Maryniak M., Guskos N.

Materials Science Poland

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2005

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Vol. 23, No. 4

1047--1054

EN

A new SbVO5 compound, which can be synthesized from an equimolar mixture of Sb2O3/V2O5 or ?-Sb2O4/V2O5 oxides by heating in air to temperatures below 650 °C, is stable in air up to 710 °C and in argon atmosphere up to ~645 °C. At higher temperatures it decomposes into a phase with a rutile-type structure. Using electron spin resonance (ESR) we have studied the magnetic properties of the thermal decomposition products of SbVO5 in air (sample 1D) and in argon atmosphere (sample 2D), as well as two phases of the of the rutile-type structure (samples 3S and 4S) synthesized at conditions similar to the previous two samples. The ESR spectra of all four samples consisted mostly of two types of lines: a narrow line (designated as the N component) and a very broad line (designated as the VB component). Close inspection of the ESR parameters for these components allowed the samples to be grouped according to the environment they were annealed in (air or oxygen-free argon). The origin of these lines and the implications concerning the phase composition of the decomposition products are discussed. ESR results confirm that the solid decomposition product of SbVO5 in air is a nonstoichiometric compound with a rutile structure and formula Sb0.95+V0.13+V0.84+ 0.2O4 and in argon a near-stoichiometric V4+Sb5+O4.5.

8

FMR study of gamma-Fe2O3 magnetic nanoparticles in a multiblock poly(ether-ester) copolymer matrix

Guskos N., Typek J., Maryniak M., Roslaniec Z., Petridis D., Kwiatkowska M.

Materials Science Poland

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2005

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Vol. 23, No. 4

971--976

EN

Four samples containing gamma-Fe2O3 magnetic nanoparticles dispersed at a concentration of 0.1 % (samples I and I') and 0.3 % (samples II and II') in a polymer matrix have been prepared. The polymer filler was in two forms: as solid-state grains (samples I and II) and as a liquid solution in trichloromethane (samples I' and II'). The typical size of the magnetic nanoparticles was 10 nm. The samples were characterized by XRD and TEM spectroscopy. Ferromagnetic resonance (FMR) measurements were carried out at room (RT) and liquid nitrogen (LNT) temperatures for all four samples. An intense resonance absorption line from gamma-Fe2O3 was recorded, with a slightly asymmetric line shape. The FMR spectra at RT and LNT are almost the same, as could be expected for the composite matrix. For samples II and II', the resonance lines are centred at Hr = 3039(10) Gs and Hr = 3197 (10) Gs, respectively, with linewidths of deltaH = 1289(5) Gs and deltaH = 1364(5) Gs, respectively. For samples I and I', the following values of resonance line parameters were obtained: Hr = 3172(10) Gs for sample I', and Hr = 2958(10) Gs for sample I, with linewidths of deltaH = 1279(5) Gs and deltaH = 1200(5) Gs, respectively. In both cases the resonance field for samples obtained from a solid state filler is shifted to lower magnetic fields as compared to samples made from a suspension filler, which suggests stronger ferromagnetic interactions in these materials.

9

FMR study of agglomerated nanoparticles in a Fe3C/C system

Guskos N., Typek J., Maryniak M., Narkiewicz U., Kucharewicz I., Wróbel R.

Materials Science Poland

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2005

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Vol. 23, No. 4

1001--1008

EN

Three samples with various Fe3C/C ratios have been prepared by the carburisation of iron with ethylene or an ethylene-hydrogen mixture. Carburisation was controlled with thermogravimetry. After carburisation, the samples were characterized using XRD and scanning electron microscopy. XRD measurements have shown the presence of the Fe3C (cementite) phase only. The mean size of cementite crystallites estimated using Scherrer's equation was in the range of 40-46 nm. Ferromagnetic resonance (FMR) absorption signals were investigated at room temperature. In all samples an asymmetric, very broad, and intense FMR line shifted toward low magnetic field was recorded. The linewidth, intensity, and position of the resonance field depended strongly on carbon concentration. With increasing carbon concentration the linewidth and integrated intensities of the FMR spectra decreased, and the resonance line shifted towards higher magnetic fields. The separation of granules from each other by carbon could drastically influence the FMR absorption spectrum due to decreasing intergranular interaction with increasing carbon concentration.

10

Characterization and EPR studies of TiC and TiN ceramics at room temperature

Bodziony T., Guskos N., Biedunkiewicz A., Typek J., Wróbel R., Maryniak M.

Materials Science Poland

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2005

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Vol. 23, No. 4

899--907

EN

Four samples, namely TiC/C, TiN/C, (TiC + FexCy + Fe)/C and TiN/amorphous carbon, have been prepared and investigated. In the former three samples titanium compounds were placed in a carbon matrix, while in the fourth one TiN was surrounded by an amorphous carbon. The samples have been characterized by XRD, SEM, and electron diffraction spectroscopy. The crystallite sizes and lattice parameters of TiC and TiN have been determined by the X-ray diffraction method. XRD measurements have shown that the lattice constants of nanosized samples were smaller than those of microsized samples. An essential influence of the carbon matrix during the crystallization process on the lattice parameters and grain size was observed. Electron paramagnetic resonance (EPR) measurements of the samples were carried out at room temperature. A narrow EPR absorption line has been recorded for the TiC/C, TiN/C, and TiN/amorphous carbon samples, whereas for the (TiC + FexCy + Fe)/C sample a ferromagnetic resonance spectrum, mainly of ?-Fe and cementite Fe3C, has been recorded. The narrow resonance EPR line is explained by carrier motion - free electrons in the case of the TiN/C sample and holes (carbon vacancies) in the case of TiC/C and TiN/amorphous carbon samples - which could lead to the creation of the pseudogap state in TiCx or TiNx compounds.