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1

Nanocrystallines as core materials for contactless power transfer (CPT)

Ghosh P. C., Sadhu P. K., Ghosh A., Pal N.

Journal of Power Technologies

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2018

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Vol. 98, nr 1

20--29

EN

Efficient contactless power transfer (CPT) is an emerging technology which is attracting great scientific interest because it can mitigate some of the problems commonly associated with conventional wired power transfer systems. CPT systems suffer from very low efficiency because of the poor coupling coefficient, which is due to the large air gap between the transmitter and receiver coils. Therefore, CPT transformers are mostly operated at high frequencies to improve the quality factor of transmitter and receiver coils and thus counterbalance the effect of the low coupling coefficient. On the other hand, informed selection and design of core materials for CPT transformers can improve the coupling coefficient and thereby boost the overall power transfer efficiency of the system. However, at high power and high frequency CPT applications, core losses become very high and play an important role in determining the efficiency of the system. This paper reports on a detailed investigation into the suitability of nanocrystallines as core materials for high power and high frequency CPT systems.

2

Wpływ osnowy polimerowej na piezooptykę nanokrystalitów γ-glicyny

Oźga K., Nabiałek M., Szota M., Rakus P., Czaja P., Dośpiał M., Berdowski J., Tylczynski Z.

Przetwórstwo Tworzyw

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2011

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[R.] 17, nr 6

483-487

PL

Ustalono główną rolę polarności osnów polimerowych na dyspersję zjawiska piezooptyki nanokrystalitów γ-glicyny wprowadzonych w osnowy polimerowe poli(metakrylanu metylu) (PMMA) oraz poliwęglanu (PC). Stwierdzono pojawienie się efektu piezooptycznego pod wpływem obróbki laserowej dwoma wiązkami świetlnymi o długości fali 1064 nm oraz 532 nm, generowanymi z jednego źródła laserowego YAG: Nd. Optymalne rozmiary nanokrystalitów γ-glicyny, dla których otrzymano odpowiednie wartości współczynników piezooptyczych wynosiły 50-80 nm (optymalna koncentracja 5,5 % w j. wag.). W pracy badano relaksacje oraz zależności spektralne odpowiednich współczynników tensora piezooptycznego.

EN

We have established a principal role of the polarity of polymer matrices on the piezooptical dispersion of the γ-glycine nanocrystallites embedded into the polymethymethacrylate (PMMA) and polycarbonate (PC) matrices. We have found that the optical treatment by bicolor two laser beams at 1064 nm and 532 nm which are originating from the same 10 ns Nd:YAG lasers, causing occurrence of the piezooptical effects. The optimal content of the γ-glycine nanocrystallites with respect to the magnitude of piezooptical coefficients with the sizes within the range 50-80 nm correspondence to the 5.5 % in weighting unit. We studied relaxation and spectral dependences of the corresponding coefficients of piezooptic tensor.

3

Elaboration of magnetron deposition conditions of TiN/Si3N4 nanocomposite coatings

Morgiel J., Major Ł., Grzonka J., Mania R., Rakowski M.

Problemy Eksploatacji

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2006

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nr 2

33-42

EN

The TiN/Si3N4 coatings were deposited by reactive single target magnetron sputtering. The TiSi10 and TiSi6 targets were prepared from titanium and silicon elemental powders. The transmission electron microscopy helped to confirm the nanocomposite nanocrystalline TIN/ amorphous Si3N4 microstructure of coatings. The experiments helped to determine the critical coatings thickness at close to 1 žm. The micro-hardness of such coatings deposited on high speed steel was estimated at 11.9 - 13 GPa and characterized by critical loading in the range of 13 - 14 N. The measurements of chemical compositions of coatings showed that the ratio of silicon to titanium was at least twice as high as those in the targets, what might have lowered the coatings mechanical properties.

PL

Powłoki TiN/Si3N4 naniesiono techniką rozpylania magnetronowego przy użyciu targetu o składzie TiSi10 lub TiSi6 (% at.). Targety te zostały przygotowane na drodze spiekania na gorąco proszków krzemu i tytanu. Analizę mikrostruktury nanokompozytowych nanokrystalicznych powłok TiN/Si3N4 o krytycznej grubości delaminacji zbliżonej do l žm, przeprowadzono przy użyciu mikroskopu transmisyjnego. Mikrotwardość powłok na podłożu ze stali szybkotnącej określono na poziomie 11.9 - 13 GPa. Analiza składu chemicznego powłok wykonana techniką EDS wykazała, że stosunek zawartości krzemu do tytanu jest dwa razy większy niż w targetach, co może stanowić przyczynę ich niższej od oczekiwań twardości.

4

Band energy approach and nonlinear optical phenomena in large-sized nanoparticles

Kityk I. V.

Journal of Telecommunications and Information Technology

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2006

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nr 4

96-101

EN

This report presents principal optical properties of semiconducting large-sized nanocrystalline (LSNC) material with thickness within 10-50 nm range. A quantitative parameter for description of the LSNC state is introduced. Influence of the surrounding polymer matrices on the properties of the LSNC is shown. Role of the surrounding polymer matrix background in the manifestation of material optoelectronic properties is studied. Superposition of long-range ordering with the localized nano-quantized effects is analyzed within a framework of different one-electron band energy approaches. Manifestation of the LSNC nonlinear optical (NLO) properties will be presented separately. It is clearly demonstrated that appropriate choice of LSNC geometry parameters together with proper modification of chemical composition could enhance the key NLO parameters.

5

Electrochemical Synthesis and Properties of Micro- and Nanocrystallites of Cobalt

Wiśniewski A., Paklepa P., Wrona P.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 9

1327-1337

EN

The electrochemical synthesis of cobalt particles has been performed by electroreduction of Co(II) ions on the mercury electrode at potentials about -1.4 V vs. SCE. The electroreduction of Co(II) observed in cyclic voltammetry (CV), was a totally irreversible process due to the formation of an unstable cobalt amalgam, which decomposed into metallic cobalt. It has also been observed that metallic cobalt, practically insoluble in mercury, tends to aggregate, forming nanocrystallites and clusters that finally separate from mercury in the form of a black powder. The black cobalt powder, obtained this way, has been characterized using scanning electron microscope (SEM) imaging, X-ray analysis and specific surface measurements (nitrogen adsorption according to BET isotherm). The results of these experiments indicate that the cobalt powder obtained from the amalgam consists of partially oxidized crystallites of dimensions less than 20 nm. These nanocrystallites form aggregates of dimensions up to several or more _m. Due to their specific surface exceeding 30 m2/g, such crystallites can be used for the preparation of metallic catalysts.Ahypothesis, concerning the nucleation and further aggregation of Co from a homogeneous cobalt amalgam, leading to the formation of nanocrystallites, is discussed according to the burst-nucleation theory.

6

Structure, spectroscopy and dielectric properties of BaTiO3:Eu3+ nanocrystallites prepared by the sol-gel method

Hreniak D., Łukowiak E., Maruszewski K., Pązik R., Stręk W.

Materials Science

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2002

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Vol. 20, No. 1

43-50

EN

Eu3+-doped BaTiO3 nanocrystalline powders have been obtained by sol-gel method. Their morphology, structure and dielectric properties have been investigated as a function of sintering temperature. The powders sintered at the temperatures below 800 st.C demonstrate luminescence behaviour characteristic of the inversed symmetry Eu3+ sites, where only the 5D0 ??7F1 transitions are allowed. Above this temperature the system undergoes a phase transition characterized by lack of inversion symmetry enabling the dipole-electric transitions.