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Profesor Jan Fiutak, nasz „Szef ” pionier fizyki teoretycznej na Wybrzeżu

Czub J., Kryszewski S., Miklaszewski W., Żukowski M.

Postępy Fizyki

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2017

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T. 68, z. 2

87--89

PL

Profesor Jan Fiutak odszedł na zawsze 25 lutego 2016 r. Nazywaliśmy go „Szefem”, bo dla nas był nim przez długie lata. Historia fizyki teoretycznej na Wybrzeżu zaczyna się od Niego

2

Anomalous structural properties of some RCu2Ge2 compounds (R = La, Gd-Tm)

Rusinek D., Niewolski J., Czub J., Gondek Ł, Szytuła A.

Materials Science Poland

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2013

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Vol. 31, No. 4

495--500

EN

In this paper, we address the issue of possible quadrupole ordering in RCu2Ge2 compounds. In the literature, there are reports on anomalous behaviour of lattice parameters, however, lack of high quality data makes the relevant analysis dubious. Therefore, we attempt to perform precise, non-ambient XRD measurements within 12 – 300 K temperature range. Our results confirm peculiar temperature behaviour of the c-lattice parameter that exhibits a well defined minimum at about 60 – 120 K for majority of investigated compounds. However, in contrast to the literature, the anomalous behaviour does not exhibit discontinuities. On the other hand, such behaviour has been evidenced for La-based compounds (LaCu2Ge2 and LaNi2Ge2), where the 4f orbitals are unoccupied.

3

Znaczenie mikroporowatych materiałów metaloorganicznych (MOF ) dla potrzeb magazynowania wodoru

Czub J., Gondek Ł, Figiel H.

Wiadomości Chemiczne

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2012

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[Z] 66, 3-4

227-247

EN

Currently, the metal-organic frameworks (MOF s) are considered among the most promising materials for hydrogen storage. In this paper, the properties of MOF s that are particularly important for application purposes are presented. Examples include simplicity of their syntheses on an industrial scale, low synthesis costs, high thermal stability and durability, an excellent repeatability and very low degree of degradation during cyclic hydrogen loading and recovery. On the other hand, the potential use of MOF s as hydrogen reservoirs is to some extent limited due to the fact that the low temperatures of 77 K are required for effective adsorption of hydrogen in the microporous structures of MOF s. Nowadays, the research on MOF s is carried in two directions. In particular, there are intensive studies on increasing of the concentration of hydrogen adsorbed at low temperatures in order to determine the limiting value for which maintaining the reservoir at the temperature of liquid hydrogen would be economically viable. It seems that the limiting concentration is being currently reached. The second direction of research is to increase the limiting value of temperature at which the concentration of adsorbed hydrogen is acceptable.

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Microstructure and magnetic properties of the Cu-1% Co single crystal

Czub J., Dubiel B., Tokarz W., Czyrska-Filemonowicz A.

Inżynieria Materiałowa

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2010

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Vol. 31, nr 3

309-311

EN

This paper reports the results of transmission electron microscopy (TEM) and magnetic properties investigations of the Cu-1% Co (wt. %) single crystal. Particle size measurements were performed using quantitative TEM metallography methods. Two classes of Co particles were identified, each one with different magnetic properties: superparamagnetic (SPM) and ferromagnetic (FM). The hysteresis loop measured at 295 K was analysed taking into account SPM and FM contributions. The mean size of the SPM Co particle was determined and compared with the result of the TEM metallography results.

PL

W pracy przestawiono wyniki badań monokryształu Cu-1% Co (% mas.) metodą transmisyjnej mikroskopii elektronowej (TEM) oraz pomiarów własności magnetycznych. Wyznaczono średnią średnicę cząstek Co metodą metalografii ilościowej TEM. Zidentyfikowano dwa rodzaje cząstek Co różniące się własnościami magnetycznymi: superparamagnetyczne (SPM) i ferromagnetyczne (FM). Przeprowadzono analizę pętli histerezy zmierzonej w temperaturze 295 K, uwzględniając przyczynek superparamagnetyczny i ferromagnetyczny. Wyznaczono średnią średnicę superparamagnetycznej cząstki Co i porównano z wartością uzyskaną na podstawie wynikow TEM.

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Mesomorphic and dielectric properties of esters useful for formulation of nematic mixtures for dual frequency addressing system

Ziobro D., Kula P., Dziaduszek J., Filipowicz M., Dąbrowski R., Parka J., Czub J., Urban S. S., Wu S. T.

Opto-Electronics Review

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2009

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Vol. 17, No. 1

16-19

EN

Mesomorphic and dielectric properties of three homologous series of two and three ring fluorosubstituted esters are described. They are 4-cyano-3-fluorophenyl 4-alkyloxy-2-fluorobenzoates, 4-cyano-3-fluorophenyl 4-(4-alkylbenzoyloxy)-2-fluorobenzoates and 3-fluoro-4-cyanophenyl, or 3-fluoro-4-isothiocyanatophenyl or 3,4-difluorophenyl 4'-alkyl-2,3-difluoro-biphenyl-4-carboxylates. The compounds exhibit the nematic mesophase accompanied by the smectic A or smectic C mesophase in some cases. Most of them show strong dependence of the dielectric anisotropy Δ ε upon frequency, at low frequencies Δ ε reaches a value ∼ 200, while at high frequencies a small negative dielectric anisotropy appears.

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Mesomorphic, dielectric, and optical properties of fluorosubstituted biphenyls, terphenyls, and quaterphenyls

Kula P., Spadło A., Dziaduszek J., Filipowicz J., Dąbrowski R., Czub J., Urban S.

Opto-Electronics Review

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2008

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Vol. 16, No. 4

379-385

EN

Compounds with moderate and large negative dielectric anisotropy (Δ ε ) are very attractive liquid crystal (LC) for vertical alignment mode (VA). Materials with such properties can be achieved by lateral substitution of a polar group into a mesogenic molecule. We synthesized some new LC materials with a negative value of Δ ε, a moderately high birefringence (Δ n), and a low viscosity. The mesomorphic and physical behaviour of the novel biphenyls, terphenyls and quaterphenyls fluorosubstituted in the rigid core and also with fluorinated alkyl and alkoxy chains are investigated. The prepared series of four LC compounds are promising for new LC mixtures for various applications. Examples of nematic mixtures with Δ ε ∼ -3.25 will be presented.