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Your search keyword '"Kołodziejak, K."' showing total 9 results
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9 results on '"Kołodziejak, K."'

1. Anisotropic transport and Negative Resistance in a polycrystalline metal-semiconductor (Ni-TiO2) hybrid

Author

G, Harikrishnan, Chattopadhyay, Shashwata, Bandopadhyay, K., Kolodziejak, K., Pawlak, Dorota A., and Mitra, J.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We investigate anomalous electrical transport properties of a Ni-TiO2 hybrid system displaying a unique nanostructured morphology. The system undergoes an insulator to metal transition below 150 K with a low temperature metallic phase that shows negative resistance in a four-probe configuration. Temperature dependent transport measurements and numerical modelling show that the anomalies originate from the dendritic architecture of the TiO2 backbone interspersed with Ni nanoparticles that paradoxically renders this polycrystalline, heterogeneous system highly anisotropic. The study critiques inferences that may be drawn from four-probe transport measurements and offers valuable insights into modelling conductivity of anisotropic hybrid materials.

Published
2023

2. Anomalous Photoresponse in a Reduced Metal-Semiconductor Hybrid of Nickel and Titanium Oxide

Author

G., Harikrishnan, Bandopadhyay, K., Kolodziejak, K., Kamble, Vinayak B., Pawlak, Dorota A., and Mitra, J.

Subjects
Physics - Applied Physics
Abstract

Eutectic NiTiO$_3$-TiO$_2$ samples and their H$_2$ reduced Ni-TiO$_2$ samples, where high aspect ratio TiO$_2$ nanostructures are axially decorated with nodular Ni globules, are thoroughly explored to understand their effect in photo-response. We show that by employing this novel eutectic architecture, effectively exploiting the nano-structuring process along with the chosen material properties, the overall efficiency of the ensuing photoactive device is improved. We also show the competing photo-driven and photothermal-driven carrier mechanisms to define the total photo-response of the system. Additionally, the ability to function self-powered poses this approach as a potential strategy for achieving efficient photodetectors.

Published
2023

7. Tb3Sc2Al3O12-TbScO3 eutectic self-organized microstructure for metamaterials and photonic crystals application.

Author

Kołodziejak, K., Turczyński, S., Diduszko, R., Klimek, L., and Pawlak, D.

Abstract

Eutectics are the materials with foreseen application in the field of photonic crystals and metamaterials. In this paper, the dependence on chemical composition of the microstructures of terbium-scandium-aluminium gamet and terbium-scandium perovskite (Tb3Sc2Al3O12-TbScO3) eutectics has been studied. The growth of the eutectic rods by the micro-pulling down method is presented, using compositions with several different volume fractions of the garnet and the perovskite phases, VTSAG:VTSP = 4, 3, 2, 1, 1/2. The phases have been characterized by powder X-ray diffraction and energy dispersive spectrometry. The relationship between the lattice constant of individual phases and the chemical composition is presented. The unidirectional growth of microrods has been also investigated by electron backscattering diffraction. [ABSTRACT FROM AUTHOR]

Published
2006
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8. Intensity of optical transitions of Er3+ in Yb3Al5O12 crystal

Author

Kaczkan, M., Borowska, M., Kołodziejak, K., Łukasiewicz, T., and Malinowski, M.

Subjects
*SPECTRUM analysis, *ERBIUM, *CRYSTALS, *WAVELENGTHS
Abstract

Abstract: An analysis of the optical transitions in Er3+ ions located in Yb3Al5O12 (YbAG) crystal is given. The room temperature absorption spectrum from the UV to IR wavelength region have been measured and discussed. The intensity parameters of Er3+ in investigated host were evaluated using the Judd–Ofelt theory to be Ω 2 =0.27×10−20, Ω 4 =0.90×10−20, Ω 6 =1.16×10−20 cm2 and compared with the values for the YAG:Er3+ and other erbium doped laser materials. Based on the obtained results the radiative transition probability, branching ratios and radiative lifetimes of the excited states of Er3+ in YbAG were calculated. [Copyright &y& Elsevier]

Published
2008
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9. XPS study of PrAlO3–PrAl11O18 and PrAlO3–Pr2O3 eutectics

Author

Kruczek, M., Talik, E., Pawlak, D.A., Kołodziejak, K., and Łukasiewicz, T.

Subjects
*ALUMINUM, *LIGHT metals, *ALUMINUM alloying
Abstract

Abstract: The praseodymium-aluminium perovskite–praseodymium oxide, PrAlO3–Pr2O3, and praseodymium-aluminium perovskite–praseodymium hexaluminate, PrAlO3–PrAl11O18, eutectics have been recently obtained by the micro-pulling down method. The aim of this work was determination of the chemical composition and electronic structure examination of the above-mentioned eutectics. [Copyright &y& Elsevier]

Published
2007
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