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604 results on '"Lis, Stefan"'

1. GdBO$_3$ and YBO$_3$ Nanocrystals under Compression

Author

Turnbull, Robin, Errandonea, Daniel, Sans, Juan Ángel, Cuenca-Gotor, Vanesa Paula, Vilaplana, Rosario Isabel, Ibáñez, Jordi, Popescu, Catalin, Szczeszak, Agata, Lis, Stefan, and Manjón, Francisco Javier

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

High-pressure X-ray diffraction studies on nanocrystals of the pseudo-vaterite-type borates GdBO$_3$ and YBO$_3$ are herein reported up to 17.4(2) and 13.4(2) GPa respectively. The subsequent determination of the room-temperature pressure-volume equations of state is presented and discussed in the context of contemporary publications which contradict the findings of this work. In particular, the isothermal bulk moduli of GdBO$_3$ and YBO$_3$ are found to be 170(13) and 163(13) GPa respectively, almost 50% smaller than recent findings. Our experimental results provide an accurate revision of the high-pressure compressibility behaviour of GdBO$_3$ and YBO$_3$ which is consistent with the known systematics in isomorphic borates and previous ab initio calculations. Finally we discuss how experimental/analytical errors could have led to unreliable conclusions reported elsewhere.

Published
2020

12. GdBO3 and YBO3 crystals under compression

Author

Turnbull, Robin, Errandonea, Daniel, Sans, Juan Ángel, Cuenca-Gotor, Vanesa Paula, Vilaplana, Rosario Isabel, Ibáñez, Jordi, Popescu, Catalin, Szczeszak, Agata, Lis, Stefan, and Manjón, Francisco Javier

Published
2021
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15. Bifunctional upconverting luminescent-magnetic FeS2@NaYF4:Yb3+,Er3+ core@shell nanocomposites with tunable luminescence for temperature sensing.

Author

Woźny, Przemysław, Soler-Carracedo, Kevin, Perzanowski, Marcin, Moszczyński, Jan, Lis, Stefan, and Runowski, Marcin

Abstract

Advanced optically active materials have experienced significant development in recent years. Light-emitting materials combined with materials that exhibited magnetic properties result in bifunctional materials with an expanded range of capabilities and applications. New functionalities as a result of the core@shell structure enable interactions with the light and the external magnetic field as well. Continuous progress in materials science leads to innovations that enhance data storage and transmission, bioimaging, sensing, optical thermometry, and other applications crucial to advanced technology. In this research, we have focused on the optimization of the synthesis of a nano-sized FeS2 material as an optically active, magnetic component of the core, and NaYF4:Yb3+,Er3+ nanoparticles (NPs) as a temperature sensitive, up-conversion (UC) luminescence part of the shell. The synthesized core@shell type nanocomposite (NC) material FeS2@NaYF4:Yb3+,Er3+ exhibits simultaneously the unique features of the core and shell components. The recorded UC emission spectra under 975 nm laser excitation show the possibility of tuning the UC luminescence color with the application of a highly absorbing FeS2 component in the composite material. Moreover, the magnetic properties of the FeS2 core nanoparticles and the synthesized NC were compared to confirm the potential application of the NC as a novel bifunctional luminescent-magnetic sensing platform. For both materials the luminescence color changed with the increasing laser power density, allowing color-tunable light generation. Additionally, optical temperature sensing properties of the NPs and NC were compared, resulting in a very high relative temperature sensitivity of ∼2.0% K−1 for both materials. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Furoic Acid-Capped LaF3:Tb Nanoparticles for Al3+ Detection Based on Aggregation-Induced Luminescence Enhancement.

Author

Adusumalli, Venkata N. K. B., Woźny, Przemysław, Lis, Stefan, and Park, Yong Il

Abstract

The importance of aluminum usage in our everyday life and its adverse impact on health and the environment stimulate the development of excellent probes for the detection of Al3+ ions. In this study, we developed a luminescence enhancement-based detection probe for the selective detection of Al3+ ions. For this purpose, we developed water-dispersible 2-furoic acid-capped LaF3:5%Tb3+ nanocrystals (NCs) via the microwave irradiation method. Here, 2-furoic acid acts as a surfactant and an antenna for the Tb3+ ions. Oxygen in the furan ring has a hard base nature and prefers to bind with hard acid-natured metal ions. Upon excitation at 258 nm, the NCs show characteristic Tb3+ emissions via 2-furoic acid sensitization. The excitation and emission spectra of the NCs increased continuously with the gradual addition of Al3+ ions from 1 to 700 μm in the aqueous medium. More than 2-fold enhancement was found for 700 μM Al3+ ions. The luminescence enhancement results from aggregation caused by hard acid and hard base interactions between Al3+ ions and oxygen atoms in the furan ring. In this way, the quenching of nonradiative energy transfer by solvent molecules was reduced, and the efficiency of energy transfer from ligand to Tb3+ ions was increased. The luminescence increment is highly selective toward Al3+ ions with very minimal interference. The developed method shows a remarkably high sensitivity for Al3+ ion detection, and the calculated LOD was 1.67 μM, which is much lower than the maximum aluminum content allowable by the WHO in drinking water. Furthermore, we applied this method for the determination of Al3+ ions in actual water samples. [ABSTRACT FROM AUTHOR]

Published
2024
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