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Monks MJ, Würth C, Kemnitz E, Resch-Genger U. Dopant ion concentration-dependent upconversion luminescence of cubic SrF 2:Yb 3+,Er 3+ nanocrystals prepared by a fluorolytic sol-gel method. NANOSCALE 2022; 14:11590-11599. [PMID: 35856187 DOI: 10.1039/d2nr02337g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A fluorolytic sol-gel method was used for the fast and simple synthesis of small cubic-phase SrF2:Yb3+,Er3+ upconversion (UC) nanocrystals (UCNC) of different composition at room temperature. Systematic studies of the crystal phase and particle size of this Yb3+,Er3+-concentration series as well as excitation power density (P)-dependent UC luminescence (UCL) spectra, UCL quantum yields (ΦUCL), and UCL decay kinetics yielded maximum UCL performance for doping amounts of Yb3+ of 13.5% and Er3+ of 1.3% in the studied doping and P-range (30-400 W cm-2). Furthermore, ΦUCL were determined to be similar to popular β-NaYF4:Yb3+,Er3+. The relative spectral UCL distributions revealed that all UCNC show a strong red emission in the studied doping and P-range (30-400 W cm-2) and suggest that the UCL quenching pathway for unshelled cubic-phase SrF2:Yb3+,Er3+ UCNC differs from the commonly accepted population and depopulation pathways of β-NaYF4:Yb3+,Er3+ UCNC. In SrF2:Yb3+,Er3+ UCNC the 4S3/2 → 4I13/2 transition exhibits a notably stronger sensitivity towards P and reveals increasing values for decreasing Yb3+-Yb3+ distances while the 4I9/2 → 4I15/2 transition is significantly less affected by P and energy migration facilitated UCL quenching. These results emphasize the complexity of the UC processes and the decisive role of the crystal phase and symmetry of the host lattice on the operative UCL quenching mechanism in addition to surface effects. Moreover, the room temperature UCNC synthesis enabled a systematic investigation of the influence of the calcination temperature on the crystal phase of powder-UCNC and the associated UCL properties. Calcination studies of solid UCNC of optimized doping concentration in the temperature range of 175 °C and 800 °C showed the beneficial influence of temperature-induced healing of crystal defects on UCL and the onset of a phase separation connected with the oxygenation of the lanthanide ions at elevated temperature. This further emphasizes the sensitivity of the UC process to the crystal phase and quality of the host matrix.
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Affiliation(s)
- Melissa-Jane Monks
- Federal Institute for Materials Research and Testing (BAM), Division Biophotonics, Richard-Willstätter-Str. 11, D-12489 Berlin, Germany.
- School of Analytical Sciences Adlershof SALSA, Humboldt-Universität zu Berlin, Albert-Einstein-Straße 5-11, 12489 Berlin, Germany
| | - Christian Würth
- Federal Institute for Materials Research and Testing (BAM), Division Biophotonics, Richard-Willstätter-Str. 11, D-12489 Berlin, Germany.
| | - Erhard Kemnitz
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor-Straße 2, 12489 Berlin, Germany
| | - Ute Resch-Genger
- Federal Institute for Materials Research and Testing (BAM), Division Biophotonics, Richard-Willstätter-Str. 11, D-12489 Berlin, Germany.
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Abstract
AbstractThe recently developed fluorolytic sol–gel route to metal fluorides opens a very broad range of both scientific and technical applications of the accessible high surface area metal fluorides, many of which have already been applied or tested. Specific chemical properties such as high Lewis acidity and physical properties such as high surface area, mesoporosity and nanosize as well as the possibility to apply metal fluorides on surfaces via a non-aqueous sol make the fluorolytic synthesis route a very versatile one. The scope of its scientific and technical use and the state of the art are presented.
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Brites CDS, Kuznetsov SV, Konyushkin VA, Nakladov AN, Fedorov PP, Carlos LD. Simultaneous Measurement of the Emission Quantum Yield and Local Temperature: The Illustrative Example of SrF
2
:Yb
3+
/Er
3+
Single Crystals. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000113] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Carlos D. S. Brites
- Phantom‐g CICECO – Aveiro Institute of Materials Department of Physics Universidade de Aveiro 3810‐193 Aveiro Portugal
| | - Sergey V. Kuznetsov
- CICECO – Aveiro Institute of Materials Prokhorov General Physics Institute of the Russian Academy of Sciences 119991 Moscow Russia
| | - Vasilii A. Konyushkin
- CICECO – Aveiro Institute of Materials Prokhorov General Physics Institute of the Russian Academy of Sciences 119991 Moscow Russia
| | - Andrey N. Nakladov
- CICECO – Aveiro Institute of Materials Prokhorov General Physics Institute of the Russian Academy of Sciences 119991 Moscow Russia
| | - Pavel P. Fedorov
- CICECO – Aveiro Institute of Materials Prokhorov General Physics Institute of the Russian Academy of Sciences 119991 Moscow Russia
| | - Luís D. Carlos
- Phantom‐g CICECO – Aveiro Institute of Materials Department of Physics Universidade de Aveiro 3810‐193 Aveiro Portugal
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Kaawar Z, Paulus B. Adsorption of hydrogen fluoride on alkaline earth fluoride surfaces: A first-principles study. J Fluor Chem 2019. [DOI: 10.1016/j.jfluchem.2018.09.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abstract
By applying first principles density functional theory (DFT) methods, different metal fluorides and their surfaces have been characterized. One of the most investigated metal fluorides is AlF3 in different polymorphs. Its chloride-doped analogon AlClxF3−x (ACF) has recently attracted much attention due to its application in catalysis. After presenting a summary of different first-principle studies on the bulk and surface properties of different main group fluorides, we will revisit the problem of the stability of different α -AlF3 surfaces and extend the investigation to chloride-doped counterparts to simulate the surface properties of amorphous ACF. For each material, we have considered ten different surface cuts with their respective terminations. We found that terminations of ( 01 1 ¯ 0 ) and ( 11 2 ¯ 0 ) yield the most stable surfaces for α -AlF3 and for the chlorine substituted surfaces. A potential equilibrium shape of the crystal for both α -AlF3 and ACF is visualized by a Wulff construction.
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Kaawar Z, Mahn S, Kemnitz E, Paulus B. On the Morphology of Group II Metal Fluoride Nanocrystals at Finite Temperature and Partial Pressure of HF. Molecules 2017; 22:molecules22040663. [PMID: 28430134 PMCID: PMC6154342 DOI: 10.3390/molecules22040663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/03/2017] [Accepted: 04/14/2017] [Indexed: 11/16/2022] Open
Abstract
We have investigated the bulk and surface properties of the group II metal fluorides CaF2, SrF2 and BaF2 using periodic density functional theory (DFT) calculations and surface thermodynamics. Our bulk results show that the best agreement with experiment is achieved with the B3LYP and PBE functionals. We determined the relative importance of the low index surfaces in vacuum and found that an fluoride microcrystal exposes only the (111) surface in which the undercoordinated cations are sevenfold coordinated. With methods of ab initio surface thermodynamics, we analyzed the stability of different surfaces under hydrogen fluoride (HF) pressure and determined the presumable shape of the crystals with respect to different HF concentrations and temperatures. In the case of CaF2 and SrF2, the calculated shapes of the crystals agree well with TEM images of fluorolytic sol-gel synthesized nanocrystals at room temperature and high HF concentration.
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Affiliation(s)
- Zeinab Kaawar
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
| | - Stefan Mahn
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany.
| | - Erhard Kemnitz
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany.
| | - Beate Paulus
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
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Pak АM, Ermakova JA, Kuznetsov SV, Ryabova AV, Pominova DV, Voronov VV. Efficient visible range SrF2:Yb:Er- and SrF2:Yb:Tm-based up-conversion luminophores. J Fluor Chem 2017. [DOI: 10.1016/j.jfluchem.2016.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ritter B, Haida P, Fink F, Krahl T, Gawlitza K, Rurack K, Scholz G, Kemnitz E. Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF2, SrF2 and BaF2 nanoparticles – structure and luminescence. Dalton Trans 2017; 46:2925-2936. [DOI: 10.1039/c6dt04711d] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu3+ and Tb3+ doped CaF2, SrF2 and BaF2 particles via the fluorolytic sol–gel synthesis route is presented.
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Affiliation(s)
- Benjamin Ritter
- Humboldt-Universität zu Berlin
- Institut für Chemie
- D-12489 Berlin
- Germany
| | - Philipp Haida
- Humboldt-Universität zu Berlin
- Institut für Chemie
- D-12489 Berlin
- Germany
| | - Friedrich Fink
- Humboldt-Universität zu Berlin
- Institut für Chemie
- D-12489 Berlin
- Germany
| | - Thoralf Krahl
- Humboldt-Universität zu Berlin
- Institut für Chemie
- D-12489 Berlin
- Germany
- Nanofluor GmbH
| | - Kornelia Gawlitza
- Bundesanstalt für Materialforschung und -prüfung (BAM)
- Fachbereich Chemische und optische Sensorik
- D-12489 Berlin
- Germany
| | - Knut Rurack
- Bundesanstalt für Materialforschung und -prüfung (BAM)
- Fachbereich Chemische und optische Sensorik
- D-12489 Berlin
- Germany
| | - Gudrun Scholz
- Humboldt-Universität zu Berlin
- Institut für Chemie
- D-12489 Berlin
- Germany
| | - Erhard Kemnitz
- Humboldt-Universität zu Berlin
- Institut für Chemie
- D-12489 Berlin
- Germany
- Nanofluor GmbH
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Navarro L, Mogosanu DE, de Jong T, Bakker AD, Schaubroeck D, Luna J, Rintoul I, Vanfleteren J, Dubruel P. Poly(polyol sebacate) Elastomers as Coatings for Metallic Coronary Stents. Macromol Biosci 2016; 16:1678-1692. [PMID: 27500500 DOI: 10.1002/mabi.201600105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/15/2016] [Indexed: 11/06/2022]
Abstract
Biocompatible polymeric coatings for metallic stents are desired, as currently used materials present limitations such as deformation during degradation and exponential loss of mechanical properties after implantation. These concerns, together with the present risks of the drug-eluting stents, namely, thrombosis and restenosis, require new materials to be studied. For this purpose, novel poly(polyol sebacate)-derived polymers are investigated as coatings for metallic stents. All pre-polymers reveal a low molecular weight between 3000 and 18 000 g mol-1 . The cured polymers range from flexible to more rigid, with E-modulus between 0.6 and 3.8 MPa. Their advantages include straightforward synthesis, biodegradability, easy processing through different scaffolding techniques, and easy transfer to industrial production. Furthermore, electrospraying and dip-coating procedures are used as proof-of-concept to create coatings on metallic stents. Biocompatibility tests using adipose stem cells lead to promising results for the use of these materials as coatings for metallic coronary stents.
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Affiliation(s)
- Lucila Navarro
- Centro Científico Tecnológico, Ruta Nacional 168, Paraje El Pozo 3000, Santa Fe, Argentina
| | - Diana-Elena Mogosanu
- Polymer Chemistry and Biomaterials Research Group, Ghent University, Krijgslaan 281, Building S4, Ghent, 9000, Belgium.,Center for Microsystem Technology, Ghent University, Technologiepark - iGent floor 6e, Gent-Zwijnaarde, 9052, Belgium
| | - Thijs de Jong
- Academic Centre for Dentistry Amsterdam, Department of Oral Cell Biology, Gustav Mahlerlaan 3004 - Room 11N43, 1081, LA Amsterdam, The Netherlands
| | - Astrid D Bakker
- Academic Centre for Dentistry Amsterdam, Department of Oral Cell Biology, Gustav Mahlerlaan 3004 - Room 11N43, 1081, LA Amsterdam, The Netherlands
| | - David Schaubroeck
- Center for Microsystem Technology, Ghent University, Technologiepark - iGent floor 6e, Gent-Zwijnaarde, 9052, Belgium
| | - Julio Luna
- Centro Científico Tecnológico, Ruta Nacional 168, Paraje El Pozo 3000, Santa Fe, Argentina
| | - Ignacio Rintoul
- Centro Científico Tecnológico, Ruta Nacional 168, Paraje El Pozo 3000, Santa Fe, Argentina
| | - Jan Vanfleteren
- Center for Microsystem Technology, Ghent University, Technologiepark - iGent floor 6e, Gent-Zwijnaarde, 9052, Belgium
| | - Peter Dubruel
- Polymer Chemistry and Biomaterials Research Group, Ghent University, Krijgslaan 281, Building S4, Ghent, 9000, Belgium
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Kemnitz E, Noack J. The non-aqueous fluorolytic sol-gel synthesis of nanoscaled metal fluorides. Dalton Trans 2016; 44:19411-31. [PMID: 25952312 DOI: 10.1039/c5dt00914f] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review article focuses on the mechanism of the non-aqueous fluorolytic sol gel-synthesis of nanoscopic metal fluorides and hydroxide fluorides. Based on MAS-NMR, XRD, WAXS and SAXS investigations in combination with computational calculations, it is shown that a stepwise replacement of alkoxide by F-ions takes place resulting in the formation of a large variety of metal alkoxide fluoride clusters, some of them being isolated and structurally characterised. It is shown that these nanoscopic metal fluorides obtained via this new synthesis approach exhibit distinctly different properties compared with their classically prepared homologues. Thus, extremely strong solid Lewis acids are available which give access to new catalytic reactions with sometimes unexpectedly high conversion degrees and selectivity. Even more interestingly, metal hydroxide fluorides can be obtained via this synthesis route that are not accessible via any other approach for which the hydroxide to fluoride ratios can be adjusted over a wide range. Optically fully transparent sols obtained in this way can be used for the first time to manufacture antireflective coatings, corundum ceramics with drastically improved properties as well as novel metal fluoride based organic-inorganic composites. The properties of these new fluoride based materials are presented and discussed in context with the above mentioned new fields of application.
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Affiliation(s)
- Erhard Kemnitz
- Humboldt-Universität zu Berlin, Chemistry Department, Brook-Taylor-Str. 2, D12489 Berlin, Germany.
| | - Johannes Noack
- Humboldt-Universität zu Berlin, Chemistry Department, Brook-Taylor-Str. 2, D12489 Berlin, Germany.
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Scholz G, Dreger M, Bertram R, Kemnitz E. Nanoscopic yttrium oxide fluorides: non-aqueous fluorolytic sol-gel synthesis and structural insights by 19F and 89Y MAS NMR. Dalton Trans 2015; 44:13522-9. [PMID: 26133504 DOI: 10.1039/c5dt00710k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nanoscopic yttrium acetate fluorides Y(CH(3)COO)(3-z)F(z) and yttrium oxide fluorides YO(3-z)/(2)F(z )were prepared with tunable Y/F molar ratios via the fluorolytic sol-gel route. All samples were characterized by X-ray diffraction, elemental analysis and thermal analysis. In addition, local structures of all samples were studied by (19)F MAS, (19)F-(89)Y CP MAS and (1)H-(89)Y CP MAS NMR spectroscopy and the respective chemical shifts are given. For both classes of compounds, only the fluorination using one equivalent of F (z = 1) leads to defined, well crystalline matrices: yttrium acetate fluoride Y(CH(3)COO)(2)F and r-YOF.
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Affiliation(s)
- G Scholz
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook - Taylor - Strasse 2, D - 12489 Berlin, Germany.
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