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7. Defect-Mediated Crystallization of the Particulate TiO2Photocatalyst Grown by Atomic Layer Deposition

Author

Bhuskute, Bela D., Ali-Löytty, Harri, Saari, Jesse, Hiltunen, Arto, Ruoko, Tero-Petri, Salminen, Turkka, and Valden, Mika

Abstract

Nanopowders or films of pure and mixed oxides in nanoparticulate form have gained specific interest due to their applicability in functionalizing high-surface-area substrates. Among various other applications, our presented work primarily focuses on the behavior of TiO2as a photocatalyst deposited by atomic layer deposition (ALD) on a quartz particle. The photocatalytic activity of TiO2on quartz particles grown by ALD was studied in terms of ALD growth temperature and post-treatment heating rate. Amorphous TiO2thin films (30 nm) were grown from tetrakis(dimethylamido)titanium (TDMAT) at 100 and 200 °C on quartz particles (0.35–3.5 μm) and crystallized using oxidative heat treatment at 500 °C with variable heating rates. The growth temperature was found to affect the TiO2defect structure: TiO2grown at 200 °C is black due to Ti3+defects, whereas the film grown at 100 °C is white but contains some traces of the TDMAT ALD precursor. During the oxidative heat treatment, precursor traces desorbed and Ti3+defects were oxidized. ALD TiO2grown at 100 °C crystallized as anatase, whereas the rutile-to-anatase ratio of 200 °C grown TiO2increased with the heating rate. The hydrogen production rate of mixed-phase TiO2was found to outperform that of anatase TiO2.

Published
2025
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9. Highly ductile amorphous oxide at room temperature and high strain rate

Author

Frankberg, Erkka J., Kalikka, Janne, Ferré, Francisco García, Joly-Pottuz, Lucile, Salminen, Turkka, Hintikka, Jouko, Hokka, Mikko, Koneti, Siddardha, Douillard, Thierry, Le Saint, Bérangère, Kreiml, Patrice, Cordill, Megan J., Epicier, Thierry, Stauffer, Douglas, Vanazzi, Matteo, Roiban, Lucian, Akola, Jaakko, Di Fonzo, Fabio, Levänen, Erkki, and Masenelli-Varlot, Karine

Published
2019

16. High-Entropy Carbides: Processing And Characterization

Author

George Mathews, Nidhin, primary, Lagerbom, Juha, additional, Laakso, Jarmo, additional, Salminen, Turkka, additional, Honkanen, Mari, additional, Lindroos, Tomi, additional, Laukkanen, Anssi, additional, Huttunen-Saarivirta, Elina, additional, and Mohanty, Gaurav, additional

Published
2023
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17. Exceptional Microscale Plasticity in Amorphous Aluminum Oxide at Room Temperature

Author

Frankberg, Erkka J., primary, Lambai, Aloshious, additional, Zhang, Jiahui, additional, Kalikka, Janne, additional, Khakalo, Sergei, additional, Paladino, Boris, additional, Cabrioli, Mattia, additional, Mathews, Nidhin G., additional, Salminen, Turkka, additional, Hokka, Mikko, additional, Akola, Jaakko, additional, Kuronen, Antti, additional, Levänen, Erkki, additional, Fonzo, Fabio Di, additional, and Mohanty, Gaurav, additional

Published
2023
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19. Mikroskopiakonferenssi Scandem 2022

Author

Honkanen, Mari, Salminen, Turkka, Valtonen, Kati, Vippola, Minnamari, Tampere University, Materiaalitiede ja ympäristötekniikka, and Fysiikka

Subjects
216 Materiaalitekniikka
Abstract

publishedVersion

Published
2022

27. Controlling the phase of iron oxide nanoparticles fabricated from iron(III) nitrate by liquid flame spray

Author

Sorvali, Miika, Nikka, Markus, Juuti, Paxton, Honkanen, Mari, Salminen, Turkka, Hyvärinen, Leo, Mäkelä, Jyrki M., Tampere University, Physics, Doctoral Programme in Engineering and Natural Sciences, Research group: Aerosol Synthesis, Research area: Aerosol Physics, Research group: Materials Characterization, Materials Science and Environmental Engineering, and Research group: Applied Material Science

Subjects
216 Materials engineering
Abstract

Iron oxide nanoparticles were synthesized in a liquid flame spray process from iron(III) nitrate. The choice of chemicals and all other process parameters affects the crystallographic phase composition and the quality of the material. Adjustment of the solvent composition and the gas flow rates was used to control the phase composition of the produced particles. All samples consisted of pure maghemite (γ‐Fe2O3) or a mixture of maghemite and hematite (α‐Fe2O3). When using pure alcohols as solvents, the maghemite/hematite phase ratio could be adjusted by changing the equivalence ratio that describes the oxidation conditions in the flame zone. A large residual particle mode formed in the size range of ~20‐700 nm along with a dominant very fine particle mode (2‐8 nm). Both phases seemed to contain large particles. A partial substitution of methanol with carboxylic acids turned the hematite phase into maghemite completely, even though some of particles were possibly not fully crystallized. Residual particles were still present, but their size and number could be decreased by raising the heat of combustion of the precursor solution. 30 vol‐% substitution of methanol with 2‐ethylhexanoic acid was adequate to mostly erase the large particles. publishedVersion

Published
2019

30. An Unexpected Role of Hyaluronic Acid in Trafficking siRNA Across the Cellular Barrier: The First Biomimetic, Anionic, Non‐Viral Transfection Method

Author

Paidikondala, Maruthibabu, primary, Rangasami, Vignesh Kumar, additional, Nawale, Ganesh N., additional, Casalini, Tommaso, additional, Perale, Giuseppe, additional, Kadekar, Sandeep, additional, Mohanty, Gaurav, additional, Salminen, Turkka, additional, Oommen, Oommen P., additional, and Varghese, Oommen P., additional

Published
2019
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31. An Unexpected Role of Hyaluronic Acid in Trafficking siRNA Across the Cellular Barrier : The First Biomimetic, Anionic, Non-Viral Transfection Method

Author

Paidikondala, Maruthibabu, Rangasami, Vignesh Kumar, Nawale, Ganesh N., Casalini, Tommaso, Perale, Giuseppe, Kadekar, Sandeep, Mohanty, Gaurav, Salminen, Turkka, Oommen, Oommen P., Varghese, Oommen P., Paidikondala, Maruthibabu, Rangasami, Vignesh Kumar, Nawale, Ganesh N., Casalini, Tommaso, Perale, Giuseppe, Kadekar, Sandeep, Mohanty, Gaurav, Salminen, Turkka, Oommen, Oommen P., and Varghese, Oommen P.

Abstract

Circulating nucleic acids, such as short interfering RNA (siRNA), regulate many biological processes; however, the mechanism by which these molecules enter the cell is poorly understood. The role of extracellular-matrix-derived polymers in binding siRNAs and trafficking them across the plasma membrane is reported. Thermal melting, dynamic light scattering, scanning electron microscopy, and computational analysis indicate that hyaluronic acid can stabilize siRNA via hydrogen bonding and Van der Waals interactions. This stabilization facilitated HA size- and concentration-dependent gene silencing in a CD44-positive human osteosarcoma cell line (MG-63) and in human mesenchymal stromal cells (hMSCs). This native HA-based siRNA transfection represents the first report on an anionic, non-viral delivery method that resulted in approximately 60% gene knockdown in both cell types tested, which correlated with a reduction in translation levels.

Published
2019
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32. In situ deformation of nanocrystalline Al2O3 thin films at room temperature

Author

Frankberg, Erkka J, Joly-Pottuz, Lucile, Garcia, Francisco, Salminen, Turkka, Kalikka, Janne, Siddardha Koneti, Roiban, Lucian, Douillard, Thierry, Saint, Bérangère Le, Akola, Jaakko, Levänen, Erkki, Fonzo, Fabio Di, Masenelli-Varlot, Karine, Matériaux, ingénierie et science [Villeurbanne] (MATEIS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Center for Nano Science and Technology@PoliMi, Instituto Italiano di Tecnologia, Douillard, Thierry, and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)

Subjects
[SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics], [SPI.MAT] Engineering Sciences [physics]/Materials, ComputingMilieux_MISCELLANEOUS, [SPI.MAT]Engineering Sciences [physics]/Materials
Abstract

International audience

Published
2017

36. Carbon coated TiO2 nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2.

Author

Singh, Amandeep, Salminen, Turkka, Honkanen, Mari, Nikkanen, Juha-Pekka, Vuorinen, Tommi, Kari, Risto, Vihinen, Jorma, and Levänen, Erkki

Subjects
*LASER ablation, *PULSED lasers, *NANOPARTICLES, *LASER pulses, *NANOPARTICLE size
Abstract

We report on the synthesis of TiO2 nanoparticles using nanosecond pulse laser ablation of titanium in liquid, gaseous and supercritical CO2. The produced particles were observed to be mainly anatase-TiO2 with some rutile-TiO2. In addition, the particles were covered by a carbon layer. Raman and x-ray diffraction data suggested that the rutile content increases with CO2 pressure. The nanoparticle size decreased and size distribution became narrower with the increase in CO2 pressure and temperature, however the variation trend was different for CO2 pressure compared to temperature. Pulsed laser ablation in pressurized CO2 is demonstrated as a single step method for making anatase-TiO2/carbon nanoparticles throughout the pressure and temperature ranges 5–40 MPa and 30 °C–50 °C, respectively. [ABSTRACT FROM AUTHOR]

Published
2020
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37. Carbon coated TiO2 nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2.

Author

Singh, Amandeep, Salminen, Turkka, Honkanen, Mari, Nikkanen, Juha-Pekka, Vuorinen, Tommi, Kari, Risto, Vihinen, Jorma, and Levänen, Erkki

Subjects
LASER ablation, PULSED lasers, NANOPARTICLES, LASER pulses, NANOPARTICLE size
Abstract

We report on the synthesis of TiO2 nanoparticles using nanosecond pulse laser ablation of titanium in liquid, gaseous and supercritical CO2. The produced particles were observed to be mainly anatase-TiO2 with some rutile-TiO2. In addition, the particles were covered by a carbon layer. Raman and x-ray diffraction data suggested that the rutile content increases with CO2 pressure. The nanoparticle size decreased and size distribution became narrower with the increase in CO2 pressure and temperature, however the variation trend was different for CO2 pressure compared to temperature. Pulsed laser ablation in pressurized CO2 is demonstrated as a single step method for making anatase-TiO2/carbon nanoparticles throughout the pressure and temperature ranges 5–40 MPa and 30 °C–50 °C, respectively. [ABSTRACT FROM AUTHOR]

Published
2020
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43. In situ deformation of nanocrystalline Al2O3 thin films at room temperature

Author

Frankberg, Erkka, primary, Joly-Pottuz, Lucile, additional, Garcia, Francisco, additional, Salminen, Turkka, additional, Douillard, Thierry, additional, Saint, Bérangère Le, additional, Kekkonen, Ville, additional, Chaudhuri, Saumyadip, additional, Liimatainen, Jari, additional, Fonzo, Fabio Di, additional, Levänen, Erkki, additional, and Masenelli-Varlot, Karine, additional

Published
2016
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45. Influence of powder composition and manufacturing method on electrical and chromium barrier properties of atmospheric plasma sprayed spinel coatings prepared from MnCo2O4 and Mn2CoO4 + Co powders on Crofer 22 APU interconnectors

Author

Puranen, Jouni, Pihlatie, Mikko, Lagerbom, Juha, Salminen, Turkka, Laakso, Jarmo, Hyvärinen, Leo, Kylmälahti, Mikko, Himanen, Olli, Kiviaho, Jari, and Vuoristo, Petri

Subjects
solid oxide fuel cells, metallic interconnect, ASR, ProperPart, plasma spraying, spinel coatings
Abstract

Protective coatings based on manganese cobalt oxide spinels are required in solid oxide fuel cells (SOFCs) to prevent the evaporation of volatile Cr(VI)-compounds from the metallic interconnectors and to minimize high temperature corrosion. Atmospheric plasma spraying (APS) was used to manufacture dense manganese cobalt oxide protective coatings on Crofer 22 APU substrates by employing two different spinel powders. The spray powders were MnCo2O4 and Mn2CoO4 + Co (equivalence for Mn1.5Co1.5O4). The Mn2CoO4 + Co powder was prepared by agglomerating the oxide powder with fine metallic cobalt powder. The coated substrates were oxidized at 700 °C in air for 1000 h. During the high temperature oxidation, a four-point on-line measurement technique with a current density of 640 mA/cm² was simultaneously used for area specific resistance (ASR) studies. The coatings were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), an energy dispersive spectrometer (EDS) and Raman spectroscopy. The APS coatings had dense microstructure, which decreased the oxidation of the substrate. The MnCo2O4 coating showed indication of some Cr-migration, whereas Mn2CoO4 + Co showed good Cr-barrier properties. The ASR test showed that APS coated Mn2CoO4 + Co is a promising candidate material for SOFC interconnect applications.

Published
2014
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46. Effect of Partial Crystallization on the Structural and Luminescence Properties of Er3+-Doped Phosphate Glasses.

Author

Lopez-Iscoa, Pablo, Salminen, Turkka, Hakkarainen, Teemu, Petit, Laeticia, Janner, Davide, Boetti, Nadia G., Lastusaari, Mika, Pugliese, Diego, Paturi, Petriina, and Milanese, Daniel

Subjects
*PHOSPHATE glass, *CERAMICS, *NUCLEATION, *LUMINESCENCE, *CRYSTALLIZATION
Abstract

Er-doped phosphate glass ceramics were fabricated by melt-quenching technique followed by a heat treatment. The effect of the crystallization on the structural and luminescence properties of phosphate glasses containing Al2O3, TiO2, and ZnO was investigated. The morphological and structural properties of the glass ceramics were characterized by Field Emission-Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), and micro-Raman spectroscopy. Additionally, the luminescence spectra and the lifetime values were measured in order to study the influence of the crystallization on the spectroscopic properties of the glasses. The volume ratio between the crystal and the glassy phases increased along with the duration of the heat treatment. The crystallization of the glass ceramics was confirmed by the presence of sharp peaks in the XRD patterns and different crystal phases were identified depending on the glass composition. Sr(PO3)2 crystals were found to precipitate in all the investigated glasses. As evidenced by the spectroscopic properties, the site of the Er3+ ions was not strongly affected by the heat treatment except for the fully crystallized glass ceramic which does not contain Al2O3, TiO2, and ZnO. An increase of the lifetime was also observed after the heat treatment of this glass. Therefore, we suspect that the Er3+ ions are incorporated in the precipitated crystals only in this glass ceramic [ABSTRACT FROM AUTHOR]

Published
2017
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47. Influence of powder composition and manufacturing method on electrical and chromium barrier properties of atmospheric plasma sprayed spinel coatings prepared from MnCo2O4 and Mn2CoO4 + Co powders on Crofer 22 APU interconnectors

Author

Puranen, Jouni, primary, Pihlatie, Mikko, additional, Lagerbom, Juha, additional, Salminen, Turkka, additional, Laakso, Jarmo, additional, Hyvärinen, Leo, additional, Kylmälahti, Mikko, additional, Himanen, Olli, additional, Kiviaho, Jari, additional, and Vuoristo, Petri, additional

Published
2014
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