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Publications (10 of 12) Show all publications
Gavilán, H., Kowalski, A., Heinke, D., Sugunan, A., Sommertune, J., Varón, M., . . . Morales, M. P. (2017). Colloidal Flower-Shaped Iron Oxide Nanoparticles: Synthesis Strategies and Coatings. Particle & particle systems characterization, 34(7), Article ID 1700094.
Open this publication in new window or tab >>Colloidal Flower-Shaped Iron Oxide Nanoparticles: Synthesis Strategies and Coatings
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2017 (English)In: Particle & particle systems characterization, ISSN 0934-0866, E-ISSN 1521-4117, Vol. 34, no 7, article id 1700094Article in journal (Refereed) Published
Abstract [en]

The assembly of magnetic cores into regular structures may notably influence the properties displayed by a magnetic colloid. Here, key synthesis parameters driving the self-assembly process capable of organizing colloidal magnetic cores into highly regular and reproducible multi-core nanoparticles are determined. In addition, a self-consistent picture that explains the collective magnetic properties exhibited by these complex assemblies is achieved through structural, colloidal, and magnetic means. For this purpose, different strategies to obtain flower-shaped iron oxide assemblies in the size range 25–100 nm are examined. The routes are based on the partial oxidation of Fe(OH)2, polyol-mediated synthesis or the reduction of iron acetylacetonate. The nanoparticles are functionalized either with dextran, citric acid, or alternatively embedded in polystyrene and their long-term stability is assessed. The core size is measured, calculated, and modeled using both structural and magnetic means, while the Debye model and multi-core extended model are used to study interparticle interactions. This is the first step toward standardized protocols of synthesis and characterization of flower-shaped nanoparticles.

Keywords
colloids, magnetic properties, magnetite, nanoflowers, self-assembly, Association reactions, Iron, Iron compounds, Iron oxides, Magnetic cores, Magnetism, Nanoparticles, Self assembly, Synthesis (chemical), Inter-particle interaction, Iron acetylacetonate, Iron oxide nanoparticle, Long term stability, Polyol-mediated synthesis, Self assembly process, Synthesis and characterizations, Synthesis parameters, Nanomagnetics
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-30284 (URN)10.1002/ppsc.201700094 (DOI)2-s2.0-85020161573 (Scopus ID)
Note

 This work was partially supported by the European Commission Framework Program 7 (NanoMag project, NO 604448) and by the Spanish Ministry of Economy and Competitiveness (Mago project, No. MAT2014-52069-R).

Available from: 2017-08-11 Created: 2017-08-11 Last updated: 2019-06-27Bibliographically approved
Lobov, G. S., Marinins, A., Etcheverry, S., Zhao, Y., Vasileva, E., Sugunan, A., . . . Popov, S. (2017). Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component. Optical Materials Express, 7(1), 52-61
Open this publication in new window or tab >>Direct birefringence and transmission modulation via dynamic alignment of P3HT nanofibers in an advanced opto-fluidic component
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2017 (English)In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 7, no 1, p. 52-61Article in journal (Refereed) Published
Abstract [en]

Poly-3-hexylthiophene (P3HT) nanofibers are semiconducting high-aspect ratio nanostructures with anisotropic absorption and birefringence properties found at different regions of the optical spectrum. In addition, P3HT nanofibers possess an ability to be aligned by an external electric field, while being dispersed in a liquid. In this manuscript we show that such collective ordering of nanofibers, similar to liquid crystal material, significantly changes the properties of transmitted light. With a specially fabricated opto-fluidic component, we monitored the phase and transmission modulation of light propagating through the solution of P3HT nanofibers, being placed in the electric field with strength up to 0.1 V/μm. This report describes a technique for light modulation, which can be implemented in optical fiber-based devices or on-chip integrated components.

Keywords
Absorption spectroscopy, Aspect ratio, Birefringence, Electric fields, Light modulation, Liquid crystals, Modulation, Nanofibers, Optical fiber fabrication, Optical fibers, Anisotropic absorption, Birefringence property, External electric field, Fiber-based device, High aspect ratio nano-structures, Liquid crystal materials, Poly-3-hexylthiophene, Transmission modulation, Light transmission
National Category
Physical Sciences
Identifiers
urn:nbn:se:ri:diva-29201 (URN)10.1364/OME.7.000052 (DOI)2-s2.0-85008157720 (Scopus ID)
Note

Export Date: 3 April 2017; Article

Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2019-01-03Bibliographically approved
Bender, P., Bogart, L. K., Posth, O., Szczerba, W., Rogers, S. E., Castro, A., . . . Johansson, C. (2017). Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method. Scientific Reports, 7, Article ID 45990.
Open this publication in new window or tab >>Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 45990Article in journal (Refereed) Published
Abstract [en]

The structural and magnetic properties of magnetic multi-core particles were determined by numerical inversion of small angle scattering and isothermal magnetisation data. The investigated particles consist of iron oxide nanoparticle cores (9 nm) embedded in poly(styrene) spheres (160 nm). A thorough physical characterisation of the particles included transmission electron microscopy, X-ray diffraction and asymmetrical flow field-flow fractionation. Their structure was ultimately disclosed by an indirect Fourier transform of static light scattering, small angle X-ray scattering and small angle neutron scattering data of the colloidal dispersion. The extracted pair distance distribution functions clearly indicated that the cores were mostly accumulated in the outer surface layers of the poly(styrene) spheres. To investigate the magnetic properties, the isothermal magnetisation curves of the multi-core particles (immobilised and dispersed in water) were analysed. The study stands out by applying the same numerical approach to extract the apparent moment distributions of the particles as for the indirect Fourier transform. It could be shown that the main peak of the apparent moment distributions correlated to the expected intrinsic moment distribution of the cores. Additional peaks were observed which signaled deviations of the isothermal magnetisation behavior from the non-interacting case, indicating weak dipolar interactions.

National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-29602 (URN)10.1038/srep45990 (DOI)2-s2.0-85017457020 (Scopus ID)
Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2019-06-27Bibliographically approved
Lobov, G. S., Zhao, Y., Marinins, A., Yan, M., Li, J., Sugunan, A., . . . Popov, S. (2016). Dynamic manipulation of optical anisotropy of suspended Poly-3-hexylthiophene nanofibers. Advanced Optical Materials, 4(10), 1651-1656
Open this publication in new window or tab >>Dynamic manipulation of optical anisotropy of suspended Poly-3-hexylthiophene nanofibers
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2016 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 4, no 10, p. 1651-1656Article in journal (Refereed) Published
Abstract [en]

Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications.​.

Keywords
anisotropic optical materials, electrooptical materials, nanofibers, optical properties, polymers, Anisotropy, Birefringence, Electric fields, Optical anisotropy, Optical fibers, Refractive index, Alternating electric field, Electric birefringence, Electro-optical applications, External electric field, Quadrupole configuration, Semiconducting nanostructures, Transmission ellipsometry
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics Composite Science and Engineering Materials Chemistry
Identifiers
urn:nbn:se:ri:diva-27605 (URN)10.1002/adom.201600226 (DOI)2-s2.0-84979574389 (Scopus ID)
Available from: 2016-12-22 Created: 2016-12-21 Last updated: 2019-06-13Bibliographically approved
Lobov, G. S., Zhao, Y., Marinins, A., Yan, M., Li, J., Sugunan, A., . . . Popov, S. (2016). Size impact of ordered P3HT nanofibers on optical anisotropy. Macromolecular Chemistry and Physics, 217(9), 1089-1095
Open this publication in new window or tab >>Size impact of ordered P3HT nanofibers on optical anisotropy
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2016 (English)In: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 217, no 9, p. 1089-1095Article in journal (Refereed) Published
Abstract [en]

Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline structures with semiconductor properties. When P3HT nanofibers are dispersed in nonconducting solvent, they react to external alternate electric field by aligning along the field lines. This can be used to create layers of ordered nanofibers and is referred to as alternating current poling method. P3HT nanofibers with three different size distributions are fabricated, using self-assembly mechanism in marginal solvents, and used for the alignment studies. Anisotropic absorption of oriented 2 μm long nanofibers exponentially increases with the magnitude of applied field to a certain asymptotic limit at 0.8 V μm-1, while 100-500 nm long nanofibers respond to electric field negligibly. Effective optical birefringence of oriented 2 μm long nanofibers is calculated, based on the phase shift at 633 nm and the average layer thickness, to be 0.41. These results combined with further studies on real-time control over orientation of P3HT nanofibers in liquid solution or host system are promising in terms of exploiting them in electroabsorptive and electrorefractive applications.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2016
Keywords
anisotropic optical materials, electro-optical materials, optical properties, polymers
National Category
Physical Chemistry Atom and Molecular Physics and Optics Other Chemistry Topics
Identifiers
urn:nbn:se:ri:diva-126 (URN)10.1002/macp.201500516 (DOI)2-s2.0-84964734770 (Scopus ID)
Available from: 2016-06-02 Created: 2016-05-31 Last updated: 2019-06-18Bibliographically approved
Zhao, Y., Sugunan, A., Wang, Q., Yang, X., Rihtnesberg, D. B. & Toprak, M. S. (2015). Direct Determination of Spatial Localization of Carriers in CdSe-CdS Quantum Dots. Journal of Nanomaterials, 2015, Article ID 321354.
Open this publication in new window or tab >>Direct Determination of Spatial Localization of Carriers in CdSe-CdS Quantum Dots
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2015 (English)In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2015, article id 321354Article in journal (Refereed) Published
Abstract [en]

Colloidal quantum dots (QDs) have gained significant attention due to their tunable band gap, simple solution processability, ease of scale-up, and low cost. By carefully choosing the materials, core-shell heterostructure QDs (HQDs) can be further synthesized with a controlled spatial spread of wave functions of the excited electrons and holes for various applications. Many investigations have been done to understand the exciton dynamics by optical characterizations. However, these spectroscopic data demonstrate that the spatial separation of the excitons cannot distinguish the distribution of excited electrons and holes. In this work, we report a simple and direct method to determine the localized holes and delocalized electrons in HQDs. The quasi-type-II CdSe-CdS core-shell QDs were synthesized via a thermolysis method. Poly(3-hexylthiophene) (P3HT) nanofiber and ZnO nanorods were selected as hole and electron conductor materials, respectively, and were combined with HQDs to form two different nanocomposites. Photoelectrical properties were evaluated under different environments via a quick and facile characterization method, confirming that the electrons in the HQDs were freely accessible at the surface of the nanocrystal, while the holes were confined within the CdSe core.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2015
National Category
Nano Technology Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:ri:diva-172 (URN)10.1155/2015/321354 (DOI)2-s2.0-84941255127 (Scopus ID)
Note

Publication no: A3584

Available from: 2016-06-20 Created: 2016-06-07 Last updated: 2019-07-03Bibliographically approved
Lobov, G. S., Zhao, Y., Marinins, A., Yan, M., Li, J., Toprak, M. S., . . . Popov, S. (2015). Electric field induced optical anisotropy of P3HT nanofibers in a liquid solution. Optical Materials Express, 5(11), 2642-2647
Open this publication in new window or tab >>Electric field induced optical anisotropy of P3HT nanofibers in a liquid solution
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2015 (English)In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 5, no 11, p. 2642-2647Article in journal (Refereed) Published
Abstract [en]

The nanofiber morphology of regioregular Poly-3- hexylthiophene (P3HT) is a 1D crystalline structure organized by π - π stacking of the backbone chains. In this study, we report the impact of electric field on the orientation and optical properties of P3HT nanofibers dispersed in liquid solution. We demonstrate that alternating electric field aligns nanofibers, whereas static electric field forces them to migrate towards the cathode. The alignment of nanofibers introduces anisotropic optical properties, which can be dynamically manipulated until the solvent has evaporated. Time resolved spectroscopic measurements revealed that the electro-optical response time decreases significantly with the magnitude of applied electric field. Thus, for electric field 1.3 V ·μm-1 the response time was measured as low as 20 ms, while for 0.65 V ·μm-1 it was 110-150 ms. Observed phenomenon is the first mention of P3HT supramolecules associated with electrooptical effect. Proposed method provides real time control over the orientation of nanofibers, which is a starting point for a novel practical implementation. With further development P3HT nanofibers can be used individually as an anisotropic solution or as an active component in a guest-host system.

Place, publisher, year, edition, pages
Optical Society of America, 2015
National Category
Atom and Molecular Physics and Optics Materials Chemistry
Identifiers
urn:nbn:se:ri:diva-165 (URN)10.1364/OME.5.002642 (DOI)2-s2.0-84947753945 (Scopus ID)
Note

Publication no: A3598

Available from: 2016-06-18 Created: 2016-06-07 Last updated: 2019-07-03Bibliographically approved
Lobov, G. S., Zhao, Y., Marinins, A., Yan, M., Li, J., Toprak, M. S., . . . Popov, S. (2015). Electro-optical response of P3HT nanofibers in liquid solution. In: Asia Communications and Photonics Conference 2015: . Paper presented at Asia Communications and Photonics Conference (ACPC 2015), November 19-23, 2015, Hong Kong, Hong Kong. Optical Society of America, Article ID ASu1A.5.
Open this publication in new window or tab >>Electro-optical response of P3HT nanofibers in liquid solution
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2015 (English)In: Asia Communications and Photonics Conference 2015, Optical Society of America, 2015, article id ASu1A.5Conference paper, Published paper (Refereed)
Abstract [en]

AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals.

Place, publisher, year, edition, pages
Optical Society of America, 2015
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Materials Chemistry
Identifiers
urn:nbn:se:ri:diva-335 (URN)10.1364/ACPC.2015.ASu1A.5 (DOI)2-s2.0-84971612086 (Scopus ID)9781943580064 (ISBN)
Conference
Asia Communications and Photonics Conference (ACPC 2015), November 19-23, 2015, Hong Kong, Hong Kong
Note

Publication no: A3616

Available from: 2016-06-18 Created: 2016-06-17 Last updated: 2019-07-10Bibliographically approved
Sommertune, J., Sugunan, A., Ahniyaz, A., Stjernberg Bejhed, R., Sarwe, A., Johansson, C., . . . Fornara, A. (2015). Polymer/iron oxide nanoparticle composites—A straight forward and scalable synthesis approach. International Journal of Molecular Sciences, 16(8), 19752-19768
Open this publication in new window or tab >>Polymer/iron oxide nanoparticle composites—A straight forward and scalable synthesis approach
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2015 (English)In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 16, no 8, p. 19752-19768Article in journal (Refereed) Published
Abstract [en]

Magnetic nanoparticle systems can be divided into single-core nanoparticles (with only one magnetic core per particle) and magnetic multi-core nanoparticles (with several magnetic cores per particle). Here, we report multi-core nanoparticle synthesis based on a controlled precipitation process within a well-defined oil in water emulsion to trap the superparamagnetic iron oxide nanoparticles (SPION) in a range of polymer matrices of choice, such as poly(styrene), poly(lactid acid), poly(methyl methacrylate), and poly(caprolactone). Multi-core particles were obtained within the Z-average size range of 130 to 340 nm. With the aim to combine the fast room temperature magnetic relaxation of small individual cores with high magnetization of the ensemble of SPIONs, we used small (<10 nm) core nanoparticles. The performed synthesis is highly flexible with respect to the choice of polymer and SPION loading and gives rise to multi-core particles with interesting magnetic properties and magnetic resonance imaging (MRI) contrast efficacy.

Place, publisher, year, edition, pages
MDPI, 2015
Keywords
iron oxide nanoparticle, multi core, nanocomposite, polymer encapsulation, single core
National Category
Nano Technology Atom and Molecular Physics and Optics Materials Chemistry
Identifiers
urn:nbn:se:ri:diva-157 (URN)10.3390/ijms160819752 (DOI)2-s2.0-84939863635 (Scopus ID)
Note

Publication no: A3571

Available from: 2016-06-19 Created: 2016-06-07 Last updated: 2019-07-08Bibliographically approved
Zhao, Y., Sugunan, A., Muhammed, M. & Toprak, M. S. (2015). Synthesis of nanostructured antimony telluride for thermoelectric applications. In: Materials Research Society Symposium Proceedings: . Paper presented at 2014 MRS Fall Meeting; Boston; United States; November 30 - December 5, 2014 (pp. 1-6). , 1742
Open this publication in new window or tab >>Synthesis of nanostructured antimony telluride for thermoelectric applications
2015 (English)In: Materials Research Society Symposium Proceedings, 2015, Vol. 1742, p. 1-6Conference paper, Published paper (Refereed)
Abstract [en]

Thermoelectric (TE) materials have been studied during past decades since they can generate electricity directly from waste heat. Antimony chalcogenides (Sb2M3, M = S, Se, Te) are well known as one of the promising candidates among the inorganic TE materials. We report on the synthesis of Sb2Te3 nanoparticle via thermolysis method. A systematic study was done to investigate the effect of reaction time and ratio between the precursors as well as the method of cooling on the morphology and composition of obtained nanoparticles. The ratio between precursors was varied to study the effect on the morphology. Furthermore, the high purity phase Sb2Te3 was obtained by a rapid cooling process.

National Category
Materials Engineering
Identifiers
urn:nbn:se:ri:diva-164 (URN)10.1557/opl.2015.141 (DOI)2-s2.0-84938859140 (Scopus ID)9781510806221 (ISBN)
Conference
2014 MRS Fall Meeting; Boston; United States; November 30 - December 5, 2014
Note

Publication no: A3570

Available from: 2016-06-20 Created: 2016-06-07 Last updated: 2018-07-19Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3186-6507

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