Infotech Oulu Annual Report 2016 - Electronics Materials, Packaging and Reliability Techniques (EMPART)

Professor Heli Jantunen, Microelectronics Research Unit, University of Oulu
Research Professor Pentti Karioja, VTT Oulu
heja(at)ee.oulu.fi, pentti.karioja(at)vtt.fi
http://www.infotech.oulu.fi/empart

Background and Mission

The EMPART research group is a multidisciplinary research unit. Its main activities lie in micro- and nano-electronics materials and devices. Our overall target is to research and create micro- and nanostructures ena-bling novel functionality for electronic, telecommuni-cation, energy/environmental and bio/medical devices. The group brings together all the essential know-how required to accomplish the main goal of “embedded multifunctional electronics integrations” based on 1) new, difficult-to-copy, hyper-active, high dielectric and optical performance materials, 2) most feasible, cost-aware fabrication technologies for hybrid electronics, and 3) high-end state-of-the-art electronics integrations enabling functional diversification in line with the “More-than-Moore” (MtM) concept of future electron-ics. The group is the main leader of the More-than-Moore research group that was ranked with the highest score 6 (outstanding) in the Research Assessment Ex-ercise (RAE 2013) of the University by an international panel, aided by a bibliometric analysis made by Leiden University.

The group is funded recently by the European Research Council Advanced Grant (Professor Heli Jantunen), Tekes, the EU, the Academy of Finland, ERA.Net, and by domestic and foreign industry. Global research co-operation is a characteristic feature of the EMPART group, having key roles in several EU and other international projects.

The group is comprised of specialists in electronics, electronic materials, micro- and nanoelectronics, mechanical and process engineering, measuring techniques, and also in chemistry and physics. In 2016 the EMPART group had four professors including one FiDiPro professor, 18 senior research fellows and post-doctoral researchers and 15 doctoral students. The unit is highly international: 44 % of our researchers (professors, doctors, doctoral students) are from abroad.

In accordance with the long-term research targets, we have continued the integration of interdisciplinary topics towards future advanced electronics devices and component implementations. In addition, a wide range of application areas utilizing the generic materials knowledge of the group have been of great importance. From January 1st 2017 to December 31st 2019, the group leader, Professor Jantunen, was appointed as the International Chair Professor in recognition of an outstanding academic and research activity in the discipline of Electronic ceramics to National Taipei University of Technology.

Value chain within the EMPART group with collaboration and driving forces in general.

Scientific Progress

Materials, components and technologies developed by the group are widely applied in the electronics industry, especially in wireless telecommunication, sensors/actuators and hybrid microelectronics technology. Piezoelectric devices and printed electronics applications are important examples of current exploitation, together with recent scientific achievements in nanotechnology with applications. Novel materials, as well as our progress in fabrication, have been utilized in antennas, sensors, ceramic/polymer integrations, filters, micro-pumps, lens and mirror positioning systems, energy harvesters etc.

The research achievements of the group are presented through examples covering selected doctoral thesis in 2016 and two Academy of Finland funded post-doctoral projects. These are linked to the EMPART research areas in materials science, manufacturing processes development and electronics applications.

 

Linkage of the selected doctoral thesis and academy post-doctoral projects in 2016 to the EMPART group’s research focus areas in materials science, manufacturing processes development and electronics applications.

A Room-temperature Fabrication Method for Electroceramics

(Doctoral thesis by Hanna Kähäri: A room-temperature fabrication method for microwave dielectric LiMoO ceramics and their applicability for antennas)

Microwave dielectric ceramics are commonly used in portable devices with wireless communication technologies because their properties enable the miniaturization of several components. Generally, the dielectric ceramics are sintered at temperatures much higher than 1000 °C, or in the case of Low Temperature Co-fired Ceramics technology, at about 850 °C to achieve their optimal properties. In addition to high energy consumption, such high sintering temperatures cause many problems. The reactivity with other materials increases, which can cause unwanted extra-phases with unexpected properties, and volatile components can evaporate affecting the composition and therefore the properties of the ceramic. The high processing temperature also complicates integration with other materials, such as low melting temperature electrode metals, semiconductors like silicon and gallium arsenide, or polymers. Furthermore, during the sintering process the formed compact shrinks, making the dimensional management of the final product demanding.

This thesis presents a method for the fabrication of relatively dense ceramics at room-temperature with competent microwave dielectric properties. The method utilizes a small amount of water with Li2MoO4 powder and the densification occurs during sample pressing. To remove any residual water molecules, the samples are typically post-processed at 120 °C.

The room-temperature fabrication method is based on utilizing a small amount of water with Li2MoO4 powder. The densification of the ceramic takes place during pressing.

The method has several advantages. The dielectric properties of Li2MoO4 ceramic can be optimized by the composite technology enabling applications, for example, in electronics packaging and wireless communication. Also, the post-processing temperature of the fabricated ceramics can be chosen to be suitable to the associated integrated materials, for example the electrode material, as long as the post-processing time is sufficient to ensure the removal of the residual water. The low fabrication temperature can prevent the high-temperature induced formation of unwanted extra phases with the electrode material or additives, which can be used to modify the properties of the Li2MoO4 ceramics. Furthermore, the size of the ceramic component is easily controlled by managing the size of the mould and the amount of the ceramic powder. This is an important advantage in the fabrication of size sensitive ceramic component applications, such as antennas.

 

Room-temperature densification method is especially suitable for size-sensitive ceramic components, such as antennas, since there is no shrinkage in the ceramic after pressing.

Additional studies of the applicability for antenna design of the ceramics fabricated by the room-temperature method were also conducted. The results showed that temperature stabilization of these ceramics could be achieved by the fabrication of Li2MoO4–TiO2 composites. The dielectric properties of fabricated composites were similar to those of commercial substrates that have been reported to be suitable for antennas operating at microwave frequencies. A high humidity level slightly affected the peak resonance frequency of a Li2MoO4 based patch antenna and decreased its total and radiation efficiencies. A silicone conformal coating reduced these changes and expedited their reversibility when the humidity level was again lowered.

The method developed in this work offers new possibilities for the seamless integration of ceramic components with temperature-sensitive substrate materials such as polymers or paper. Fabrication methods such as 2D and 3D printing already provide interesting new options for components and modules, especially if integration with polymers and other temperature-sensitive materials is needed. It is also plausible that the method is suitable for other similar ceramic materials, providing even more possibilities to utilize the method in advanced packaging and in the fabrication of composites.

This work is part of the European Research Council (ERC) Advanced Grant project (FP7/2007-2013, No. 291132).

Fabrication of Functional Scaffolds for Tissue Engineering based on Carbon Nanotubes

(Academy of Finland Post-Doctoral project by Gabriela Simone Lorite: 3D hierarchical scaffold based on bio-decorated carbon nanotubes for bone and cartilage tissue engineering, CNT4Tissue)

Over the years, it has become clear that the groundbreaking nature of tissue engineering relies on the cross-domain of material science, life science, medicine and engineering. In this context, materials development represents a major area of this field. While developing a material to be used on scaffolds, important requirements have to be achieved to address the crucial outcomes: biocompatibility, biodegradability, positive cellular response and withstand physiological conditions. After the implantation the scaffold should become fully functional part of the tissue, and in the case of biodegradable biomaterial, also be totally replaced by living tissue without scar formation.

Schematic diagram of the inter-relation between scaffold development and outcomes.

Although there are several advantages of using synthetic or natural polymers for scaffolds, the current biomaterials still suffer from crucial disadvantages. For example, natural polymers present rapid degradation and loss of biological properties during processing, while the synthetic materials can cause adverse tissue reaction and lack of cellular adhesion/interaction. Furthermore, these materials lack mechanical robustness as well as good electrical and thermal conductivity, which eventually could offer further functionality to promote cell growth and proliferation. In contrast, carbon nanotubes (CNTs) show impressive mechanical, electrical and structural properties that have opened a new era in materials science and nanotechnology. CNTs have been widely investigated reaching a total number of articles and reviews of 140 000 in the past 20 years. Already commercialized in other fields such as sport equipment, automotive and aeronautics, CNTs has been considered to be applied in medical application just lately with limited amount of data and publications (2 500 according to Web of Science). Following things are known from the available literature:

  • Extraordinary mechanical properties to withstand in vivo stress;

  • Ability to quickly absorb significant amount of protein enhancing cell adhesion;

  • Synthesis flexibility to create hierarchical structure by means of scale, i.e. nano/micro/macro-structure as well as porosity on the same scaffold;

  • Freedom of shape (physical) and functional (chemical functionalization) design;

  • Electrical properties which could be used in nerve regeneration/healing by physioelectrical stimulation.

The CNT4Tissue project explores CNT -assemblies as a 3D solid macrostructure. The main goal is to combine biochemical composition, surface texture, porosity and interconnectivity into a 3D hierarchical CNTs based scaffold for bone and cartilage tissue engineering. In addition, CNT4Tissue also address the challenge to enhance the scaffold functional properties. For example, the outstanding electrical properties of CNTs could facilitate physio-electrical signal transfer which could be used to promote tissue healing via electrical stimulation. Furthermore, CNT4tissue proposes CNT-bio-functionalization in order to promote the bioactivity during tissue growth as well as improve biocompatibility.

During the first year of the CNT4Tissue project, four CNTs-based scaffolds were developed: CNTs pillars on 2D surfaces, 3D CNTs-hydrogel scaffolds, porous PLA/CNT thin membrane, and 3D carbon foam-CNTs. The CNTs pillars on 2D surfaces are used to stimulate mesenchymal stem cells to differentiate to cartilage cells. This work is performed in collaboration with Prof. Mikko Lammi from Umeå University, Sweden.

Mesenchymal stem cells were growth into CNTs pillars on 2D silicon (Si) surfaces. The distance between the pillars were 5, 10 and 20 µm. CNT film, Si and PS were used as control surfaces. MTT assay results clear show that the cells adhesion and proliferation on CNTs surfaces are as good as on control samples. Our results also indicate that the distance between the pillars may affect the cell shape. New CNT patterns are under preparation to further investigate the cartilage tissue growth.

Hydrogels are hydrophilic, water-swollen, crosslinked polymer networks which contain over 90% water while still retaining seemingly solid macroscopic structure and they are one of the main scaffold material types studied for tissue engineering. Combining CNTs into the hydrogel structure can yield a functional composite, with enhanced material properties. Literature reports that the challenge of create hybrid CNTs-hydrogel is to obtain a homogenous CNT dispersion in aqueous media. In CNT4Tissue, 3D CNT-hydrogels scaffolds were successful synthesized with different CNTs concentration. Mechanical and electrical characterization are ongoing. The next step is to growth neural cells under electrical stimulation.

Homogeneous 3D CNTs-hydrogel hybrid scaffolds with different CNTs concentrations. Collaboration with Prof. Minna Kellomäki from Tampere University of Technology, Finland.

Pristine PLA porous honeycomb-like membranes have been synthetized by breath figure method in collaboration with Prof. Minna Kellomäki (Tampere University of Technology, Finland). In brief, PLA is dissolved in chloroform and let it dry in high humidity conditions (70-80%) forming a porous honeycomb-like thin membrane. In order to incorporate CNTs into this easy 2-step protocol, we are investigating common solvent for good CNTs dispersion and dissolving PLA. Our preliminary data shows that CNTs does not disperse well in chloroform and, as consequence, the thin PLA/CNTs membranes are not homogeneous; although we still can see honeycomb-like structure. This particular membrane has been investigated for retinal tissue engineering.

(A) PLA thin membrane picture, (B) PLA porous honeycomb-like SEM image, (C) PLA/CNT thin membrane, (D) PLA/CNTs porous honeycomb-like SEM image and (E) CNTs dispersion in chloroform.

Recent article has demonstrated that CNT spheres used in the reinforcement of an elastomer matrix can mimic the stiffening behavior from health bone i.e. under dynamic loads the composite exhibit significant self-stiffening. In addition, CNTs also demonstrated to promote adhesion, growth and osteogenic differentiation of cells and as well bone mineralization. To this end, we have synthesized 3D carbon foam-CNTs scaffolds for bone tissue engineering. Cell growth and biomechanics characterization are ongoing.

3D carbon foam-CNTs scaffolds.

Controlling Ferroelectrics for Adaptive Nanoelectronic Devices

(Academy of Finland Post-Doctoral project by Jani Peräntie: Towards adaptive nanoelectronic devices by mechanical control of ferroelectric domains)

During the postdoctoral researcher project in 2016−2019, new approaches for controlling ferroelectric (FE) thin films materials are explored and realized to enable improved and adaptive ferroelectric nanoelectronic devices. The project work is performed in collaboration with universities from Netherlands and USA.  

The increasing integration density and miniaturization trends in modern electronics push devices to become smaller, more efficient and intelligent. A recent trend in modern electronic devices is towards diversification, where variety and adaptability are required particularly in terms of different energy conversions enabling intelligent functionality. A high potential for the realization of such multiactive sensor-actuator nanoelectronic devices is found in high-perfomance epitaxial perovskite oxide heterostructures utilizing ferroelectric thin films. In general, the existence of high dielectric polarization and its exceptionally strong couplings to mechanical strain, electric field and temperature in perovskite oxide FE films lead to strong effects, such as piezo- and pyroelectricity, unmatched by other materials. These effects enable construction of highly advanced solid-state devices utilizing for example energy storage and harvesting, sensing, actuation, and switching capabilities.

 

Ferroelectric materials show for example (a) piezo- and (b) pyroelectricity, which can be used for sensing, actuating, and energy harvesting. (c) Ferroelectric polarization is divided into domains, which can be altered to show different configurations.

The optimized or enhanced performance of FE device requires a specific arrangement of its polarization regions, i.e. domains. In fact, the ferroelectric domain structure plays a significant role in operation of practically all the most important FE-based devices and applications. Therefore, a detailed control of the FE domain configuration becomes essentially important in realization and optimization of existing and prospective future multifunctional FE-based devices. This control can be implemented most efficiently by epitaxial FE heterostructures.

The ferroelectric domain configuration (arrangement, type and size of domains) of a FE sample is basically controlled by electrical and mechanical means. In epitaxial FE films, the FE domain configuration is typically decided beforehand by a combination of growth- and design-related strain components (e.g. film thickness, substrate-film misfit & thermal expansion). The resulting strain state of the FE film is fixed and cannot be reconfigured very easily. For this reason, any subsequent control of ferroelectric domains is very limited. Although some great advances in atomic force microscopy related techniques (i.e. piezo response force microscopy) have enabled local and flexible FE domain controlling techniques, new solutions are required especially for advanced, active and/or large-scale control ferroelectrics to address the adaptability and multifunctionality of future devices.

 

Examples of different approaches for ferroelectric domain control: (a) misfit strain-engineering, (b) strain-engineering by growth parameters, and (c and d) electrical and mechanical domain writing.

This research project aims to find new and advanced ways to mechanically control and manipulate ferroelectric domain structure for multifunctional FE-based devices. Specifically, two approaches are studied in more detail: (a) use of chemical strain for FE domain control and (b) realize active FE domain control by substrate deformation.

Different thin film heterostructures based on perovskite oxides, such as BaTiO3, Pb(Zr,Ti)O3, SrRuO3 and SrTiO3, are prepared. The formation and changes in domain structure and mechanical strains are studied first by using different materials and deposition parameters. Later on, the structures are affected by chemical strains and active substrate deformation. Finally, the effect of adjusted domain configuration on functional properties is evaluated especially by means of different electrical measurements.

Some example results from the utilized characteriza-tion techniques: (a) nanobeam electron diffraction pattern of SrTiO3 substrate, (b) secondary electron image from the surface of epitaxial PbTiO3 thin film, (c) x-ray diffraction from epitaxial BaTiO3/SrRuO3/SrTiO3 heterostructure and (d) ferroelectric hysteresis loop of epitaxial Pb(Zr0.2Ti0.8)O3 thin film.

Personnel

professors

4

senior research fellows

6

postdoctoral researchers

12

doctoral students

15

other research staff

2

total

39

person years for research

12

 

External Funding

Source

EUR

Academy of Finland

910 000

Tekes

 650 000

domestic private

200 000

international

790 000

total

2 550 000

 

Doctoral Theses

Rautio A-R (2016) On the stability of carbon nanotube and titania nanowire based catalyst materials: from synthesis to applications. Acta Universitatis Ouluensis. Series C, Technica 561.

Kähäri H (2016) A room-temperature fabrication method for microwave dielectric LiMoO ceramics and their applicability for antennas. Acta Universitatis Ouluensis. Series C, Technica 584.

Selected Publications

Tuhkala M., Juuti J., Teirikangas M., Myllymäki S., Jantunen H., Loading efficiency equation for the estimation of dielectric properties of ceramic-polymer 0-3 composites, Materials Today Communications 5:  60-63 (2015).

Hannu, J., Peräntie, J., Stratulat, S.M., Jantunen, H., Tyunina, M., Aging in epitaxial ferroelectric PbTiO3 films (2016) Journal of Advanced Dielectrics, 6 (4), art. no. 1650026, DOI: 10.1142/S2010135X16500260

Myllymäki, S., Maček Kržmanc, M., Sloma, M., Juuti, J., Nelo, M., Teirikangas, M., Jakubowska, M., Suvorov, D., Jantunen, H., Microwave properties of sphere-, flake-, and disc-shaped BaFe12O19 nanoparticle inks for high-frequency applications on printed electronics (2016) Journal of Magnetism and Magnetic Materials, 419, pp. 218-224 DOI: 10.1016/j.jmmm.2016.06.026

Joseph, N., Varghese, J., Siponkoski, T., Teirikangas, M., Sebastian, M.T., Jantunen, H., Glass-Free CuMoO4 Ceramic with Excellent Dielectric and Thermal Properties for Ultralow Temperature Cofired Ceramic Applications (2016) ACS Sustainable Chemistry and Engineering, 4 (10), pp. 5632-5639. DOI: 10.1021/acssuschemeng.6b01537

Rashidian, A., Shafai, L., Shafai, C., Sobocinski, M., Perantie, J., Juuti, J., Jantunen, H., Development of planar dielectric passive microwave circuits and antennas (2016) 2016 17th International Symposium on Antenna Technology and Applied Electromagnetics, ANTEM 2016, art. no. 7550201, DOI: 10.1109/ANTEM.2016.7550201

Tolvanen, J., Hannu, J., Nelo, M., Juuti, J., Jantunen, H., Dielectric properties of novel polyurethane-PZT-graphite foam composites (2016) Smart Materials and Structures, 25 (9), art. no. 095039, DOI: 10.1088/0964-1726/25/9/095039

Tolvanen, J., Hannu, J., Palosaari, J., Nelo, M., Jantunen, H., Screen-printed mechanical switch based on stretchable PU-foam film (2016) Electronics Letters, 52 (16), pp. 1395-1397. DOI: 10.1049/el.2016.2002

Chen, M.-Y., Juuti, J., Hsi, C.-S., Jantunen, H., Sintering behavior and characteristics study of BaTiO3 with 50wt% of B2O3-Bi2O3-SiO2-ZnO glass (2016) Journal of the European Ceramic Society, Article in Press. DOI: 10.1016/j.jeurceramsoc.2016.10.036

Varghese, J., Siponkoski, T., Teirikangas, M., Sebastian, M.T., Uusimäki, A., Jantunen, H., Structural, dielectric, and thermal properties of Pb free molybdate based ultralow temperature glass (2016) ACS Sustainable Chemistry and Engineering, 4 (7), pp. 3897-3904.  DOI: 10.1021/acssuschemeng.6b00721

Kähäri, H., Teirikangas, M., Juuti, J., Jantunen, H., Room-temperature fabrication of microwave dielectric Li2MoO4-TiO2 composite ceramics (2016) Ceramics International, 42 (9), pp. 11442-11446. DOI: 10.1016/j.ceramint.2016.04.081

Sebastian, M.T., Wang, H., Jantunen, H., Low temperature co-fired ceramics with ultra-low sintering temperature: A review (2016) Current Opinion in Solid State and Materials Science, 20 (3), pp. 151-170. DOI: 10.1016/j.cossms.2016.02.004

Leinonen, M., Juuti, J., Jantunen, H., Palosaari, J., Energy Harvesting with a Bimorph Type Piezoelectric Diaphragm Multilayer Structure and Mechanically Induced Pre-stress (2016) Energy Technology, 4 (5), pp. 620-624. DOI: 10.1002/ente.201500429

Tuhkala, M., Maček, M., Siponkoski, T., Juuti, J., Teirikangas, M., Suvorov, D., Jantunen, H., The effect of BaTiO3 particle shape on complex permittivity of 0.98MgTiO3-0.02BaTiO3 composite powders at GHz frequencies (2016) Materials Research Bulletin, 76, pp. 300-304. DOI: 10.1016/j.materresbull.2015.12.043

Rashidian, A., Shafai, L., Sobocinski, M., Perantie, J., Juuti, J., Jantunen, H., Printable Planar Dielectric Antennas (2016) IEEE Transactions on Antennas and Propagation, 64 (2), art. no. 7332737, pp. 403-413. Cited 2 times. DOI: 10.1109/TAP.2015.2502265

Kähäri, H., Ramachandran, P., Juuti, J., Jantunen, H., Room-Temperature Densified Li2MoO4 Ceramic Patch Antenna and the Effect of Humidity (2016) International Journal of Applied Ceramic Technology, Article in Press.  DOI: 10.1111/ijac.12615

Peräntie, J., Stratulat, M.S., Hannu, J., Jantunen, H., Tyunina, M., Enhancing polarization by electrode-controlled strain relaxation in PbTiO3 heterostructures (2016) APL Materials, 4 (1), art. no. 016104, DOI: 10.1063/1.4939790

Myllymäki, S., Putaala, J., Hannu, J., Kunnari, E., Mäntysalo, M., RF measurements to pinpoint defects in inkjet-printed, thermally and mechanically stressed coplanar waveguides (2016) Microelectronics Reliability, 65, pp. 142-150. DOI: 10.1016/j.microrel.2016.08.021

Dunce, M., Birks, E., Peräntie, J., Hagberg, J., Antonova, M., Ignatans, R., Sternberg, A., Phase transitions in Na0.5Bi0.5TiO3-(Sr0.7Bi0.2)TiO3-PbTiO3 solid solutions (2016) Ferroelectrics, 498 (1), pp. 94-101. DOI: 10.1080/00150193.2016.1168213

Tyunina, M., Savinov, M., Dynamic nonlinearity in epitaxial BaTi O3 films (2016) Physical Review B - Condensed Matter and Materials Physics, 94 (5), art. no. 054109, DOI: 10.1103/PhysRevB.94.054109

Chernova, E., Pacherova, O., Kocourek, T., Jelinek, M., Dejneka, A., Tyunina, M., Optical properties of ferroelectric epitaxial K0.5Na0.5NbO3 films in visible to ultraviolet range (2016) PLoS ONE, 11 (4), art. no. e0153261, DOI: 10.1371/journal.pone.0153261

Klinger, M., Polívka, L., Jäger, A., Tyunina, M. Quantitative analysis of structural inhomogeneity in nanomaterials using transmission electron microscopy (2016) Journal of Applied Crystallography, 49, pp. 762-770. DOI: 10.1107/S1600576716003800

Salmela, O., Putaala, J., Nousiainen, O., Uusimaki, A., Sarkka, J., Tammenmaa, M., Multipurpose lead-free reliability prediction model (2016) 2016 Pan Pacific Microelectronics Symposium, Pan Pacific 2016, art. no. 7428389, DOI: 10.1109/PanPacific.2016.7428389

Induja, I.J., Sebastian, M.T., Microwave dielectric properties of mineral sillimanite obtained by conventional and cold sintering process (2016) Journal of the European Ceramic Society, Article in Press. DOI: 10.1016/j.jeurceramsoc.2017.01.007

Nair, I.I.J., Varma, M.R., Sebastian, M.T., Low cost room temperature curable alumina ink for printed electronic applications (2016) Journal of Materials Science: Materials in Electronics, 27 (9), pp. 9891-9899. DOI: 10.1007/s10854-016-5058-4

Manu, K., Sebastian, M.T., Tape casting of low permittivity Wesselsite-Glass composite for LTCC based microwave applications (2016) Ceramics International, 42 (1), pp. 1210-1216. DOI: 10.1016/j.ceramint.2015.09.052

Rajala, S., Siponkoski, T., Sarlin, E., Mettänen, M., Vuoriluoto, M., Pammo, A., Juuti, J., Rojas, O.J., Franssila, S., Tuukkanen, S., Cellulose Nanofibril Film as a Piezoelectric Sensor Material (2016) ACS Applied Materials and Interfaces, 8 (24), pp. 15607-15614. Cited 4 times. DOI: 10.1021/acsami.6b03597

Poikselkä, K., Leinonen, M., Palosaari, J., Vallivaara, I., Haverinen, J., Röning, J., Juuti, J., End cap profile optimization of a piezoelectric Cymbal actuator for quasi-static operation by using a genetic algorithm (2016) Journal of Intelligent Material Systems and Structures, 27 (4), pp. 444-452. DOI: 10.1177/1045389X14566526

Akbari, M., Sydanheimo, L., Juuti, J., Ukkonen, L., Flash reduction of inkjet printed graphene oxide on flexible substrates for electronic applications (2016) IEEE-NANO 2015 - 15th International Conference on Nanotechnology, art. no. 7388775, pp. 93-96. DOI: 10.1109/NANO.2015.7388775

Aldea, S., Snåre, M., Eränen, K., Grenman, H., Rautio, A.-R., Kordás, K., Mikkola, J.-P., Salmi, T., Murzin, D.Y., Crystallization of Nano-Calcium Carbonate: The Influence of Process Parameters (2016) Chemie-Ingenieur-Technik, 88 (11), pp. 1609-1616. DOI: 10.1002/cite.201600028

Kukovecz, Á., Kordás, K., Kiss, J., Kónya, Z., Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires (2016) Surface Science Reports, 71 (3), pp. 473-546. DOI: 10.1016/j.surfrep.2016.06.001

Pham, T.N., Samikannu, A., Rautio, A.-R., Juhasz, K.L., Konya, Z., Wärnå, J., Kordas, K., Mikkola, J.-P., Catalytic Hydrogenation of d-Xylose Over Ru Decorated Carbon Foam Catalyst in a SpinChem® Rotating Bed Reactor (2016) Topics in Catalysis, 59 (13-14), pp. 1165-1177. DOI: 10.1007/s11244-016-0637-4

Bourajoini, H., Rautio, A.-R., Kordas, K., Mikkola, J.-P., Calcium manganese oxide catalysts for water oxidation: Unravelling the influence of various synthesis strategies (2016) Materials Research Bulletin, 79, pp. 133-137. DOI: 10.1016/j.materresbull.2016.03.018

Jokinen, K., Popov, A., Lappalainen, J., Sliz, R., Fabritius, T., Kordas, K., Myllylä, R., Vasiliev, A., Performance Enhancement of Polymer Electrolyte MEIS Hydrogen Sensor by DC-Biasing (2016) IEEE Sensors Journal, 16 (13), art. no. 7463465, pp. 5292-5297. DOI: 10.1109/JSEN.2016.2561318

Asres, G.A., Dombovari, A., Sipola, T., Puskás, R., Kukovecz, A., Kónya, Z., Popov, A., Lin, J.-F., Lorite, G.S., Mohl, M., Toth, G., Lloyd Spetz, A., Kordas, K., A novel WS2 nanowire-nanoflake hybrid material synthesized from WO3 nanowires in sulfur vapour (2016) Scientific Reports, 6, art. no. 25610, DOI: 10.1038/srep25610

Sarkar, A., Gracia-Espino, E., Wågberg, T., Shchukarev, A., Mohl, M., Rautio, A.-R., Pitkänen, O., Sharifi, T., Kordas, K., Mikkola, J.-P., Photocatalytic reduction of CO2 with H2O over modified TiO2 nanofibers: Understanding the reduction pathway (2016) Nano Research, pp. 1-13. Article in Press. DOI: 10.1007/s12274-016-1087-9

Sterchele, S., Biasi, P., Centomo, P., Shchukarev, A., Kordás, K., Rautio, A.-R., Mikkola, J.-P., Salmi, T., Canton, P., Zecca, M., Influence of Metal Precursors and Reduction Protocols on the Chloride-Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers (2016) ChemCatChem, 8 (8), pp. 1564-1574. DOI: 10.1002/cctc.201600021

Fu, Q., Lorite, G.S., Rashid, M.M.-U., Neuhaus, R., Cada, M., Hubicka, Z., Pitkänen, O., Selkälä, T., Uusitalo, J., Glanz, C., Kolaric, I., Kordas, K., Nicolescu, C.-M., Toth, G., High dynamic stiffness mechanical structures with nanostructured composite coatings deposited by high power impulse magnetron sputtering (2016) Carbon, 98, pp. 24-33. DOI: 10.1016/j.carbon.2015.10.074

Gemo, N., Menegazzo, F., Biasi, P., Sarkar, A., Samikannu, A., Raut, D.G., Kordás, K., Rautio, A.-R., Mohl, M., Boström, D., Shchukarev, A., Mikkola, J.-P., TiO2 nanoparticles: Vs. TiO2 nanowires as support in hydrogen peroxide direct synthesis: The influence of N and Au doping (2016) RSC Advances, 6 (105), pp. 103311-103319.DOI: 10.1039/c6ra24357f

Sainio, S., Palomäki, T., Rhode, S., Kauppila, M., Pitkänen, O., Selkälä, T., Toth, G., Kordas, K., Moram, M., Koskinen, J., Laurila, T., Corrigendum to "Carbon nanotube (CNT) forest on diamond-like carbon (DLC) electrode improves electrochemical sensitivity towards dopamine by two orders of magnitude" [Sens. Actuators B 211 (2015) 177-186] (2016) Sensors and Actuators, B: Chemical, Article in Press. DOI: 10.1016/j.snb.2016.04.120

Lángi, Z., Naszódi, M., Pach, J., Tardos, G., Tóth, G., Separation with restricted families of sets (2016) Journal of Combinatorial Theory. Series A, 144, pp. 292-305. DOI: 10.1016/j.jcta.2016.06.002

Altenburg, S., Wölk, S., Tóth, G., Gühne, O., Optimized parameter estimation in the presence of collective phase noise (2016) Physical Review A - Atomic, Molecular, and Optical Physics, 94 (5), art. no. 052306, DOI: 10.1103/PhysRevA.94.052306

Selkälä, T., Sirviö, J.A., Lorite, G.S., Liimatainen, H., Anionically Stabilized Cellulose Nanofibrils through Succinylation Pretreatment in Urea–Lithium Chloride Deep Eutectic Solvent (2016) ChemSusChem, 9 (21), pp. 3074-3083. DOI: 10.1002/cssc.201600903

Bastuck, M., Puglisi, D., Huotari, J., Sauerwald, T., Lappalainen, J., Lloyd Spetz, A., Andersson, M., Schütze, A., Exploring the selectivity of WO3 with iridium catalyst in an ethanol/naphthalene mixture using multivariate statistics (2016) Thin Solid Films, 618, pp. 263-270. DOI: 10.1016/j.tsf.2016.08.002

Huotari, J., Lappalainen, J., Eriksson, J., Bjorklund, R., Heinonen, E., Miinalainen, I., Puustinen, J., Lloyd Spetz, A., Synthesis of nanostructured solid-state phases of V7O16 and V2O5 compounds for ppb-level detection of ammonia (2016) Journal of Alloys and Compounds, 675, pp. 433-440. DOI: 10.1016/j.jallcom.2016.03.116

Huotari, J., Cao, W., Niu, Y., Lappalainen, J., Puustinen, J., Pankratov, V., Lloyd Spetz, A., Huttula, M., Separation of valence states in thin films with mixed V2O5 and V7O16 phases (2016) Journal of Electron Spectroscopy and Related Phenomena, 211, pp. 47-54. DOI: 10.1016/j.elspec.2016.06.001

Bastuck, M., Puglisi, D., Huotari, J., Sauerwald, T., Lappalainen, J., Lloyd Spetz, A., Andersson, M., Schütze, A., Exploring the selectivity of WO3 with iridium catalyst in an ethanol/naphthalene mixture using multivariate statistics (2016) Thin Solid Films, Article in Press. DOI: 10.1016/j.tsf.2016.08.002

Möller, P., Andersson, M., Lloyd Spetz, A., Puustinen, J., Lappalainen, J., Eriksson, J., NOx sensing with SiC field effect transistors (2016) Materials Science Forum, 858, pp. 993-996. DOI: 10.4028/www.scientific.net/MSF.858.993

Puglisi, D., Eriksson, J., Andersson, M., Huotari, J., Bastuck, M., Bur, C., Lappalainen, J., Schuetze, A., Lloyd Spetz, A., Exploring the gas sensing performance of catalytic metal/metal oxide 4H-SiC field effect transistors (2016) Materials Science Forum, 858, pp. 997-1000. DOI: 10.4028/www.scientific.net/MSF.858.997

 

Last updated: 28.4.2017