Author: Mar Tristany

Unveiling the Nucleation and Coarsening Mechanisms of Solution-Derived Self-Assembled Epitaxial Ce0.9Gd0.1O2–y Nanostructures

Albert Queraltó*, María de la Mata, Jordi Arbiol, Ruben Hühne∥, Xavier Obradors, and Teresa Puig. Cryst. Growth Des., 2017, 17 (2), pp 504–516. DOI: 10.1021/acs.cgd.6b01358

 

Self-assembling approaches based on chemical solution deposition (CSD) are ideal methods for the cost-effective production of epitaxial nanostructures with high throughput. Therefore, an in-depth investigation of the nucleation and coarsening processes involved in the self-assembly of nanostructures is mandatory to achieve a good control over nanostructure shape, dimensions, and orientation. Heteroepitaxial Ce0.9Gd0.1O2-y (CGO) is an ideal model system to unveil the underlying nanostructure development mechanisms in addition to their promising properties for catalysis, gas sensors, and ionic conductivity. Rapid thermal annealing furnaces have been used to study separately the thermodynamic and kinetic nucleation and coarsening mechanisms of self-assembled CGO isotropic and anisotropic nanostructures based on strain-engineering and surface energies control. Different CGO nanoislands are obtained: isotropic (001)CGO nanodots are grown on (001)-oriented Y2O3:ZrO2 (YSZ) and LaAlO3 (LAO) substrates, whereas (011)LAO substrates promote the growth of elongated (011)CGO nanowires. HRTEM and RHEED analyses are used to study the early stages of nucleation, as well as the shape and interfacial structure of CGO nanostructures. A systematic study with the heating ramp, annealing temperature and time, and strain in combination with thermally activated theoretical models provides information on the nucleation behavior, nucleation barriers, and atomic diffusion coefficients along in-plane and out-of-plane island orientations. Highly anisotropic atomic diffusion constants have been shown to be at the origin of the high aspect ratios of some of the nanostructures. Overall, our study provides a general method for the evaluation of nucleation and coarsening of multiple CSD-derived oxide nanostructures and understanding the shape development by combining thermodynamic and kinetic approaches.

Welcome to Hailin Wang!

Hi everyone! My name is Hailin Wang. I’m from China. I have a master degree in Inorganic Chemistry, and I come to ICMAB to do my PhD about functional oxide thin films under the supervision of Dr. Narcis Mestres and Dr. Benjamin Martinez.
In my spare time, I like reading, travelling and bicycling.

The CSIC Institutes of Materials Science of Barcelona and Aragón together with Gamesa Innovation and Technology develop the first prototype of an electric Superconducting generator for medium power wind turbines (2MW)

• The prototype is the first in the world to be used in medium-power wind turbines. • The use of Superconducting materials simplifies the system obtaining greater reliability and greater efficiency thus reducing maintenance needs. • This breakthrough opens the way to a new conception of wind turbines and offers a new perspective to the wind energy industry. Monday, December 12, 2016. Gamesa Innovation and Technology, a leading Spanish technology company in the wind energy industry, the Institute of Materials Science of Barcelona (ICMAB-CSIC) and the Institute of Materials Science of Aragón (ICMA-CSIC), partially funded by the Spanish Ministry of Economy and Competitiveness (Retos Colaboración RTC-2014-1740-3), have successfully completed the first phase of development of the first medium speed Superconducting generator to be used in conventional medium power wind turbines (2MW). It is a generator that, being built using Superconducting materials, can rotate at a lower rotation speed (one third of the usual) thus reducing the weight of the multiplier gearbox significantly as well as the inertia of the system simplifying and lightening all the mechanical assembly or drivetrain and the structure itself. The electric Superconducting generator is the result of an innovative architecture with a lower use of cooper and an iron-less magnetic circuit which results in a greater efficiency and, consequently, a much lower generation of heat thus drastically reducing cooling requirements. The advantages of this new type of electric generator that uses Superconducting materials compared to the conventional generators are diverse: it simplifies the entire mechanical structure of the wind turbine as well as the electronic system; simplifies assembly and maintenance, reduces the risk of breakdowns; the time of intervention for maintenance is extended; and, in the near future, the cost will be reduced according to the rapid evolution of Superconducting materials. The future implementation of this type of electric Superconducting generator in the wind turbines opens a new perspective to the wind energy industry, making windmills more efficient and robust and reducing the costs of energy production. After four years of intense collaboration between the three entities, the culmination of the first phase of the project in early 2016 with the successful construction of this prototype and the corresponding trials has become a clear success case of Technology Transfer from research in superconducting materials to its possible applications in the generation of wind energy. ICMAB-CSIC, ICMA-CSIC and Gamesa Innovation and Technology continue to collaborate in order to carry out field trials to offer new innovative technological solutions in this sector.

Superconducting YBa2Cu3O7–δ Nanocomposites Using Preformed ZrO2 Nanocrystals: Growth Mechanisms and Vortex Pinning Properties

keukeleere_et_al-2016-advanced_electronic_materials Katrien De Keukeleere, Pablo Cayado, Alexander Meledin, Ferran Vallès, Jonathan De Roo, Hannes Rijckaert, Glenn Pollefeyt, Els Bruneel, Anna Palau, Mariona Coll, Susagna Ricart, Gustaaf Van Tendeloo, Teresa Puig, Xavier Obradors, Isabel Van Driessche. Advanced Electronic Materials. DOI: 10.1002/aelm.201600161 Although high temperature superconductors are promising for power applications, the production of low-cost coated conductors with high current densities—at high magnetic fields—remains challenging. A superior superconducting YBa2Cu3O7–δ nanocomposite is fabricated via chemical solution deposition (CSD) using preformed nanocrystals (NCs). Preformed, colloidally stable ZrO2 NCs are added to the trifluoroacetic acid based precursor solution and the NCs’ stability is confirmed up to 50 mol% for at least 2.5 months. These NCs tend to disrupt the epitaxial growth of YBa2Cu3O7–δ, unless a thin seed layer is applied. A 10 mol% ZrO2 NC addition proved to be optimal, yielding a critical current density JC of 5 MA cm−2 at 77 K in self-field. Importantly, this new approach results in a smaller magnetic field decay of JC(H//c) for the nanocomposite compared to a pristine film. Furthermore, microstructural analysis of the YBa2Cu3O7–δ nanocomposite films reveals that different strain generation mechanisms may occur compared to the spontaneous segregation approach. Yet, the generated nanostrain in the YBa2Cu3O7–δ nanocomposite results in an improvement of the superconducting properties similar to the spontaneous segregation approach. This new approach, using preformed NCs in CSD coatings, can be of great potential for high magnetic field applications.

One-Step Route to Iron Oxide Hollow Nanocuboids by Cluster Condensation: Implementation in Water Remediation Technology

Lluís BalcellsCarlos Martínez-Boubeta*José Cisneros-FernándezKonstantinos SimeonidisBernat BozzoJudith Oró-SoleNúria BaguésJordi ArbiolNarcís Mestres, and Benjamín Martínez*. ACS Appl. Mater. Interfaces, 2016, 8 (42), pp 28599–28606. DOI: 10.1021/acsami.6b08709

 

The fabrication procedure of hollow iron oxide nanoparticles with a large surface to volume ratio by a single-step gas condensation process at ambient temperature is presented. Fe clusters formed during the sputtering process are progressively transformed into hollow cuboids with oxide shells by the Kirkendall mechanism at the expense of oxygen captured inside the deposition chamber. TEM and Raman spectroscopy techniques point to magnetite as the main component of the nanocuboids; however, the magnetic behavior exhibited by the samples suggests the presence of FeO as well. In addition, these particles showed strong stability after several months of exposure to ambient conditions, making them of potential interest in diverse technological applications. In particular, these hierarchical hollow particles turned out to be very efficient for both As(III) and As(V) absorption (326 and 190 mg/g, respectively), thus making them of strong interest for drinking water remediation.

Dr. Luisa CHIESA_ICMAB Lecture_8th NOVEMBER

Dear friends and colleagues,
It is a pleasure for us invite you to the ICMAB Lecture entitled:
High temperature superconductors: how do we go from a single HTS tape to its deployment in high-field magnets and large scale applications? By Dr. Luisa CHIESA Mechanical Engineering Department, Tufts University, Medford, MA, USA Date:   8th NOVEMBER Time:   12:00 h Place:  ICMAB Meeting room Short abstract: After 25 years of development, several high temperature superconductors (HTS) are becoming engineering materials commercially available in long-length wires. Those conductors are capable of carrying enormous electrical current in strong magnetic fields while meeting various other challenges. Such characteristics enable the construction of a broad spectrum of devices useful for basic science, medicine, and energy. In this talk, the state-of-art manufacturing, properties and challenges of key HTS conductors will be discussed with particular focus on REBCO coated conductors. The electrical, magnetic, and mechanical properties and failure mechanisms important for constructing devices will be discussed and examples of large scale projects employing those materials will be given to illustrate the positive impact those new materials could have in future generation’s magnets. Further details will be given to HTS tape cabling methods for these magnet applications. To improve fabrication methods and maximize operational performance of these cables, it is necessary to characterize both the electromechanical behavior of the full scale cables and of the individual tapes under anticipated thermal, mechanical and electromagnetic loads. Some laboratory experimentation and structural finite element analysis (FEA) that have been used to investigate the electromechanical behavior of single HTS tapes and Twisted Stacked-Tape Cable (TSTC) conductors will be discussed. The numerical and experimental results discussed in this talk, provide important details about the strain dependence of the critical current for various load types expected during high field magnet operations. Short bio— Luisa Chiesa is an associate professor at Tufts University. Before joining the faculty at Tufts in 2009, Dr. Chiesa received her Ph.D. in Nuclear Science and Engineering at MIT and her bachelor in Physics from the Universita’ Statale in Milan (Italy). Dr. Chiesa worked in the field of superconducting magnets for the past 15 years. After a year as a visiting student at Fermilab working on quench protection for the LHC quadrupoles, she joined the Superconducting Magnets group at LBNL where she was heavily involved in the experimental characterization of high field superconducting magnets. Currently, her primary research area is the electro-mechanical characterization of low temperature and high temperature superconductors for large magnets used in high-energy physics and fusion power devices. In particular her laboratory specializes in experimental and numerical techniques to characterize the critical current of superconducting strands, tapes and cables under different mechanical loading conditions. Dr. Chiesa is an active member of the IEEE Council on Superconductivity and serves as technical editor on the IEEE Transaction on Applied Superconductivity journal and as board member of major conferences in the field of superconductivity. If you would like to arrange a meeting with her please contact: Prof. Teresa PUIG (teresa.puig@icmab.es) or Dr. Mar TRISTANY (mtristany@icmab.es)

Thesis Alba Garzón

twitter Congratulation to Alba Garzón for obtaining her PhD! Tittle: SYNTHESIS OF METAL OXIDE NANOPARTICLES FOR SUPERCONDUCTING NANOCOMPOSITES AND OTHER APPLICATIONS Abstract: Thermal and microwave methodologies are used to synthesize different metal oxides nanoparticles such as magnetite (Fe3O4) and cerium oxide (CeO2). By modifying the precursors (Fe(R2diket)3 (R= Ph, tBu and CF3), Ce(acac)3 and Ce(OAc)3), and following the same synthetic route, it is possible to control the size and shape of the nanocrystals obtained. The general route is carried out in triethylene glycol (TREG) or benzyl alcohol (BnOH) media, due to its high boiling point and, which acts also as a capping ligand of the nanoparticles, stabilizing them in polar solvents. Nanoparticles have been characterized by several common physical laboratory techniques: High Resolution Transmission Electron Microscopy (HR TEM), infrared spectroscopy (IR), X-ray Powder Diffraction (XRPD), magnetometry via Superconducting Quantum Interference Device (SQUID), Nuclear Magnetic Resonance (RMN), Gas Chromatography-Mass Spectroscopy (GC-MS), X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA). With all these techniques, the final size, shape, composition, crystal structure, magnetic behaviour and capping ligand interaction have been studied, showing the high quality crystals generated. In addition, we demonstrate the high efficiency of all two one-pot methodologies optimized to synthesize different families of nanoparticles in a reproducible way. The stable colloidal solutions obtained in methanol have been used to generate new nanocomposite YBa2Cu3O7-δ (YBCO) superconducting layers by the preformed nanoparticles (ex-situ) approach. The YBCO nanocomposite layers present enhanced magnetic properties. Finally, a new application as an antioxidant behaviour in human cells is tested for the case of CeO2 nanoparticles due to their specifically properties that make them really interested in this new field. Date and place: 4th November 2016. Sala de Graus Dept. Química UAB  

Ultrafast Epitaxial Growth Kinetics in Functional Oxide Thin Films Grown by Pulsed Laser Annealing of Chemical Solutions

cm-2016-01968a_0008 Albert Queraltó*Angel Pérez del PinoMaría de la MataJordi ArbiolMar TristanyXavier Obradors, and Teresa Puig; Chem. Mater., 2016, 28 (17), pp 6136–6145. DOI: 10.1021/acs.chemmater.6b01968 The crystallization process and physical properties of different functional oxide thin films (Ce0.9Zr0.1O2-y, LaNiO3, Ba0.8Sr0.2TiO3, and La0.7Sr0.3MnO3) on single crystal substrates (Y2O3:ZrO2, LaAlO3, and SrTiO3) are studied by pulsed laser annealing (PLA). A Nd:YAG laser source (λ = 266 nm, 10 Hz and τ ∼ 3 ns) is employed to crystallize chemical solution deposited (CSD) amorphous/nanocrystalline films under atmospheric conditions. We provide new insight on the influence of photochemical and photothermal interactions on the epitaxial crystallization kinetics of oxide thin films during the transformation from amorphous/polycrystalline material (i.e., atomic diffusion, epitaxial growth rates, and activation energies of nucleation and crystallization). The epitaxial growth is investigated by varying the laser fluence and the applied number of pulses. The morphology, structure, and epitaxial evolution of films are evaluated by means of atomic force and transmission electron microscopies and X-ray diffraction. Highly epitaxial oriented films of 20–40 nm in thickness are obtained by PLA. The crystallization kinetics of laser treatments is determined to be orders of magnitude faster than thermal treatments with similar activation energies (1.5–4.1 eV), mainly due to the large temperature gradients inducing modified atomic diffusion mechanisms derived mainly from photothermal interactions, as well as a minor contribution of photochemical effects. The fast heating rates achieved by PLA also contribute to the fast epitaxial growth due to reduced coarsening of polycrystalline material. The measurement of the physical properties (electrical resistivity and magnetism) of laser processed CSD films has revealed significantly good functionalities, close to those of thermally grown films, but with much shorter processing times.

Welcome to Pengmei Yu!

pengmeiyu ¡Hola todos, Soy Pengmei Yu de China, y un placer conoceros! My background is light chemical engineering, and I’ll be working here for my PhD degree for the next 4 years, under the supervision of Dr. Mariona Coll. In my spare time, I like to do some readings, listening to music, playing badminton and hiking.

Institut de Ciència de Materials de Barcelona ICMAB CSIC

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