BUSCADOR RECOLECTA

Resumen del trabajo presentado en la 40th International and 20th European Thermoelectric Conference (ICT/ECT 2024), celebrada en Cracovia (Polonia), del 30 de junio al 4 de julio de 2024, Fe2VAl is a family of full Heusler alloys that has attracted considerable interest due to
its large potential and tunable thermoelectric properties via doping with elements such as W,
Ti, or Si [1-2], or self-substitution with Fe, V, or Al [3]. Doping allows the alloy to alternate
between p and n types, paving the way toward device fabrication and, in specific cases, resulting
in a significant increase in thermoelectric performance [4]. Magnetron sputtering is a highly
convenient technique for the fabrication of semiconducting thin films, owing to its versatility
of materials, cost-effectiveness, and industry-friendly characteristics. In a codeposition
configuration, the composition of the synthesized materials can be easily tuned to optimize
material concentration for thermoelectric applications [5].
Besides doping, other parameters like crystal orientation may influence their
thermoelectric properties, for example, via changes in electronic structure or grain morphology
and size. Therefore, depositing monocrystalline thin films with different crystal orientations
using adequate substrates is of great interest.
In this work, we present experimental results of Fe2VAl thin films grown by magnetron
sputtering from a Fe2VAl target at temperatures ranging from RT to 950ºC, on Al2O3 (1 1 -2
0), and on MgO (1 0 0) substrates, exhibiting different epitaxial relations and, therefore,
different crystalline orientations ((1 1 0) and (1 0 0) respectively). In both series, for growth
temperatures exceeding 850ºC, the (1 1 1) diffraction peak is observed, confirming the
attainment of the L21 fully ordered phase while the disordered B2 phase is obtained at lower
temperatures. The film’s structural characterization shows, for both series, epitaxial growth and
a change in phase and morphology when higher deposition temperatures are used.
Electrical conductivity, charge carrier concentration, Seebeck coefficient, and power
factor were measured, observing a significant enhancement in thermoelectric performance for
films with L21 phase with respect to those with B2 phase, with differences as a function of
crystalline orientation that might be attributed to differences in the granular structure., Financial support by the Ministerio de Ciencia e Innovación with the ThermHeus (TED2021-
131746B-I00) project and the ERC Advanced Grant POWERbyU (ERC-2021-ADG-101052603) are
acknowledged. We acknowledge the service from the MiNa Laboratory at IMN, and funding from CM
(project S2018/NMT-4291 TEC2SPACE), MINECO (project CSIC13-4E-1794) and the EU (FEDER,
FSE).

The resistance of an ordered 3D-Bi2Te3 nanowire nanonetwork was studied at low temperatures. Below 50 K the increase in resistance was found to be compatible with the Anderson model for localization, considering that conduction takes place in individual parallel channels across the whole sample. Angle-dependent magnetoresistance measurements showed a distinctive weak antilocalization characteristic with a double feature that we could associate with transport along two perpendicular directions, dictated by the spatial arrangement of the nanowires. The coherence length obtained from the Hikami-Larkin-Nagaoka model was about 700 nm across transversal nanowires, which corresponded to approximately 10 nanowire junctions. Along the individual nanowires, the coherence length was greatly reduced to about 100 nm. The observed localization effects could be the reason for the enhancement of the Seebeck coefficient observed in the 3D-Bi2Te3 nanowire nanonetwork compared to individual nanowires., The authors would like to acknowledge the financial supportfrom the projects ERC Adv. POWERbyU 101052603,PID2020-118430GB-100, and PID2019-106165GB-C21 (MI-CINN) and project 2D-MESES from CSIC. This work wasalso cofinanced by the 2014−2020 ERDF OperationalProgramme and the Department of Economy, Knowledge,Business and University of the Regional Government ofAndalusia, project reference no. FEDER-UCA18-107139. Theauthors would also like to acknowledge the service from theMiNa Laboratory at IMN, and its funding from CM (projectSpaceTec, S2013/ICE2822), MINECO (project CSIC13-4E-1794), and EU (FEDER, FSE). F.P. acknowledges the supportfrom ICREA Academia 2022 and 2021SGR00242, Generalitatde Catalunya., Peer reviewed

According to the open access nature and its exceptions in the datasets regulation of the Call ERC-2021-ADG, and having reflected the following statements in the Data Management Plan of such project (ID: 101052603; POWERbyU; ERC-2021-ADG), the authors of the data associated with this publication state the following:
The datasets associated with this publication will be available upon request, due to these datasets being subjected to Intellectual Property Restrictions; requests by externals for the use of these datasets will be approved by the project coordinator. Please, contact Prof. Marisol Martín-González: marisol.martin@csic.es
This modus operandi will remain in effect, at least until the end of the project., This Dataset is referring to thefollowing study, which presents an approach for powering wearable sensors by integrating nanostructured bismuth telluride (Bi2Te3 and Te legs) into flexible polyester substrates. The choice of polyester as the substrate is because it is widely used in clothing, especially in items such as shirts, blouses, dresses, and sportswear. This enables seamless integration with wearable devices. By capturing wasted body heat, our small and flexible thermoelectric generators (TEGs) offer long-term operation without the need to plug the batteries. We demonstrate the feasibility of using commercially available polyester for reproducible electrochemical deposition of highly oriented Bi2Te3 and Te material. Through electrodeposition, we embed Bi2Te3 and Te legs within the flexible polyester, creating a cost-effective and easily scalable hybrid system for wearable energy harvesting. Our optimized TEG design, which can be worn on the arm or forehead, achieves impressive power density compared to existing state-of-the-art solutions. With a mere 3.5 °C temperature difference, only two pairs of p- and n-type legs, and a thickness of approximately 15 µm, our TEG generates a maximum open circuit voltage of ∼0.1 mV and a maximum power density of ∼0.04 mW·K-1·cm−2. With 250 pairs, 10 mV can be reached. This cost-effective design also integrates electrical contacts, surpassing previous flexible TEG performances. These advancements make our TEGs suitable for driving microwatt-level electronic sensors and open new avenues for efficient energy harvesting in wearable applications., We acknowledge the European Synchrotron Radiation Facility (ESRF) for provision of synchrotron radiation facilities under proposal number MA-4864 and we would like to thank Dr. Federico Monaco and Dr. Peter Cloetens for assistance and support in using beamline ID16A-NI. O.C-C would also like to acknowledge fruitful discussions with Dr. Germán Alcalá, David López Romero and the assistance with SEM images from Raquel Álvaro Bruna. The authors would like also to acknowledge the service from the MiNa Laboratory at IMN, and its funding from CM (project SpaceTec, S2013/ICE2822), MINECO (project CSIC13–4E-1794), and EU (FEDER, FSE). This work has been supported by the Ramon Areces Foundation through the micro-TENERGY project and by the ERC PowerbyU., No

Thermoelectricity has long been recognized as a transformative technology for power generation and cooling, owing to its capability to convert heat directly into electricity and vice versa, thereby facilitating cost-effective and environmentally friendly energy conversion. Following a period of modest activity, the field has experienced a remarkable resurgence since 2000, driven by significant advancements in the development of a diverse array of new materials and compounds, alongside enhanced capabilities for controlled nanostructuring. This rapid growth and the innovative breakthroughs observed over the past two decades can be largely attributed to a deeper understanding of the physical properties at the nanoscale. Among the various thermoelectric materials, nanostructured variants exhibit the highest potential for commercial application due to their unprecedented thermoelectric performance, which arises from substantial reductions in thermal conductivity. However, further advancements will not rely solely on nanostructuring; they will also necessitate novel electronic structure design concepts that require a comprehensive understanding of the complexities of electronic and phonon transport. These developments present significant opportunities for thermoelectric energy harvesting, power generation, and cooling applications. This article aims to summarize and elucidate the breakthroughs reported in recent years, discuss future avenues that integrate nanostructuring concepts with the rich electronic structures of novel materials, and provide a critical overview of the future directions in thermoelectric materials research. Additionally, it offers a comprehensive overview of state-of-the-art thermoelectric materials and devices and a summary of the challenges associated with transitioning these materials into practical devices., This work was supported by a Grant named ERC Advanced (POWERbyU Grant Agreements No.
101052603) and ERC Starting Grant (NANOthermMA grant agreement No. 678763)., Peer reviewed

This study demonstrates the direct correlation between the presence of the L21 ordered phase and the significant enhancement in the thermoelectric performance of Fe2VAl thin films deposited on MgO and Al2O3 substrates at temperatures varying between room temperature and 950 °C. We employ both experimental techniques and computational modeling to analyze the influence of crystallographic orientation and deposition temperature on the thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and thermal conductivity. Our findings indicate that the presence of the L21 phase significantly enhances the power factor (PF) and figure of merit (zT), surpassing previously reported values for both bulk and thin film forms of Fe2VAl, achieving a PF of 480 μW m-1 K-2 and a zT of 0.025., The authors would also like to acknowledge the service from the
MiNa Laboratory at IMN, and its funding from EU (FEDER,
FSE), MCIN/AEI/10.13039/501100011033 and Next Generation
EU/PRTR (EQC2021-006944-P). This work was funded by
projects THERMHEUS grant TED2021-131746B-I00 funded by
MICIU/AEI/10.13039/501100011033 and by the “European
Union NextGenerationEU/PRTR” and ERC Adv. POWERbyU
grant agreements ID: 101052603 funded by European Research
Council (ERC), and grant PID2022-138063OB-I00 funded by
MICIU/AEI/10.13039/501100011033 and by FEDER, UE. We
gratefully acknowledge the computer resources at Lusitania
(Cenits-COMPUTAEX), Red Española de Supercomputaci´on,
RES (QHS-2023-1-0028) and Albaic´ın (Centro de Servicios de
Inform´atica y Redes de Comunicaciones – CSIRC, Universidad
de Granada)., Peer reviewed

According to the open access nature and its exceptions in the datasets regulation of the Call ERC-2021-ADG, and having reflected the following statements in the Data Management Plan of such project (ID: 101052603; POWERbyU; ERC-2021-ADG), the authors of the data associated with this publication state the following:
The datasets associated with this publication will be available upon request, due to these datasets being subjected to Intellectual Property Restrictions; requests by externals for the use of these datasets will be approved by the project coordinator. Please, contact Prof. Marisol Martín-González: marisol.martin@csic.es
This modus operandi will remain in effect, at least until the end of the project., This Dataset refers to the following study which demonstrates the direct correlation between the presence of the L21 ordered phase and the significant enhancement in the thermoelectric performance of Fe2VAl thin films deposited on MgO and Al2O3 substrates at temperatures varying between room temperature and 950 °C. The researchers employ both experimental techniques and computational modeling to analyze the influence of crystallographic orientation and deposition temperature on the thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and thermal conductivity. Their findings indicate that the presence of the L21 phase significantly enhances the power factor (PF) and figure of merit (zT), surpassing previously reported values for both bulk and thin film forms of Fe2VAl, achieving a PF of 480 μW m−1 K−2 and a zT of 0.025., The authors would also like to acknowledge the service from the MiNa Laboratory at IMN, and its funding from EU (FEDER, FSE), MCIN/AEI/10.13039/501100011033 and Next Generation EU/PRTR (EQC2021-006944-P). This work was funded by projects THERMHEUS grant TED2021-131746B-I00 funded by MICIU/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR” and ERC Adv. POWERbyU grant agreements ID: 101052603 funded by European Research Council (ERC), and grant PID2022-138063OB-I00 funded by MICIU/AEI/10.13039/501100011033 and by FEDER, UE. We gratefully acknowledge the computer resources at Lusitania (Cenits-COMPUTAEX), Red Española de Supercomputación, RES (QHS-2023-1-0028) and Albaicín (Centro de Servicios de Informática y Redes de Comunicaciones – CSIRC, Universidad de Granada)., Peer reviewed

Thermoelectricity has long been recognized as a transformative technology for power generation and cooling, owing to its capability to convert heat directly into electricity and vice versa, thereby facilitating cost-effective and environmentally friendly energy conversion. Following a period of modest activity, the field has experienced a remarkable resurgence since 2000, driven by significant advancements in the development of a diverse array of new materials and compounds, alongside enhanced capabilities for controlled nanostructuring. This rapid growth and the innovative breakthroughs observed over the past two decades can be largely attributed to a deeper understanding of the physical properties at the nanoscale. Among the various thermoelectric materials, nanostructured variants exhibit the highest potential for commercial application due to their unprecedented thermoelectric performance, which arises from substantial reductions in thermal conductivity. However, further advancements will not rely solely on nanostructuring; they will also necessitate novel electronic structure design concepts that require a comprehensive understanding of the complexities of electronic and phonon transport. These developments present significant opportunities for thermoelectric energy harvesting, power generation, and cooling applications. This Dataset refers to the article which summarize and elucidate the breakthroughs reported in recent years, discuss future avenues that integrate nanostructuring concepts with the rich electronic structures of novel materials, and provide a critical overview of the future directions in thermoelectric materials research. Additionally, it offers a comprehensive overview of state-of-the-art thermoelectric materials and devices and a summary of the challenges associated with transitioning these materials into practical devices., This work was supported by a Grant named ERC Advanced (POWERbyU Grant Agreements No. 101052603) and ERC Starting Grant (NANOthermMA grant agreement No. 678763)., Peer reviewed