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Enhanced Thermoelectric Performance in Sputtered Epitaxial Fe2VAl Thin Films via Crystal Orientation Selection
Digital.CSIC. Repositorio Institucional del CSIC
- Conca, André
- Domínguez-Vázquez, José María
- Caballero-Calero, Olga
- Cebollada, Alfonso
- Martín-González, Marisol
Resumen del trabajo presentado en el 2024 MRS Spring Meeting, celebrado en Seattle (Estados Unidos), del 22 al 26 de abril de 2024 y de forma virtual del 7 al 9 de mayo de 2024, Heusler intermetallic compounds present a wide variety of compositions that fulfill the requirement of avoiding toxic or scarce elements. The Fe<sub>2</sub>VAl family of Heusler alloys shows a large potential and versatility for thermoelectric thin films with tunable properties via doping with additional elements such as Ti, Ta, Si, W, and others [1-3]. The doping allows the fabrication of p- and n-type alloys in the same family, which simplifies future thermoelectric device fabrication. While the undoped alloy Fe<sub>2</sub>VAl is a p-type material, the introduction of W, Si, or Ta results in a n-type one. P-type alloys are obtained with Ti and Zr, both with an increase in Seebeck values compared to the undoped case. The addition of these materials can also be performed in an off-stoichiometric manner [4,5].<br/>Sputter deposition is a well-established, inexpensive, and very versatile technique for the fabrication of a wide variety of material systems. The chemical composition can be highly controlled by the simultaneous use of several magnetrons with different elements (codeposition) to achieve the desired film content or doping concentration, which is needed to optimize the thermoelectric properties [6].<br/>From a fundamental point of view, the possibility to explore the influence of crystal orientation on thermoelectric performance is very appealing, offering a perfect scope for experiment versus theory comparison. In this sense, physical vapor deposition techniques are excellent tools for obtaining thin films with desired orientations through the use of adequate substrates in terms of crystal symmetry and lattice match. In this contribution, we present results on Fe<sub>2</sub>VAl thin films fabricated by magnetron dc sputtering. Two different sample series have been prepared with varying deposition temperatures (RT-950°C) and with two different substrates and, consequently, two crystalline orientations owing to the different epitaxial relations. Films grown on MgO (100) are (100)-oriented, while Al<sub>2</sub>O<sub>3</sub> (11-20) substrates induce a (110) orientation. In both cases, the (111) diffraction peak Fe<sub>2</sub>VAl corresponding to the L21 fully ordered phase can be observed in asymmetric configuration diffraction measurements.<br/>The results of the characterization of the thin films with X-Ray Diffraction and SEM imaging are shown, proving epitaxial growth for both series. The electric conductivity, Seebeck parameter, and power factor are reported. We observe a large difference in the thermoelectric performance depending on the growth orientation of the films.<br/>With these results, we prove the large potential of sputtering to produce high-quality Fe<sub>2</sub>VAl films ready for further desired compositional variation and tuned doping via codeposition., 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) is 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 EU (FEDER, FSE).
Proyecto: EC/HE/101052603
Thermoelectric efficiency of sputtered epitaxial Fe2VAI (100) and (110) thin films
Digital.CSIC. Repositorio Institucional del CSIC
- Domínguez-Vázquez, José María
- Lohani, Ketan
- Caballero-Calero, Olga
- Cebollada, Alfonso
- Martín-González, Marisol
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).
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).
Localization and Directionality of Surface Transport in Bi2Te3 Ordered 3D Nanonetworks
Digital.CSIC. Repositorio Institucional del CSIC
- Ruiz-Clavijo, Alejandra
- Pérez, Nicolás
- Caballero-Calero, Olga
- Blanco, Javier
- Peiró, Francesca
- Plana-Ruiz, Sergi
- López-Haro, Miguel
- Nielsch, Kornelius
- Martín-González, Marisol
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
DOI: http://hdl.handle.net/10261/370827, https://api.elsevier.com/content/abstract/scopus_id/85164967499
Flexible polyester-embedded thermoelectric device with Bi2Te3 and Te legs for wearable power generation [Dataset]
Digital.CSIC. Repositorio Institucional del CSIC
- Caballero-Calero, Olga
- Cervino-Solana, Pablo
- Cloetens, Peter
- Monaco, Federico
- Martín-González, Marisol
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
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
Proyecto: EC/HE/101052603
Localization and Directionality of Surface Transport in Bi2Te3 Ordered 3D Nanonetworks [Dataset]
Digital.CSIC. Repositorio Institucional del CSIC
- Ruiz-Clavijo, Alejandra
- Pérez, Nicolás
- Caballero-Calero, Olga
- Blanco, Javier
- Peiró, Francesca
- Plana-Ruiz, Sergi
- López-Haro, Miguel
- Nielsch, Kornelius
- Martín-González, Marisol
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., Nanowires are excellent model systems for investigating the effects of low dimensionality in materials. Controlling the diameter of the nanowires, and hence its surface-to-volume ratio, the presence or relevance of surface-related characteristics can be addressed. This is of particular interest in the case of topological insulators owing to electronic surface states (topologically protected) independent from bulk states. Tetradymite chalcogenides Bi2Te3, Bi2Se3, and Sb2Te3 are small band gap semiconductors with wide application in state-of-the-art Peltier cooling devices or thermoelectric power generators. They are also strong 3D-topological insulator, with topologically protected states predicted to appear on any free surface regardless of the crystallographic orientation. This Dataset is referring to the following study, in which 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 support from the projects ERC Adv. POWERbyU 101052603, PID2020-118430GB-100, and PID2019-106165GB-C21 (MICINN) and project 2D-MESES from CSIC. This work was also cofinanced by the 2014–2020 ERDF Operational Programme and the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia, project reference no. FEDER-UCA18-107139. The authors would also like 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). F.P. acknowledges the support from ICREA Academia 2022 and 2021SGR00242, Generalitat de Catalunya., No
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., Nanowires are excellent model systems for investigating the effects of low dimensionality in materials. Controlling the diameter of the nanowires, and hence its surface-to-volume ratio, the presence or relevance of surface-related characteristics can be addressed. This is of particular interest in the case of topological insulators owing to electronic surface states (topologically protected) independent from bulk states. Tetradymite chalcogenides Bi2Te3, Bi2Se3, and Sb2Te3 are small band gap semiconductors with wide application in state-of-the-art Peltier cooling devices or thermoelectric power generators. They are also strong 3D-topological insulator, with topologically protected states predicted to appear on any free surface regardless of the crystallographic orientation. This Dataset is referring to the following study, in which 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 support from the projects ERC Adv. POWERbyU 101052603, PID2020-118430GB-100, and PID2019-106165GB-C21 (MICINN) and project 2D-MESES from CSIC. This work was also cofinanced by the 2014–2020 ERDF Operational Programme and the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia, project reference no. FEDER-UCA18-107139. The authors would also like 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). F.P. acknowledges the support from ICREA Academia 2022 and 2021SGR00242, Generalitat de Catalunya., No