abstract
Currently, magnetocaloric refrigeration technologies are emerging as ecofriendly and more energy-efficient alternatives to conventional expansion-compression systems. However, major challenges remain. A particular concern is the mechanical properties of magnetocaloric materials, namely, their fatigue under cycling and difficulty in processing and shaping. Nevertheless, in the past few years, using multistimuli thermodynamic cycles with multicaloric refrigerants has led to higher heat-pumping efficiencies. To address simultaneously the challenges and develop a multicaloric material, in this work, we have prepared magnetocaloric-based flexible composite mats composed of micrometric electroactive (EA) polyvinylidene fluoride (PVDF) fibers with embedded magnetocaloric/strictive La(Fe,Si)(13) particles by the simple and cost-effective electrospinning technique. The composite's structural characterization, using X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, and measurements of the local-scale piezoresponse, revealed a cubic NaZn13-type structure of the La(Fe,Si)(13) phase and the formation of the dominant polar beta-phase of the PVDF polymer. The PVDF-La(Fe,Si)(13) composite showed an enhancement of the longitudinal piezoelectric coefficient (effective d(33)) (-11.01 pm/V) compared with the single PVDF fiber matrix (-9.36 pm/V). The main magnetic properties of La(Fe,Si)(13) powder were retained in the PVDF-La(Fe,Si)(13) composite, including its giant magnetocaloric effect. By retaining the unique magnetic properties of La(Fe,Si)(13) embedded in the electroactive piezoelectric polymer fiber mats, we have designed a flexible, easily shapeable, and multifunctional composite enabling its potential application in multicaloric heat-pumping devices and other sensing and actuating devices.
keywords
MAGNETIC ENTROPY CHANGE; COMPOSITES; ALPHA; BETA; PHASES
subject category
Science & Technology - Other Topics; Materials Science
authors
Isfahani, VB; Coondoo, I; Bdikin, I; Skokov, K; Gomes, JRD; Baptista, RMF; Pereira, CR; Araújo, JP; Belsley, MS; Gomes, ED; Belo, JH; Almeida, BG
our authors
Indrani Coondoo
Assistant Researcher
João Silva
Post-Doc FellowshipProjects
Electric-Field Engineered Lattice Distortions (E-FiELD) for optoelectronic devices (E-FiELD)
Demagnetizing-based magnetocaloric refrigeration (MAGCAL)
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
acknowledgements
The work was supported, in terms of TEMA Research Infrastructure equipment, by the projects UIDB/00481/2020 and UIDP/00481/2020yFundacao para a Ciencia e a Tecnologia, and CENTRO-01-0145-FEDER-022083yCentro Portugal Regional Operational Programme (Centro2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund. FCT/MCTES is also acknowledged in the framework of the projects UIDB/50006/2020, UIDP/50006/2020, and LA/P/0008/2020. This work was also supported by the Portuguese Foundation for Science and Technology (FCT) through FEDER (European Fund for Regional Development)-COMPETE-QREN-EU (ref UID/FIS/04650/2013 and UID/FIS/04650/2019) and the projects PTDC/NAN-MAT/0098/2020 and 2022.03564.PTDC. J.H.B. thanks EEA Grants for the project FBR OC1 85 and also thanks FCT for the projects PTDC/EME-TED/3099/2020, UIDB/04968/2020, UIDP/04968/2020, NECL-NORTE-010145-FEDER-022096, and CERN/FISTEC/0003/2019, PINFRA/22096/NECL/2016 and for his contract DL57/2016, with reference SFRH-BPD-87430/2012, and DL57/2016/CP1454/CT0013, with reference 10.54499/DL57/2016/CP1454/CT0013, DOI: 10.54499/DL57/2016/CP1454/CT0013. V.B.I. acknowledges the postdoc grant from the project NORTE-01-0145-FEDER-028538 and FCT project EXPL/CTM-CTM/0687/2021. I. Coondoo and I. Bdikin gratefully acknowledge financial support through the FCT project "MultiFlex" EXPL/CTM-CTM/0687/2021 (http://doi.org/10.54499/EXPL/CTM-CTM/0687/2021). I.C. would also like to acknowledge financial assistance by national funds (OE), through FCTyFundacao para a Ciencia e a Tecnologia, I.P., through DL57/2016/CP1482/CT0048(DOI: 10.54499/688 DL57/2016/CP1482/CT0048). I.B. gratefully acknowledges financial support through the Project "Agenda ILLIANCE" [C644919832-00000035 | Project no. 46], financed by PRRyRecovery and Resilience Plan, under the Next Generation EU from the European Union. R.M.F.B. acknowledge financial assistance by national funds (OE), through FCT - Fundacao para a Ciencia e a Tecnologia, I.P., through DL 57/2016/CP1377/CT0064 (DOI: 10.54499/DL57/2016/CP1377/CT0064). C.R.P. thanks FCT for funding through the Individual Call to Scientific Employment Stimulus, ref. 2021.04120.CEECIND/CP1662/CT0008 (DOI: 10.54499/2021.04120.CEECIND/CP1662/CT0008).