The electrocaloric effect of lead-free Ba<sub>1-y Ca<sub>y Ti<sub>1-x Hf<sub>x O<sub>3 from direct and indirect measurements

Gracia, David ; Lafuerza, Sara ; Blasco, Javier ; Evangelisti, Marco

Resumen: We report on the dielectric and electrocaloric properties of Ba1−yCayTi1−xHfxO3 for compositions 0.12 < x< 0.18 and y = 0.06, as well as x = 0.15 and 0 < y < 0.15, synthesized by the conventional solid-state reaction method. The addition of Hf/Ca broadens the ferroelectric-paraelectric phase transition while moving it toward room temperature. Two interferroelectric transitions are seen to converge, together with the ferroelectric–paraelectric phase transition, at ∼335 K for 0.12 < x_{c < 0.135 and y = 0.06. Consistent with the dielectric properties, the electrocaloric effect maximizes closer to room temperature with increasing Hf/Ca substitutions, which promote larger temperature spans. The electrocaloric responsivity gradually decreases from 0.2 to 0.1 K mm kV^{−1 with the addition of Hf/Ca. A homemade quasi-adiabatic calorimeter is employed to measure “directly” the electrocaloric data, which are also calculated from polarization-versus-electric-field cycles using “indirect” standard procedures. The comparison between measured and calculated values highlights the importance of having access to direct methods for a reliable determination of the electrocaloric effect.}}

Idioma: Inglés

DOI: 10.1063/5.0173585

Año: 2023

Publicado en: APL Materials 11, 12 (2023), 121101 [8 pp.]
ISSN: 2166-532X

Factor impacto JCR: 5.3 (2023)

Categ. JCR: PHYSICS, APPLIED rank: 43 / 179 = 0.24 (2023) - Q1 - T1
Categ. JCR: NANOSCIENCE & NANOTECHNOLOGY rank: 46 / 141 = 0.326 (2023) - Q2 - T1
Categ. JCR: MATERIALS SCIENCE, MULTIDISCIPLINARY rank: 122 / 439 = 0.278 (2023) - Q2 - T1

Factor impacto CITESCORE: 9.6 - Materials Science (all) (Q1) - Engineering (all) (Q1)

Factor impacto SCIMAGO: 1.527 - Materials Science (miscellaneous) (Q1) - Engineering (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E11-23R
Financiación: info:eu-repo/grantAgreement/ES/DGA-FSE/E12-23R-RASMIA
Financiación: info:eu-repo/grantAgreement/EC/H2020/101029019/EU/Exploring Aurivillius phases for Green Electrocaloric Refrigeration/EAGER
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2021-124734OB-C21

Tipo y forma: Article (Published version)