Relaxor behavior and electrothermal properties of Sn- and Nb-modified (Ba,Ca)TiO3 Pb-free ferroelectric

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  • Sarangi Venkateshwarlu, City University of Hong Kong
  • ,
  • Sanjib Nayak, City University of Hong Kong
  • ,
  • Frederick P. Marlton
  • ,
  • Florian Weyland, Technische Universität Darmstadt
  • ,
  • Nikola Novak, Institute Jo-zef Stefan
  • ,
  • Deepam Maurya, Virginia Polytechnic Institute and State University
  • ,
  • Yashaswini Veerabhadraiah, City University of Hong Kong
  • ,
  • Olaf Borkiewicz, Argonne National Laboratory
  • ,
  • Kevin A. Beyer, Argonne National Laboratory
  • ,
  • Mads R.V. Jorgensen
  • Abhijit Pramanick, City University of Hong Kong

Relaxor ferroelectrics have drawn attention for possible applications in solid-state cooling and thermal energy harvesting, owing to their electrothermal energy conversion properties. Here, we have synthesized and characterized the structure-property correlations of a new Sn- and Nb-doped (Ba,Ca)TiO3 relaxor ferroelectric with large pyroelectric and electrocaloric effects over a broad temperature range. We observed two peaks for the temperature-dependent pyroelectric coefficient: (i) -(∂P/∂T) ∼ 563 μC/(m2 K) at T∼ 270 K and (ii) -(∂P/∂T) ∼ 1021 μC/(m2 K) at T∼ 320 K. In addition, a broad peak for electrocaloric temperature change is observed near 320 K with a relative cooling power of ∼17 J/kg. These properties could be correlated to structural changes observed using X-ray diffraction at two different temperature ranges in the material. Analysis of high-energy X-ray scattering and specific heat capacity data revealed a transition from the cubic to tetragonal phase near Tm∼ 320 K, whereas an additional increase in the tetragonality (c/a) of the polar phase is observed below Ts∼ 270 K.

Original languageEnglish
JournalJournal of Materials Research
Pages (from-to)1017-1027
Publication statusPublished - Apr 2020

    Research areas

  • electrical properties, ferroelectric, X-ray diffraction

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