Relaxor behavior and electrothermal properties of Sn- and Nb-modified (Ba,Ca)TiO 3 Pb-free ferroelectric
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Relaxor behavior and electrothermal properties of Sn- and Nb-modified (Ba,Ca)TiO3 Pb-free ferroelectric Sarangi Venkateshwarlu1, Sanjib Nayak1, Frederick P. Marlton2, Florian Weyland3, Nikola Novak4, Deepam Maurya5, Yashaswini Veerabhadraiah1, Olaf Borkiewicz6, Kevin A. Beyer6, Mads R.V. Jørgensen7, Abhijit Pramanick1,a) 1
Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR, China Center for Materials Crystallography, Department of Chemistry and INANO, Aarhus University, Aarhus C 8000, Denmark 3 Institute of Materials Science, Technische Universitat Darmstadt, Darmstadt 64287, Germany 4 Department of Condensed Matter Physics, Institute Joz ef Stefan, Ljubljana 1000, Slovenia 5 Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA 6 Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, United States of America 7 Center for Materials Crystallography, Department of Chemistry and INANO, Aarhus University, 8000 Aarhus C, Denmark; and MAX IV Laboratory, Lund University, SE-221 00 Lund, Sweden a) Address all correspondence to this author. e-mail: [email protected] This paper has been selected as an Invited Feature Paper. 2
Received: 15 October 2019; accepted: 7 January 2020
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 lC/(m2 K) at T ∼ 270 K and (ii) -(@P/@T) ∼ 1021 lC/(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.
Abhijit Pramanick
Abhijit Pramanick is an Assistant Professor at the City University of Hong Kong. He obtained his Bachelors in Engineering from the National Institute of Technology, India, and his Masters in Engineering from the Indian Institute of Science, Bangalore. He received his Ph.D. in Materials Science and Engineering in 2009 from the University of Florida, Gainesville, working under the mentorship of Prof. Jacob L Jones. After his Ph.D., he held a postdoctoral appointment in the research group of Prof. Scott Misture at the Alfred University in New York, USA. Subsequently, he moved to the Oak Ridge
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