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Abstract The hafnate perovskites PbHfO3(antiferroelectric) and SrHfO3(“potential” ferroelectric) are studied as epitaxial thin films on SrTiO3(001) substrates with the added opportunity of observing a morphotropic phase boundary (MPB) in the Pb1−xSrxHfO3system. The resulting (240)‐oriented PbHfO3(Pba2) films exhibited antiferroelectric switching with a saturation polarization ≈53 µC cm−2at 1.6 MV cm−1, weak‐field dielectric constant ≈186 at 298 K, and an antiferroelectric‐to‐paraelectric phase transition at ≈518 K. (002)‐oriented SrHfO3films exhibited neither ferroelectric behavior nor evidence of a polarP4mmphase . Instead, the SrHfO3films exhibited a weak‐field dielectric constant ≈25 at 298 K and no signs of a structural transition to a polar phase as a function of temperature (77–623 K) and electric field (–3 to 3 MV cm−1). While the lack of ferroelectric order in SrHfO3removes the potential for MPB, structural and property evolution of the Pb1−xSrxHfO3(0 ≤x < 1) system is explored. Strontium alloying increased the electric‐breakdown strength (EB) and decreased hysteresis loss, thus enhancing the capacitive energy storage density (Ur) and efficiency (η). The composition, Pb0.5Sr0.5HfO3produced the best combination ofEB = 5.12 ± 0.5 MV cm−1,Ur = 77 ± 5 J cm−3, and η = 97 ± 2%, well out‐performing PbHfO3and other antiferroelectric oxides.
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Large Polarization and Susceptibilities in Artificial Morphotropic Phase Boundary PbZr 1− x Ti x O 3 Superlattices
Abstract The ability to produce atomically precise, artificial oxide heterostructures allows for the possibility of producing exotic phases and enhanced susceptibilities not found in parent materials. Typical ferroelectric materials either exhibit large saturation polarization away from a phase boundary or large dielectric susceptibility near a phase boundary. Both large ferroelectric polarization and dielectric permittivity are attained wherein fully epitaxial (PbZr0.8Ti0.2O3)n/(PbZr0.4Ti0.6O3)2n(n= 2, 4, 6, 8, 16 unit cells) superlattices are produced such that the overall film chemistry is at the morphotropic phase boundary, but constitutive layers are not. Long‐ (n≥ 6) and short‐period (n= 2) superlattices reveal large ferroelectric saturation polarization (Ps= 64 µC cm−2) and small dielectric permittivity (εr≈ 400 at 10 kHz). Intermediate‐period (n= 4) superlattices, however, exhibit both large ferroelectric saturation polarization (Ps= 64 µC cm−2) and dielectric permittivity (εr= 776 at 10 kHz). First‐order reversal curve analysis reveals the presence of switching distributions for each parent layer and a third, interfacial layer wherein superlattice periodicity modulates the volume fraction of each switching distribution and thus the overall material response. This reveals that deterministic creation of artificial superlattices is an effective pathway for designing materials with enhanced responses to applied bias.
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- Award ID(s):
- 1708615
- PAR ID:
- 10458784
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 6
- Issue:
- 3
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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