Giant negative electrocaloric effect in antiferroelectric PbZrO<sub>3</sub> thin films in an ultra-low temperature range

Guo, Mengyao; Wu, Ming; Gao, Weiwei; Sun, Bin; Lou, Xiaojie

doi:10.1039/c8tc05108a

Cited by 48 publications

(18 citation statements)

References 41 publications

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“…If yes, what does this mean for the dynamical stability of the AFE P bam phase? Now that the technological importance of AFE materials have been realized, it is crucial to return to address these fundamental issues to ensure that new AFE technologies including solid state cooling (exploitative of the large negative electrocaloric effect [19][20][21][22]) and energy storage devices [23] are built upon stable foundations.…”

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confidence: 99%

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

Baker,

Paściak,

Shenton

et al. 2021

Preprint

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First principles density functional theory (DFT) simulations of antiferroelectric (AFE) PbZrO3 and PbHfO3 reveal a dynamical instability in the phonon spectra of their purported low temperature P bam ground states. This instability doubles the c-axis of P bam and condenses five new small amplitude phonon modes giving rise to an 80-atom P nam structure. Compared with P bam, the stability of this structure is slightly enhanced and highly reproducible as demonstrated through using different DFT codes and different treatments of electronic exchange & correlation interactions. This suggests that P nam is a new candidate for the low temperature ground state of both materials.With this finding, we bring parity between the AFE archetypes and recent observations of a very similar AFE phase in doped or electrostatically engineered BiFeO3.Nearly seventy years have passed since the theory of the antiferroelectric (AFE) phenomenon was proposed by Kittel[1] and the observation in PbZrO 3 (PZO) by Shirane, Sawaguchi and Takagi [2]. Today, although most consider PZO and PbHfO 3 (PHO, PZO's isoelectronic and isostructural partner) the AFE archetypes, many fundamental aspects of these materials remain hotly contested. Indeed, recent years have brought the very nature of the AFE phase transition into question with no clear consensus in sight [3][4][5][6][7][8]. Even the crystal structure of the low temperature AFE phase is a point of order. The majority of the community regard the structure as being best described with P bam symmetry [9-13], but the path to this agreement was a contentious one. Several different space group assignments were proposed (which are summarized in [9]) as well as suggestions of structural disorder [10]. Compounded with this, the presence of complex twinning [10,14,15] and incommensurations [16,17] are ubiquitous in these materials *

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confidence: 99%

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

Baker,

Paściak,

Shenton

et al. 2021

Preprint

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“…The samples examined in this study are ceramics of pure PZO, an archetypal anti-ferroelectric with a large negative electrocaloric effect. [5,27,28] Thanks to the electrocaloric temperature change concomitant with the AFE-FE phase transition (with Pbam [29] and R3c [30] symmetries, respectively), it is possible to use an infrared camera to observe how the electrocaloric front linked to the AFE switching nucleates/propagates across the sample in real time at a maximum frequency of 1253 Hz. In order to be able to switch the bulk ceramic capacitors with electric fields lower than the breakdown field, we work at temperatures close to, but below, the Curie temperature, which for PZO is T C ≈ 230 °C.…”

Section: Resultsmentioning

confidence: 99%

“…The samples examined in this study are ceramics of pure PbZrO 3 (PZO), an archetypal antiferroelectric with a large negative electrocaloric effect [5], [24], [25]. Thanks to the electrocaloric temperature change concomitant with the AFE-FE phase transition, it is possible to use an infrared camera to observe how the electrocaloric front linked to the AFE switching nucleates/propagates across the sample in real time at a maximum frequency of 1253 Hz.…”

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confidence: 99%

Direct Visualization of Anti‐Ferroelectric Switching Dynamics via Electrocaloric Imaging

Vales-Castro

Vellvehı́

Perpiñà

et al. 2021

Adv Elect Materials

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or even the standard gas cooling cycle (50%). [1] First theorized in 1878 by William Thomson, [2] the high-temperature changes (ΔT = 12 K) calculated for ferroelectric (FE) thin films [3] and the discovery of an anomalous electrocaloric effect in anti-ferroelectrics (AFE) [3] have renewed its interest, with an eye put on its potential application as a solid-state cooling solution in integrated circuits.FE materials display what is regarded as the "conventional" electrocaloric effect (or positive electrocaloric effect), whereby the material increases temperature (ΔT > 0) when a voltage step is applied and decreases temperature (ΔT < 0) when it is removed. In contrast, AFE display the opposite response; they decrease temperature (ΔT < 0) when an electric field E is applied, and increase (ΔT > 0) when it is removed. The ability of anti-ferroelectrics to cool down despite electrostatic energy being pumped into them is intriguing, and different underlying mechanisms have been proposed for the negative electrocaloric effect. [4,5] Recent experimental evidence indicates that, in the archetypal anti-ferroelectric PbZrO 3 (PZO), the so-called giant negative electrocaloric effect is due to the latent heat absorbed during the adiabatic-field-induced AFE-FE transition, which is endothermic. [6] In PbZrO 3 , the direct link between the anomalous electrocaloric effect and the first-order anti-ferroelectric-ferroelectric switching implies that the field-induced nucleation and motion of the AFE-FE phase boundary will dictate the dynamics of the large negative ECE and, ultimately, the dynamics of electrocaloric devices based on first-order transitions. In ferroelectrics, the study of domain wall dynamics [7][8][9][10][11][12][13][14][15][16] has been examined in detail on account of their relevance for ferroelectric memories. In contrast, there are far fewer works regarding the dynamics of the ferroelectric-paraelectric phase boundaries in FE [17,18] or the anti-ferroelectric-ferroelectric ones in anti-ferroelectrics. [19][20][21][22][23] Yet, a priori, one cannot assume that the dynamics of domain walls will be the same as the dynamics of phase boundaries, while the former separate different domains within the same ferroelectric phase, the latter separate different phases-in antiferroelectrics, an antipolar phase from a field-induced polar one. Domain switching dynamics is defined by a nucleationpropagation process. On the one hand, nucleation refers to the appearance of "hotspots," where nanoscopic nuclei of switched domains appear and rapidly expand forward across the thickness The large electrocaloric coupling in PbZrO 3 allows using high-speed infrared imaging for visualizing anti-ferroelectric switching dynamics via the associated temperature change. It is found that in ceramic samples of homogeneous temperature and thickness, switching is fast due to the generation of multiple nucleation sites, with devices responding in the millisecond range. By introducing gradients of thickness, however, it is possible to change the dyn...

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“…where ρ is the density, C p is the specific heat capacity per mass, T is the testing temperature, P is the ferroelectric polarization, E 1 and E 2 are the initial and final external electric fields, respectively [19,20,21]. For ferroelectrics, when the FP phase transition occurred with the elevated temperature, Eq.…”

Section: Introductionmentioning

confidence: 99%

Enhanced electrocaloric effect in compositional driven potassium sodium niobate‐based relaxor ferroelectrics

Zhang

Zheng

Zhao

et al. 2021

Journal of Materials Research

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Lead-free ferroelectric electrocaloric ceramics that could convert electrical energy into heat are the promising candidate for environment-friendly cooling devices. For refrigeration devices, a large temperature change (ΔT ) and good temperature stability are required, which are highly related to the phase structure and the applied electric field. In this work, a diffused ferroelectric-paraelectric (FP) phase transition is formed in (K, Na)NbO 3 (KNN) by using appropriate composition engineering. The relaxor ferroelectrics in this work present both a large ΔT of 1.24 K and a high ΔT/ΔE of 0.19 K mm/kV. In addition, a wide temperature span exceeds 55°C at the high electrocaloric effect (ECE) criterion (ΔT ≥ 0.5 K) could also be observed. This work not only opens a new strategy for obtaining high-performance ceramics for refrigeration devices but also extends the application area of the KNN-based lead-free ferroelectrics from sensors, actuators and energy harvesting to solid-state cooling applications.

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Giant negative electrocaloric effect in antiferroelectric PbZrO₃ thin films in an ultra-low temperature range

Abstract: Antiferroelectric thin films have demonstrated an excellent negative electrocaloric effect, and are potential candidates for future refrigeration applications.

Cited by 48 publications

References 41 publications

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

Direct Visualization of Anti‐Ferroelectric Switching Dynamics via Electrocaloric Imaging

Enhanced electrocaloric effect in compositional driven potassium sodium niobate‐based relaxor ferroelectrics

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Giant negative electrocaloric effect in antiferroelectric PbZrO3 thin films in an ultra-low temperature range

Abstract: Antiferroelectric thin films have demonstrated an excellent negative electrocaloric effect, and are potential candidates for future refrigeration applications.

Cited by 48 publications

References 41 publications

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

A re-examination of antiferroelectric PbZrO$_3$ and PbHfO$_3$: an 80-atom $Pnam$ structure

Direct Visualization of Anti‐Ferroelectric Switching Dynamics via Electrocaloric Imaging

Enhanced electrocaloric effect in compositional driven potassium sodium niobate‐based relaxor ferroelectrics

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Giant negative electrocaloric effect in antiferroelectric PbZrO₃ thin films in an ultra-low temperature range