Impact of critical point on piezoelectric and electrocaloric response in barium titanate

Novak, Nikola; Pirc, R.; Kutnjak, Zdravko

doi:10.1103/physrevb.87.104102

Cited by 82 publications

(71 citation statements)

References 46 publications

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“…408,409 Criticality is apparent in the C phase above under electric fields of (0.40 ± 0.12) kV/mm and was also observed for other relaxors and BT. 107,188,191 The 33 at the line of critical points is maximized and comparable to the values observed at the O to T PPB due to high reversible switching and intrinsic contributions.…”

Section: Strain Mechanisms Of the (1-x)ba(zr 02 Ti 08 )O 3 -X(ba 0supporting

confidence: 69%

“…It is noted, however, that an electric field induced nucleation of an O phase at expense of the T phase 321 or a change in the relative content of R and T phases cannot be discarded. The peak in piezoelectric response observed above marked with indicates that the electric field induced paraelectric to ferroelectric transitions in BZT-BCT are of first order 156,188,191 , which is supported by the non-zero thermal hysteresis in dielectric properties. 194 The high 33 values above that were obtained at finite bias-fields ( 33 ) = (0.40 ± 0.12) kV/mm implies a line of critical points.…”

Section: Bias-field-and Temperature-dependent Quasi-static Small Signmentioning

confidence: 72%

“…157,187 Some authors extended the concept of a free energy anisotropy further and evoked criticality as the fundamental reason behind enhanced properties. [188][189][190][191] A critical point is defined as a continuous transition from a first order to a second order phase transition under thermodynamic equilibrium that does not involve thermal hysteresis. Near these critical points, the energy barrier for a phase transition is considerably diminished.…”

Section: Electromechanical Enhancements In Ferroelectricsmentioning

confidence: 99%

“…194 The high 33 values above that were obtained at finite bias-fields ( 33 ) = (0.40 ± 0.12) kV/mm implies a line of critical points. [188][189][190][191] This observation casts doubt on the assertion that triple points of the zero-field pseudo-binary phase diagram are also tricritical points. 194,333 In order to allow a better understanding of the strain mechanisms in BZT-BCT, quantification of the intrinsic and extrinsic contributions to 33 .3 is valid with the assumption that reversible switching is considerably reduced at zero bias-field.…”

Section: Bias-field-and Temperature-dependent Quasi-static Small Signmentioning

confidence: 99%

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Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

Acosta

2016

Springer Theses

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Section: Strain Mechanisms Of the (1-x)ba(zr 02 Ti 08 )O 3 -X(ba 0supporting

confidence: 69%

Section: Bias-field-and Temperature-dependent Quasi-static Small Signmentioning

confidence: 72%

Section: Electromechanical Enhancements In Ferroelectricsmentioning

confidence: 99%

Section: Bias-field-and Temperature-dependent Quasi-static Small Signmentioning

confidence: 99%

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Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

Acosta

2016

Springer Theses

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“…ΔT EC of BaTiO 3 [23] (solid line) and PVDF-based relaxor polymers (dashed line) as a function of E calculated for P r = 0 following Eq. (7) in comparison to ΔT EC determined along the coexistence curve of the ferroelectric-paraelectric phase transition [27]. Experimental data of single crystal (sc), polycrystalline (pc) BaTiO 3 , and PVDF-based polymers were taken from Refs.…”

Section: Introductionmentioning

confidence: 99%

Electrocaloric Cooling

Suchaneck¹,

Pakhomov²,

Gerlach³

2017

Refrigeration

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The electrocaloric effect describes a reversible temperature change in dielectric materials submitted to an applied electric field. Adiabatic polarization raises their temperature, and adiabatic depolarization lowers it, analogous to temperature changes that occur when a gas is compressed or expanded. For refrigerator application, the reverse Brayton cycle is currently the most promising for practical implementation. The electrocaloric effect provides a large material efficiency. However, existing refrigerator prototypes lack from the absence of efficient heat switches for thermal linkage to the load and the heat sink. Cooling power densities of a few W/cm 2 and temperature spans in the order of 20 K (in regeneration systems) are achievable at a cycle time of 100 ms.Keywords: electrocaloric effect, thermodynamic cycles, coefficient of performance, refrigeration devices IntroductionFor almost 150 years, refrigeration applications were solved by means of vapour compression. While the most efficient fluids for this approach are based on chlorofluorocarbons, hydrochlorofluorocarbons and hydrofluorocarbons, they come with the severe drawback of contributing to global warming and ozone depletion. Therefore, in 1987, the Montreal Protocol issued a ban on these chemicals providing regulations for phasing them out. Promising natural alternative substances are impractical due to their toxicity (ammonia) or-in particular-their flammability (propane) [1].Vapour compression refrigerators (VCRs) are operated as reverse Rankine cycles. They use a circulating liquid refrigerant as a medium. The refrigerant is: (i) adiabatically compressed, (ii) condensed at constant pressure undergoing a phase transition (thereby rejecting heat to the heat sink), (iii) adiabatically throttled in an expansion valve and (iv) evaporated at constant © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.pressure undergoing the reverse phase transition (thereby absorbing heat from the load). The amount of transferred heat is determined by the latent heat of the first-order phase transition. Similarly, in solid-state electrocaloric (EC) cooling, the adiabatic compression/expansion of the refrigerant is analogous to adiabatic polarization/depolarization, while the isobaric processes are replaced by isofield ones. Contrary to VCR, where the adiabatic expansion of the vapour is thermodynamically irreversible, the EC and the magnetocaloric (MC) effects are thermodynamically reversible processes that could reach the limit of the Carnot efficiency. This is another aspect making them promising for future application.Electric fields required for the EC refrigeration cycle can be supplied much easier and less expensively than the high magnetic fields required for the MC refrigeration [2]. Other advantages in compar...

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Giant Electrocaloric Response Over A Broad Temperature Range in Modified BaTiO₃ Ceramics

Qian

Zhang

et al. 2013

Adv Funct Materials

385

261

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1300www.MaterialsViews.com wileyonlinelibrary.com . IntroductionElectrocaloric effect (ECE), an electric fi eld induced temperature and/or entropy change of an insulating material, has attracted a great deal of attention after the recent fi ndings of large ECE in ceramic thin fi lms, polymers, and a dielectric fl uid. [1][2][3][4][5][6][7][8][9][10] Several recent works have also demonstrated potential of realizing high performance cooling devices exploiting large ECE in new electrocaloric (EC) materials. [11][12][13][14] In these newly developed EC materials, the giant ECE, i.e., large adiabatic temperature change Δ T and isothermal entropy change Δ S, were obtained under high applied electrical fi elds. For example, a | Δ T| = 35 K and Δ S = 160 Jkg −1 K −1 were induced in a high energy electron irradiated P(VDFTrFE) relaxor polymer under an electric fi eld change Δ E of 180 MVm −1 . [ 15 ] Analogously, in ferroelectric BaTiO 3 (BT) thick fi lms, a | Δ T| = 7.1 K and Δ S = 10.1 Jkg −1 K −1 were generated under the application of high electric fi elds change Δ E = 80 MVm −1 . [ 16 ] As one starts to address these EC materials for practical cooling devices applications, additional parameters should be considered besides a large Δ T and Δ S to measure the performance of EC materials. For instance, in order for cooling devices to be operated at low voltage such as <200 volts which is the normal voltage range for most cooling devices, an EC material with a large ECE induced under small electric fi elds is also important. In addition, a wide operational temperature range near room temperature is highly desired in order to develop high performance and practical EC cooling devices. [11][12][13][14] Therefore, one critical question is how to design and develop dielectric materials which are capable of generating giant ECE over a broad operation temperature with relatively low applied electric fi eld change Δ E.As a lead-free ferroelectric material which is environmentally friendly and is in fact the most widely used ferroelectric material, ECE in BT has been studied quite extensively in the past several years by many groups and in various forms including thin fi lms, bulk ceramics (including thick fi lms multilayer ceramic capacitors (MLCC)), and single crystals. [16][17][18][19][20][21][22] Large Δ T and Δ S have been reported in BT ceramics at temperatures near the ferroelectric-paraelectric (FE-PE) transition. [ 16 ] It is noted that for BT, besides the high temperature FE-PE transition (the transition temperature T FE-PE > 100 ° C) between the tetragonal ferroelectric (Tet) and cubic paraelectric phase, also exhibits an orthorhombic (O) and a rhombohedral (Rhom) phases as illustrated in Figure 1 (a). [ 23 ] As ECE is directly related to the entropy change of an insulation dielectric under the change of the applied electric fi eld, a dielectric with a polar phase which contains a large number of polar-states with similar energy levels can be induced under a reasonable electric fi eld from a nonpolar phase (i.e., belo...

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Impact of critical point on piezoelectric and electrocaloric response in barium titanate

Cited by 82 publications

References 46 publications

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

Electrocaloric Cooling

Giant Electrocaloric Response Over A Broad Temperature Range in Modified BaTiO₃ Ceramics

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Impact of critical point on piezoelectric and electrocaloric response in barium titanate

Cited by 82 publications

References 46 publications

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

Electrocaloric Cooling

Giant Electrocaloric Response Over A Broad Temperature Range in Modified BaTiO3 Ceramics

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Product

Resources

About

Giant Electrocaloric Response Over A Broad Temperature Range in Modified BaTiO₃ Ceramics