Enhanced electrocaloric, pyroelectric and energy storage performance of BaCexTi1−xO3 ceramics

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Enhanced electrocaloric, pyroelectric and energy storage performance of BaCex Ti1−x O3 ceramics K.S. Srikanth, Rahul Vaish ∗ School of Engineering, Indian Institute of Technology Mandi, H.P. 175 005, India

a r t i c l e

i n f o

Article history: Received 7 December 2016 Received in revised form 12 April 2017 Accepted 22 April 2017 Available online xxx Keywords: Electrocaloric Pyroelectric Energy storage

a b s t r a c t BaCex Ti1−x O3 (BCT) ceramics with compositions x = 0, 0.1, 0.12 and 0.15 were synthesized using conventional solid state reaction route. Systematic exploration of enhancing electrocaloric effect (ECE) in BaTiO3 by rare earth dopant Ce is presented. BaCe0.12 Ti0.88 O3 exhibited an electrocaloric strength of ∼0.35 K m/MV at 351 K, which caters the need for a series of high-level ECE material. Further, the temperature dependence of pyroelectric coefficient is established for all compositions. The pyroelectric figure of merits (FOMs) for current responsivity (Fi ), voltage responsivity (Fv ), detectivity (Fd ) and energy harvesting (Fe and Fe * ) are calculated and the results reveal that x = 0.1 could be a technologically superior candidate for pyroelectric devices. Further, BaCe0.15 Ti0.85 O3 exhibited highest electrical energy storage performance of 115 kJ/m3 compared with 71 kJ/m3 in BaTiO3 . Our findings in this work may provide a better understanding for developing high ECE materials combined with pyroelectric and energy storage performance of Ce substituted BaTiO3 ceramics. © 2017 Elsevier Ltd. All rights reserved.

1. Introduction Effective heat transfer in electronic devices can enhance efficiency and increases life of the devices. Solid state refrigeration techniques have untapped potential in micro to macro scale refrigerators for cooling these devices [1,2]. Amongst the known solid-state refrigeration technologies, electrocaloric effect is more promising. It refers to the reversible change in temperature of a material under the influence of an electric field under adiabatic conditions has undergone extensive scrutiny over the past decade [3–6]. The interest captivated the researcher’s eye upon the discovery of giant ECE in PbZr0.95 Ti0.05 O3 thin films in 2006 [3]. Thereafter, ferroelectrics became the subject of intense research, with the objective of conceiving a practical solid-state refrigeration system. Such technology would break ground for efficient, environmental-friendly, and miniaturized cooling devices. Many kinds of ferroelectric materials like bulk materials, thin films, thick films and polymers are used in this direction and abundant data have already been reported for these materials [7]. Thin films give largest caloric effects but it has limited heat extraction capacity [8,9]. Conversely, bulk ceramics possess higher thermal inertia, suited for practical cooling applications [10]. Conventional

∗ Corresponding author. E-mail address: [email protected] (R. Vaish).

lead-based ferroelectric materials are used in this direction [9]. Nevertheless, lead has carcinogen nature which is main cause of cancer and other serious health hazards. Therefore, due to environmental worry demands has been increasing to eliminate toxic lead for these materials systems. In this context, various lead-free ceramics with perovskite structure have emerged over the years, e.g. BaTiO3 (BT), Na0.5 Bi0.5 TiO3 and K0.5 Na0.5 NbO3 based solid solutions [11–13]. Amongst the lead-free ceramics, BaTiO3 is the oldest ferroelectric ceramic known that has been largely investigated over the period of time because of its promising dielectric, piezoelectric and ferroelectric properties [14]. It possess a large d33 value of 350–460 pC/N [15]. These findings incited worldwide exploration on BaTiO3 -based materials for replacement of lead-based materials for various dielectric applications. Owing to a very low ECE in BaTiO3 ceramics, various chemical modifications were done by researchers to improve its ECE performance to shift the curie temperature in the proximity of room temperature [16]. In this direction, numerous solid solutions were prepared in order to improve the ferroelectric, piezoelectric and ECE characteristics by replacing Ba with Mg, Sn, Sr, Ca and Ti with Nb, Zr, etc. [17,18]. One of the captivating feature of BaTiO3 ceramics is that by forming solid solutions with some of the rare earth ions like Zr [19], Ce [20], Hf [21] and Y [22], a relaxor behavior with enhanced dielectric, piezoelectric and pyroelectric performance can be induced. In this direction, few researchers have studied the effect of rare earth

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dopants on dielectric properties and Curie temperature of BaTiO3 [23–26]. Amongst the BaTiO3 based relaxor ferroelectrics, BaTiO3 doped with Ce garnered researchers scrutiny both due to application and fundamental interests [27–30]. The dopant ion Ce can enter into BaTiO3 lattice as Ce3+ or Ce4+ . The ionic radii of Ce3+ is in close proximity to that of Ba2+ ion which makes Ce3+ to occupy Ba site [31]. Ce4+ having an ionic radius in close proximity with that of Ti4+ will substitute Ti sites [32]. Further it is the fact that Ce4+ ion being more stable than Ce3+ ion will occupy Ti site. Therefore, it is of prime importance to study the site occupancy of Ce in BaTiO3 perovskite lattice. In this context, few studies reveal the substitution of Ce ions can take place at both sites (A and B) in the BaTiO3 perovskite unit cell when concentration of Ce < 8% which can result in completely different characteristics [29]. One possibility to find the site occupancy of Ce in BaTiO3 , is to use Raman spectroscopy [33]. Curecheriu et al. studied the site occupancy for Ce ≥ 0.1 and the peculiar features observed by him indicated the B site occupancy of Ce [33]. The ECE characteristic in rare earth doped BT (Ba0.94 R0.04 TiO3 , R = Nd, La, Sm, Ce, Eu, Dy, Gd Er) came into the limelight very recently where the addition of rare earth promoted shift of curie toward lower temperature side as compared with pristine BT for room temperature based ECE applications [16]. Li et al. investigated the EC characteristic of Hf substituted BT ceramics and found a T of 1 K (for 17% Hf) under the applied field of 50 kV/cm [34]. The electric field induced strain behavior for few Ce doped BT compositions have already been reported by Ang et al. [20,22]. Recently, the dielectric and ferroelectric P-E hysteresis characteristics were investigated by Curecheriu et al. for BaCey Ti1−y O3 ceramics with y = 0.1, 0.2 and 0.3 and explored these materials for application as tunable capacitors [35]. Therefore, part of the present work investigates the BaCex Ti1−x O3 with (x = 0–15%) for potential candidates for solid state refrigeration applications. Apart from the solid state refrigeration applications of ferroelectric ceramics, these materials can also be widely put into use for various applications ranging from sensor, actuator, transducer, pulse power circuit to transportation, spacecraft, medical devices, weapons and X-ray equipment [36,37]. Most of these listed applications are based on either the pyroelectric or piezoelectric response in a direct or indirect manner. It is because all the ferroelectric ceramics are necessarily piezoelectric and pyroelectric in nature which enthralls the researchers to use them for multiphysical applications [12]. In this direction, the present work also focuses the pyroelectric aspects of BCT compositions under study. To evaluate the quality of such materials for put into use for pyroelectric devices, we have systematically studied the influence of Ce dopant on the pyroelectric figure of merits (FOMs) which determine the suitability of materials for pyroelectric applications. Further, ferroelectric materials are also promising for efficient energy storage capacity [11,36]. Thus, the energy storage characteristics for all the under study compositions are also discussed in this article.

2. Experimental procedure The ceramics of composition BaCex Ti1−x O3 (x = 0, 0.1, 0.12, 0.15) were synthesized using conventional solid state reaction route. High purity reagents BaCO3 (99% pure), TiO2 (99% pure) and rare earth oxide CeO2 (99.99% pure) powders were the starting precursors. The raw powders were weighed and thoroughly mixed and grinded in an agate mortar according to their stoichiometric ratio. Calcination was done at 1000 ◦ C for 4 h to stimulate the solid-state reaction followed by further milling. The powders were pressed to form a disk shaped pellet having a diameter of 12 mm and a thickness of 1 mm after grinding using 2 wt% polyvinyl alcohol (PVA)

Fig. 1. X-ray diffraction patterns of BaCex Ti1−x O3 ceramics with x = 0, 0.1, 0.12 and 0.15, sintered at 1500 ◦ C for 9 h.

which acts as a binder-lubricant. The green samples were then subjected to sintering at 1500 ◦ C for 9 h. Afterwards, the density of the samples was measured employing Archimedes principle. The phase purity of the sintered ceramics was characterized by X-ray diffraction (XRD) (Rigaku Smart Lab, Japan) employing Cu K␣ radiation with a scan step of 2◦ /min. Scanning electron microscopy (SEM) (FEI SEM NOVA Nanosem 450, Hillsboro, OR) was used to study the samples surface morphology after polishing the surfaces. For the electrical measurements, silver electrodes were used on the polished surface of the ceramic samples. The polarization-electric field (P-E) hysteresis loops were recorded at 50 Hz at various electric fields and temperatures using a modified Sawyer Tower circuit (Marine India). The dielectric constant and loss were determined at room temperature using impedance analyzer (Agilent E4990A, Agilent Technologies Inc., Santa Clara, CA). 3. Results and discussion 3.1. Microstructural characterizations Fig. 1 shows the XRD patterns of the BaCex Ti1−x O3 ceramics for various Ce composition (x = 0, 0.1, 0.12, 0.15) sintered at 1500 ◦ C for 9 h. The lack of any secondary peaks indicates that the solid state reaction has occurred in the specified sintering conditions and the incorporation of Ce in the perovskite lattice was complete. The structural analysis evidences that the limit of solid solubility of Ce4+ onto Ti ions in BaTiO3 lattice is around x = 0.3 as reported by Ang et al. [38]. The nature of XRD indicates the formation of single phase perovskite solid solutions as evident from Fig. 1. The diffraction peaks of the undoped ceramic correspond well to T-symmetry (PDF#05-0626) [39]. We observe that the peak intensity splits into two {(0 0 2), (2 0 0)} at angles ranging from 44◦ to 46◦ as evident from Fig. 1 which indicates that the ceramic also possess an O-phase corresponding to (PDF#81-2200) [39]. Also, we observe three peaks at 56◦ in x = 0 sample which corresponds well to the standard card (PDF#81-2200), which further confirms the existence of O-phase in pristine BaTiO3 [39]. However, with the introduction of Ce into the lattice of BaTiO3 , the diffraction peaks around 44◦ –46◦ merge into a single peak, suggesting that the host phase undergoes an obvious phase transition. These three peaks at 56◦ also merges into a single peak for all Ce added samples under study. Apart from the structural

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Fig. 2. Scanning electron micrographs of BaCex Ti1−x O3 ceramics with (a) x = 0, (b) x = 0.1, (c) x = 0.12 and (d) x = 0.15.

phase transition, we also noticed a gradual shift of diffraction peak toward lower angle with increasing x content. It could be due to the ˚ for Ti4+ (r = 0.6507 A) ˚ at replacement of larger ion Ce4+ (r = 0.87 A) the B site of perovskite structure [20]. Hence, in the present work, XRD is limited only to confirm the phase as the main focus of this article is to explore these materials for specific properties as discussed later. However, we believe a detailed discussion on XRD analysis is required to understand the structural evolution. The scanning electron microscopy (SEM) images of all the investigated compositions exhibit a good densification, with well interconnected grains and without major voids or anomaly, having a bimodal grain size distribution(larger grains coexist with smaller grains) as shown in Fig. 2. With Ce addition, a further increase of larger grains on the expense of smaller grains takes place which is in agreement with the work reported by Curecheriu et al. [33]. Further, the densities of BaCex Ti1−x O3 sintered ceramics were found employing Archimedes principle and the relative densities were >94% for all compositions. 3.2. Differential scanning calorimetry Fig. 3. DSC heat flow curves of Ce doped BaTiO3 ceramics.

Fig. 3 portrays the differential scanning calorimetry (DSC) heat flow patterns of the Ce added BaTiO3 ceramics which was sintered at 1500 ◦ C. The phase transition temperature of pure BaTiO3 is around 395 K which has been substantially reduced to 371 K (x = 0.1), 349 K (x = 0.12) and 335 K (x = 0.15) by addition of Ce dopant. Therefore, it can be inferred from such study that on increasing Ce concentration, the endothermic peak shifts to a lower temperature side. 3.3. Electrocaloric studies To examine the role of Ce dopant in changing the switching properties of BaCex Ti1−x O3 ceramics, the ferroelectric hysteresis polarization-electric field loops (P-E) have been recorded at various operating temperature and at constant electric field as depicted in Fig. 4. The measurement frequency 50 Hz was kept constant. All the samples exhibited well saturated P-E loops due to their high den-

sity. In order to evaluate the electrocaloric capacity of under study compositions, the temperature dependent P-E hysteresis loops are shown in Fig. 4. It is seen that as the temperature increases, the P–E loops of all ceramics under study shrank and the intensity of polarization decreased. It illustrates that the thermal agitation gradually destroys the dipoles order arrangement. And the change in polarization reflects the corresponding change in entropy. Therefore, considering the temperature dependence of polarization, the ECE adiabatic temperature change (T) was calculated using Maxwell’s relation (Eq. (1)):

T T = − Cp

E2 

∂P ∂T

 dE

(1)

E1

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Fig. 4. P-E hysteresis loops for BaCex Ti1−x O3 ceramics with (a) x = 0, (b) x = 0.1, (c) x = 0.12 and (d) x = 0.15 measured at various operating temperature. Inset shows the comparative P-E loops.

where P stands for polarization (extracted from upper branches of P-E loop),  denotes density and Cp refers to specific heat capacity. Fig. 5(a) depicts the variation of T as a function of material temperature. The undoped ceramic displays a maximum T of 0.9 (0.9 ± 0.04) K at 395 K and at an applied field of 24 kV/cm. However, upon incorporation of 10% Ce, this value is reduced to 0.5 (0.5 ± 0.02) K at 374 K. On further increasing the Ce dopant concentration to x = 0.12 in BaCex Ti1−x O3 , T has been tuned toward room temperature to 0.8 (0.8 ± 0.03) K at 351 K, this value is achieved at a substantial 44 K lower than the parent material. Furthermore, the T is lowered to 0.6 (0.6 ± 0.04) K when x = 0.15. This value is reduced in comparison with x = 0.12 and x = 0 samples, but with a substantial reduction of Curie temperature by 60 K than the parent material under study. Therefore, it can be inferred from such study that the incorporation of Ce into BaTiO3 significantly lowers the peak Curie temperature. The error factor in these numerical data has been added since these data are the results of indirect caloric measurements employing Maxwell relations. However, we believe direct measurements are warranted to confirm our findings. Additionally, the most enthralling hallmark lays in the fact that the peak T value can be tuned toward room temperature with Ce addition which is good to obtain a meliorated room temperature based EC performance. This peak shifting with Ce addition has been confirmed using DSC measurements within some experimental errors. All these improvements combine boast of an overall advancement that can help mitigate most of the drawbacks currently associated with ferroelectric solid-state refrigeration. However, the T alone is insufficient to predict the feasibility of a ferroelectric material for determining the overall EC performance. The mass-specific entropy change (S) is another important factor which helps to figure out the overall heat extraction capacity of

the material used, per unit mass. The entropy change (S) was calculated using Maxwell’s relation (Eq. (2)): 1 S = − 

E2 

∂P ∂T

 dE

(2)

E1

Fig. 5(b) shows the S of all compositions under investigation against material temperature. It can be said that a similar pattern analogous to T can be noticed for S. The peak entropy change capacity has been computed to 0.5 (0.5 ± 0.07), 0.9 (0.9 ± 0.02) and 0.7 (0.7 ± 0.03) J/kg K at x = 0.1, 0.12 and 0.15 respectively when contrasted with 1.0 (1.0 ± 0.01) J/kg K in undoped ceramic. The EC strength of 12% Ce doped BaTiO3 ceramics is higher than many other similar class of materials [16]. It symbolizes that our work provides excellent material with high-level EC strength. Thus, it can be said that BCT is a promising lead free material for solid state refrigeration purpose. 3.4. Pyroelectric study These materials are known for their unique pyroelectric (temporal temperature gradient for electric current generation) conversion ability [40]. This trademark makes it popular for number of applications like sensor, thermal imaging, infrared detectors and energy harvesting applications [41,42]. These operations manifests high pyroelectric coefficient together with low dielectric loss and dielectric constant, low conductivity and specific heat capacity. Fig. 6 shows the comparative plots of pyroelectric coefficient vs temperature for various Ce concentration. Based on the P-E hysteresis loops obtained upon heating, the representative parameters like remnant polarization (Pr ) are extracted to illustrate the impact of Ce dopant to the base composition. The pyroelectric coefficients

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Fig. 5. (a) Electrocaloric temperature change (T) and (b) entropy change (S) with Ce concentrations at applied field of 24 kV/cm.

Fig. 7. Energy storage density and storage efficiency as a function of Ce concentration. Inset explains the procedure to calculate energy storage density. Fig. 6. Comparative plots of pyroelectric coefficient vs. temperature for all samples.

were calculated utilizing the Pr values using a static method (Eq. (3)): p=

dPr dT

(3)

Table 1 lists the values of pyroelectric coefficient (p) at room temperature for different materials. The pyroelectric coefficient and dielectric constant determined at room temperature are used to calculate the pyroelectric figure of merits (FOMs). There are number of FOMs derived for use in pyroelectric applications. The most prevalent FOM is based on pyroelectric sensor application for generating maximum voltage or current for a given power input. The FOM for current responsivity (Fi ) is expressed as Fi = p/Cv [43–45]. It is observed from Table 1 that there is a substantial increment in Fi for x = 0.12 sample compared to the other samples under study as the pyroelectric coefficient was larger for this sample. Similarly, to obtain maximum pyroelectric voltage for a given heat input, the FOM for voltage responsivity is written as (Fv ) = p/Cv εε0 , where Cv , ε0 and ε are volume specific heat capacity, permittivity of free space and dielectric constant, respectively [44,46]. Furthermore, high detectivity based FOM is written as  (Fd ) = p/Cv εε0 tan ı [47,48]. The Fd is found to be 3.38, 3.85, 4.07, 0.33 ␮ Pa−1/2 respectively for x = 0, 0.1, 0.12 and 0.15 samples. The values of ε and tan ı are determined at room temperature using impedance analyzer for all compositions. In general, these FOMs are used for materials selection and indirect performance evaluation for heat, infrared sensors, etc. [49]. On the contrary,

the thermo-electric energy conversion is also a pivotal application of pyroelectric ceramics. In this direction, energy harvesting FOM [(Fe ) = p2 /εε0 and (Fe∗ ) = p2 /εε0 Cv2 ] have been used by many researchers for pyroelectric energy harvesting materials selection [44,46,50]. Table 1 lists the various FOMs for the investigated compositions at room temperature and at frequency 1 MHz. With low ε and moderate tan ı, the BaCe0.1 Ti0.9 O3 ceramics exhibit highest FOMs of Fv = 0.009 m2 /C, Fe = 6.8 J/m3 K2 and Fe * = 1.53 pm3 /J and a competing Fi = 171 pm/V and Fd = 3.85 ␮ Pa−0.5 amongst the other Ce doped samples. Therefore, BaCex Ti1−x O3 ceramic with x = 0.1 can be a superficial lead-free candidate for fabrication of pyroelectric devices. In order to compare the performance of Ce doped BaTiO3 with other well-known lead free pyroelectric material, Table 1 summarizes few selected materials with their pyroelectric properties. One could say that Ce doped BaTiO3 will be a potential material for pyroelectric application for replacing lead-based counterparts.

3.5. Energy storage characteristics In order to compare the electrical energy storage performance of BaTiO3 ceramics with different Ce contents, the energy storage density (ESD) has been calculated by using data generated from hysteresis P-E loops. Fig. 7 provides a direct comparison of the samples capacity of electrical energy storage density. In general, the electrical energy storage capacity in ferroelectric materials can be estimated by integrating the area between the P-E loops discharge curve and the polarization, within the interval of Pr to Ps as depicted

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Table 1 Comparison of pyroelectric FOMs for well-known lead-free ferroelectric materials and investigated compositions at room temperature. Material

p (10−4 C/m2 K)

Fi (p m/V)

Fv (m2 /C)

Fe (J/m3 K2 )

Fe * (pm3 /J)

Ref.

BaCe0.1 Ti0.9 O3 BaCe0.12 Ti0.88 O3 BaCe0.15 Ti0.85 O3 P(VDF-TrFE) 50/50 [(K0.5 Na0.5 )0.96 Li0.04 ]Nb0.84 Ta0.1 Sb0.06 O3 [(K0.5 Na0.5 )0.96 Li0.04 ]Nb0.8 Ta0.2 O3 BaTiO3 [Bi0.5 (Na0.95 K0.05 )0.5 ]0.95 Ba0.05 TiO3 P(VDF-TrFE) 80/20 LiNbO3 Ca0.15 (Sr0.5 Ba0.5 )Nb2 O6 PVDF [Bi0.5 (Na0.94 K0.05 Li0.016 )0.5 ]0.95 Ba0.05 TiO3

3.57 3.81 0.47 0.4 1.9 1.65 2 3.25 0.31 0.83 3.61 0.27 3.6

171 182 23 17 42 62 80 112 13 35 171 100 127

0.009 0.005 0.0008 0.109 0.003 0.006 0.008 0.015 0.218 0.141 0.02 0.147 0.017

6.8 4.3 0.08 12 3 2.8 4.2 – 17.5 31 17 10 19

1.53 0.97 0.02 1.9 0.1 0.4 0.6 1.7 – 6 3.4 1.7 2.1

This work This work This work [51] [41] [41] [52] [41] [51] [52] [53] [51] [41]

in the inset of Fig. 7. An expression for finding the energy storage density is (Eq. (4)):



Ps

W=

E.dP

(4)

Pr

where W refers to the stored electrical energy density in the material, E signifies applied external field and Ps and Pr denotes saturation and remnant polarization, respectively. The energy storage density has been shown as bar graphs in Fig. 7 and found to be 71 kJ/m3 for BaTiO3 which increased to 115 kJ/m3 (62% improvement) after adding 15% Ce and remained almost constant at 77 kJ/m3 (9% improvement) and 78 kJ/m3 (10% improvement) for the sample with x = 0.1 and 0.12 respectively. However, Eq. (4) depicts only the recoverable energy density as we integrate with respect to the P-E loops discharging curve. It is the fact that the amount of energy required in charging a ferroelectric capacitor is the arithmetic addition of recoverable energy (W) and dielectric losses (Wloss ). This unreleased energy density i.e. the loss is defined as the energy tantamount to the inherent hysteresis in the material. These losses are generally manifested in the form of self-heating or ferroelectric noise within the material. The area confined by charging–discharging curve constitutes the unrecoverable energy. Therefore, Eq. (5) gives the total energy required for capacitor charging; WTotal = W + Wloss

Acknowledgements One of the author (Rahul Vaish) acknowledges the support from the Indian National Science Academy (INSA), New Delhi, India through a grant by the Department of Science and Technology (DST), New Delhi, India under the INSPIRE faculty award-2011 (ENG-01).

(5)

Considering Eqs. (4) and (5), the storage efficiency of the material can be estimated as shown in Eq. (6). W = WTotal

There is a substantial improvement in ECE for all Ce doped samples over pure BaTiO3 for room temperature based applications and the highest being 0.8 K obtained for x = 0.12 sample. Further, the pyroelectric coefficient of all BCT ceramics are studied and found maximum for x = 0.12 sample with 3.81 × 10−4 C/m2 K at room temperature. The pyroelectric FOMs at room temperature have been calculated for all ceramics. There is a tremendous improvement of FOMs over undoped ceramic. However, the x = 0.1 sample exhibited the highest FOMs for voltage responsivity (Fv ) and energy harvesting (Fe and Fe * ) and a competing value for current responsivity (Fi ) and detectivity (Fd ) amongst the other Ce doped samples. Therefore, it could be a technologically superficial lead-free candidate for fabrication of pyroelectric devices. Further, the energy storage density and storage efficiency showed remarkable improvement over pristine BaTiO3 and the results advocates strongly in favor of 15% Ce sample as being the optimum material for enhanced electrical energy storage.

(6)

A small value of  implies considerable losses in the form of hysteresis. By reducing the dielectric losses, one can achieve high energy storage efficiency as evident from Eq. (6). The storage efficiency for all Ce doped BaTiO3 ceramic under consideration have been plotted as bar chart in Fig. 7. It is evident from the bar chart that the Ce doped BaTiO3 ceramics perform relatively better. It is noteworthy that there is a tremendous improvement in storage efficiency for x = 0.15 sample over pristine BaTiO3 (179% improvement). These observations advocates strongly in favor of 15% Ce sample as being the optimum material for achieving enhanced electrical energy storage. 4. Conclusions BaCex Ti1−x O3 perovskite ceramics were synthesized by solid state reaction method and the influence of dopant Ce on the ferroelectric, pyroelectric and energy storage capacity of BCT ceramics with x = 0, 0.1, 0.12 and 0.15 were investigated in detail. The ECE of various Ce dopant concentrations in BCT ceramics were studied.

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Please cite this article in press as: K.S. Srikanth, R. Vaish, Enhanced electrocaloric, pyroelectric and energy storage performance of BaCex Ti1−x O3 ceramics, J Eur Ceram Soc (2017), http://dx.doi.org/10.1016/j.jeurceramsoc.2017.04.058