237
Original scientific paper
Journal of Microelectronics, 
Electronic Components and Materials
Vol. 54, No. 4(2024), 237 – 245
https://doi.org/10.33180/InfMIDEM2024.401
How to cite:
S. Merselmiz et al., “Electrocaloric and pyroelectric properties of 0.6Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
 –0.4BaTi
0.89
Sn
0.11
O
3
 ceramics" , Inf. Midem-J. Micro-
electron. Electron. Compon. Mater., Vol. 54, No. 4(2024), pp. 237–245
Electrocaloric and pyroelectric properties of 
0.6Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
 –0.4BaTi
0.89
Sn
0.11
O
3
 
ceramics
Soukaina Merselmiz
1,2
, Zouhair Hanani
2
, Hana Uršič
2,3
, Uroš Prah
2
, Daoud Mezzane
1,4
,  
El-houssaine Ablouh
5
, Matjaž Spreitzer
2
, Lahoucine Hajji
1
, Zahra Abkhar
1
, Brigita Rožič
2
, 
Mimoun El Marssi
4
 and Zdravko Kutnjak
2
1
IMAD-Lab, Cadi Ayyad University, Marrakesh, Morocco
2
Jožef Stefan Institute, Ljubljana, Slovenia
3
Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
4
LPMC, University of Picardy Jules Verne, Amiens, France 
5
MSN, Mohammed VI Polytechnic University (UM6P), Benguerir, Morocco
Abstract: Ferroelectric materials are gaining considerable attention for energy storage, electrocaloric and pyroelectric energy 
harvesting applications. In particular, Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
 (BCZT) and BaTi
0.89
Sn
0.11
O
3
 (BTSn) ceramics are among the best-studied lead-
free BaTiO
3
-based ferroelectrics with high piezoelectric and electrocaloric properties. In this work, we prepared a 0.6BCZT–0.4BTSn 
solid solution. The structural, energy storage, electrocaloric, and pyroelectric properties are investigated. An energy density of            
61.4 mJ cm
-3
 with a high energy efficiency of 82.4 % at 90 °C is achieved. The electrocaloric temperature change, which is determined 
indirectly via the Maxwell relation, is 0.5 K at 86 °C and 25 kV cm
-1
. It is stable over a wide temperature range of around 65 °C and has a 
coefficient of performance of 15. Moreover, a pyroelectric energy density of 124.1 mJ cm
-3
 is achieved. The results of this study show 
that the 0.6BCZT–0.4BTSn ceramics is a multifunctional material with energy storage, electrocaloric and pyroelectric properties.
Keywords: Lead-free; ceramic; BCZT; energy storage; electrocaloric; pyroelectric; energy harvesting
Elektrokalorične in piroelektrične lastnosti 
0.6Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
 –0.4BaTi
0.89
Sn
0.11
O
3
 
keramike
Izvleček: Feroelektrični materiali pridobivajo veliko pozornost v raziskavah, ki se osredotočajo na elektrokalorične in piroelektrične 
pojave ter na shranjevanje energije. Zlasti keramiki Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
 (BCZT) in BaTi
0.89
Sn
0.11
O
3
 (BTSn) sodita med najbolj raziskane 
keramične materiale brez svinca na osnovi BaTiO
3
. V tem delu smo pripravili trdno raztopino 0.6BCZT–0.4BTSn. Raziskali smo strukturne, 
elektrokalorične in piroelektrične lastnosti keramike 0.6BCZT-0.4BTSn ter njeno zmožnost shranjevanja energije. Keramika izkazuje 
gostoto shranjevanja energije v višini 61.4 mJ cm
-3
 z najvišjim energijskim izkoristkom 82.4 % pri temperaturi 90 °C. Elektrokalorična 
temperaturna sprememba določena preko Maxwellove enačbe, znaša 0.5 K pri temperature 86 °C in električnem polju 25 kV cm
-1
 
ter je stabilna v širokem temperaturnem območju 65 °C  s koeficientom učinkovitosti 15. Keramika izkazuje tudi piroelektrično 
gostoto energije 124.1 mJ cm
-3
. Rezultati kažejo, da je keramika 0.6BCZT-0.4BTSn večfunkcijski material, ki izkazuje elektrokalorične in 
piroelektrične lastnosti ter zmožnost shranjevanja energije.
Ključne besede: keramika brez svinca; BCZT; shranjevanje energije; elektrokalorik; piroelektrik; zbiranje energije
* Corresponding Author’s e-mail: soukaina.merselmiz@ijs.si; hana.ursic@ijs.si

238
S. Merselmiz et al.; Informacije Midem, Vol. 54, No. 4(2024), 237 – 245
1 Introduction
To alleviate growing environmental concerns, the 
green energy industry is developing rapidly [1]–[4]. In 
particular, high-efficiency electrocaloric (EC) cooling 
technologies have attracted much attention, especially 
in ferroelectric materials. This is due to their ability to 
be efficiently driven by electric fields that are readily 
available, making them promising for use in solid-state 
cooling systems to cool microelectronic devices [5]–[7]. 
This is due to their polarization and entropy change 
near the ferroelectric phase transition upon applica-
tion/removal of an electric field, resulting in an adia-
batic temperature change (ΔT), known as the EC effect 
[8]–[10]. In addition, dielectric capacitors such as fer-
roelectric materials have been widely used in energy-
scavenging technologies based solely on their intrinsic 
polarization [11], [12].
The waste heat produced by many electronic devices 
presents an opportunity for energy harvesting tech-
nologies, which can convert it in various ways [13]. 
One approach to enhance device efficiency, involves 
harvesting and converting this wasted heat through 
pyroelectric energy harvesting [14], [15]. This method 
requires converting heat energy into clean electricity 
using materials exhibiting the pyroelectric effect [16]. 
This effect known as the converse of the EC effect, in-
volves the transformation of waste or heat energy into 
electrical voltage when subjected to temperature vari-
ations [17]. Its magnitude can be assessed using the 
Olsen cycle, similar to the Ericson cycle [18], [19]. Ac-
cordingly, the density of pyroelectric energy harvest-
ing (U
pyro
) can be calculated from the recorded polariza-
tion–electric field (P–E) hysteresis loop of ferroelectric 
materials. Since ferroelectrics are a subgroup of pyro-
electrics, BaTiO
3
 (BT)-based materials are considered 
promising candidates for pyroelectric energy harvest-
ing. These materials exhibit significant spontaneous po-
larization and can undergo polarization changes across 
a broad temperature range, fulfilling the requirements 
of the EC effect. For example, U
pyro
 value of 229 mJ cm
-3
 
was found in 0.5BaZr
0.2
Ti
0.8
O
3
–0.5Ba
0.7
Ca
0.3
TiO
3
 ceramics 
[20]. In addition, a comparable U
pyro
 value of 210 mJ cm
-3
 
was obtained in BaTi
0.91
Sn
0.09
O
3
 ceramics [21]. 
Ceramic dielectric capacitors play crucial roles as en-
ergy conversion and storage devices by absorbing and 
releasing large voltages or current pulses within a short 
lifetime between microseconds and milliseconds [22]. 
This property makes them promising candidates for 
energy-storage devices within pulsed-power and pow-
er-conditioning electronic applications [2], [23]. Pure 
BT ceramics capacitors exhibit a ferroelectric tetrago-
nal phase with high dielectric permittivity close to the 
Curie temperature (T
c
) and a relatively square-like P–E 
hysteresis loop, with both large remanent polarization 
(P
r
) and coercive field (E
c
). These properties lead to high 
energy loss (U
loss
), low recovered energy density (U
rec
) 
as well as low energy storage efficiency (η), limiting BT 
ceramics from practical application in energy storage 
devices [24]. Doping BT material with Ca
2+
 at the A-site 
and with Zr
4+
/Sn
4+
 at the B-site could be beneficial to 
adjust the P–E hysteresis loop by reducing the P
r
 and 
increasing the difference ΔP between the maximal po-
larization (P
max
) and P
r
, thereby enhancing simultane-
ously its U
rec
 and η [22], [24]–[27].
In 2009, Liu et al. reported a high piezoelectric coeffi-
cient of d
33
 ~ 620 pC N
-1
 in Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
 (abbre-
viated as BCZT) ceramics related to the morphotropic 
phase boundary occurring at room temperature. Sub-
sequently, BaTi
0.89
Sn
0.11
O
3
 (abbreviated as BTSn) with a 
quasi-quadruple point (coexistence of cubic–tetrago-
nal–orthorhombic–rhombohedral phases) was found 
to have high dielectric permittivity (~ 75 000) and im-
proved piezoelectric coefficient of d
33
 ~ 697 pC N
-1
 at 
~ 42 °C [28]. As a result, the chemical modification of  
BT (e.g., Ca, Zr, Sn, etc.) enhance further the dielectric 
and piezoelectric poperties [29]–[35]. With the chemi-
cal modification, the thermal stability of the properties 
can be tailored by approaching the rhombohedral–or-
thorhombic (R–O, T
R–O
) and orthorhombic–tetragonal 
(O–T, T
O–T
) phase boundaries with the corresponding 
phase transition temperatures to the T
c
 peak tempera-
ture together with shifting T
c
 to room temperature [31]. 
The sequence of phase boundaries enhance the ther-
mal stability of the properties over a wide temperature 
range, which is essential to achieve practical applica-
tions [31]. 
We have previously reported the EC properties of BCZT 
and BTSn ceramics studied by the indirect Maxwell ap-
proach [36], [37]. BTSn ceramics showed high ΔT~0.71 K 
at 40 °C at 25 kV cm
-1
, but in a relatively narrow temper-
ature span (T
span
) [37]. Meanwhile, BTSn ceramic showed 
a U
rec
 of 84.4 mJ cm
-3
 with high η of 91.0 %. In contrast, 
BCZT ceramics showed a ΔT~0.57 K at 100 °C at the 
same electric field in a relatively broader T
span
 of 70 K 
[36]. However, the U
rec
 was ~75 mJ cm
-3
 with a very low 
η of  37 %, limiting BCZT from practical applications. In 
order to prepare multifunctional material with both en-
hanced electrical properties and thermal stability, we 
prepared (1−x)Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
–xBaTi
0.89
Sn
0.11
O
3
 
solid solution system (x = 0.2, 0.4 and 0.6) as  previously 
reported in our previous work [38]. In this work, we 
investigated structural, energy storage, EC effect and 
pyroelectric energy harvesting properties of 0.6BCZT-
0.4BTSn ceramics (abbreviated as 0.4BTSn).

239
2 Materials and methods
The 0.6Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
–0.4BaTi
0.89
Sn
0.11
O
3
 (abbrevi-
ated as 0.4BTSn) ceramics was prepared by conventional 
solid-state method, by homogenizing BCZT and BTSn 
calcined powders. The preparation process of 0.4BTSn 
ceramics is described in detail in our previous work [38].
The crystalline structure of crushed 0.4BTSn ceramic pel-
let at room-temperature (RT) was investigated by X-ray 
powder diffractometer (XRD, BRUKER AXS D4 ENDEAV-
OR) equipped with Cu-Kα-radiation. Diffraction patterns 
were recorded in the 10–80° 2θ-range with a step size of 
0.02° using Cu-Kα-radiation. Phase identification was per-
formed with the COD-2020 database using the standard 
diffraction peaks of BaTiO
3
 with orthorhombic (PDF#81–
2200) and tetragonal (PDF#05–0626) symmetries [39]. 
The microstructure of sintered ceramics was examined 
using a scanning electron microscope (SEM, Zeiss EVO 
10 SEM, Carl Zeiss Microscopy, Germany) equipped 
with an energy dispersive X-ray spectrometer (EDXS, 
ZEISS SmartEDX Instrument, Carl Zeiss Microscopy, 
Germany). Prior to the microstructural analysis, the 
samples were ground and finely polished using a col-
loidal silica suspension. The bulk density of the sintered 
ceramics was determined by the Archimedes’ method 
using deionized water as medium. In addition, the av-
erage grain size was determined from the digitized im-
ages of the polished surfaces processed with ImageJ 
software (version 1.52a, National Institutes of Health, 
USA) by measuring more than 300 grains using the av-
erage grain intercept (AGI) method.
For the electrical properties, the ceramic pellets were 
cut, thinned, and polished to a thickness of about 400 
μm and then the Cr/Au electrodes were sputtered on 
sample’ surfaces. The dielectric properties were meas-
ured using a precision LCR Meter instrument (Agilent, 
4284A, USA) in the temperature range from −50 to 200 
°C. The polarization versus electric field (P–E) hysteresis 
loops were recorded using Aixacct TF analyzer 2000 
(Aixacct, Aachen, Germany) from 30 to 140 °C using a 
triangular excitation signal with a frequency of 10 Hz.
3 Results
The XRD patterns of the 0.4BTSn ceramic at room tem-
perature is shown in Figure 1 (a). It shows peaks charac-
teristic of the perovskite phase. The XRD fitting pattern 
extended by 2θ ≈ 45° using the Lorentz fitting method is 
shown in the inset (Figure 1 (b)). The enlarged peak pre-
sents a splitting of two peaks that could be the coexist-
ence of orthorhombic (022)
O
 and tetragonal (200)
T
 peaks 
Figure 2: SEM image and EDXS maps show the distribution of elements Ba, Ca, Zr, Ti, Sn and O on the surface of the 
0.4BTSn ceramic (Scale bar: 50 µm).
Figure 1: (a) Room-temperature XRD pattern of the 
0.4BTSn ceramics, and (b) the enlarged view of the 
peak splitting at 2θ ≈ 45°.
S. Merselmiz et al.; Informacije Midem, Vol. 54, No. 4(2024), 237 – 245

240
forming a (022)
O
/(200)
T
 doublet [40]. These results were 
confirmed by using Rietveld refinement, as reported in 
our previous work [38].
To gain insight into the microstructure and chemical 
composition of the 0.4BTSn ceramics, Figure 2 shows 
the SEM and the elemental mapping images on the 
polished surface of the sample. A compact and dense 
microstructure with an average grain size of (12.0 ± 4.8) 
µm were observed. The density of the ceramic was 5.5 
g cm
-3
, which corresponds to 93 % of the theoretical 
density. Furthermore, the EDXS mapping images show 
a homogeneous distribution of all contained elements 
(Ba, Ca, Zr, Ti, Sn and O).
The temperature dependence of the dielectric per-
mittivity (ε´) and dielectric loss (tanδ) of the 0.4BTSn 
sample are shown in Figure 3 (a). Sequential anomalies 
corresponding to R–O (T
R–O
), O–T (T
O–T
), and tetragonal-
cubic (T
c
) phase transitions at about –23, 37, and 75 °C, 
respectively, are observed. The maximum value of per-
mittivity (ε´
max
) and the peak-permittivity temperature 
(T
m
) were found to be ~ 10630 at ~ 77 °C and 1 kHz, cor-
responding to a dielectric loss of tanδ ~ 0.04.
P–E hysteresis loops at different temperatures are 
shown in Figure 3 (b). As the temperature increases, 
the P
max
 decreases continuously due to the ferroelec-
tric-paraelectric phase transition above temperatures 
around ~ 80 °C. To further investigate the energy stor-
age properties, the recorded P–E hysteresis loops as a 
function of applied electric field and temperature were 
used. Inset in Figure 3 (b) shows schematically the ar-
eas presenting the U
rec
 and the U
loss
 in blue and gray 
colors, respectively. The total energy density (U
tot
) can 
be calculated by integrating and gathering U
rec 
and U
loss
 
areas using equations (1) and (2). Therefore, the η can 
be estimated using equation (3) [41]. The temperature 
dependence of the energy storage properties is plot-
ted in Figure 3 (c). At room temperature, the U
rec
 value 
was found to be ~ 55 mJ cm
-3
 with η ~ 65 %, which is 
twice as high as that of pure BCZT (η ~ 37 %) at 25 kV 
cm
-1
 [36]. At 120 °C, high η value of 86 % was found 
in 0.4BTSn ceramic, exceeding that of pure BCZT (η ~ 
72%) [36].
 
0
U
max
P
tot
EdP 

    (1)
U
max
r
P
rec
P
EdP 

    (2)
 
 % 100 100
recr ec
totr ec loss
UU
UU U
  

 (3)
For environmentally friendly solid-state cooling de-
vices, the electrocaloric properties of 0.4BTSn ceram-
ics were indirectly evaluated via the Maxwell relation 
using the measured electric polarization P (T, E). First, 
a fifth-order polynomial fit of the upper polarization 
branches was performed at each fixed applied electric 
field [5]. The thermal evolution of the polarization was 
Figure 3: Temperature dependence of (a) ε´ and tanδ, 
and (b) P–E hysteresis loops for 0.4BTSn ceramics. Inset: 
A schematic depiction of the relevant U
rec
 and U
loss
 de-
termined via P–E hysteresis loops. (c) The corresponding 
energy storage properties as a function of temperature.
S. Merselmiz et al.; Informacije Midem, Vol. 54, No. 4(2024), 237 – 245

241
derived. The polarization (P) decreases continuously 
with increasing temperature as presented in Figure 
4 (a). The isothermal entropy change (ΔS) and the ΔT 
were estimated using Maxwell relation with equations 
(4) and (5), where E, ρ and C
p
 denote the applied elec-
tric field, mass density and specific heat of the sample, 
respectively [5]. The value of C
p
 (0.48 J g
−1
 K
−1
) was taken 
from Ref. [42].
 
2
1
E
E
E
P
Sd E
T
 





    (4)
 
2
1
E
E
E p
TP
Td E
CT 
 
 




   (5)
Figure 4 (b) shows the temperature dependence of 
ΔT at different applied electric fields. The T
O–T
 and T
c
 
are visible and more pronounced with increasing the 
applied E. The maximum ΔT was found to be around 
the T
c
. As the E increases, ΔT increases and its maxima 
shift slightly to higher temperatures. At 25 kV  cm
-1
, ΔT 
reaches a maximum of 0.5 K at 86 °C, then gradually de-
creases. A crucial parameter for evaluating the EC effect 
of a material is the EC responsivity, written as ζ = ΔT/
ΔE. This calculated coefficient was found to be ζ = 0.20 
K mm  kV
-1
 at the peak temperature. Table 1 presents 
comparable results for some of the previously pub-
lished EC outcomes for lead-free ferroelectric materials 
compared to 0.4BTSn ceramics.
For practical cooling applications, maintaining a sig-
nificant EC effect over a wide temperature range (T
span
) 
is of great importance. T
span
 is usually specified as the 
full width at half maximum (FWHM) of the EC peak (at 
the FE–PE phase transition), which can exceed 45–60 
°C at a high EC effect benchmark [43]. The diffuse 
phase transition has been found to be directly related 
to the broadened EC peaks at low electric fields [44]. 
Improved T
span
 value of 65 °C is obtained, which could 
be explained by the successive phase transitions and to 
the diffuse phase transition.
Another important parameter for evaluating the suit-
ability of EC materials for use in solid-state refrigeration 
systems, is the refrigerant capacity RC = ΔS. T
span
 [5]. This 
parameter was found to be 33.1 J kg
-1
. In addition, the co-
efficient of performance (COP = input power/output cool-
ing power = |T. ΔS|/|U
rec
|) is considered a crucial parameter 
for estimating the refrigeration cycle performance and 
evaluating the efficiency of the material [5]. The calcu-
lated COP value is 15 at 90 °C, which is higher than some 
other lead-free [45]–[47]. In summary, the 0.4BTSn ceram-
ics could be an advantageous material for some specific 
EC cooling systems in a wide temperature range.
Ferroelectric materials with enhanced polarization 
change upon heating have a high potential for use in 
pyroelectric energy harvesting [18]. For this reason, 
the pyroelectric energy harvesting performances of 
0.4BTSn ceramic were evaluated. The magnitude of the 
pyroelectric effect can be evaluated using the Olsen cy-
cle. Figure 5 (a) depicts a diagram illustrating the func-
tioning of the pyroelectric energy harvesting effect 
employing the Olsen cycle. It involves two isothermal 
(AYB, CYD) and two isoelectric (BYC, DYA) process-
es per cycle [18]. The pyroelectric energy density (U
pyro
), 
which is achieved in certain temperature and electric 
field ranges, corresponds to the area AYBYCYDYA, 
which can be described by equation (6) [48]. The U
pyro
 
divided by the total heat energy that is absorbed by 
this process gives the pyroelectric energy efficiency 
(η
pyro
) (see equation 7). Analogous to the EC effect, we 
define the pyroelectric responsivity (ζ
pyro
) by the equa-
tion (8), when the energy harvesting density can be 
rationalized by the temperature change of the corre-
sponding Olsen cycle,
Figure 4: Temperature dependence of (a) P and (b) ΔT 
of the 0.4 BTSn ceramics measured at different applied 
electric fields from 5 to 25 kV cm
-1
, showing the transi-
tion temperatures T
O–T
 and T
c
.
S. Merselmiz et al.; Informacije Midem, Vol. 54, No. 4(2024), 237 – 245

242
 
pyro
UE dP       (6)
 

pyro
pyro
pH L
U
CT T




     (7)
 
.
pyro
pyro
U
ET
 

    (8)
Figure 5 (b) shows the high-temperature dependence 
of U
pyro
 and η
pyro
 at T
L
 = 30 °C, E
L
 = 5 kV cm
-1
 and E
H
 = 
25 kV cm
-1
 in 0.4BTSn ceramic. It is observed that U
pyro
 
increases with T
H
, and the maximum U
pyro
 value is 124.1 
mJ cm
-3
 at T
H 
= 140 °C. Meanwhile, η
pyro
 increases an-
dreaches a maximum value of 0.08 % at T
H
 = 120 °C. 
Accordingly, ζ
pyro
 is calculated to be 0.56 × 10
−7
 J cm
-2
 
V
-1
 K
-1
. The obtained pyroelectric energy harvesting 
parameters are improved compared to some reported 
lead-free BaTiO
3
-based ceramics [48], [53], [54]. Accord-
ingly, 0.4BTSn ceramic has the potentials to be used as 
a working material in pyroelectric energy harvesting 
applications.
4 Conclusions
In summary, the multifunctional lead-free 0.4BTSn ce-
ramic was prepared by the solid-state reaction method. 
The energy storage, electrocaloric and pyroelectric en-
ergy harvesting properties were systematically inves-
tigated. Increased energy storage performances (U
rec
 
= 61.4 mJ cm
-3
 and η = 82.4 % at 90 °C), electrocaloric 
properties (ΔT = 0.50 K, ζ = 0.20 K mm kV
-1
, RC = 33.1 J 
kg
-1
 and COP = 15 at T
c
 = 86 °C with T
span 
= 64.9 °C) as well 
as pyroelectric energy harvesting performances (U
pyro 
= 
124.1 mJ cm
-3
, η
pyro
 = 0.08 % and ζ
pyro
 = 0.56 × 10
−7
 J cm
-2
 
V
-1
 K
-1
 at T
L
 = 30 °C and T
H 
= 140 °C) were obtained. These 
results indicate that the 0.4BTSn sample is a good, eco-
friendly, and thermally-stable multifunctional ferro-
electric material for energy storage, electrocaloric, and 
pyroelectric applications.
Table 1: Comparison of the electrocaloric properties of 0.4BTSn ceramics with other lead-free BT-based ceramics 
reported in the literature.
Ceramic T
c
 (°C) ΔT (K) ΔE (kV cm
-1
) ζ (K mm V
-1
) Ref.
Ba
0.94
Ca
0.06
Ti
0.90
Sn
0.10
O
3
47 0.55 20 0.280 [49]
Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
-0.4BaTi
0.89
Sn
0.11
O
3
86 0.50 25 0.200 This work
BaTi
0.89
Sn
0.11
O
3
52 0.71 25 0.284 [37]
Ba
0.85
Ca
0.15
Zr
0.10
Ti
0.90
O
3
100 0.57 25 0.228 [36]
0.8Ba(Ti
0.89
Sn
0.11
)O
3
–0.2(Ba
0.7
Ca
0.3
)TiO
3
 65 0.63 25 0.025 [43]
0.3BaHf
0.2
Ti
0.8
O
3
–0.7Ba
0.94
Sm
0.04
TiO
3
64 0.46 30 0.180 [47]
Ba
0.97
Ce
0.03
Ti
0.99
Mn
0.01
O
3
55 0.41 30 0.140 [50]
Ba
0.85
Ca
0.15
Zr
0.1
Ti
0.88
Sn
0.02
O
3
80 0.84 32 0.262 [44]
Ba
0.7
Sr
0.3
TiO
3
40 0.67 40 0.160 [51]
Ba
0.82
Ca
0.18
Sn
0.065
Ti
0.935
O
3
30 0.59 50 0.118 [52]
Figure 5: (a) A diagram illustrating the principle of py-
roelectric energy harvesting using P–E hysteresis loops 
measured at two different temperatures based on the 
Olsen cycle. The green region represents the U
pyro
. (b) 
The high-temperature dependence of U
pyro
 and η
pyro
 of 
0.4BTSn ceramics between 5 and 25 kV cm
-1
.
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5 Acknowledgments
The authors would like to thank the CNRST Priority 
Program PPR 15/2015, the Slovenian research agency 
grants (No. P2-0105, No. N2-0212 and No. P1-0125, 
No. J1-9147, No. P2-0091) and the European Union 
Horizon 2020 Research and Innovation actions MSCA-
RISE-ENGIMA (No. 778072) and MSCA-RISE-MELON (No. 
872631). 
6 Conflict of interest
The authors declare no conflict of interest.
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Arrived: 22. 05. 2024
Accepted: 12. 09. 2024
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