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Page 2 of 10 Li et al. Microstructures 2023;3:2023007 https://dx.doi.org/10.20517/microstructures.2022.27

INTRODUCTION
Dielectric materials, an essential part of capacitors, would generate polarization under an electric field,
enabling them to be widely used in electrocaloric, actuator, and energy storage devices. According to
different polarization behaviors, dielectrics can be divided into linear dielectrics (LDs), ferroelectrics (FEs),
[1-4]
and antiferroelectrics (AFEs) . The energy storage performances of dielectric materials could be
determined by the polarization-electric field (P-E) curves as follow:

where W , η, W , P and P are the recoverable energy density, the energy efficiency, the dissipated
loss
r
max,
rec
energy, the maximum polarization, and the remnant polarization under an applied electric field E,
respectively. Therefore, FE and AFE materials are suitable for energy storage applications due to a large P ,
max
low P and moderate E. Meanwhile, dielectric films with much larger breakdown strength E could attain
r,
b
higher energy density than their bulk counterparts .
[3-6]
AFE materials possess a characteristic known as a double hysteresis loop, which corresponds to four current
peaks under an applied electric field. The current peaks represent the AFE-to-FE phase transition at forward
switching field E and FE-to-AFE phase transition at backward switching field E , respectively [7-10] . PbZrO
3
A
F
(PZO), as a prototype AFE material, exhibits an apparent double hysteresis loop characteristic, while the
antiferroelectricity's origin is still controversial [11,12] . Hao et al. used the tolerance factor (t) to evaluate the
antiferroelectricity of PZO films, and later an increasing researches focus on chemical doping to adjust
antiferroelectricity of Pb-based and Pb-free AFE materials using t value . The equation of tolerance factor
[13]
(t) of perovskite structure can be expressed as follow:

where r , r and r denote the ion radius of A-site, B-site, and oxygen, respectively. It is accepted that the
A
B
O
AFE phase is stabilized at t < 1, and the FE phase is stabilized at t > 1. For example, a reduced t value can be
found in La-doped PZO and Ca-doped AgNbO materials corresponding to an enhanced E and E to
F
A
3
stabilize the AFE phase [14,15] . In 2017, Zhao et al. prepared Ag(Nb Ta )O ceramics in a similar t value and
3
x
1-x
[10]
proposed that enhanced antiferroelectricity should be attributed to reduced polarizability of the B-site . In
addition, (Ca, Zr), (Sr, Zr) and (Ca, Hf) modified NaNbO AFE ceramics both possess a double hysteresis
3
loop by decreasing the value of t while keeping the value of electronegativity fixed [16-18] . It can be seen that
the electric field-induced AFE phase could be affected by a tolerance factor, polarizability, and
electronegativity in A/B-sites for Pb-based and Pb-free materials. In the case of only considering the
tolerance factor t, whether the role of A/B-sites on influencing antiferroelectricity of PZO films exists
difference.
3+
2+
Following the above discussion, we choose Bi (~1.38 Å for CN = 12 and 1.03 Å for CN = 6) to replace Pb
(1.49 Å for CN = 12) and Zr (0.72 Å for CN = 6) at A/B-sites respectively , compare the difference of
4+
[19]
A/B-sites on influencing antiferroelectricity of PZO, and hence fabricate (Pb Bi )ZrO (PBZ),
0.05
3
0.95
Pb(Zr Bi )O (PZB) and pure PbZrO (PZO) films. A schematic representation of the crystal structure of
0.95
0.05
3
3
the Bi-doping PZO material can be seen in Figure 1. Based on Equation (3), calculated t values are 0.9639,