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Page 2 of 10 Wang et al. Microstructures 2023;3:2023023 https://dx.doi.org/10.20517/microstructures.2023.04

necessitates the exploration of alternative energy sources such as solar and wind power. However, the
intermittent nature of these energy sources presents limitations on their practical applications. Therefore, it
is crucial to develop new energy storage technologies. Currently, the primary electrical energy storage
devices include batteries, chemical capacitors, and ceramic capacitors. Ceramic capacitors, in particular,
offer many advantages, such as high-power density, rapid charging and discharging rates, and a broad
operating temperature range. As a result, they are widely used in various applications, including pulsed
power supplies, microwave circuits, and electric vehicles. Nevertheless, the low energy storage density of
ceramic capacitors compared to chemical batteries restricts their potential applications. Consequently, there
is an urgent need to develop ceramic capacitors with higher energy storage density to address the growing
energy challenges.

The key performance indicators of ceramic capacitors comprise the recoverable energy storage density (W ),
r
total energy storage density (W), and energy storage efficiency (η). These parameters can be derived from
[1,2]
the electrical hysteresis loops (P-E) of ceramics or calculated by following Equation (1-3) :

where P is the maximum polarization, and P is the remanent polarization.
m
r
Equations (1-3) indicate that achieving high energy storage capacity (W ) and efficiency (η) requires a large
r
polarization (P ) and a small remnant polarization (P ). The ferroelectric ceramic Na Bi TiO (BNT)
r
3
0.5
m
0.5
possesses a large P , making it a promising candidate for developing high-energy storage capacitors.
m
However, pristine BNT ceramic has a large P , resulting in low W and η. Recent studies have focused on
r
r
developing BNT-based ceramics with large P and small P through doping, which can significantly reduce
r
m
the grain size of the ceramics and increase their dielectric breakdown strength (DBS), W , and η . For
[3]
r
instance, Qi et al. prepared linear-like anti-ferroelectric BNT-based ceramics with a W of 7.02 J/cm and η
3
r
[5-8]
of 85% . Similar results have been reported in other studies . Therefore, chemical doping of pure BNT is
[4]
an important method for preparing ceramics with high-energy storage properties.
The material 0.94Na Bi TiO -0.06BaTiO (BNT-BT) is a type of relaxor ferroelectric material that exhibits
3
0.5
0.5
3
a morphotropic phase boundary (MPB) structure. When an external electric field is applied, this material
undergoes a reversible transition from a relaxor state to a long-range ferroelectric order, resulting in a large
P and a lower P r [9,10] . However, the dielectric breakdown electric field of BNT-BT is relatively low. In
m
general, the breakdown electric field of dielectric ceramics increases with decreasing grain size. Therefore, in
this study, we aim to improve the breakdown electric field and enhance the energy storage properties of
BNT-BT by using Sr Bi γ Ti Zr O (SBTZ) as a modifier to regulate the relaxation behavior and
0.1 0.1
0.8
2.95
0.2
0.8
decrease the grain size. SBTZ is a newly developed relaxor ferroelectric material obtained by doping Bi and
3+
Zr into the cubic-phase perovskite material of SrTiO . The introduction of Bi and Zr ions into the A-site
4+
3+
4+
3
of SrTiO reduces the chemical ratio of Bi and creates an A-site vacancy, which disrupts the ferroelectric
3+
3
order and results in relaxation behavior [11,12] . It is expected that the energy storage performance of BNT-BT