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dominated phase stabilization, atomic disorder with lattice distortion, sluggish diffusion kinetics and
property synergy from multiple components [12-16] . Recently, Chen’s group proposed a high-entropy strategy
to successfully promote piezoelectric and energy storage performance in perovskite oxide ceramics by
tuning the polarization configuration [Acta Mater. 236 (2022) 118115 - high entropy piezoelectrics
N
Pb(Ni,Sc,In,Ti,Nb)O ; a t . C o m m u n . 1 3 ( 2 0 2 2 ) 3 0 8 9 - h i g h e n t r o p y d i e l e c t r i c
[17]
3
[18]
(K,Na,Li,Ba,Bi)(Nb,Sc,Hf,Zr,Ta,Sb)O ], opening up new ideas for high-entropy piezoelectrics and high-
3
entropy energy storage materials.
It is well known that different elements have different valence states, ionic radii, electronic configurations,
electronegativity and polarizabilities. In recent studies, the high-entropy concept has been tuned to enable
2+
4+
4+
3+
3+
4+
5+
2+
3+
various elements, such as Ni , Mg , Sc , Yb , In , Zr , Hf , Ti , and Nb , to simultaneously occupy
equivalent lattice sites, such as B-sites, in perovskites to enhance the local polarization fluctuation as much
as possible, achieving the effect of increasing entropy . After introducing multiple components, as shown
[17]
in Figure 1A, large-scale transition regions (green color) that are spread out over the whole area
demonstrate the high flexibility of this unique polarization configuration. An almost even distribution of
polarization angles (θ) over the whole range of 0-45° can be observed in the statistical results [Figure 1B],
breaking the constraints of crystallographic symmetry and promoting the polarization rotation under
[19]
excitation by an electric field . From another perspective, the unique polarization configuration can be
considered as coexisting multiple monoclinic phases with different θ values on the atomic scale, which play
a bridge-like role between the polarizations of different phases , facilitating the flexible rotation between
[20]
different phases under electric fields. Benefiting from this unique polarization configuration caused by
increasing configuration entropy, an ultrahigh piezoelectric coefficient (d ) of ~1210 pC/N can be achieved
33
in the multi-component perovskite ceramics [Figure 1C].
A local diverse polarization configuration can greatly enhance the polarization response rate under electric
[21]
fields, leading to high W and efficiency η in energy storage capacitors . Chen’s group introduced the
rec
high-entropy concept into KNN-based ceramics and designed “local polymorphic distortion” to tune the
local diverse polarization configuration with coexisting rhombohedral - orthorhombic - tetragonal - cubic
+
[18]
2+
5+
(R-O-T-C) multiphase nanoclusters [Figure 1D] . Notably, the cations (Li , Ba , Bi , Sc , Hf , Zr , Ta ,
3+
3+
4+
4+
Sb ) introduced by the high entropy strategy take into account the substitution on A-sites and B-sites in
5+
perovskites, greatly enhancing the occupancy disorder and perturbation of the polarization. Meanwhile, the
cations are also considered as additives used to tailor the phase transition temperatures T , T , and T to
R-O
T-C
O-T
construct room-temperature R-O-T-C multiphase nanoclusters coexisting at the local scale. Compared with
the dielectrics with single-phase and coexisting two-phase polarization configuration, the high-entropy
sample exhibited smaller and more diverse PNRs with weak correlation embedded in the nonpolar cubic
phase, providing higher η and delayed polarization saturation under electric fields. In addition, different
types of oxygen octahedral distortions exist in different nanophases, which would introduce coexisting
multiple randomly-distributed oxygen octahedral tilts, further breaking the local polarization order. As a
result, high-entropy designed KNN-based ceramics with local polymorphic distortion achieved
breakthroughs in the ultrahigh W (≥ 10 J cm ) and ultrahigh η (≥ 90%) for lead-free ceramics for the first
-3
rec
time [Figure 1E]. The results demonstrate that high-entropy design opens a new avenue to enhance
electrical performance by tuning the polarization configuration.
The multiple components introduced by high entropy can cause significant local compositional disorder
and random fields, resulting in flexible and diverse local polarization configurations in both high-entropy
piezoelectrics and high-entropy energy storage dielectrics. It has to be mentioned that the various elements
introduced by the high-entropy strategy endow the material with more performance control freedom and