Piezoelectric materials with unique properties are hugely appealing for high sensitivity sensors and ultrasonic transducers. Here, Pb(Ni 1/3 Nb 2/3 )O 3 -Pb(Yb 1/2 Nb 1/2 )O 3 -PbTiO 3 piezoelectric system was designed and investigated in detail. The optimized piezoelectric response ( d 33 = 826 pC/N, d 33 * = 1017 pm/V) together with good temperature stability and negligible performance degradation up to 10 6 cycles was achieved in 0.58PNN-0.10PYN-0.32PT composition. Rayleigh analysis revealed the amplification of intrinsic and extrinsic contributions in MPB region due to more spontaneous polarization orientations and an increase in chemical disorder of system after the introduction of PYN. The origin of high piezoelectric response was investigated through the combination of scanning electron microscopy and piezoresponse force microscopy. The diversity of B -site cations was shown to enhance local structural heterogeneity, weaken long-range ferroelectric ordered domains, and lower free energy barrier via the formation of nanodomain configuration that promoted polarization rotation, thereby improving piezoelectric properties of the material. Therefore, it is suggested that increasing the diversity of B -site cations is an effective strategy for achieving outstanding piezoelectric performance.
With the pursuit of higher operating temperatures and longer service lifetimes in aero-engines and gas turbines, thermal barrier coatings (TBCs) are facing increasingly stringent requirements in thermal and mechanical performance. Guided by the principle of entropy engineering, two high-entropy rare-earth niobate ceramics, (Lu 0.2 Gd 0.2 Er 0.2 Y 0.2 Yb 0.2 ) 3 NbO 7 (LGEYY) and (Dy 0.2 Gd 0.2 Er 0.2 Y 0.2 Yb 0.2 ) 3 NbO 7 (DGEYY), were successfully synthesized via solid-state reactive sintering. Benefiting from the high configurational entropy, these materials form stable single-phase fluorite-type structures (space group Fm m). The high-entropy effect induces significant lattice distortion and local chemical disorder, which not only suppress grain boundary mobility—leading to excellent sintering resistance and a low grain growth rate (∼0.059 μm/h at 1600 °C)—but also enhances phonon scattering, resulting in glass-like low thermal conductivity (LGEYY: 1.126–1.354 W⋅m -1 ⋅K -1 ; DGEYY: 1.195–1.450 W⋅m -1 ⋅K -1 ) over 25–800 °C. In addition, both ceramics exhibit high thermal expansion coefficients (∼10.6–10.9 × 10 -6 K -1 at 1200 °C), ensuring good thermal compatibility with metallic substrates. LGEYY shows superior mechanical properties (10.924 GPa, 1.486 MPa·m 1/2 ) over DGEYY (10.215 GPa, 1.249 MPa·m 1/2 ), attributed to its finer grains and enhanced lattice energy. Comprehensive performance evaluations indicate that both samples—particularly LGEYY—exhibit a unique combination of low thermal conductivity, high thermal expansion coefficients, and mechanical reliability under extreme thermal conditions, highlighting their potential as next-generation ultra-high-temperature TBCs and offering new insights for the engineering design of high-entropy ceramics.
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