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Abstract: In this work, we fabricated the (1‐x)BiFeO3‐xBaTiO3+y‰ mol CuO ceramics by the modified thermal quenching technique. The pure perovskite phase was formed and a morphotropic phase boundary (MPB) was observed in the ceramics with x = 0.30‐0.33. The addition of CuO can significantly enhance the density of the BiFeO3‐BaTiO3 material. Importantly, an enhanced piezoelectric constant (d33=165 pC/N), a large electric‐field‐induced strain (∆S = 0.54%: peak to peak strain) and a large piezoelectric actuator constant (d33*=449 pm/V) together with a high Curie temperature (TC) of 503°C were observed in the ceramics with x = 0.30 and y = 5. As a result, the enhanced piezoelectricity and large electric‐field‐induced strain could significantly stimulate further researches in BFO‐based ceramics. [ABSTRACT FROM AUTHOR]

One of the key problems in the existing lead‐free piezoelectrics lies in how to further boost their dynamic piezoelectric responses, i.e., electrostrain and dynamic piezoelectric constants, in an effective and facile manner, making them comparable to those of widely used lead‐based counterparts. In this work, a new strategy is developed to largely improve the dynamic piezoelectric properties of lead‐free ferroelectrics using phase field simulations by combining the relaxor/ferroelectric crossover rendering potentially reversible electrostrain and the morphotropic phase boundary (MPB) providing easy paths of ferroelectric polarization rotations. Following the guidance of simulation results, Mn‐doped (Bi0.5Na0.5)TiO3–BaTiO3 lead‐free piezoelectric ceramics with relaxor/MPB crossover are synthesized. A large reversible electrostrain (Smax) of 0.55% with a promising piezoelectric constant d33* (Smax/Emax) of 917 pm V–1 at the designed relaxor/MPB crossover is obtained, outperforming almost all practical lead‐free counterparts when taking both electrostrain and dynamic piezoelectric constants into consideration. The strategy of utilizing relaxor/MPB crossover provides a new route for enhancing the dynamic piezoelectric responses in lead‐free ferroelectric perovskites. [ABSTRACT FROM AUTHOR]

Piezocatalysis, converting mechanical vibration into chemical energy, has emerged as a promising candidate for water‐splitting technology. However, the efficiency of the hydrogen production is quite limited. We herein report well‐defined 10 nm BaTiO3 nanoparticles (NPs) characterized by a large electro‐mechanical coefficient which induces a high piezoelectric effect. Atomic‐resolution high angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and scanning probe microscopy (SPM) suggests that piezoelectric BaTiO3 NPs display a coexistence of multiple phases with low energy barriers and polarization anisotropy which results in a high electro‐mechanical coefficient. Landau free energy modeling also confirms that the greatly reduced polarization anisotropy facilitates polarization rotation. Employing the high piezoelectric properties of BaTiO3 NPs, we demonstrate an overall water‐splitting process with the highest hydrogen production efficiency hitherto reported, with a H2 production rate of 655 μmol g−1 h−1, which could rival excellent photocatalysis system. This study highlights the potential of piezoelectric catalysis for overall water splitting. [ABSTRACT FROM AUTHOR]

Piezocatalysis, converting mechanical vibration into chemical energy, has emerged as a promising candidate for water‐splitting technology. However, the efficiency of the hydrogen production is quite limited. We herein report well‐defined 10 nm BaTiO3 nanoparticles (NPs) characterized by a large electro‐mechanical coefficient which induces a high piezoelectric effect. Atomic‐resolution high angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and scanning probe microscopy (SPM) suggests that piezoelectric BaTiO3 NPs display a coexistence of multiple phases with low energy barriers and polarization anisotropy which results in a high electro‐mechanical coefficient. Landau free energy modeling also confirms that the greatly reduced polarization anisotropy facilitates polarization rotation. Employing the high piezoelectric properties of BaTiO3 NPs, we demonstrate an overall water‐splitting process with the highest hydrogen production efficiency hitherto reported, with a H2 production rate of 655 μmol g−1 h−1, which could rival excellent photocatalysis system. This study highlights the potential of piezoelectric catalysis for overall water splitting. [ABSTRACT FROM AUTHOR]