In this work, the (1−x)Bi0.5Na0.5TiO3-xBaNi0.5Nb0.5O3 (BNT-BNN; 0.00 ⩽ x ⩽ 0.20) ceramics were prepared via a high-temperature solid-state method. The crystalline structures, photovoltaic effect, and electrical properties of the ceramics were investigated. According to X-ray diffraction, the system shows a single perovskite structure. The samples show the normal ferroelectric loops. With the increase of BNN content, the remnant polarization (Pr) and coercive field (Ec) decrease gradually. The optical band gap of the samples narrows from 3.10 to 2.27 eV. The conductive species of grains and grain boundaries in the ceramics are ascribed to the double ionized oxygen vacancies. The open-circuit voltage (Voc) of ∼15.7 V and short-circuit current (Jsc) of ∼1450 nA/cm2 are obtained in the 0.95BNT-0.05BNN ceramic under 1 sun illumination (AM1.5G, 100 mW/cm2). A larger Voc of 23 V and a higher Jsc of 5500 nA/cm2 are achieved at the poling field of 60 kV/cm under the same light conditions. The study shows this system has great application prospects in the photovoltaic field.
A bandgap-tunable KNbO 3 ferroelectric ceramic was prepared by introducing Bi/Co ion. The existence of mixed valence states of Co 2+ /Co 3+ in the system induced the bandgap reduction and its tunable behavior. KNbO 3 -BiCoO 3 solid solutions showed a typical orthogonal perovskite structure and maintained good ferroelectricity (P s = 15.13 µC/cm 2 ) and high-field polarization ability. The devices based on the .98KNbO 3 -.02BiCoO 3 sample exhibited an improved shortcircuit photocurrent density (J sc ) of 19.2 nA/cm 2 under simulated solar radiation, and this was further enhanced to 79.8 nA/cm 2 after a 60-kV/cm polarizing. The structural analysis of the samples after polarization reveals the effect of ferroelectric polarization on photovoltaic performance. This work provides new insights into the effects of ferroelectric polarization on photovoltaic performance.
Mn-doped 0.97Bi 0.47 Na 0.47 Ba 0.06 TiO 3 -0.03K 0.5 Na 0.5 NbO 3 (BNBT-KNN) lead-free energy storage ceramics were prepared by the conventional solid-state reaction methods. Effects of Mn addition on the microstructures and energy storage properties of the ceramics were investigated. XRD analysis revealed that all the ceramics possessed a single perovskite structure. As the Mn content arose from 0 to 3 mol. %, the average grain size of the BNBT-KNN ceramics increased by nearly 4 times (from *1.6 to *6.2 lm). The energy storage density of the BNBT-KNN ceramics firstly increased and then decreased with increment of Mn addition. With the rise of external electric field loaded on the ceramics, the energy storage density increased drastically, and a maximum value of 0.938 J/cm 3 at 79 kV/cm was achieved by the BNBT-KNN samples with 1.0 mol. % Mn content.
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