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Piezoelectric devices based on d 36 mode are remarkably stable that depolarization rarely occurs in d 36 face shear mode, because d 36 mode is completely different from d 15 thickness shear mode, where the applied electric field is perpendicular to poling direction and depolarization is ineluctable due to 90° dipole rotation. However, piezoelectric ceramics conventionally possess three piezoelectric coefficients (i.e., d 33 , d 31 , and d 15), while d 36 only exists in single crystals of specific point groups and cut directions. In this work, we propose a method to realize d 36 piezoelectric coefficient in tetragonal piezoelectric ceramics by mechanical and electric domain engineering. This method is successfully applied in bismuth scandium-lead titanate (abbreviated as BS-PT) high-temperature piezoelectric ceramics with a resultant d 36 up to 160 pC/N, which broadens the application of BS-PT ceramics, such as face shear actuator, energy harvester, transducer, etc. We find that domain engineering by transversal electric poling is preferred compared with the transversal mechanical poling, due to the simpler process, higher reliability, and higher resultant d 36 piezoelectric coefficient. By combining the Diffraction-Plane-Transformation (DPT) model with the domain engineering via transversal electric poling, we demonstrate a quantitative domain engineering method for the first time, which could be used for optimizing the piezoelectric properties by precise design of the domain structures in piezoelectric materials. d 36 piezoelectric coefficient in tetragonal piezoelectric ceramics is successfully realized by a quantitative domain engineering, demonstrating a novel method for optimizing the piezoelectric properties via precise design of the domain structures in piezoelectric materials. Image, graphical abstract [ABSTRACT FROM AUTHOR]

We report the growth of ferroelectric Pb 0.92 La 0.08 Zr 0.52 Ti 0.48 O 3 (PLZT) thick films using a poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA)-modified sol–gel process. A per-coating thickness of ≈0.66 μm has been demonstrated using PVP/VA-modified solution, which is more than doubled that of the PLZT films grown by PVP-modified method, and nearly 6 times the per-coating thickness of films prepared by conventional sol–gel process. PLZT thick films grown on LNO/Ni substrates exhibited denser microstructure, higher remanent polarization (11 μC/cm 2 ) and dielectric tunability (45%), lower leakage current density (≈1.2 × 10 −8 A/cm 2 ), and higher breakdown strength (≈1.6 MV/cm) than those for the samples grown on PtSi substrates. These results demonstrated great potential of using PVP/VA-modified sol–gel process for high power film capacitor applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] High quality PLZT film was deposited on Al foil by in-air crystallization process. [•] LaNiO3 buffer layer improved the electrical properties of overlying PLZT films. [•] PLZT/LaNiO3/Al capacitor had low leakage current and fatigue-free behavior. [•] A high energy storage density of ≈20J/cm3 was calculated. [•] Integration of oxide materials with Al foils are useful for embedded devices. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric lead lanthanum zirconate titanate (PLZT) films with 8mol% lanthanum and different Zr/Ti ratios (70/30, 65/35, 58/42, 52/48, 45/55, and 40/60) have been grown on platinized silicon substrates by chemical solution deposition. The effects of the Zr/Ti ratios on the dielectric and ferroelectric properties were investigated for high-power energy storage applications. These films exhibited relaxor behavior and slim polarization–electric field hysteresis loops, and the degree of phase transition diffuseness decreased with increasing Ti. The PLZT films with Zr/Ti=52/48 had a high spontaneous polarization of ≈51.2μC/cm2, a low remanent polarization of ≈9.1μC/cm2, and a low coercive electric field of ≈25.9kV/cm, leading to a recoverable energy density of ≈30J/cm3 and a charge–discharge efficiency of ≈78% at room temperature. The high energy density and high efficiency indicate that relaxor PLZT with La/Zr/Ti=8/52/48 is a promising candidate for high-power film capacitors. [Copyright &y& Elsevier]

Abstract: Pure BiFeO3 (BFO), 15% Nd doped BFO (BNF), and 15% Nd and 2% high-valence Mn co-doped BFO (BNFM) multiferroic ceramics were prepared by a rapid liquid phase sintering technique. A structural transition from rhombohedral to orthorhombic occurred in the BNF and BNFM ceramics. The co-doped BNFM ceramics exhibit the largest dielectric constant, the smallest dielectric loss and leakage current, and an improved rectangular-shaped polarization hysteresis loop with a remnant polarization as high as 31 μC/cm2, which could be attributed to the lower concentration of charge defects and the structural transition. Besides, enhanced ferromagnetism is confirmed in BNFM with a remnant magnetization of 0.075 emu/g and a coercive magnetic field of 5.8 kOe, which might be attributed to the effective suppression of the spatially modulated spin structure by the Nd and Mn co-doping. [Copyright &y& Elsevier]

Strain-mediated magnetoelectric effect can be utilized as an energy-efficient approach for spin manipulation. However, over 90° magnetization rotation is still challenging in un-patterned magnetic films, as the piezo-strain driven by ferroelectric domain switching is generally uniaxial rather than unidirectional, which limits the developments of non-volatile magnetic memory and logic devices. Here we demonstrate the rotation of local magnetization with a large angle of 136° by applying strains with a shear component at a fixed magnetic field of 45 Oe in FeCoSiB/PMN-PT (011) multiferroic heterostructures, revealed by a vector-resolved quantitative magneto-optical Kerr effect (MOKE) microscopy. Phase-field simulations confirm that the approximate 140° rotation of magnetization vectors is a consequence of the shear strain associated with ferroelectric/ferroelastic switching of PMN-PT (011) substrates. The visualization of over 90° magnetization rotation induced by the strain with a shear component paves the way for deterministic magnetization switching that has important implications in the energy-efficient spintronic devices. Image, graphical abstract [ABSTRACT FROM AUTHOR]

We incorporated a ≈5-nm-thick MnO x insertion layer in the middle of a ≈1.38-μm-thick Pb 0.92 La 0.08 Zr 0.52 Ti 0.48 O 3 (PLZT) film grown by a modified sol–gel process and measured the dielectric and ferroelectric properties of PLZT films with and without MnO x insertion layer. By incorporation of the MnO x layer, residual stress was reduced from ≈350 MPa to ≈125 MPa, dielectric permittivity decreased from ≈1300 to ≈950, while dielectric loss increased from ≈0.04 to ≈0.07 as measured at 10 kHz. Also, remanent polarization increased from ≈9.1 μC/cm 2 to ≈11.7 μC/cm 2 , coercive field increased from ≈28.7 kV/cm to ≈40.3 kV/cm, and internal bias field from ≈3 kV/cm to ≈14 kV/cm. We have observed decreased irreversible Rayleigh coefficient and dielectric nonlinearity on samples with MnO x insertion layer. These changes in properties are attributable to Mn cation doping as acceptors near the MnO x /PLZT interface, which forms oxygen vacancies and defect induced dipoles like 2 M n ′ T i − V O • • (or M n ″ T i − V O • • ), acting effectively as pinning centers to hinder domain wall movement. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the bipolar resistive switching effect in a SrTiO3/NiO stacked heterostructure which was epitaxially deposited on an Nb doped SrTiO3 substrate by pulsed laser deposition. This heterostructure shows high resistive switching ratio of over 104 at the read voltage of −0.5V and an expected retention ability of ten years, which is better than that of NiO-based device. Moreover, the resistive switching ratio can be adjusted by changing the maximum applied voltage or compliance current, which shows promising for multilevel nonvolatile memories application. Meanwhile, these results have been discussed by carrier injection-trapped/detrapped process. [Copyright &y& Elsevier]

Abstract: The CoFe2O4 (CFO)/Bi3.15Nd0.85Ti3O12 (BNT) multiferroic composite coaxial nanotubes were prepared by a sol–gel template method. The morphologies of the coaxial nanotubes were characterized and the selected area electron diffraction patterns confirmed the coexistence of spinel CFO and perovskite BNT phase. The vibrating sample magnetometer measurements showed that the saturation magnetization and coercive field of the coaxial nanotubes were 1emu/g and 0.7kOe, respectively, which was contributed totally from the inner CFO nanotubes. The CFO/BNT coaxial nanotubes showed typical ferroelectric hysteresis loop, while the increased leakage current density is likely due to the high conductivity in the inner CFO nanotubes. Our study demonstrated that the CFO/BNT coaxial nanotubes were of both ferroelectric and magnetic features in nanoscale. [Copyright &y& Elsevier]

Ferroelectric resistive switching has recently attracted considerable attention as a promising candidate for next-generation non-volatile memory. In this work, we report an electro and photon double-driven bipolar resistive switching behavior in Pt /Bi 0.9 Eu 0.1 FeO 3 (BEFO) /Nb-doped SrTiO 3 (NSTO) heterostructures prepared via pulsed laser deposition. In addition to the polarization-based control of the resistive memory, a switchable photovoltaic effect is observed that can be used to detect the polarization direction non-destructively. Significantly, the electric field-modulated interfacial barrier can be further affected by photon-generated carriers. This phenomenon is attributed to the barrier modulation in the Pt /BEFO and BEFO /NSTO interfaces by electric field and photon excitation. These results indicate the feasibility of non-volatile and non-destructive readout from ferroelectric memory. [ABSTRACT FROM AUTHOR]

Ferroelectric (FE) materials, owing to their remarkable photovoltaic effects, are one class of the most promising materials candidates for self-powered photodetectors. Here, with the pronounced rectification ratio as large as 103 at electric bias of± 1.0 V and a low dark current of 12 pA, the self-polarized Bi 0.9 Eu 0.1 FeO 3 (BEFO)/Nb-doped SrTiO 3 (NSTO) p-n heterojunctions are synthesized. It is revealed that the BEFO/NSTO p-n heterojunctions achieve the excellent photovoltaic effect with a short-circuit current as high as 0.23 μA and an open-circuit voltage of 0.41 V under the light illumination of 405 nm in wavelength and intensity of 151.7 mW/cm2. More importantly, the built-in potential in the as-prepared heterojunctions offers the self-powered photo-detecting functionality, with the high light-on/off current ratio of 2.0 × 104, high responsivity of 0.64 mA/W and sensitive detectivity D* of 1.63 × 1010 Jones, and fast response speed of 50/44 ms without external bias voltage. In particular, the super-performance with R ~ 1.97 mA/W and D*~ 5.0 × 1010 Jones in the weak incident light intensity (1.4 mW/cm2) are demonstrated, better than most previously reported FE-based self-powered photodetectors. Moreover, the devices possess good ambient stability and reproducibility. This work provides a demo for optically driven high-performance electronic devices based on self-polarized ferroelectric materials. • The self-polarized BEFO/NSTO p-n heterojunctions with the pronounced rectification ratio and a low dark current. • The BEFO/NSTO p-n heterojunctions achieve the excellent photovoltaic effect to serve as a self-powered photodetector. • The self-powered photo-detecting functionality surpass those of most previously reported FE-based self-powered photodetectors. • The devices possess good ambient stability and reproducibility. [ABSTRACT FROM AUTHOR]

The microstructures of Bi 0.85 Nd 0.15 FeO 3 ceramics were investigated by using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), convergent-beam electron diffraction (CBED) and X-ray energy dispersive spectrometry (EDS). The superstructure phase related to 1/4( hh 0) p and 1/4(00 l ) p diffraction spots were observed in the samples. It is found that the superstructure phase can co-exist with R 3 c phase in a single grain. The bright and dark field images accompanied with SAED patterns provided evidences of the superstructure phase dispersed into the matrix with R3c symmetry and evolution of the domain. The ferroelectric domain wall was observed according to the displacement of Fe 3+ ions respect to Bi 3+ sub-lattice in the ferroelectric R 3 c phase based on HRTEM observations. The space group Pnam of the superstructure was identified by combining SAED and CBED techniques. EDS measurement revealed that the concentration of Nd in the Pnam phase is higher than that in R 3 c phase. This might mean that the transition from R 3 c to Pnam structure is due to the inhomogeneous distribution of the Nd concentration and the weakened stereochemical activity of Bi 3+ lone electron pair, arisen from the increase in Nd content. [ABSTRACT FROM AUTHOR]

Abstract: A series of dye-sensitized solar cells (DSSCs) with different graphene-P25 (G-P25) photoelectrodes were prepared by a ball milling method. The influences of graphene on the structures and performance of G-P25 cells were studied. Studies indicated that the rutile contents in G-P25 photoelectrodes increased with increasing graphene-oxide (GO) additions and reached the maximum value at GO addition of 4.5ml. And with the increase of GO additions, the porosity of the G-P25 photoelectrodes, the interface recombination resistances, and the short current densities increased. When the GO addition was 4.5ml, the G-P25 cells showed the best performance with the largest interface recombination resistance of 15.12Ω and the largest photoelectric conversion efficiency of 5.09%, which was remarkably higher than those of pure P25 DSSC. Since the tendency of the photoelectric conversion efficiency varying with the GO additions was in consistence with that of the rutile contents, the enhancement of the photoelectric conversion properties of the G-P25 DSSCs was preliminary attributed to the increase of the rutile contents and the porosity in the photoelectrodes due to graphene adding. [Copyright &y& Elsevier]

Abstract: Ba-doped BiFeO3 thin films were prepared on Pt/TiO2/SiO2/Si (100) substrate at various oxygen pressures by pulsed laser deposition. The influences of oxygen pressure on the crystalline structures, magnetic and electrical properties of these films were studied. Studies showed that the oxygen vacancy content and accordingly the leakage current density of the films decreased with the increase of the oxygen pressure, and the concentration of the Fe2+ increased with the decrease of the oxygen pressure. Strong ferromagnetism was observed in these films. The magnetization of the films increased with the decrease of the oxygen pressure and the largest remnant magnetization of 2.46×104 A/m was obtained at an oxygen pressure of 0.7Pa. This enhancement of the magnetization can be attributed to the increase of the Fe2+ concentration which may be related closely to the increase of the oxygen vacancy in the films. [Copyright &y& Elsevier]