ORCID Profile
0000-0002-7121-1652
Current Organisation
Nanchang University
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Publisher: Elsevier BV
Date: 12-2014
Publisher: AIP Publishing
Date: 04-05-2021
DOI: 10.1063/5.0048925
Abstract: The recently discovered large flexoelectricity in relaxor ferroelectrics has rekindled considerable research interest. In this paper, several Sm-doped Pb(Mg2/3Nb1/3)O3–xPbTiO3 (PMN–xPT) ferroelectric ceramics were prepared and the relationship between flexoelectricity and PT content was systematically investigated. The largest flexoelectric response (∼550 μC/m) was observed in the Sm-doped PMN–32PT ceramic, which should be accounted for in the reorientation of the polar nanoregions. At room temperature, the flexoelectric response of Sm-doped PMN–32PT ceramic is an order of magnitude higher than that of the parent PMN–PT ceramics and even 50% higher than that of Bi–PMN–32PT ceramic (∼300 μC/m). Such a big increment is directly related to the greater local structural heterogeneity caused by Sm3+ ions into PMN–PT. Therefore, the result presented in this paper verifies that introducing local structural heterogeneity is a feasible approach to achieve ultrahigh flexoelectricity.
Publisher: AIP Publishing
Date: 17-04-2023
DOI: 10.1063/5.0142555
Abstract: We report a thickness-dependent flexoresistance effect caused by strain gradient in SrTiO3 (STO) epitaxial thin films. The strain gradient in STO was induced by using an atomic force microscope diamond-coated tip. The depolarization field caused by the strain gradient changes the electrical state of the film, resulting in a decrease in the resistance of the films by 4–6 orders of magnitude. By testing the current–voltage (I–V) curves of STO films with different thicknesses, it is found that the flexoresistance behavior of STO films is obvious thickness dependent: the thicker the film, the higher the force threshold to trigger the film to enter a highly conductive state. The comparison of the surface morphology before and after the I–V test with loading shows that only when the thickness of the STO film is below 8 nm, the film can enter the conductive state from the insulating state without damaging the surface. During the electrical state switching process, the strain gradient caused by tip loading play an important role in the modification of the film barrier.
Publisher: Springer Science and Business Media LLC
Date: 20-04-2020
Publisher: AIP Publishing
Date: 09-06-2014
DOI: 10.1063/1.4882060
Publisher: AIP Publishing
Date: 08-07-2022
DOI: 10.1063/5.0087676
Abstract: Significant flexoelectricity is expected to exist in materials with colossal permittivity. Here, we systematically studied the interplay of flexoelectricity and permittivity in CaCu3Ti4O12 (CCTO) ceramic by examining the thickness and electrode dependence of the flexoelectric coefficients over a wide range of temperatures. We found that an abnormal flexoelectric transition occurs at 95 °C. Below this critical temperature, the barrier layer mechanism dominates the significant flexoelectricity in CCTO ceramic, whereas above this critical temperature, the flexoelectric response mainly originates from the contributions of semiconducting grains and insulating grain boundaries. The observed flexoelectric transition is beneficial not only for developing new materials with high flexoelectric coefficients but also for understanding the colossal permittivity mechanism in CCTO ceramics.
Publisher: Tsinghua University Press
Date: 06-2019
Publisher: Elsevier BV
Date: 12-2020
Publisher: World Scientific Pub Co Pte Lt
Date: 10-2019
DOI: 10.1142/S2010135X19500425
Abstract: Hybrid perovskite solar cells (PSCs) have been intensively studied in recent years because of their high efficiency and low costs. For PSCs, the electron transport layer (ETL) is a key for its photoelectric conversion efficiency. Here we demonstrate the application of amorphous InGaZnO 4 thin films as ETL for efficient PSCs by pulsed laser deposition (PLD). The PSC device using such InGaZnO 4 amorphous film as ETL has achieved an efficiency of 15.1%. The outstanding performance is attributed to the excellent properties of amorphous InGaZnO 4 oxide thin films, including high electron mobility and high transparency, what is more, the electronic properties of the films can be controlled by changing the partial pressure of oxygen in the deposition chamber and post-deposition annealing process. Our result will be helpful for preparation of large area PSCs and other opto-electric devices at low temperature by physical vapor deposition method.
Publisher: AIP Publishing
Date: 16-12-2019
DOI: 10.1063/1.5126987
Abstract: Coupling between polarization and the strain gradient, namely, flexoelectricity, is a universal phenomenon that widely exists in all solid dielectrics and polymers. At a low level of the applied strain gradient, this electromechanical coupling is strictly a linear effect. In this Letter, a strong nonlinearity between the polarization and the strain gradient was experimentally found in polyvinylidene fluoride when the strain gradient was higher than a material-dependent threshold value. Such nonlinear behavior was in good accordance with an ion chain theory and could be fitted by a nonlinear equation. The observed flexoelectric nonlinearity in this work will help in the understanding of the discrepancy between the previous findings about the bulk materials and their nanoscale counterparts.
Publisher: AIP Publishing
Date: 29-10-2018
DOI: 10.1063/1.5045716
Abstract: In this letter, we report on significant flexoelectric fatigue in lead-free (K,Na,Li)(Nb,Sb)O3 (KNNLS) ceramics. In the ferroelectric phase of KNNLS, the observed effective transverse flexoelectric coefficient, which is initially as high as 1 μC/m, decreases nonlinearly with increasing cycles of strain gradient, and the fatigue regulation is well reproduced by a stretched exponential function. By comparing the time dependence of dielectric permittivity and ferroelectricity in KNNLS ceramics, we conclude that large flexoelectric and flexocoupling coefficients in the ferroelectric phase originate mainly from ferroelectricity and that the related flexoelectric fatigue is likely due to the pinning effect of ferroelectric domains.
Publisher: AIP Publishing
Date: 02-2023
DOI: 10.1063/5.0134531
Abstract: In spite of the flexoelectric effect being a universal phenomenon in the ferroelectric perovskites, the current understanding of flexoelectric aging in ferroelectrics is, actually, rather incomplete. In this paper, we have fabricated a series of Mn-doped BaTiO3 perovskite ceramics (BaTi1–xMnxO3, x = 0.1% and 1%, BTMO) to systematically investigate the corresponding flexoelectric aging behavior by controlling the concentration of Mn. We found that the variation of Mn dopant significantly effects the Curie temperature, dielectric constant, flexoelectric aging, and flexoelectric coefficient of the BTMO ceramics. Especially for the BTMO (0.1%) ceramics, obvious ferroelectric aging and flexoelectric aging phenomenon are observed at room temperature. The main reason for aging of BTMO ceramics is that the doping of Mn introduces oxygen vacancies, which tend to be stable under the action of strain gradient and electric field. Therefore, the results presented in this paper verify that the flexoelectric aging in Mn-doped BTO ceramics is closely related to ferroelectric fatigue.
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 06-2019
Publisher: AIP Publishing
Date: 30-09-2019
DOI: 10.1063/1.5115561
Abstract: Flexoelectricity yields electric polarization through graded strains and exists in various kinds of solid dielectrics but usually with a weak coupling response. In this letter, several Bi-doped Pb(Mg2/3Nb1/3)O3-xPbTiO3 (PMN-xPT) ferroelectric ceramics were prepared and the interplay of their piezoelectricity and flexoelectricity was systematically investigated. The largest flexoelectric response (∼300 μC/m) was 30 times larger than that of pure PMN-PT and was observed in the Bi-doped PMN-32PT, where the after poling piezoelectric coefficients were also the largest (990 pC/N) among all the compositions. This suggests that the apparent flexoelectricity in ferroelectrics is highly related to the bulk piezoelectricity. Therefore, introducing a local structural heterogeneity is considered as a feasible approach to achieve an ultrahigh piezoelectric response while also providing an ultrahigh flexoelectricity.
Publisher: Elsevier BV
Date: 03-2022
Publisher: AIP Publishing
Date: 16-10-2017
DOI: 10.1063/1.5001265
Abstract: Flexoelectricity couples strain gradient to polarization and usually exhibits a large coefficient in the paraelectric phase of the ferroelectric perovskites. In this study, we employed the relaxor 0.3Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (PIN-PMN-PT) single crystals to study the relationship between flexoelectric coefficients and the crystal structure. The flexoelectric coefficients in PIN-PMN-PT single crystal are found to vary from 57 μC/m at orthorhombic/monoclinic phase to 135 μC/m at tetragonal phase, and decreases to less than 27 μC/m in the temperature above Tm. This result discloses that ferroelectricity can significantly enhance the flexoelectricity in this kind of perovskite.
Publisher: Elsevier BV
Date: 02-2020
Publisher: AIP Publishing
Date: 15-01-2018
DOI: 10.1063/1.5010358
Abstract: In this paper, high-performance conducting Al-doped ZnO (AZO) electrodes were deposited on transparent and flexible muscovite mica substrates. The use of mica as a substrate material makes a van der Waals epitaxy possible, which significantly improves the structural, electrical, and optical properties of deposited AZO single-crystal-like films. AZO/mica retains its low electric resistivity, even after continuous bending of up to 1000 times on account of the unique layered structure of mica. When used as a transparent heater, AZO/mica shows an ultrahigh heating rate (200 °C/s) across large areas, which is a record among flexible transparent heaters.
Publisher: American Physical Society (APS)
Date: 20-07-2022
Publisher: AIP Publishing
Date: 25-02-2019
DOI: 10.1063/1.5082803
Abstract: Ultrathin and transparent metal films are considered as desirable materials to substitute indium-tin oxide based transparent electrodes. In this work, we report that an Al-doped ZnO layer effectively induced the formation of epitaxial ultrathin and ultrasmooth Au films on mica. The ultrathin Au film shows optimum electrical conductivity, optical properties, and high tolerance to mechanical bending, including a low sheet resistance of 8 Ω/sq and a high average transmittance of 80.1%, and maintains low electric resistivity even after 1000 continuous bending cycles. Moreover, the Au/AZO anode-based organic light-emitting diode was fabricated with the maximum luminance intensity of 32 540 cd/cm2, which demonstrates that it is promising for application in next generation optoelectronic devices.
Publisher: Elsevier BV
Date: 11-2020
Publisher: American Physical Society (APS)
Date: 07-12-2022
Publisher: American Physical Society (APS)
Date: 26-04-2022
Publisher: Elsevier BV
Date: 09-2019
Publisher: AIP Publishing
Date: 12-2014
DOI: 10.1063/1.4904024
Abstract: A fabrication method by combining precision mechanical dicing and wet etching was developed to prepare micro-pyramid structures based on (Ba0.67Sr0.33)TiO3 ceramics. The effective piezoelectric properties of flexoelectric pyramid structures in ten micrometers scale were investigated and measured through converse flexoelectric effect. The scaling effect of the flexoelectric response was demonstrated as the structure size shrinks down. The results do suggest the great potential of flexoelectric micro pyramids as an alternative to lead-free piezoelectric material.
Publisher: AIP Publishing
Date: 07-11-2022
DOI: 10.1063/5.0097238
Abstract: Flexoelectricity of semiconductors usually exhibits large flexoelectric coefficients due to their significantly enhanced surface piezoelectricity caused by surface symmetry breaking. In this Letter, we reported a general paradigm to tune the semiconductor flexoelectricity through interface engineering. We selected Nb-SrTiO3 (Nb-STO) single crystals as the targets and tuned their surface piezoelectricity through depositing TiO2-terminated and SrO-terminated ultra-thin BaTiO3 (BTO) films. The results suggested that the deposition of TiO2-terminated and SrO-terminated ultra-thin BaTiO3 films to Nb-STO can induce a downward and upward out-of-plane surface polarization, respectively, thereby significantly increasing/decreasing the apparent flexoelectric coefficients of Nb-STO single crystals. Our work proves the feasibility of interface engineering in the application of flexoelectricity and also provides a possible route to achieve the large apparent flexoelectricity of semiconductor materials.
Publisher: American Physical Society (APS)
Date: 29-09-2022
Publisher: Elsevier BV
Date: 12-2019
Publisher: Tsinghua University Press
Date: 24-02-2021
DOI: 10.1007/S40145-020-0442-1
Abstract: The resistive switching (RS) mechanism of hybrid organic-inorganic perovskites has not been clearly understood until now. A switchable diode-like RS behavior in MAPbBr 3 single crystals using Au (or Pt) symmetric electrodes is reported. Both the high resistance state (HRS) and low resistance state (LRS) are electrode-area dependent and light responsive. We propose an electric-field-driven inner p-n junction accompanied by a trap-controlled space-charge-limited conduction (SCLC) conduction mechanism to explain this switchable diode-like RS behavior in MAPbBr 3 single crystals.
No related grants have been discovered for Longlong Shu.