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Optomechanical manipulation of ferroelectric domain area and reversibility: out‐of‐plane phase images acquired in a) dark, b) post optical poling, and c) after turning the laser off at the mechanical force of 0.07 μN. The phase images of the same area acquired in d) dark, e) post optical poling, and f) after turning the laser off at a mechanical force of 1 μN. g) Normalized area of the up (red) domains obtained from the analysis of data shown in (a–f). (Scale = 500 nm). The dark spots in (d–f) are artifacts.
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The piezo‐photovoltaic effect has been recently proposed as an analogy of the flexo‐photovoltaic effect in non‐centrosymmetric ferroelectrics that are also piezoelectric in nature. It has been demonstrated to boost the photovoltaic performance of ferroelectrics under applied uniaxial mechanical loads. The impact of the piezo‐photovoltaic effect on...
Citations
... However, ECE devices can be scaled down to the microchip level to provide local refrigeration to electronic components. The prominent ECE candidates are ferroelectric (materials exhibiting a spontaneous polarization that could be tuned with an applied electric field [11]) oxides such as PMN-PT, Pb(Zr,Ti)O 3 [12], PbZrO 3 [13], BaTiO 3 , (Bi 0.5 Na 0.5 )TiO 3 [14], K 0.5 Na 0.5 NbO 3 [15]. These are being explored in single crystalline, polycrystalline as well as thin-film forms. ...
This study reports the processing and characterization of Pb0.96Sm0.025[Mg1/3Nb2/3]0.70Ti0.30O3 (Sm-PMN-PT)
polycrystalline ceramics for solid-state refrigeration technologies. The composition illustrated maximum polarization
of nearly 40 μC/cm2 at 293 K for an applied electric field of 17.5 kV/cm and piezoelectric coefficients d33
~ 146 pm/V under application of 10 kV/cm. It also showed a pyroelectric coefficient 4610 μC/m2/K1 in the
temperature range 340 – 370 K. In contrast to parent PMN-PT, the composition showed above room-temperature
ferroelectric transition offering an appealing change in polarisation and better suitability from a device viewpoint.
Due to this, the present study explored Sm-PMN-PT for an electrocaloric effect (ECE) using Maxwell relations.
Our calculations suggest a maximum ECE entropy (|ΔS|) and temperature (|ΔT|) changes of 0.55 J/Kg.K
and 0.7 K for a broad temperature range of 20 K (390–410 K), respectively.
... Recently, however, polarization control via optical excitation has become a highly appealing topic because it entails new paradigms for technology [3][4][5][6][7][8]. Optical switching mechanisms include (piezo)photovoltaic effect [9][10][11] as well as a variety of experimentally observed phenomena based on the light control of ferroelectric domains [12][13][14]. ...
Light-induced ferroelectric domain wall motion turns out to be a promising phenomenon to develop new photocontrolled devices. However, the physical origin of this light-matter coupling when material is irradiated with visible light remains unclear. Here, a phenomenological model predicting the motion of charged domain walls (CDWs) is developed. The photoinduced electronic reconstruction mechanism is proposed as the primary absorption mechanism, leading to a linear dependence for the polarization perturbation with the light intensity. Domain wall motion is then driven by the energetic difference between domains in a CDW array, such that the macroscopic polarization can be easily tuned.
... The electronic re-construction due to the presence of strain gradient (flexoelectric field) at DWs allows the photoexcitation process even from the below bandgap excitation. The strain-gradient induced local asymmetric field (Es) effectively separates out the photo-excited carriers and hence, has angular dependence as a function of incident light polarization [52,53,54,55,56] . The photo-excited carriers screen the local polarization components, and renormalize the local electric field or strain-gradient [57] . ...
The sensitivity of ferroelectric domain walls to external stimuli makes them functional entities in nanoelectronic devices. Specifically, optically driven domain reconfiguration with in-plane polarization is advantageous and thus highly sought. Here, we show the existence of in-plane polarized sub-domains imitating a single domain state and reversible optical control of its domain wall movement in a single-crystal of ferroelectric BaTiO3. Similar optical control in the domain configuration of non-polar ferroelastic material indicates long-range ferroelectric polarization is not essential for the optical control of domain wall movement. Instead, flexoelectricity is found to be an essential ingredient for the optical control of the domain configuration and hence, ferroelastic materials would be another possible candidate for nanoelectronic device applications.
... They have been used to study strain induced variations of optical constants around domain walls [21], and the local variation of phonons around engineered domain walls in van der Waals heterostructure materials [20]. Various other SPM modes can also be combined with optical illumination to study the impact of light on topological defects, for example the displacement of domain walls in ferroelectrics [36][37][38] or optically driven vertex formation [39][40][41]. ...
Symmetry lowering phase transitions in ferroelectrics, magnets, and materials with various other forms of inherent order lead to the formation of topological defects. Their non-trivial real-space topology is characterized by a topological charge, which represents the topological invariant. The study of topological defects in such materials has seen increased interest over the last decade. Among the methods used for their study, scanning probe microscopy (SPM) with its many variants has provided valuable new insight into these structures at the nanoscale. In this perspective, various approaches are discussed, and different techniques are compared with regard to their ability to investigate topological defect properties.
... At present, the majority of studies on the FPV effect focus on BaTiO 3 and BiFeO 3 films [15,17]. Meanwhile, a limited number of ferroelectric ceramics have been reported; for example, KNbO 3 [18], PbTiO 3 -Bi(Ni 1/2 Ti 1/2 )O 3 [19], (Bi 1/2 Na 1/2 )TiO 3 -Ba(Ni 1/2 Nb 1/2 )O 3 [20], PbTiO 3 -BiFeO 3 -Bi(Ni,Ti)O 3 [21], and SrBi 2 Nb 2 O 9 [22]. For ferroelectric films, the multiple action mechanisms and surface/interface effects lead to the difficulties for mechanism analysis [10,13,23]. ...
Noncentrosymmetry ferroelectric materials coupled with switchable polarization are promising candidates for photovoltaic applications because of their unique dissociation mechanism of photogenerated excitons associated with bulk polarization. Here, we study the photovoltaic properties of relaxor-based 24Pb(In1/2Nb1/2)O3–47Pb(Mg1/3Nb2/3)O3–29PbTiO3 (24PIN–47PMN–29PT) single crystals with a large remnant polarization and a proper optical bandgap along various crystallographic orientations. The 24PIN–47PMN–29PT single crystals are found to exhibit a modulated photovoltaic response by switching the poling direction, while their current–voltage curves present a linear relation. The superior photovoltaic response in the [111]C‐oriented crystal suggests that the photovoltage is strongly dependent on the crystallographic direction because of the polarization intensity difference. In addition, the domain configuration, phase structure, ferroelectric performance, and optical characteristics of 24PIN–47PMN–29PT single crystals are investigated, providing clues to the origin of the anomalous photovoltaic effect of these single crystals. Our results indicate that the photovoltaic performance of 24PIN–47PMN–29PT single crystals can expand their potential applications in photovoltaic devices, photorefraction, and photorefractive optical applications.
The research community is in permanent search of novel materials and exploitation of already elaborated phenomena to reveal yet unknown materials characteristics. Flexoelectricity has been in the spotlight lately because of its unique capacity to modulate electrical, optoelectronic, photovoltaic, and related properties and other characteristics of materials and devices. Nonetheless, potential limits on further progress of materials performance owing to incomplete knowledge about this effect are still not investigated to a sufficient extent. This review is focused on the most recent achievements on flexoelectric materials and on strain engineering strategies for modulating a strain gradient and flexoelectric response, with an emphasis on photovoltaic and related applications. Photodetectors based on flexoelectric materials and structures are discussed, and a brief overview of alternative (nonphotovoltaic) and emerging applications and challenges is provided. It is suggested that the most important materials for photovoltaic and related applications range from low-dimensional and thin-film ferroelectric semiconductors (which for example can be designed in an alternative way, according to the “barrier layer capacitor” principle) to conducting materials that are not restricted by the Shockley–Queisser limit. Such materials enable ultrafast charge carrier separation and enhanced photocurrents, photovoltages, and other photoelectric parameters of devices under strain gradients, compared with available analogs.
Mimicking and replicating the function of biological synapses with engineered materials is a challenge for the 21st century. The field of neuromorphic computing has recently seen significant developments, and new concepts are being explored. One of these approaches uses topological defects, such as domain walls in ferroic materials, especially ferroelectrics, that can naturally be addressed by electric fields to alter and tailor their intrinsic or extrinsic properties and functionality. Here, we review concepts of neuromorphic functionality found in ferroelectric domain walls and give a perspective on future developments and applications in low-energy, agile, brain-inspired electronics and computing.
Photosensors, photodetectors or color sensors are key components for various optical and optoelectronic applications. Semiconductor‐based photodetection has been a dominator which is excellent at measuring the photon intensity of incident light. However, the wavelength of the incident light to be measured must be known beforehand and it mostly depends on auxiliary methods to filter unknown wavelengths. This work demonstrates an alternative but simple mechanism that is using a monolithic, band gap engineered photoferroelectric ceramic to blindly determine the wavelength and intensity of incident light at the same time. The photoferroelectric compound is Ba and Ni co‐doped (K,Na)NbO3 exhibiting a direct band gap of ∽2 eV and a spontaneous polarization of ∽0.25 C m‐2. The band‐band charge carrier transition is confirmed by multiple characterization methods of photoluminescence, photo‐dielectric spectroscopy and photoconductivity. The existent optoelectrical cumulative effect enabled by the simultaneous narrow band gap and strong ferroelectricity allows to reliably distinguish the wavelengths of 405 nm, 552 nm and 660 nm as well as the power density ranging from approximately 0.1‐10 W cm‐2, with the photoresponsivity of up to 60 μA/W. Consequently, this work proposes an alternative to semiconductor‐based counterparts for filterless, wavelength‐selective photodetection and color sensing. This article is protected by copyright. All rights reserved.
