Monoclinic (K,Na)NbO<sub>3</sub> Ferroelectric Phase in Epitaxial Films

Luo, Jin; Sun, Wei; Zhou, Zhen; Lee, Hyun‐Young; Wang, Ke; Zhu, Fangyuan; Bai, Yu; Wang, Zhan Jie; Li, Jing‐Feng

doi:10.1002/aelm.201700226

Cited by 27 publications

(23 citation statements)

References 49 publications

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“…The dielectric constant continued to increase above the Curie temperature, especially for thin films doped with high BZ contents, which was owing to the increased conductivity at high temperature . The phase transition temperature at around 172°C is consistent with the reported values in KNN‐based epitaxial thin films . However, the orthorhombic‐tetragonal phase transition in KNN bulk ceramics is close to 220°C.…”

Section: Resultssupporting

confidence: 85%

“…Since the in‐plane lattice parameters was no longer equal to that along the out‐of‐plane direction, the perovskite unit cell doubling no longer possessed orthorhombic symmetries as KNN bulk ceramics. We suggested the KNN thin film in this work also showed monoclinic M C phase symmetry as the reported KNN‐based epitaxial thin films …”

Section: Resultssupporting

confidence: 70%

“…This also implied the T 1 phase transition belonged to the R‐monoclinic M C phase transition. Our previous work reported that M C ‐M A phase transition occurred in KNN‐based epitaxial thin films, instead of orthorhombic‐tetragonal phase transition in KNN‐based bulk ceramics . The KNN‐based thin films in this work showed high preferential orientation along both in‐plane and out‐of‐plane directions.…”

Section: Resultsmentioning

confidence: 54%

“…However, the preferentially (001) oriented KNN‐based thin films were constraint by the substrate, which could display different crystal symmetries. It has been discovered that the KNN‐based epitaxial thin films exhibited monoclinic M C symmetry under the compressive elastic strain imposed by the substrate . Consequently, the phase transition and phase symmetry of the KNN‐based thin films should be analyzed in detail.…”

Section: Resultsmentioning

confidence: 99%

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Phase transition and piezoelectricity of BaZrO₃‐modified (K,Na)NbO₃ lead‐free piezoelectric thin films

et al. 2018

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K,Na)NbO 3 (KNN) is a promising lead-free ferroelectric/piezoelectric system, to which incorporating BaZrO 3 can greatly enhance its piezoelectricity, but the mechanism is not clear. This work was conducted to investigate the phase transition in the BaZrO 3 -modifed KNN system and its contribution to piezoelectricity enhancement, using thin films with a fixed orientation and high compositional homogeneity fabricated by a sol-gel method. Two ferroelectric-to-ferroelectric phase transitions are revealed, which correspond to monoclinic M C -M A phase transition at higher temperature and rhombohedral-monoclinic M C phase transition at lower temperature. It is difficult to distinguish these phases in KNN-based bulk materials, but their differences are clear when conducting high-resolution X-ray reciprocal space mapping (RSM) on the present thin films. Piezoresponse force microscopy experiments also revealed an interesting finding that local piezoelectricity of monoclinic phases was higher than that of rhombohedral ones in KNN-based thin films. This work could shed insights on the fundamental understandings for the effect of the chemical doping, and offer guidance for property optimization in the KNN-based lead-free piezoelectrics.

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 54%

Section: Resultsmentioning

confidence: 99%

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Phase transition and piezoelectricity of BaZrO₃‐modified (K,Na)NbO₃ lead‐free piezoelectric thin films

et al. 2018

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“…First, the OOP spontaneous polarization switching behaviors were investigated using the high-resolution PFM ( Figure S4, Supporting Information). [25] Besides the CVD Adv. Two different areas are distinguishable with high contrasts in both amplitude and phase PFM images.…”

Section: Ferroelectricity Characterizationsmentioning

confidence: 99%

Intrinsic Dipole Coupling in 2D van der Waals Ferroelectrics for Gate‐Controlled Switchable Rectifier

Dai

Wang

et al. 2019

Adv Elect Materials

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OOP) and in-plane (IP) ferroelectricity could be easily achieved in some atomically thin vdWs 2D ferroelectric films, such as SnTe, CuInP 2 S 6 , LiAlTe 2 , and In 2 Se 3 . [8][9][10][11][12][13][14] Particularly, different from ultrathin SnTe and CuInP 2 S 6 , whose polarization only involves either pure IP or OOP orientations, atomically thin 2D In 2 Se 3 shows both IP and OOP ferroelectricity in its ground state of the α phase. [12] And the IP and OOP polarizations of 2D α-In 2 Se 3 have strong interrelated coupling. [15][16][17][18] In the previous work, we found that the OOP dipole in trilayer In 2 Se 3 is locked by the IP lattice asymmetry and its switching is related to the inversion of IP lattice orientation. [18] Up to date, there are few reports in the literature regarding ultimate miniature switchable rectifiers made of these atomically thin 2D ferroelectrics by utilizing the dipole polarization coupling. [19] Here, we report the fabrication of a gate-controlled switchable ferroelectric diode based on the single crystal of α-In 2 Se 3 by utilizing the interrelated coupling effect of OOP and IP polarizations (Figure 1). This ferroelectric diode can be inversed effectively by switching the gate bias between the negative (Figure 1a) and the positive configurations (Figure 1b). With a good rectification property of the ferroelectric diode, a switchable dynamic half-wave rectifier was realized. This kind of 2D ferroelectric diode has the advantages of simplicity in fabrication compatibility with complementary Miniaturization of device elements, such as ferroelectric diodes, depends on the downscaling of ferroelectric film, which is also crucial for developing high-density information storage technologies of ferroelectric random access memories (FeRAMs). Recently emerged ferroelectric two-dimensional (2D) van der Waals (vdWs) layered materials bring an additional opportunity to further increase the density of FeRAMs. A lateral, switchable rectifier is designed and fabricated based on atomically thin 2D α-In 2 Se 3 ferroelectric diodes, thus breaking the thickness limitation of conventional ferroelectric films and achieving an unprecedented level of miniaturization. This is realized through the interrelated coupling between out-of-plane and in-plane dipoles at room temperature; that is, horizontal polarization reversal can be effectively controlled through a vertical electric field. Being further explored as a switchable rectifier, the obtained maximum value of rectification ratio for the α-In 2 Se 3 based ferroelectric diode can reach up to 2.5 × 10 3 . These results indicate that 2D ferroelectric semiconductors can offer a pathway to develop next-generation multifunctional electronics. www.advelectronicmat.de metal-oxide-semiconductor (CMOS) technology, and superior electrical rectifying characteristics, showing great potential for future integrated electronic applications.

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Local Ionic Displacements and Polarization at the Paraelectric‐Ferroelectric Heterointerface: Effect of Octahedral Distortion

Luo

Qian

Zheng

et al. 2022

Adv Materials Inter

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At the ferroelectric ABO3 perovskite heterointerface, the broken translational symmetry significantly alters the octahedral network and cation sublattices. Experimentally revealing the interaction between the polarization and atomic structure parameters is beneficial not only for understanding the novel physical phenomena but also for realizing exotic physical functionalities at the materials surface science. Here, it is demonstrated that the induced polarization can be realized by the cooperative interaction between the octahedral distortion and the cation sublattices at the paraelectric‐ferroelectric heterointerface in the (K,Na)NbO3 epitaxial thin film. It is found that the cation–cation displacement scales with the tetragonality of the perovskite unit cell but not with the polarization, which is minimal in the substrate but increases substantially in the thin film. Nevertheless, the oxygen octahedral distortion in the substrate, accompanied by octahedral rotation, is stronger than that in the film, resulting in a translated and stable polarization across the interface. These results demonstrate the octahedral network plays a significant role in the ferroelectric polarization and can also greatly advance the understanding of the heterointerface science for ferroelectrics.

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Monoclinic (K,Na)NbO₃ Ferroelectric Phase in Epitaxial Films

Cited by 27 publications

References 49 publications

Phase transition and piezoelectricity of BaZrO₃‐modified (K,Na)NbO₃ lead‐free piezoelectric thin films

Phase transition and piezoelectricity of BaZrO₃‐modified (K,Na)NbO₃ lead‐free piezoelectric thin films

Intrinsic Dipole Coupling in 2D van der Waals Ferroelectrics for Gate‐Controlled Switchable Rectifier

Local Ionic Displacements and Polarization at the Paraelectric‐Ferroelectric Heterointerface: Effect of Octahedral Distortion

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Monoclinic (K,Na)NbO3 Ferroelectric Phase in Epitaxial Films

Cited by 27 publications

References 49 publications

Phase transition and piezoelectricity of BaZrO3‐modified (K,Na)NbO3 lead‐free piezoelectric thin films

Phase transition and piezoelectricity of BaZrO3‐modified (K,Na)NbO3 lead‐free piezoelectric thin films

Intrinsic Dipole Coupling in 2D van der Waals Ferroelectrics for Gate‐Controlled Switchable Rectifier

Local Ionic Displacements and Polarization at the Paraelectric‐Ferroelectric Heterointerface: Effect of Octahedral Distortion

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Product

Resources

About

Monoclinic (K,Na)NbO₃ Ferroelectric Phase in Epitaxial Films

Phase transition and piezoelectricity of BaZrO₃‐modified (K,Na)NbO₃ lead‐free piezoelectric thin films

Phase transition and piezoelectricity of BaZrO₃‐modified (K,Na)NbO₃ lead‐free piezoelectric thin films