Fabrication of inorganic-organic composites containing ferroelectric nanoplates and evaluation of their piezoelectric response characteristics

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a- and b-axis-oriented (Bi3.25Nd0.75 - x Eu x )Ti3O12 (BNEuT, x = 0–0.75) films of 3.0 µm thickness were fabricated on conductive Nb:TiO2(101) substrates containing 0.79 mass % Nb by high-temperature sputtering at 650 °C, and their structural and ferroelectric characteristics were investigated. All the films had a mostly single-phase orthorhombic structure, with high degrees of a- and b-axis orientations of 99.0–99.8%. The lattice parameters (a-, b-, and c-axis lengths) and the calculated orthorhombic lattice distortion decreased monotonically with increasing Eu content. The microstructure of BNEuT films with x = 0–0.50 was nanoplate-like, whereas that of films with x≥0.60 was significantly more bulk-like. The real room-temperature remanent polarization (2P r *), taking the porosity between the nanoplates into account, had a maximum value of 2P r * = 87 µC/cm2 at x = 0.10, which was approximately 1.3 times larger than that (65 µC/cm2) of the nondoped BNT film. It is shown that lattice distortion caused by rotation of octahedra in the a–b plane due to the Eu substitution plays a significant role in the improvement of ferroelectricity.

Section: Resultsmentioning

confidence: 93%

Effects of Eu³⁺ Doping on Characteristics of (Bi_3.25Nd_0.75)Ti₃O₁₂ Nanoplates

Kobune

Kaneko

Kishimoto

et al. 2013

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“…It can therefore be concluded that the developed BNEuT nanoplates have the potential for piezoelectric microelement applications. [29][30][31][32] 4. Conclusions The results can be summarized as follows.…”

Section: Resultsmentioning

confidence: 99%

Lattice distortions and piezoelectric properties in (Bi_3.25Nd_0.75− _xEu_x)Ti₃O₁₂ nanoplates with a- and b-axis orientations

Kobune¹,

Kugimiya²,

Kaneko³

et al. 2014

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a- and b-axis-oriented (Bi3.25Nd0.75− x Eu x )Ti3O12 (BNEuT, x = 0–0.75) films of 3.0 µm thickness were fabricated on conductive Nb:TiO2(101) substrates containing 0.79 mass % Nb by high-temperature sputtering at 650 °C, and their structural and piezoelectric characteristics were investigated. The room-temperature remanent polarization (2P r) and effective piezoelectric coefficient (d 33) values for the BNEuT films exhibited maxima of 87 µC/cm2 and 15 pm/V, respectively, at x = 0.10, which were approximately 1.3 times larger than those (2P r = 65 µC/cm2 and d 33 = 12 pm/V) of the nondoped (Bi3.25Nd0.75)Ti3O12 (BNT) nanoplate. The BNEuT film with x = 0.10 had a high a-axis orientation judging from the X-ray diffraction measurement and the observation of the phase image by piezoresponse force microscopy. It is shown that adequate Eu3+ doping of BNT nanoplates produces a larger displacement magnitude of the octahedra than that in the nondoped BNT nanoplate, resulting in an improvement of piezoelectric properties in addition to the ferroelectricity.

“…The degree of aand b-axis orientations ¡ (h00)/(0k0) was calculated by a method similar to that previously reported for the aand b-axis orientations. [7][8][9][10][11] To determine the out-of-plane and inplane lattice parameters (a, b, and c), XRD reciprocal space mapping (XRD-RSM) measurements were carried out in a high-resolution XRD system (Rigaku SmartLab) using Cu K¡ radiation. Componential (Bi content) analyses and surface microstructural observations of the films were performed using a field-emission scanning electron microscopy (FE-SEM; JEOL JSM-7001FA) system equipped with an energy dispersive X-ray spectrometer (EDS).…”

Section: Methodsmentioning

confidence: 99%

“…In recent years, lead-free bismuth layer-structured ferroelectrics (BLSFs) [1][2][3][4] have attracted much attention as promising alternatives to lead zirconium titanate (PZT) 5,6) for ferro-and piezoelectric device applications. In previous studies, we succeeded in achieving heteroepitaxial growth of (Bi 3.25 Nd 0.75 )Ti 3 O 12 (BNT) nanoplates with strong aand baxis orientations, [7][8][9] and (Bi 3.25 Nd 0.75¹x Eu x )Ti 3 O 12 (BNEuT, x = 0-0.075) nanoplates with a strong a-axis orientation, 10,11) by high-temperature sputtering using conductive singlecrystal Nb:TiO 2 (101) substrates with 0.79 mass % Nb. Moreover, high-resolution cross-sectional transmission electron microscopy (TEM) images showed that for a BNEuT epitaxial layer with x = 0.10, good long-range lattice matching was achieved between the BNEuT unit cell and seven lattice units of the underlying Nb:TiO 2 substrate.…”

Section: Introductionmentioning

confidence: 99%

“…As for the relation between the m number and the major polarization of the BLSF compounds, it is known that when m is an odd number greater than 3, significant macroscopic polarization due to ionic displacement appears along the a-axis direction, which is the major polarization axis. 12) We have previously reported the results of studies on the growth of epitaxial films with a high a-axis orientation, and the formation of a nanoplate structure, for BLSFs such as BNT [7][8][9] and BNEuT 10,11) with m = 3. BLSF compounds with m = 5, represented by the general formula A 2 Bi 4 Ti 5 O 18 (ABTO, A = Ba, Sr, and Ca), which consist of stacked (Bi 2 O 2 ) 2+ and (A 2 Bi 2 Ti 5 O 16 ) 2¹ layers, have received considerable attention because of their high potential for use in ferroelectric, piezoelectric, and multiferroic applications.…”

Section: Introductionmentioning

confidence: 99%

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Effects of deposition temperature on characteristics of ferroelectric Sr₂Bi₄Ti₅O₁₈nanoplates fabricated by RF sputtering

Kobune

Ueshima

Kaneko

et al. 2014

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Sr 2 Bi 4 Ti 5 O 18 (SBTO) films with a-and b-axis orientations, and thicknesses of 0.9-1.2 µm were sputter-deposited on conductive Nb:TiO 2 (101) substrates containing 0.79 mass % Nb. The deposition temperature was varied from 575 to 700 °C under a fixed gas pressure of 0.4 Pa, and the structural and ferroelectric characteristics of the films were investigated. SBTO films deposited at 625-700 °C had a mostly single-phase orthorhombic structure, with a high degree of a-and b-axis orientations [α (h00)/(0k0) ] of 99.0-99.8%. In addition, the full width at half maximum of the (200) diffraction peak was 0.69-0.86°, which indicated good crystallinity. SBTO films deposited at 625-650 °C had a nanoplate-like microstructure with the plates aligned along the [010] direction. The real room-temperature remanent polarization ð2P Ã r Þ, taking the porosity between the nanoplates into account, exhibited a maximum of 40 µC/cm 2 at 650 °C. Thus, the optimal deposition temperature for heteroepitaxial growth of SBTO nanoplates with a high α (h00)/(0k0) of ;99.0% and excellent ferroelectric properties on conductive Nb:TiO 2 substrates is 650 °C under a gas pressure of 0.4 Pa.