Lead-free ferroelectric BaTiO3 doped-(Na0.5Bi0.5)TiO3 thin films processed by pulsed laser deposition technique (original) (raw)
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Ferroelectric (Na1/2Bi1/2)TiO3-BaTiO3thin films obtained by pulsed laser deposition
Journal de Physique IV (Proceedings), 2005
The solid solution of the ferroelectric relaxor (Na 1/2 Bi 1/2)TiO 3 with BaTiO 3 , (1-x) NBT-x BT (NBT-BT) shows a morphotropic phase boundary with enhanced properties at x = 0.06-0.07. We have prepared targets of (1-x) NBT-x BT with x = 0.06 by solid state reaction and sintering at 1200 • C, up to a final relative density of 97.8%. Films from these targets have been deposited on MgO substrates by pulsed laser deposition, in different substrate temperature and heating rate conditions. First results obtained from structural, AFM and electrical characterization are reported. The obtained films are polycrystalline perovskite with a slight (100) orientation. High relative dielectric constant, of about 1300, have been obtained.
Lead-free Bi 0.5 Na 0.5 TiO 3 (BNT)-Bi 0.5 K 0.5 TiO 3 (BKT)-BaTiO 3 (BT) piezoelectric thin films with compositions near the morphotropic phase boundary (MPB) were deposited by metal-organic solution deposition on Pt/Ti/SiO 2 /Si (1 0 0) substrates. The compositional dependences of their microstructure and ferroelectric/piezoelectric properties were investigated. The results indicated that all the thin films have a single-phase perovskite structure and show outstanding electrical properties at room temperature. We found that the thin film with a composition of 0.884BNT-0.08BKT-0.036BT showed the best structural and electrical properties, with a dielectric constant, remnant polarization, and effective piezoelectric constant of 638,638, 638,27 lC/cm 2 and $79 pC/N, respectively. We suggest that these superior properties are due to this sample's high degree of alignment of ferroelectric domains in the MPB region and largest grain size.
Journal of Alloys and …, 2012
Lead-free 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 (BNT-BT) piezoelectric thin films were prepared by metalorganic solution deposition onto a Pt/Ti/SiO 2 /Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700°C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200 nm. Thin films of 356 nm thickness exhibited a small signal dielectric constant and a loss tangent at 1 kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5 lC/cm 2 with a coercive field of 164.5 kV/cm. The leakage current density of the thin film was 4.08 Â 10 À4 A/cm 2 at an applied electric field of 200 kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d 33 ) of the BNT-BT thin film was approximately 51.6 pm/V.
The piezoelectric and the ferroelectric properties of x-mol% Li-doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 x = 0, lead-free piezoelectric thin films deposited on Pt (111)/Ti/SiO2/Si substrates via a metal-organic solution deposition method were investigated. Our results show that the Li-substituted film has a remarkable improvement in electrical properties compared with the BNT-BT film. We also found that the substitution was effective in decreasing the coercive field in the thin films. The enhanced electromechanical properties are contributed by both crystal structure evolution and improved microstructure. The optimal ferroelectric properties were obtained in the film with x = 10 providing a remanent polarization (Pr) and a coercive field (Ec) of ∼23.9 µC/cm 2 and ∼124 kV/cm, respectively.
Rb doped 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 (BNT-BT-Rb x ) thin films with x mol% Rb (x = 0, 2.5, 5, 7.5, 10) were deposited on Pt/Ti/SiO 2 /Si substrate by metal-organic solution deposition method. Experiments were conducted to investigate the effect of Rb doping on phase formation, microstructure, leakage current, and the resulting ferroelectric and piezoelectric property. It was found that substantial enhancement in structural, morphological and electrical properties can be achieved by Rb doping of BNT-BT thin films. Optimal electrical properties were obtained for 5 mol% Rb doped BNT-BT thin films, with a dielectric constant, remnant polarization, and effective piezoelectric constant of 681,681, 681,28.9 lC/cm 2 and $86 pm/V, respectively. It was suggested that the enhanced electrical properties in the case of 5 mol% Rb BNT-BT thin films can be attributed to domain wall movement induced by A-site substitutions, large grain size, and lattice distortion.
Dielectric and piezoelectric properties of lead-free (Bi, Na) TiO 3-based thin films
Dielectric and piezoelectric properties of morphotropic phase boundary ͑Bi, Na͒TiO 3 -͑Bi, K͒TiO 3 -BaTiO 3 epitaxial thin films deposited on SrRuO 3 coated SrTiO 3 substrates were reported. Thin films of 350 nm thickness exhibited small signal dielectric permittivity and loss tangent values of 750 and 0.15, respectively, at 1 kHz. Ferroelectric hysteresis measurements indicated a remanent polarization value of 30 C / cm 2 with a coercive field of 85-100 kV/cm. The thin film transverse piezoelectric coefficient ͑e 31,f ͒ of these films after poling at 600 kV/cm was found to be −2.2 C / m 2 . The results indicate that these BNT-based thin films are a potential candidate for lead-free piezoelectric devices.
Mn-doped 0.15BiInO3-0.85PbTiO3 piezoelectric films deposited by pulsed laser deposition
Applied Physics Letters, 2012
Pure low-frequency flexural mode of [011]c poled relaxor-PbTiO3 single crystals excited by k32 mode Appl. Phys. Lett. 100, 213501 (2012) Elastic, dielectric, and piezoelectric anomalies and Raman spectroscopy of 0.5Ba(Ti0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 Appl. Phys. Lett. 100, 192907 (2012) Microstructure and dielectric properties of piezoelectric magnetron sputtered w-ScxAl1−xN thin films J. Appl. Phys. 111, 093527 (2012) Ultrahigh electromechanical response in (1−x)(Na0.5Bi0.5)TiO3-xBaTiO3 single-crystals via polarization extension J. Appl. Phys. 111, 093508 (2012) Enhanced dielectric and piezoelectric properties of xBaZrO3-(1−x)BaTiO3 ceramics
Applied Surface Science, 2013
Ferroelectric lead-free (Na 0.5 Bi 0.5) 1−x Ba x TiO 3 thin films obtained by pulsed laser deposition have been structurally and electrically investigated for compositions, x = 0 and x = 0.06, in and out of the morphotropic phase boundary (MPB). Sodium bismuth titanate Na 0.5 Bi 0.5 TiO 3 (NBT), pure or in solid solution with other materials (like BaTiO 3), is considered to be the best candidate material for lead-free ferroelectric and piezoelectric applications such as actuators and nonvolatile memory devices. Bulk solid solutions with BaTiO 3 (BT), (1−x)NBT-xBT (NBT-x%BT) have been investigated widely, also due to a morphotropic phase boundary (MPB) with enhanced dielectric and ferroelectric properties between a rhombohedral and a tetragonal ferroelectric phase, at x = 0.06. Nonetheless, to transpose bulk properties to NBT-BT thin films is a major achievement. XRD technique has been used for structural characterizations of NBT-BT films. Dielectric spectroscopy measurements were performed at room temperature in the frequency range 100 Hz-1 MHz. The best films show pure perovskite phase and good crystalline structure, as a function of specific deposition conditions. Unusual characteristics, especially dielectric constant values higher than those for bulk, have been found for films with specific crystallographic orientations.
Ferroelectric properties in thin film barium titanate grown using pulsed laser deposition
The characteristics of polycrystalline BaTiO 3 metal-insulator-metal capacitors, fabricated using pulsed laser deposition, are investigated from room temperature to 420 K. The capacitance-voltage characteristics show ferroelectric behaviour at room temperature, with a phase transition to paraelectric at higher temperature. However, the permittivity response shows paraelectric behaviour across all measured temperatures. So BaTiO 3 exists here in a mixture of cubic and tetragonal phases. The BaTiO 3 films have a columnar structure, with grain size increasing with film thickness due to their increasing height but not diameter. This correlates with an increase in remnant polarization. The results support a size driven phase transition in thin films of polycrystalline BaTiO 3 .