Growth of (111)-Oriented Epitaxial Bi(Mg&lt;sub&gt;0.5&lt;/sub&gt;Ti&lt;sub&gt;0.5&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt; Films and their Characterization

Self Cite

111)-oriented epitaxial (1 % x)Bi(Mg 1/2 Ti 1/2 )O 3 -xBi(Zn 1/2 Ti 1/2 )O 3 solid solution films were grown on (111) c SrRuO 3 /(111)SrTiO 3 substrates by pulsed laser deposition, and their crystal structure and electrical properties were characterized. The solid solution films consisted of a perovskite single phase in the x range of 0-0.93. The coexistence region of rhombohedral and tetragonal phases was observed in the x range of 0.18-0.60, which differed from reported data for the powders synthesized at high temperatures and high pressures. The polarization-electric field hysteresis loops originating from ferroelectricity were observed at room temperature and 1 kHz in the x range of 0-0.33, and the remanent polarization monotonously decreased with increasing x. The relative dielectric constant measured at room temperature and 100 kHz and the apparent piezoelectric constant evaluated by piezoresponse force microscopy at room temperature and 5 Hz were maximum at approximately x = 0.14. These results suggest that these tendencies of the electrical and electromechanical properties were related to the volume fractions of the constituent phases in the solid solution films.

Section: Introductionmentioning

confidence: 99%

Characterizations of epitaxial Bi(Mg_1/2Ti_1/2)O₃–Bi(Zn_1/2Ti_1/2)O₃solid solution films grown by pulsed laser deposition

Oikawa¹,

Yasui²,

Watanabe³

et al. 2014

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“…They observed polarization-electric field (P-E) hysteresis loops and two stable polarization states, which are inherent to ferroelectric materials, by piezoelectric force microscopy. 18) However, the ferroelectricity of the films might have been induced by the strain from the substrate, even if the clamping effect of the (111) orientation is smaller than that of the (100) orientation in the case of the epitaxially grown perovskite oxide films. 19) In this paper, we report on the film thickness dependences of the crystal structure and electrical properties of (111)-oriented epitaxial Bi(Mg 1=2 Ti 1=2 )O 3 films to investigate the contribution of substrate clamping to the ferroelectricity of these films, because the clamping effect becomes smaller with increasing film thickness.…”

Section: Introductionmentioning

confidence: 99%

Film Thickness Dependence of Ferroelectric Properties of (111)-Oriented Epitaxial Bi(Mg_1/2Ti_1/2)O₃ Films

Oikawa

Yasui

Watanabe

et al. 2012

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The origin of the ferroelectricity of Bi(Mg1/2Ti1/2)O3 films was investigated. Epitaxial Bi(Mg1/2Ti1/2)O3 films with film thicknesses of 50 to 800 nm were grown on (111)cSrRuO3/(111)SrTiO3 substrates by pulsed laser deposition. A Bi(Mg1/2Ti1/2)O3 film was not strongly clamped from the substrate and identified to have rhombohedral symmetry with a = 0.398 nm and α= 89.8°, which was independent of film thickness within 100 to 800 nm. The relative dielectric constant, remanent polarization, and coercive field of the Bi(Mg1/2Ti1/2)O3 films at room temperature were almost constant at about 250, 60 µC/cm2, and 240 kV/cm, respectively, for film thicknesses above 200 nm. These data suggest that Bi(Mg1/2Ti1/2)O3 films are ferroelectric.

“…13) The piezoelectric (field-induced) strain by the application of a high voltage reaches a maximum of about 330 pm/V at x between 0.31 and 0.35. 13) Bi(Mg 1=2 Ti 1=2 )O 3 (BMT) also shows ferroelectricity with a large spontaneous polarization in film form [15][16][17] and cannot be obtained in bulk form unless high-pressure synthesis is carried out. 18,19) However, some of the authors revealed that a single-phase BT-BMT solid solution can be synthesized by a conventional method under ambient pressure if the BMT content is 50% or less, and BT-BMT samples with BMT contents up to 70% can be obtained with only a small amount of the bismuth oxide secondary phase.…”

Section: Introductionmentioning

confidence: 99%

Microstructure of BaTiO₃–Bi(Mg_1/2Ti_1/2)O₃–BiFeO₃Piezoelectric Ceramics

Yabuta

Shimada

Watanabe

et al. 2012

Self Cite

The dependence of the ferroelectric and piezoelectric properties of (1-x)(0.33BaTiO3–0.67BiFeO3)–xBi(Mg1/2Ti1/2)O3 (x = 0, 0.05, 0.10, and 0.15) on Bi(Mg1/2Ti1/2)O3 content x associated with microstructural changes is studied. From the behaviour of electric field-induced polarization and strain, polarization switching and depolarizing become easier as Bi(Mg1/2Ti1/2)O3 content x increases. Remanent polarization and dielectric constant decrease, while polarization saturation field increases with increasing x. Microstructural observation reveals that Bi(Mg1/2Ti1/2)O3 addition enhances the compositional fluctuation of BaTiO3/BiFeO3 ratio, which probably creates a nanometre-sized domain region with slightly BaTiO3-rich composition. Since this nanometre-sized domain may cause relatively large responses of polarization and strain to the applied electric field, an appropriate amount of Bi(Mg1/2Ti1/2)O3 enhances the electric field-induced strain, resulting in the largest piezoelectric response at x = 0.05. However, excessive Bi(Mg1/2Ti1/2)O3 degrades polarization and strain characteristics, because a number of Ba(Fe1-x Mg x/2Ti x/2)12O19 grains are created as a secondary phase and cause the segregation of excess bismuth oxide phases with low dielectric constant into the boundaries of the ferroelectric/piezoelectric grains.