Bismuth Layer-structured Ferroelectrics Research Articles

反応制御焼結法を用いた Bi 層状構造強誘電体の作製

反応制御焼結法を用いた Bi 層状構造強誘電体の作製

Temperature Dependences of Piezoelectric Properties of Grain-Oriented SrBi2Nb2O9–Bi4Ti3O12 Ceramics

Bismuth layer-structured ferroelectrics (BLSFs) have been studied for resonator applications due to its low-temperature coefficient of resonance frequency (TC-f). To control the TC-f to lower, an use of the phase transition is demonstrated in which a mixed-bismuth layer structure of SrBi2Nb2O9-Bi4Ti3O12 (SBN-BIT) is focused on as the new approach. Thus, the TC-f was tried to be controlled by using the phase transition of the SBN-BIT system. The electrical properties and the temperature dependences of the piezoelectric properties were investigated for the proposed system. The temperature dependence of resonance frequency indicated that TC-f changed from −74.8 to −14.6 ppm/°C for non oriented samples and from −42.6 to +75.8 ppm/°C for oriented samples after undergoing the phase transition.

The Formation Mechanism of Intergrowth Bismuth Layer-Structured Ferroelectric Bi4Ti3O12-CaBi4Ti4O15

The formation behavior of Intergrowth Bismuth Layer-Structured Ferroelectric (IBLSF) Bi4Ti3O12-CaBi4Ti4O15 is investigated through conventional solid-state reaction method using Bi2O3, TiO2, CaCO3 as initial powders. The mixed powders are treated from 550°C to 1000°C at 100°C intervals after being milled. The phase transition and thermal behavior of the powders are determined by X-ray diffraction (XRD) and TG/DSC. The results indicate that the compound is mostly changed to Bi4Ti3O12 at 700°C, as calcinating temperature rise to 800°C the intergrowth phase Bi4Ti3O12-CaBi4Ti4O15 (BiT-CBT) forms. When the calcinating temperature rises above 900°C, the BiT-CBT phase is obtained finally. The formation mechanism of BiT-CBT phase will be very helpful for deep understanding of the structures and ferro- and piezoelectric properties of IBLSFs.

The effect of (Li,Ce) doping in Aurivillius phase material (Na0.52K0.42Li0.06)0.5Bi2.5(Nb1.88Sb0.06Ta0.06)O9

AbstractThe effect of (Li,Ce) substitution for A‐site on the properties of [(Na0.52K0.42Li0.06)Bi]0.5Bi2 (Nb1.88Sb0.06Ta0.06)O9‐based ceramics was investigated. The piezoelectric activity of [(Na0.52K0.42Li0.06)Bi]0.5Bi2 (Nb1.88Sb0.06Ta0.06)O9‐based ceramics is significantly improved by the modification of lithium and cerium. The Curie temperature (TC) gradually decreases from 625 to 605 oC with increasing the (Li,Ce) modification. The piezoelectric coefficient d33 of the [(Na0.52K0.42Li0.06)Bi]0.44(Li,Ce)0.03[]0.03Bi2(Nb1.88Sb0.06Ta0.06)O9 ceramic was found to be 28 pC/N, the highest value among the [(Na0.52K0.42Li0.06)Bi]0.5Bi2(Nb1.88Sb0.06Ta0.06)O9‐based ceramics, also almost 50% higher than the reported d33 values of other Bismuth layer‐structured ferroelectric (BLSF) systems (∼5–19 pC/N). The planar coupling factor kp and kt were found to be 7.0 and 28.0%, together with the high TC (∼610 °C) and stable piezoelectric properties, demonstrating that the (Li,Ce) modified [(Na0.52K0.42Li0.06)Bi]0.5Bi2(Nb1.88Sb0.06Ta0.06)O9‐based material a promising candidate for high temperature applications.

The Effect of the Nb- and V-doping on the Electrical Properties in the Bismuth Layer-structured Ferroelectrics Thin Films

The Effect of the Nb- and V-doping on the Electrical Properties in the Bismuth Layer-structured Ferroelectrics Thin Films

Piezoelectric Ceramics for High Temperature Applications

Ceramic materials based on lead titanate, lead niobate and bismuth layer-structured ferroelectrics (BLSF) were studied to develop piezoelectric ceramics for high temperature sensor applications. Compositional modification enabled lead titanate and lead niobate type ceramics to exhibit good piezoelectric properties at 500°C . The Curie temperature for one BLSF, CaBi4Ti4O15 was close to 800°C, though the piezoelectric constant was smaller than those of lead titanate and lead niobate ceramics. These ceramics seem to be good candidates for use as high temperature sensor materials. In addition, textured SrBi2Nb2O9 (SBN), another BLSF, ceramics with various orientation factors were fabricated through the templated grain growth (TGG) method. The resonant frequency of 76% textured SBN varied linearly with temperature and exhibited stable temperature characteristics. The temperature coefficient of the resonant frequency was –0.85 ppm/°C from –50 to 250°C, and was smaller than that of a quartz oscillator. Therefore, textured SBN ceramics are suitable for use as a resonator material when stable resonant frequency is needed in a high temperature range.

Review: environmental friendly lead-free piezoelectric materials

Lead zirconate titanate (PZT) based piezoelectric materials are well known for their excellent piezoelectric properties. However, considering the toxicity of lead and its compounds, there is a general awareness for the development of environmental friendly lead-free materials as evidenced from the legislation passed by the European Union in this effect. Several classes of materials are now being considered as potentially attractive alternatives to PZTs for specific applications. In this paper, attempts have been made to review the recent developments on lead-free piezo materials emphasizing on their preparation, structure–property correlation, etc. In this context, perovskite systems such as bismuth sodium titanate, alkali niobates (ANbO3), etc. and non-perovskites such as bismuth layer-structured ferroelectrics are reviewed in detail. From the above study, it is concluded that some lead-free compositions show stable piezoelectric responses even though they do not match the overall performance of PZT. This has been the stimulant for growing research on this subject. This topic is of current interest to the researchers worldwide as evidenced from the large number of research publications. This has motivated us to come out with a review article with a view that it would give further impetus to the researchers already working in this area and also draw the attention of the others.

High-Power Characteristics of Thickness Shear Mode for Textured SrBi2Nb2O9 Ceramics

The high-power piezoelectric characteristics of the thickness shear mode for <00l> oriented ceramics of bismuth layer structured ferroelectrics (BLSF), SrBi2Nb2O9 (SBN), were studied by the constant current driving method. These textured ceramics were fabricated by the templated grain growth (TGG) method, and the Lotgering factor was 95%. The vibration of the thickness shear mode in the textured SBN ceramics was stable at the vibration velocity of 2.0 m/s. The resonant frequency was almost constant with increasing vibration velocity in the textured SBN ceramics, however, it decreased with increasing vibration velocity in the randomly oriented SBN ceramics. In the case of Pb(Mn,Nb)O3–Pb(Zr,Ti)O3 ceramics, the vibration velocity of the thickness shear mode was saturated at more than 0.3 m/s, and the resonant frequency decreased at lower vibration velocity than in the case of SBN ceramics. The dissipation power density of the textured SBN ceramics was the lowest among those of the randomly oriented SBN and Pb(Mn,Nb)O3–PZT ceramics. The thickness shear mode of textured SBN ceramics is a good candidate for high-power piezoelectric applications.

Bismuth layer‐structured ferroelectric ceramics with high mechanical quality factor

AbstractThe piezoelectric properties in some bismuth layer‐structured ferroelectric (BLSF) ceramics were investigated focusing on a mechanical quality factor, Qm. Many BLSF compositions with various Curie temperatures, Tc, were selected in this study, and the Qm values of (33) mode were plotted as a function of their Curie temperature, Tc. The Qm increased with increasing the Tc in the low‐Tc compositions below 500°C. It is considered to relate with the domain wall pinning because the coercive field Ec also increased with increasing the Tc. However, in the high‐Tc compositions above 750°C, the Qm decreased with increasing the Tc, because of the difficulties in poling treatment due to the Ec. On the other hand, high Qm values exceeding 10,000 were obtained in the intermediate‐Tc compositions between 500 and 750°C. These values are quite high as the piezoelectric ceramics. The key point of the high Qm in these compositions is the poling process at high temperature of 300°C. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(12): 39–45, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10185

FERROELECTRIC, PIEZOELECTRIC AND DIELECTRIC PROPERTIES OF Nb MODIFIED Bi4Ti3O12-SrBi4Ti4O15 INTERGROWTH

ABSTRACT Doping and constructing intergrowth are found to be an effectual approach to modify the electrical properties of bismuth layer-structured ferroelectrics. In this work, ferroelectric, piezoelectric and dielectric properties of Nb-doped Bi4Ti3O12-SrBi4Ti4O15 (BTN-SBTN-x) intergrowth ceramics were investigated. The ferroelectric property of Bi4Ti3O12-SrBi4Ti4O15 was improved by niobium doping. The remanent polarization (2P r ) increases at first, then decreases with the increase of niobium content, while the coercive field changes little with Nb-doping. As niobium content is 0.06, the 2P r maximizes at a value of 34.9 μC/cm2, which is increased by about 75% in comparison with that of Bi4Ti3O12-SrBi4Ti4O15 (2P r = 20.0 μC/cm2). The Curie temperature of the samples varies hardly upon Nb-doping, which indicates that the good thermal stability of Bi4Ti3O12-SrBi4Ti4O15 is not deteriorated after Nb addition. Piezoelectric coefficient d33 was increased from 9.3 pC·N−1 to 18.6 pC·N−1 due to the enlargement of 2P r .

High-power piezoelectric characteristics of textured bismuth layer structured ferroelectric ceramics

Abstract-The high-power piezoelectric characteristics in h001i oriented ceramics of bismuth layer structured ferroelectrics (BLSF), SrBi(2)Nb(2)O(9) (SBN), (Bi,La)(4)Ti(3)O(12) (BLT), and CaBi(4)Ti(4)O(15) (CBT), were studied by a constant voltage driving method. These textured ceramics were fabricated by a templated grain growth (TGG) method, and their Lotgering factors were 95%, 97%, and 99%, respectively. The vibration velocities of the longitudinal mode (33-mode) increased proportionally to an applied electric field up to 2.5 m/s in these textured BLSF ceramics, although, the vibration velocity of the 33-mode was saturated at more than 1.0 m/s in the Pb(Mn,Nb)O(3)-PZT ceramics. The resonant frequencies were constant up to the vibration velocity of 2.5 m/s in the SBN and CBT textured ceramics; however, the resonant frequency decreased with increasing over the vibration velocity of 1.5 m/s in the BLT textured ceramics. The dissipation power density of the BLT was almost the same as that of the Pb(Mn,Nb)O(3)-PZT ceramics. However, the dissipation power densities of the SBN and CBT were lower than those of the BLT and Pb(Mn,Nb)O(3)-PZT ceramics. The textured SBN and CBT ceramics are good candidates for high-power piezoelectric applications.

Temperature dependence of piezoelectric properties for textured SBN ceramics

Temperature dependences of piezoelectric properties were studied for h001i textured ceramics of bismuth layer-structured ferroelectrics, SrBi(2)Nb(2)O(9) (SBN). The textured ceramics with varied orientation degrees were fabricated by templated, grain-growth method, and the temperature dependences of resonance frequency were estimated. Excellent temperature stability of resonance frequency was obtained for the 76% textured ceramics. The resonance frequency of the 76% textured specimens varied almost linearly over a wide temperature range. Therefore, the variation was slight, even in a high temperature region above 150 degrees C. Temperature stability of a quartz crystal oscillator is generally higher than that of a ceramic resonator around room temperature. The variation of resonance frequency for the 76% textured SrBi(2)Nb(2)O(9) was larger than that of oscillation frequency for a typical quartz oscillator below 150 degrees C also in this study. However, the variation of the textured SrBi(2)Nb(2)O(9) was smaller than that of the quartz oscillator over a wide temperature range from -50 to 250 degrees C. Therefore, textured SrBi(2)Nb(2)O(9) ceramics is a major candidate material for the resonators used within a wide temperature range.

Electrical Investigations of Aurivillius Type Sr0.7A0.3Bi2Nb2O9 (A = Ca, La and Pb) Ferroelectric Ceramics

Aurivillius type bismuth layer structured ferroelectrics (BLSF) have been found to possess strong relationship between tetragonal strain (c/a) and extrinsic/ intrinsic conductivity. The extrinsic part of the conductivity is known to depend upon space charge in the sample. The present paper discusses effects of 30 atomic % doping of Ca, La and Pb on tetragonal strain, conductivity and dielectric constant/loss with temperature and frequency. Tetragonal strain increases on doping calcium and lead while it shows a decrease on doping lanthanum. The calcium and lanthanum doped samples show pronounced space charge part of dielectric constant while lead doped sample shows nearly constant permittivity values. No phase transition is observed in the calcium doped sample up to 600°C while for the lanthanum doped sample a decrease of 141°C is observed in the value of Curie temperature compared to that for the undoped sample.

A novel technique for preparation of grain oriented BLSF piezoelectric ceramics

Grain oriented bismuth layer-structured ferroelectrics (BLSFs) ceramics CaBi4Ti3.95V0.05O15 were prepared by screen-printing method. The particle size of starting materials is a very important factor for the grain orientation annealed ceramics. Highly textured ceramics can only be obtained by using nanosized TiO2 and the mechanism for grain orientation was proposed. The electrical properties of the textured ceramics showed strongly anisotropic. The dielectric constant and loss tangent in the perpendicular plane is larger than that of the parallel plane. The remanent polarization in the perpendicular plane (2.64 μC/cm2) is also much larger than that of the parallel plane (0.31 μC/cm2). Compared with other grain orientation techniques, screen-printing was a simple and effective technique to fabricate grain oriented BLSFs ceramics.

Study on Ferroelectric and Dielectric Properties of La-Doped CaBi 4Ti 4O 15-Based Ceramics

Lanthanum doped bismuth layer structured ferroelectrics (BLSFs) Ca 1- x La x Bi 4(Ti 0.9W 0.1) 4O 15( x = 0, 0.2. 0.3, 0.4, 0.6) ceramics were prepared by solid-state reaction method. X-ray diffraction (XRD) patterns showed that single phase was formed when x = 0 ∼ 0.6. The effects of La 3+ doping on dielectric, piezoelectric and ferroelectric properties of Ca 1- x La x Bi 4(Ti 0.9W 0.1) 4O 15 ceramics were studied. Ca 0.7La 0.3Bi 4(Ti 0.9W 0.1) 4O 15 ceramic had optimal properties, its dielectric constant was 166.85, dielectric loss was 0.0063, piezoelectric strain constant was 11 pc·N −1. remanent polarization was 18.1 μC·cm −2 and coercive field was 118 kV·cm −1. SEM micrographs showed that the grains of CaBi 4Ti 4O 15-based ceramics were plate-like. The results of energy spectrum analysis (EDS) showed that La 3- incorporation could increase Bi/Ca ratio.

Piezoelectric properties in textured ceramics of bismuth layer-structured ferroelectrics

Piezoelectric properties and their temperature stability were studied for the textured ceramics of bismuth layer structured ferroelectrics SrBi2Nb2O9 (SBN) type compound. The textured ceramics of 10% Nd substituted SBN were obtained by the templated grain growth (TGG) method, and the orientation degree reached 96%. Electro-mechanical coupling coefficient of thickness shear vibration for the 96%-textured specimen was three times larger than that for the randomly oriented specimen. In addition, the resonance frequency increased with increasing temperature for the 96%-textured specimen, while it decreased for the randomly oriented specimen. Therefore, textured ceramics with various orientation degrees were prepared. The gradient of the temperature variation in the resonance frequency changed from negative to positive with increasing grain orientation, and an excellent temperature coefficient of resonance frequency (TCF) of −0.4 ppm/°C was obtained for the specimen with 76% orientation. Moreover, the specimens with the major faces formed at various angles to oriented direction were fabricated from a 96%-textured ceramics. The gradient of temperature variation in resonance frequency changed from negative to positive with decreasing angle. the minimum value of TCF was −2.6 ppm/°C for the specimen with a 30° angle. Optimization of the orientation degree or the major face angle was effective to improve TCF for thickness shear vibration of SBN type ceramics.

Preparation and Electrical Properties of Dense Bi&lt;sub&gt;4&lt;/sub&gt;Ti&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; Ceramics by Spark Plasma Sintering

The family of bismuth layer-structured ferroelectrics is attractive from the viewpoint of their application as electronic materials such as dielectrics, piezoelectrics and pyroelectrics. However, during conventional sintering method, high sintering temperature and long sintering time were needed and it is difficult to get BIT ceramic with a density more than 95% of its theoretic value. In the present paper, we produce dense BIT pellet using a spark plasma sintering process. The results show that at a sintering temperature as low as 7000C/5min under a pressure of 25MPa, BIT ceramics with a density about 99% of its theoretic can be produced. The densities, grain size and electrical properties of the resulting ceramic were also investigated.

Bismuth Layer Structured Ferroelectric Ceramics with High Mechanical Quality Factor

The piezoelectric properties in some bismuth layer-structured ferroelectric (BLSF) ceramics were investigated focusing on a mechanical quality factor, Qm. Many BLSF compositions with various Curie temperature, Tc, were selected in this study, and the Qm values of (33) mode were plotted as a function of their Curie temperature, Tc. The Qm increased with increasing the Tc in the low Tc compositions below 500°C. It is considered to relate with the domain wall pinning because the coercive field, Ec also increased with increasing the Tc. However, in the high Tc compositions above 750°C, the Qm decreased with increasing the Tc contrary, because of the difficulties in poling treatment due to the Ec. On the other hand, high Qm values more than 10,000 were obtained in the intermediate Tc compositions between at 500 to 750°C. These values are quite high as the piezoelectric ceramics. The key point of the high Qm in these compositions is the poling process at high temperature of 300°C.

A NEW MICROSCOPIC MECHANISM FOR FATIGUE BEHAVIOR IN BISMUTH LAYER STRUCTURE FERROELECTRICS

ABSTRACT Systemic transmission electron microscopy investigations have been performed on bismuth layer structure ferroelectrics (BLSFs). Ferroelectric domains concluding 90° domain and 180° domain, and antiphase boundary were observed in dark field images and the characters for the 90° domain walls are summarized. We found that the fatigue behaviors of BLSFs show an obvious correlation with the morphology of the 90° domain wall. A microcosmic fatigue mechanism of BLSFs is put forward based on our study: the 180° domains are considered to nucleate at the 90° domain wall, which can be inhibited by charged oxygen defects in switching. The morphology of 90° domain wall is suggested to be a criterion for fatigue behavior in ferroelectrics.

Piezoelectric Properties of Nd and V Cosubstituted Bi&lt;sub&gt;4&lt;/sub&gt;Ti&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; Ceramics

The piezoelectric properties of Nd and V cosubstituted bismuth titanate ceramics, (Bi4-y,Ndy)1-(x/12)(Ti3-x,Vx)O12 [BNTV-y (x=0.01, y=0.00~1.00)] , are investigated. Furthermore, the grain orientation effects of BNTV-y ceramics on their piezoelectric properties are studied by the hot forging (HF) method. The electromechanical coupling factor, k33, of ordinarily fired (OF) BNTV-y0.75 ceramic was 0.21, which is one of the highest k33 values for bismuth layer-structured ferroelectrics (BLSFs). On the other hand, the k33 of the grain oriented (HF) BNTV-y0.25 ceramic was 0.30.