Ternary System Ceramics Research Articles

Effect of tuning A/B substitutions on multiferroic characteristics of BiFeO3-based ternary system ceramics

BiFeO3 is the most important type-I multiferroics, with a different origin of ferroelectricity (Bi-site) and magnetism orders (Fe-site). However, the magnetoelectric coupling effect is poor due to the huge differential between ferroelectric Curie temperature TC and Néel temperature TN. In this work, the crystal structure, ferroelectric and magnetic properties of BiFeO3-based ceramics were investigated by tuning the substitution amount of A and B sites. The XRD and Raman analyses confirmed the phase transformation from polar rhombohedral R3c to non-polar orthorhombic Pbnm with increasing substitution amount of A-site. DSC analysis indicated that the Curie temperature TC decreased linearly with increasing A-site substituted content, and the magnetic transition temperature TN decreased linearly with increasing B-site substituted content. Meanwhile, for BF008-01 sample, the obviously thermal hysteresis observed in DSC curves indicated the first-order ferroelectric transition. For other samples, the Curie temperature was hard to detect due to the relaxor ferroelectric characteristics. The ferroelectric properties obtained by PUND method indicated the enhanced ferroelectricity, which can be attributed to the decreased leakage current. The magnetic properties were improved, and the maximum remnant magnetization Mr was obtained at BF008-01 sample, where Mr = 75.4 emu/mol. The magnetic properties are mainly affected by the substitution content of B site and the structure of BiFeO3-based ceramics. This work realized the precise regulation of TC and TN of BiFeO3-based ceramics.

Microstructure and enhanced electrical properties of lead-free Bi1/2Na1/2TiO3–BaTiO3–La2CoMnO6 ternary system ceramics

The structure, field-induced strain, polarization and dielectric response of lead-free La2CoMnO6-modified 0.935Bi1/2Na1/2TiO3–0.065BaTiO3 (BNT–BT6.5–xLCMO, with x=0–0.020) ceramics were investigated. X-ray diffraction (XRD) patterns show that all compositions have a pure perovskite structure and LCMO effectively diffused into the BNT–BT6.5 lattice during sintering to form a solid solution. Around critical composition (x=0.005) at a driving field of 70kV/cm, large unipolar strain of 0.22% (Smax/Emax=328pm/V) and high piezoelectric constant of 211pC/N are obtained at room temperature. The coercive field (Ec=18.6kV/cm) drop down greatly, whereas the remnant polarization (Pr=28.8μC/cm2) decreases only a little at this critical composition. These results indicate that BNT–BT6.5–xLCMO ceramics can be considered as promising candidate materials for lead-free piezoelectric practical applications.

Enhanced energy-storage properties of 0.89Bi0.5Na0.5TiO3–0.06BaTiO3–0.05K0.5Na0.5NbO3 lead-free anti-ferroelectric ceramics by two-step sintering method

This work compared the effects of different sintering methods on the microstructure and anti-ferroelectric properties of lead-free 0.89Bi0.5Na0.5TiO3–0.06BaTiO3–0.05K0.5Na0.5NbO3 ternary system ceramics. The ceramics by two-step sintering method had smaller grain size and more uniform microstructure than those of the ceramics by single-step sintering method. The mechanism of grain growth in different sintering methods is discussed. The ceramics by two-step sintering method exhibited better anti-ferroelectricties than those of the ceramics by single-step sintering method. The polarization hysteresis (P–E) loop showed optimum electrical performances with a low remanent polarization (Pr=5.4μC/cm2) and a coercive field (Ec=8.2kV/cm), and the energy density (W) reached 0.90J/cm3 at 10Hz. The storage capacity is three times that of the single-step sintering ceramics.

ナノドメインエンジニアリングによる高性能圧電材料の創成

To develop high performance piezoelectric materials, a new method called at “nanodomain engineering” was proposed and investigated in this study. The nanodomain engineering means a method, which can produce high density nanodomain configurations by control of chemical composition, i.e., to develop an intermediate state between relaxor ferroelectrics and normal ferroelectrics. To confirm the concept, ternary system ceramics of BaTiO3-Bi(Mg1/2Ti1/2)O3-BiFeO3(BT-BMT-BF) was prepared and characterized. As the results, a formation of nanodomain configurations was confirmed by a transmission electron microscopy. Moreover, for the ceramics with the nanodomain configurations, high apparent piezoelectric constants over 500 pC/N was clearly obtained, which suggested that the concept of “nanodomain engineering” might work good.

Erratum to: Characterization and analysis of CaO–SiO2–B2O3 ternary system ceramics

Erratum to: Characterization and analysis of CaO–SiO2–B2O3 ternary system ceramics

Characterization and analysis of CaO–SiO2–B2O3 ternary system ceramics

The dielectric, thermal and mechanical properties of CaO–SiO2–B2O3 ternary system ceramics by solid-phase method have been carried out and quantitive analysis been examined by X-ray diffraction (XRD) patterns. The results showed that the major crystalline phase of CaO–SiO2–B2O3 ternary system ceramics was wollastonite (about 90 wt%) which existed at the temperature ranging from 950 to 1,100 °C. It is also observed that wollastonite could be transformed to pseudowollastonite at 1,200 °C. In addition, with increase in calcination temperature, the amount of wollastonite increases. When the sintering temperature is at 1,100 °C, the amount of wollastonite has a maximum value of 92.7 wt%. Accordingly, CaO–SiO2–B2O3 ternary system ceramics achieved excellent properties at 1,100 °C, such as dielectric constant of 8.38, dielectric loss of 1.51 × 10−3 at 1 MHz, linear thermal-expansion coefficient (300 K) of 6.68 × 10−6/K, bending strength of 121.75 Mpa. Analysis of the mechanical and dielectric properties showed that the measured bending strength, dielectric constant and loss of CaO–SiO2–B2O3 ternary system ceramics can be substantially modified and improved by controlling the sintering temperature, in particular due to the amount of wollastonite crystalline phase and size of grains.

Structure and relaxor behavior of BaTiO3–CaTiO3–SrTiO3 ternary system ceramics

This study prepared (1−x)BaTiO3–xCaTiO3 (x=0–1) (denoted as BCT), (0.95−x)BaTiO3–xCaTiO3–0.05SrTiO3 (x=0.00–0.95) (denoted as BS5CT), and (0.90–x)BaTiO3–xCaTiO3–0.10SrTiO3 (x=0.00–0.90) (denoted as BS10CT) ceramics. Their preparation and structural and dielectric properties were characterized. The results show that the x-ray diffraction (XRD) peaks of the BCT, BS5CT, and BS10CT ceramics shift toward higher angles with increasing Ca. All samples were uniform and dense by 1400 °C sintering and the grain size decreased with the Ca addition. With the Sr and Ca cosubstitutions, the phase transition temperature (TC) decreased and the rhombohedral-orthorhombic and orthorhombic-tetragonal phase transition points disappeared. The dielectric peaks became increasingly broad and the relative dielectric constant of the BCT, BS5CT, and BS10CT samples decreased with increasing Ca. The replacement of Ba2+ ions by Sr2+ and Ca2+ ions reduced the lattice constant with increasing hydrostatic pressure and moved the Curie point downwards. The index of relaxation (γ) and the broadening parameter were estimated from a linear fit of the modified Curie–Weiss law.

The Effect of Zn<sup>2+</sup> Deficiency on Ordered Micro-Regions and Dielectric Properties of Pb(Zn<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-Based Relaxor Ceramics

0.85Pb(Zn1/3Nb2/3)O3-0.10BaTiO3-0.05PbTiO3 (abbreviated as PZN-based ceramics hereafter) ternary system ceramics with Zn2+ deficiency were synthesized by the columbite method. The effect of deficient Zn2+ on phase structure, ordered micro-region size and dielectric properties was investigated in detail. The analysis of Raman scattering spectra demonstrated that Zn2+ deficiency sharply enlarged the ordered micro-region size. Zn2+ deficiency significantly increased the dielectric constant, and decreased the diffusion degree of phase transition. There is a close correlation between effective ordered micro-regions size and dielectric properties for the PZN-based ceramics.

Piezoelectric and Dielectric Properties of (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO3- (Bi<sub>0.5</sub>K<sub>0.5</sub>)TiO<sub>3</sub>-BaTiO<sub>3</sub> Lead-Free Piezoelectric Ceramics

A lead-free piezoelectric ceramic ternary system based on (Bi0.5Na0.5)TiO3 (BNT)-(Bi0.5 K0.5)TiO3(BKT)-BaTiO3(BT) near the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral phases has been investigated. The samples were prepared by a conventional sintering technique. Piezoelectric properties, dielectric properties and microstructures of BNT-BKT-BT lead-free piezoelectric ceramic were studied. The X-ray diffraction (XRD) patterns show that the ceramics possess a single-phase perovskite structure. The measurements of piezoelectric properties reveal that this system has a relatively high piezoelectric performance: the piezoelectric constant d33 reached to 178pC/N and planar electromechanical coupling factor kp enhanced to 0.325. The BNT-BKT-BT ternary system ceramics could be well sintered at 11500C with a high-density ratio of more than 95% of the theoretical density.

Electromechanical Properties and Morphotropic Phase Boundary of Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3-BaTiO3 Lead-free Piezoelectric Ceramics

The crystal structure and electromechanical properties of two ternary ceramic Na0.5Bi0.5TiO3- K0.5Bi0.5TiO3-BaTiO3 (NBT-KBT-BT) systems were investigated. A gradual change in crystalline structure and microstructure with the increase of KBT and BT concentrations were observed. It was ascertained that the rhombohedral-tetragonal morphtropic phase boundary (MPB) lies in the range of 0.024 ≰ x ≰ 0.030 for (1–5x) NBT-4x KBT-x BT system and 0.025 ≰ y ≰ 0.035 for (1 − 3y) NBT—2y KBT—y BT system at room temperature. The piezoelectric constant d33 and electromechanical coupling factor k p of the ceramics attain a maximum value of 150 pC/N and 0.298, respectively. The MPB phase diagram of NBT-KBT-BT ternary system was determined by phase analysis of XRD patterns from calcined specimens. The ferroelectric properties of the (1 − 5x) NBT—4x KBT—x BT system have been characterized. The ternary system ceramics have relatively high Curie temperature Tc.

Ordered micro-regions and dielectric properties of La 3+-doped Pb(Zn 1/3Nb 2/3)O 3-based ceramics with Nb 5+ deficiency

La 3+-doped 0.85Pb(Zn 1/3Nb 2/3)O 3–0.10BaTiO 3–0.05PbTiO 3 (abbreviated as PZN-based ceramics hereafter) ternary system ceramics with Nb 5+ deficiency were synthesized by the columbite method. The effect of deficient Nb 5+ on the phase structure, ordered micro-region size and dielectric properties of lanthanum-doped PZN-based ceramics was investigated in detail. With the increase of Nb 5+ deficiency, the content of pyrochlore phase decreased significantly. Especially, when Nb 5+ deficiency was >3 mol%, the pyrochlore phase resulting from La 3+ doping was eliminated completely. From the viewpoint of the phase structure affected by Nb 5+ deficiency, it could come to the conclusion that the non-stoichiometric 1:1 ordered micro-regions do exist in PZN-based ceramics. The analysis of Raman scattering spectra demonstrated that Nb 5+ deficiency enlarged ordered micro-region size of the lanthanum-doped PZN-based ceramics. Nb 5+ deficiency increased the dielectric constant, but it hardly affected dielectric loss. The increase of dielectric constant results not only from the elimination of pyrochlore phase but also from the size increase of “effective ordered micro-regions”.

The effect of La doping on the electrostriction and electric hysteresis of 0.85Pb(Zn 1/3Nb 2/3)O 3–0.10BaTiO 3–0.05PbTiO 3 ceramics

Lanthanum-doped 0.85Pb(Zn 1/3Nb 2/3)O 3–0.10BaTiO 3–0.05PbTiO 3 ternary system ceramics were synthesized by the columbite method. The effect of lanthanum doping on dielectric, electrostrictive properties and electric hysteresis of the specimens was investigated. With the increase in lanthanum content, the content of perovskite phase and dielectric constant decreased, but the thermostablity of the dielectric properties improved. When lanthanum content increased, electrostriction and electrostrictive coefficients decreased. The electric hysteresis of La-doped speciments also decreased, i.e. the remanent polarization and coercive fields decreased.

Fretting wear of sintered iron under low pressures : J.R.Moon et al. Wear, vol 221, no 2, 1998, 86–92

This work compared the effects of different sintering methods on the microstructure and anti-ferroelectric properties of lead-free 0.89Bi0.5Na0.5TiO3–0.06BaTiO3–0.05K0.5Na0.5NbO3 ternary system ceramics. The ceramics by two-step sintering method had smaller grain size and more uniform microstructure than those of the ceramics by single-step sintering method. The mechanism of grain growth in different sintering methods is discussed. The ceramics by two-step sintering method exhibited better anti-ferroelectricties than those of the ceramics by single-step sintering method. The polarization hysteresis (P–E) loop showed optimum electrical performances with a low remanent polarization (Pr=5.4 μC/cm2) and a coercive field (Ec=8.2 kV/cm), and the energy density (W) reached 0.90 J/cm3 at 10 Hz. The storage capacity is three times that of the single-step sintering ceramics.

Structural parameters in dispersion strengthened copper-alumina : J.Zrnik et al. (Technical University, Kosice, Czech Republic.) PokrokyPraskove Metal., vol 37, no 1, 1999, 32–37. (In Czech.)

This work compared the effects of different sintering methods on the microstructure and anti-ferroelectric properties of lead-free 0.89Bi0.5Na0.5TiO3–0.06BaTiO3–0.05K0.5Na0.5NbO3 ternary system ceramics. The ceramics by two-step sintering method had smaller grain size and more uniform microstructure than those of the ceramics by single-step sintering method. The mechanism of grain growth in different sintering methods is discussed. The ceramics by two-step sintering method exhibited better anti-ferroelectricties than those of the ceramics by single-step sintering method. The polarization hysteresis (P–E) loop showed optimum electrical performances with a low remanent polarization (Pr=5.4 μC/cm2) and a coercive field (Ec=8.2 kV/cm), and the energy density (W) reached 0.90 J/cm3 at 10 Hz. The storage capacity is three times that of the single-step sintering ceramics.

Pyroelectric properties of Pb[Zr, Ti, (Zn, Nb)]O3solid solution ceramics

Abstract Modified PZT with a complex perovskite oxide, the ternary system PbTiO3-PbZrO3-Pb(Zn1/3Nb2/3)O3 (PZT-PZN) ceramics were prepared and their pyroelectric properties were investigated by the static and dynamic measurements. Improvements of the pyroelectric coefficient and the pyroelectric figure of merit as well as the voltage responsivity at room temperature by adding the PZN content to PZT were observed. Due to the second order nature of the FR(LT) to FR(HT) phase transition, the peak values in both the pyroelectric coefficient and the voltage responsivity without thermal hysteresis were found in this ternary system ceramics.