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Crystal structure, piezoelectric, and dielectric properties were investigated in the new lead-free BKT-based piezoelectric ceramics of (1− x)( Bi1/2 K1/2) TiO3- x Bi( Mg2/3 Nb1/3) O3. The morphotropic phase boundary (MPB) of the system between tetragonal and rhombohedral phases lies near the composition of x = 0.02. The optimal piezoelectric property of small-signal d33 is much enhanced to be 96 pC/N ( x = 0.01), which is higher than any other BKT-based compositions. By the introduction of Bi( Mg2/3 Nb1/3) O3, the ceramics exhibit a lower coercive field EC. In addition, a relaxor-like behavior with a frequency-dependent Curie temperature Tm is observed, and high Curie temperature Tm around 380°C is obtained in the investigated system. This study suggests that the piezoelectric properties of BKT can be significantly improved by the means of Bi( Mg2/3 Nb1/3) O3 substitution. [ABSTRACT FROM AUTHOR]

Abstract: According to consideration on the average radius of B-site cation of BiMeO3, we reported that the Bi(Mg0.5Zr0.5)O3–xPbTiO3 compound at the morphotropic phase boundary (MPB) of x=0.58 possesses a piezoelectric coefficient d 33 as high as 306pC/N. The optimal piezoelectric and ferroelectric properties near the MPB might be attributed to its lower lattice distortion, as described by change of FWHM value for {111}PC peaks. Furthermore, Bi(Mg0.5Zr0.5)O3–xPbTiO3 displayed stable ferroelectric and piezoelectric properties over a temperature range from ambient temperature to above 160°C, as exhibited by temperature dependence polarization and strain versus electric field curves and thermal depoling process. [Copyright &y& Elsevier]

Abstract: Perovskite structure (1 − x)BaTiO3–xBiAlO3 (BT–xBA, x = 0.05, 0.08 and 0.1, corresponding to BT–5BA, BT–8BA and BT–10BA, respectively) ceramics were prepared by a solid state reaction route. Crystal structure of BT–xBA ceramics was determined by using XRD. Dielectric properties were studied as a function of temperature at different frequencies, which indicated that the phase transition temperature (T m) decreased with increasing x. With increasing temperature, thermal expansion dl/l increased while thermal expansion coefficient α had weak concentration dependence. The Burns temperature was much higher than the transition temperature T m for the BT–5BA and BT–10BA ceramics. Polarization hysteresis loops (P–E), electrostrictive (S–E) and S versus P 2 (S–P 2) at different temperatures were displayed. P max slightly decreased due to thermally activated leakage current, meanwhile, S max decreased at above T m with the contribution of ferroelectric domain reorientation decreased. The electrostrictive coefficient Q value was clearly larger than that of lead-based electrostrictors at room temperature. Furthermore, it exhibited a slim loop with negligible hysteresis and a subtle linear feature at higher temperature. [Copyright &y& Elsevier]

A new lead-free BNT-based piezoelectric ceramics of (1 − x) Bi0.5 Na0.5 TiO3- x Bi( Al0.5 Ga0.5) O3 ( x = 0, 0.02, 0.03, 0.04, and 0.05) were synthesized using a conventional ceramic fabrication method. Their structures and electrical properties were investigated. All the samples show a typical ferroelectric P( E) loops and S( E) curves at room temperature. The optimal properties are obtained at the composition of the x = 0.03. The substitution of Bi( Al0.5 Ga0.5) O3 enhances piezoelectric constant and increases Curie temperature from 58 pC/N and 310°C of pure BNT to 93 pC/N and 325°C of the x = 0.03. The temperature-dependent P( E) loops and S( E) curves of 0.97BNT-0.03BAG indicate that phase transition from ferroelectric to antiferroelectric takes place over a very wide temperature region from 80°C to 180°C. The results show that the introduction of BAG improves the electrical properties of BNT. [ABSTRACT FROM AUTHOR]

Crystal structure, piezoelectric, and dielectric properties were investigated in the new lead-free BKT-based piezoelectric ceramics of (1− x)( Bi1/2 K1/2) TiO3- x Bi( Mg2/3 Nb1/3) O3. The morphotropic phase boundary (MPB) of the system between tetragonal and rhombohedral phases lies near the composition of x = 0.02. The optimal piezoelectric property of small-signal d33 is much enhanced to be 96 pC/N ( x = 0.01), which is higher than any other BKT-based compositions. By the introduction of Bi( Mg2/3 Nb1/3) O3, the ceramics exhibit a lower coercive field EC. In addition, a relaxor-like behavior with a frequency-dependent Curie temperature Tm is observed, and high Curie temperature Tm around 380°C is obtained in the investigated system. This study suggests that the piezoelectric properties of BKT can be significantly improved by the means of Bi( Mg2/3 Nb1/3) O3 substitution. [ABSTRACT FROM AUTHOR]

Abstract: The electrical properties included temperature-dependent polarization of (1−x)Bi(Mg1/2Zr1/2)O3–xPbTiO3 (BMZ–xPT) new ferroelectric films were investigated. The films with 220nm thickness grown on Pt(111)/Ti/SiO2/Si substrates via sol–gel method were well crystallized with a phase-pure perovskite structure and homogeneous microstructure. Saturated polarization hysteresis loops are observed for all BMZ–xPT compounds, and BMZ–0.85PT films with high (100) orientation show a small leakage and remanent polarization of 36.1μCcm−2, which is comparable to the (100)-oriented BiScO3–PbTiO3 thin films. The present films have high dielectric constants about 544-833. Furthermore, the polarization with elevated temperature slightly decreases, exhibiting stable ferroelectric properties and potentials for memory applications above room temperature such as non-volatile ferroelectric random access memories. [Copyright &y& Elsevier]