Electric Field Induced Strain Behavior Research Articles

An investigation of structural, electrical and optical properties of lead-free barium zirconium titanate (BZT)-based ceramic compounds

ABSTRACT The present work is a demonstration of improved electrical and optical properties of barium zirconium titanate ceramic modified by the addition of Europium, i.e. Ba(1–x)Eu2x/3Zr0.05Ti0.95O3 (x = 0.01, 0.02, 0.03, 0.04). The Rietveld refinement studies confirmed the formation of tetragonal phase in the samples. The scanning electron microscopy (SEM) images revealed a decrease in grain size with increasing Eu concentration. The dielectric constant, dielectric loss and TCC plots are drawn to study temperature and frequency dependence of the samples. The electric field-induced strain behavior has been studied for all the compositions of the synthesized ceramic at room temperature. Conduction mechanism in the samples as a function of frequency and temperature was studied with the help of AC conductivity data. Also, the effect of grain and grain boundaries are studied in term of Cole–Cole plots. Photoluminescence (PL) emission spectra were recorded upon excitation with a wavelength of 360 nm.

Electric field–induced strain behavior and ferroelectric properties of lead zirconate titanate-barium calcium zirconate titanate ceramics

ABSTRACTIn this work, electric field-induced strain behavior and ferroelectric properties of xBCZT/PZT (with x = 0, 4 and 8 mol%) ceramics have been investigated. The Ec and Pr increased with increasing electric field and exhibited pinched-shape hysteresis loop at 60 kV/cm. The abnormal domain walls and switching behavior of the domains were used to discuss the above results. The strain value increased with increasing BCZT content and reached the maximum value of 0.27% (d*33 = 450 pm/V) for the 4 mol% BCZT sample. This offered an opportunity to obtain a good candidate for using in piezoelectric applications.

Influence of low external magnetic field on electric field induced strain behavior of 9/70/30, 9/65/35 and 9/60/40 PLZT ceramics

In this work, Pb0.91La0.09(ZrxTi1−x)0.9775O3 PLZT ceramics, where x =0.70, 0.65 and 0.60, were prepared by a solid-state mixed-oxide technique. Structural information was investigated by X-ray diffraction method. Electric field induced polarization and strain behavior of the PLZT ceramics under an influence of static magnetic field were measured by a Sawyer-Tower circuit in conjunction with Michelson interferometer at various static magnetic fields (0–30.7mT). The results showed that the imposed magnetic field affected the polarization and induced strain behaviors in PLZT ceramics More interestingly, the imposed magnetic field showed more significant influence on the PLZT ceramic composition near morphotropic phase boundary (MPB), i.e. PLZT 9/65/35. The spontaneous polarization of 180° domain switching was seen to be suppressed by the applied magnetic field.

Dielectric, ferroelectric and induced strain behavior of PLZT 9/65/35 ceramics modified by Bi2O3 and CuO co-doping

PLZT 9/65/35 (Pb0.91La0.09(Zr0.65Ti0.35)0.9775O3) ceramics with addition of 0.25, 0.5 and 1.0wt% of Bi2O3/CuO (where the ratio of Bi2O3:CuO=9:1 by mole) were prepared by sintering at the temperatures between 1000 and 1200°C. It was found that Bi2O3/CuO could bring the sintering temperature down ~50°C to obtain PLZT with no second phase. Dielectric and ferroelectric properties were investigated. Bi2O3/CuO decreased both coercive field and remnant polarization, which was caused by an increase of the degree of diffuseness in relaxor ferroelectric materials. Electric field induced strain behavior was also investigated and it was found that the addition of Bi2O3/CuO increased the maximum induced strain and maximized electrostrictive effect. Therefore, Bi2O3/CuO was useful as a sintering aid, which improved the dielectric and the relaxor ferroelectric properties as well as the electric field induced strain of PLZT ceramics.

Lead‐Free (Ba0.70Sr0.30)TiO3‐Modified Bi0.5(Na0.80K0.20)0.5TiO3 Ceramics with Large Electric Field–Induced Strains

The dielectric, ferroelectric, and electric field–induced strain behavior of Bi0.5(Na0.80K0.20)0.5TiO3 (BNKT) ceramics modified with (Ba0.70Sr0.30)O3 (BST) were investigated as a function of composition and temperature. The ceramic samples were synthesized by a solid‐state mixed oxide method and sintered at 1125°C for 2 h. The XRD and Raman spectra showed coexisting rhombohedral and tetragonal phases throughout the entire compositional range with the tetragonal phase becoming dominant at higher BST concentrations. For all compositions, the temperature dependence of the dielectric spectra revealed a frequency dependence that is characteristic of a relaxor mechanism. This suggests that these ceramics lacked long‐range order and it appears that the maximum disorder was observed for the composition with 5 mol% BST (BNKT–0.05BST sample). This was evidenced by the observation of pinched hysteresis loops, even at room temperature, and a significant decrease in the Pr and Ec values which resulted in large electric field–induced strains (Smax) of 0.40% and a normalized strain coefficient ( = Smax/Emax) of 732 pm/V. This significant strain enhancement at the composition of x = 0.05 may be attributed to both a composition‐induced structural phase transition and a field‐induced relaxor to ferroelectric phase transition.

Dielectric, ferroelectric and electric field-induced strain behavior of Ba(Ti0.90Sn0.10)O3-modified Bi0.5(Na0.80K0.20)0.5TiO3 lead-free piezoelectrics

Lead-free piezoelectric ceramics of (1−x)Bi0.5(Na0.80K0.20)0.5TiO3–xBa(Ti0.90Sn0.10)O3 or (1−x)BNKT–xBTS (when x=0–0.20mol fraction) were investigated. Optimum sintering temperature was found to be 1125°C at which all compositions had relative densities 98–99% of their theoretical values. All compositions exhibited a single perovskite structure. The unit cell size expansion was observed as BTS content increased. A slight reduction of grain size was noticeable when small amount of BTS was added. The BNKT–0.05BTS sample had a large electric field-induced strain (Smax) of 0.36% which corresponded to the normalized strain coefficient (d33∗) of 649pm/V. The highest piezoelectric coefficient (d33=215pC/N) with good dielectric (ɛr=1721, tanδ=0.0724 and Tc=333°C) and ferroelectric properties (Pr=20.49μC/cm2, Rsq=0.87) were obtained for BNKT–0.10BTS sample, suggesting that this composition had a potential to be one of the promising lead-free piezoelectric candidates for further use in actual applications.

Field induced strain response of lead-free BaZrO3-modified Bi0.5Na0.5TiO3–BaTiO3 ceramics

Lead-free (0.935−x)[Bi0.5Na0.5TiO3–0.065BaTiO3]–xBaZrO3 (BNBT–xBZ, with x=0−0.07) ceramics were prepared by a conventional solid-state reaction method. The effect of BZ addition on the crystal structure, microstructure, dielectric, ferroelectric and electric field induced strain behavior of BNBT ceramic was investigated. X-ray diffraction patterns of BNBT–xBZ ceramics revealed the formation of single phase perovskite structure in the studied composition range. Addition of BZ in BNBT transform the crystal structure from tetragonal to pseudocubic symmetry. However, with increasing BZ content, the maximum dielectric constant decreased and the dielectric maximum temperature (Tm) shifted towards lower temperature. The field induced strain response of BNBT–xBZ increases from 0.16% for x=0 to 0.38% for x=0.03, at an applied field of 7kV/mm. The corresponding dynamic piezoelectric coefficient for these composition were (Smax/Emax=231pm/V) and (Smax/Emax=542pm/V), respectively. These results suggest that the BNBT–0.03BZ ceramic can be considered as a promising candidate material for piezoelectric application.

Effect of Nd3+ substitution on electric field induced strain behavior in lead zirconate stannate titanate (68/22/10) ceramics

Abstract Pb 1−3 x /2 Nd x (Zr 0.68 Sn 0.22 Ti 0.1 )O 3 ceramics with large electrical field induced strain were prepared by Nd 3+ doping. X-ray diffraction analysis showed that the substitution of Nd 3+ for Pb 2+ enhanced the stability of antiferroelectric phase due to the decrease of tolerance factor. Besides, with the increase of Nd 3+ addition, the strain first improved with a maximum value at x  = 0.02, and then decreased. Further, with increasing electric field and decreasing measuring frequency, the strain improved obviously. This is because that the reversal of the domains is more sufficient at large electric field and long time. The largest strain of 0.63% is obtained in the specimens with x  = 0.02 at the frequency 1 Hz.

Destabilization of ferroelectric order in bismuth perovskite ceramics by A-site vacancies

This work compared the effects of isovalent Sn4+ and aliovalent Ta5+ doping on Ti-sites in lead-free perovskite type Bi1/2(Na0.82K0.18)1/2TiO3 piezoelectric ceramics on their ferroelectric and electric field-induced strain behavior. Both impurities led to a diffuse transformation from the coexistence of ferroelectric rhombohedral and tetragonal phases to a nonpolar pseudocubic symmetry. Nevertheless, Ta doping more strongly promoted the phase transition even though the ionic size difference between Ta5+ and Ti4+ was smaller than that between Sn4+ and Ti4+. The results evidenced that donor-induced A-site vacancies significantly contributed to the destabilization of ferroelectric phases in the Bi perovskite.

Hierarchical Domain Structures in Relaxor 24Pb(In1/2Nb1/2)O3–46Pb(Mg1/3Nb2/3)O3–30PbTiO3 near a Morphotropic Phase Boundary Composition Grown by Bridgman Method

The domain structures of the lead-based relaxor ferroelectric solid solution single crystal, 24Pb(In1/2Nb1/2)O3 (PIN)–46Pb(Mg1/3Nb2/3)O3 (PMN)–30PbTiO3 (PT), near a morphotropic phase boundary (MPB) composition grown by the Bridgeman method were studied by polarized light microscopy (PLM), piezoresponse force microscopy (PFM) and scanning electron microscopy (SEM). The change in domain structures with poling from rhombohedral spindlelike domains of 3–5 µm width to orthorhombic domains of ∼20 µm width with rectangular cells with a size of 3–5 µm, characterized with an antiferroelectic double hysteresis loop in the electric field-induced strain behavior, was found. Such domain structures were microscopically identified from SEM images as small circular tetragonal defects, planar monoclinic defects such as edge and screw dislocations with Burgers vector b along <110>cub and/or <100>cub directions and their agglomerate rectangular orthorhombic defects, also characterized by PFM. Hierarchical domain structures are discussed from the viewpoints of domain structures due to defects such as edge and screw dislocations originating in the chemical order region (COR) and the piezoelectric responses and dielectric properties.

Electric field-induced strain behavior in lithium- and copper-added potassium sodium niobate piezoceramics and 1-3 piezocomposites

Potassium sodium niobate (KNN)-based leadfree materials were prepared and their field-induced strain behaviors were investigated. Ceramic lead-free piezoelectric materials were prepared in bulk and fiber forms with 1 mol% CuO-added potassium sodium niobate K0.5Na0.5NbO3 and x = 7 mol% lithium-modified (K(0.5-x/2)Na(0.5-x/2)Li(x))NbO(3) compositions. Fibers were drawn using a novel alginate gelation technique. Piezocomposites were prepared from these fibers with 1-3 connectivity and an epoxy matrix. A fully recoverable electrostrain of up to approximately 0.11% was observed in the CuO-added sample, whereas the Li-modified sample yielded up to 0.10% at 50 kV/cm electric field. A strain value of up to approximately 0.03% at 50 kV/cm electric field was obtained for piezocomposites prepared from lithium-modified fibers. The high-field converse piezoelectric coefficient was calculated from the strain-electric field (x-E) graph for all samples. Strain characteristics of the bulk and piezocomposite samples were analyzed based on the variation of strain with respect to square of the polarization (x-P2) to determine the electrostrictive contribution to the strain.

Hierarchical Domain Structures in Relaxor 24Pb(In1/2Nb1/2)O3–46Pb(Mg1/3Nb2/3)O3–30PbTiO3near a Morphotropic Phase Boundary Composition Grown by Bridgman Method

The domain structures of the lead-based relaxor ferroelectric solid solution single crystal, 24Pb(In1/2Nb1/2)O3 (PIN)–46Pb(Mg1/3Nb2/3)O3 (PMN)–30PbTiO3 (PT), near a morphotropic phase boundary (MPB) composition grown by the Bridgeman method were studied by polarized light microscopy (PLM), piezoresponse force microscopy (PFM) and scanning electron microscopy (SEM). The change in domain structures with poling from rhombohedral spindlelike domains of 3–5 µm width to orthorhombic domains of ~20 µm width with rectangular cells with a size of 3–5 µm, characterized with an antiferroelectic double hysteresis loop in the electric field-induced strain behavior, was found. Such domain structures were microscopically identified from SEM images as small circular tetragonal defects, planar monoclinic defects such as edge and screw dislocations with Burgers vector b along cub and/or cub directions and their agglomerate rectangular orthorhombic defects, also characterized by PFM. Hierarchical domain structures are discussed from the viewpoints of domain structures due to defects such as edge and screw dislocations originating in the chemical order region (COR) and the piezoelectric responses and dielectric properties.

Large electrostrictive strain in lead-free Bi0.5Na0.5TiO3–BaTiO3–KNbO3 ceramics

In the present work, (1−x)(0.935Bi0.5Na0.5TiO3–0.065BaTiO3)–xKNbO3 (BNT–BT–KN, BNT–BT–100xKN) ceramics with x ranging from 0 to 0.1 were prepared by the conventional ceramic fabrication process. A large electrostrictive coefficient of ∼10−2 m4 C−2 is obtained with the composition x ranging from 0.02 to 0.1, which is close to the well-known electrostrictive material Pb(Mg1/3Nb2/3)O3. Under an electric field of 4 kV/mm, the electrostrictive strain can reach as high as 0.08%. Besides, the electric field induced strain behavior indicates a temperature independent behavior within the temperature range of 20 to 150°C. The large electrostrictive strain is suggested to be ascribed to the formation of non-polar (NP) phase developed by the KNbO3 substitution, and the high electrostrictive coefficient of BNT–BT–KN ceramics makes them great candidates to be applied in the new solid-state actuators.

Phase transitions and large electric field-induced strain in BiAlO 3-modified Bi 0.5(Na, K) 0.5TiO 3 lead-free piezoelectric ceramics

Lead-free piezoelectric (1 − x)(Bi 0.5(Na 0.78K 0.22) 0.5TiO 3)– xBiAlO 3 (abbreviated BNKT22–BA, x = 0.00–0.100) ceramics were synthesized using a conventional sintering technique. The incorporation of BA into the BNKT22 lattice was investigated by X-ray diffraction (XRD), and the dielectric and ferroelectric characterizations and electric field-induced strain behavior. We found that the structural and electrical properties of BNKT22 ceramics are significantly influenced by the presence of BA content. X-ray diffraction revealed a pure perovskite phase for x ⩽ 0.050. A phase transformation from tetragonal to pseudocubic was observed at x = 0.050. As BA content increased, the maximum dielectric constant continuously decreased, and the depolarization temperature ( T d ) shifted towards lower temperatures. The polarization and strain hysteresis loops indicate that the addition of BA significantly disrupts the ferroelectric order. The destabilization of the ferroelectric order is accompanied by an enhancement of bipolar and unipolar strains. In particular, a very large electric field-induced strain ( S = 0.35%) and a normalized strain ( d 33 ∗ = S max/ E max = 592 pm/V) were observed at x = 0.030, near the tetragonal–pseudocubic phase boundary. These results suggested that the BNKT22–BA system is a promising candidate for high performance, lead-free electromechanical applications.