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Recently, the progress of integrated electronics has led to a strong demand for materials and devices with multiple functions. In this study, we achieved Pb0.985Sm0.01 (Zr0.64Sn0.28Ti0.08)O3 ( PSZST) multifunctional ceramics which showed simultaneously large electric-field-induced strain (0.63%) and high recoverable energy density (1.743 J/cm3) at room temperature. Moreover, the strain and recoverable energy density exhibited a slight frequency fluctuation in the frequency range of 1-10 Hz. Their variations were less than 8% and 1.3% and the values were all higher than 0.58% and 1.722 J/cm3, respectively. The large strain, high-energy density, and their good frequency stability in a wide range indicate that the PSZST ceramic is quite promising for application in multifunctional devices. [ABSTRACT FROM AUTHOR]

Enhanced electrical resistivity about over two orders of magnitude for Na0.5Bi2.5Nb2O9 (NBNO) high-temperature piezoceramics potentially used in piezoelectric sensors is achieved by the introduction of highly insulating Al2O3 addition. Possible pyrochlore secondary phases of two types of grains: irregular polyhedral and platelike, forming at the grain boundaries, have significant blocking effect on the electric current paths and thus lead to improved electrical resistivity. Al2O3-modified NBNO ceramics show higher d33 values up to 16.5 pC/N than that of pure NBNO ceramics (12.4 pC/N) because higher electric field is applied during poling process owing to enhanced electrical resistivity, whereas the Tc values keep almost constant. A compromise between high Tc, good polarizability and enhanced electrical resistivity has been achieved by suitable addition of Al2O3, which would shed light on how to obtain novel Aurivillius phase ferroelectrics for practical applications at high temperature. [ABSTRACT FROM AUTHOR]

Ceramics of composition (1− x)BaTiO3- xBi(Zn1/2Ti1/2)O3 ( BT- BZT) were prepared by solid-state synthesis; they have been shown to exhibit excellent properties suited for high-temperature dielectric applications. The X-ray diffraction data showed a single-phase perovskite structure for all the compositions prepared ( x ≤ 0.1 BZT). The compositions with less than 0.075 BZT exhibited tetragonal symmetry at room temperature and pseudo-cubic symmetry above it. Most notably, a significant improvement in insulation properties was measured with the addition of BZT. Both low-field AC impedance and high-field direct DC measurements indicated an increase in resistivity of at least two orders of magnitude at 400°C with the addition of just 0.03 BZT (~107 Ω-cm) into the solid solution as compared to pure BT (~105 Ω-cm). This effect was also evident in dielectric loss data, which remained low at higher temperatures as the BZT content increased. In conjunction with band gap measurements, it was also concluded that the conduction mechanism transitioned from extrinsic for pure BT to intrinsic for 0.075 BZT suggesting a change in the fundamental defect equilibrium conditions. It was also shown that this improvement in insulation properties was not limited to BT- BZT, but could also be observed in the paraelectric SrTiO3-BZT system. [ABSTRACT FROM AUTHOR]

Piezoelectric ceramics with large energy density coefficient d33· g33 value have been found suitable for piezoelectric energy harvesting applications. In this study, the phase structures and piezoelectric properties of x Pb( Zr0.5 Ti0.5)O3− y Pb( Zn1/3 Nb2/3)O3−(1− x− y) Pb( Ni1/3 Nb2/3) O3 ( x PZT− y PZN−(1− x− y) PNN) ceramic were investigated with systematically varying PZN and PNN components. The ternary phase diagram of PZT− PZN− PNN system was illustrated and the composition region of morphotropic phase boundary (MPB) was determined. Piezoelectric and dielectric measurements verify that the materials in MPB region all present large d33 and d33· g33 values. In particular, very high d33· g33 coefficients of 20162.2 × 10−15 m2/N and 21026.3 × 10−15 m2/N are observed from samples 0.75 PZT−0.15 PZN−0.1 PNN and 0.8 PZT−0.05 PZN−0.15 PNN with compositions located on the rhombohedral phase side near MPB because the dielectric coefficient ε33T/ε0 decreases faster than the d33 coefficient at this side. [ABSTRACT FROM AUTHOR]

Magnetic properties of polycrystalline multiferroic Bi0.65La0.35Fe0.5Sc0.5O3 synthesized under high-pressure (6 GPa) and high-temperature (1500 K) conditions were studied using a SQUID magnetometer technique. The temperature dependent static magnetic moment M was measured in both zero-field-cooled and field-cooled modes over the temperature range of 5-300 K in low magnetic field H = 0.02 kOe. The field dependent magnetization M(H) was measured in magnetic fields up to 50 kOe at different temperatures up to 230 K after zero-field cooling procedure. A long-range magnetic ordering of the antiferromagnetic type with a weak ferromagnetic contribution takes place below TN ≈ 220 K. Magnetic hysteresis loops taken below TN show a huge coercive field up to Hc ≈ 10 kOe, while the magnetic moment does not saturate up to 50 kOe. A strong effect of magnetic field on the magnetic properties of the compound has been found. Below TN ≈ 220 K the derivatives of the initial magnetization curves demonstrate the existence of a temperature-dependent anomaly in fields of H = 15/25 kOe. The nature of the anomaly is unknown and requires additional study. [ABSTRACT FROM AUTHOR]

The dielectric and electromechanical properties of 0.75 Bi1/2 Na1/2 TiO3-0.25 SrTiO3 (25 ST) as a function of temperature and frequency were studied. It is shown that the 25 ST is a relaxor ferroelectric as evidenced by the temperature-dependent dielectric relaxations with an incipient piezoelectricity featured by the presence of a reversible electric-field-induced phase transformation at room temperature. The transition occurs on a broad electric field strength range depending on field amplitude and frequency. It is also accompanied by a huge strain that is attributed to repetitive poling and depoling originating due to the reversibility of the phase transition. The 25 ST makes an attractive lead-free candidate for stack actuators as it presents a high normalized d33* of ~600 pm/V at a low electric field of 4 kV/mm for frequencies ranging from 0.1 up to 100 Hz. [ABSTRACT FROM AUTHOR]

The single-phase solid solutions of the (1 − x) BaTiO3-( x) Bi( Zn1/2 Ti1/2) O3 ( BT- BZT) where x = 0.02-0.15 were prepared to investigate dielectric properties. Crystal structure of samples was obtained by using an X-ray diffraction technique and Raman spectroscopy. For compositions with x ≤ 0.08, the solid solutions exhibited clear tetragonal symmetry and transitioned to pseudocubic symmetry as the content of BZT increased. The dielectric response exhibited a sharp phase transition within the BT-rich region and the composition 0.92 BT-0.08 BZT was characterized by the onset of relaxor characteristics. As the concentration of BZT increased, the phase transition exhibited broader and more diffuse behavior. The polarization as a function of electric field ( P- E) of these solid solutions also exhibited the same trend. The BT-rich compositions showed a normal ferroelectric P- E response with a decrease in loop area as the BZT content increased. The composition at x = 0.08 exhibited a pinched hysteresis loop and with further increase in BZT content, the P- E response was characterized by slim loops. [ABSTRACT FROM AUTHOR]

The 0.72 Bi( Fe1− x Al x) O3-0.28 BaTiO3 ( x = 0, 0.01, 0.03, 0.05, and 0.07, abbreviated as BFA x- BT) lead-free high-temperature ceramics were prepared by the conventional ceramic processing. Systematic investigation on the microstructures, crystalline structures, dielectric and piezoelectric properties, and high-temperature stability of piezoelectric properties was carried out. The crystalline structures of BFA x- BT ceramics evolve from rhombohedral structure with x < 0.01 to the coexistence of rhombohedral structure and pseudocubic phases with x ≈ 0.01, finally to pseudocubic phases when x > 0.03. Remarkably high-temperature stability with near-zero temperature coefficient of piezoelectric properties ( TCkp), together with improved piezoelectric properties has been achieved for x = 0.01 BFA x- BT ceramics. The BFA x- BT( x = 0.01) ceramics simultaneously show the excellent piezoelectric properties of d33 = 151 pC/N, kp = 0.31 and super-high-temperature stability of Td = 420°C, TCkp = 1 × 10−4. It is considered that the observed strong piezoelectricity and remarkably high-temperature stability should be ascribed to the phase coexistence of rhombohedral and pseudocubic phases. The rhombohedral phases have a positive TCkp value and the pseudocubic phases possess a negative TCkp value. Thus, the TCkp value of BFA x- BT ceramics can be tuned by composition of x. [ABSTRACT FROM AUTHOR]

Nb-doped 0.9 BaTiO3-0.1 Bi0.5 Na0.5 TiO3 (0.9 BT-0.1 BNT) ceramics were prepared by conventional solid-state method. The dielectric and the structural properties were investigated. It was found that the temperature-capacitance characteristics greatly depended on Nb2 O5 content. With the addition of 2.0 mol% Nb2 O5, 0.9 BT-0.1 BNT ceramic sample could satisfy the EIA X9R specification. This material was promising for high-temperature MLCC application. Microstructure element distribution was studied using TEM and EDS. The Bi and Na were almost homogeneously distributed except grain-boundary segregation of Bi. The Nb exhibited a nonuniform distribution from the grain boundary to the interior, showing the simultaneous presence of Nb-rich and Nb-poor regions. Such microheterogeneity gave rise to the temperature stability of permittivity. The solution-precipitation mechanism was introduced to elucidate the evolution of microstructures. Degradation and recovery of insulation resistance were observed under a dc bias at 200°C, which was attributed to the electromigration and diffusion of Na+. [ABSTRACT FROM AUTHOR]

This article presents surface electric potential distributions, measured by Kelvin Probe Force Microscopy, on the (001) surface in an indentation-pre-cracked BaTiO3 single crystal with and without applied electric field. The results show that cracks are higher potential regions in comparison to other regions. The higher surface potential is induced by the crack itself in air at room temperature and an applied in-plane electric field cannot change the major feature of the potential distribution across the crack. [ABSTRACT FROM AUTHOR]

Electro-optic LiNbO3 thin films were deposited on Si(100) and Si(111) substrates using a radio-frequency magnetron sputtering process. The piezoelectric properties of the LiNbO3 films were investigated using the scanning probe microscopy in the piezoresponse mode. The obtained results show the high degree of grains orientation in polycrystalline structure. The piezoelectric modulus (dzz) was estimated to be 16 pm/V (for LiNbO3 / Si(100)) and 22 pm/V (for LiNbO3 / Si(111)) and the polarization about of 0.37 C∙m-2. These values are larger than those reported previously for LiNbO3 films. [ABSTRACT FROM AUTHOR]

Ceramics of composition (1− x)BaTiO3- xBi(Zn1/2Ti1/2)O3 ( BT- BZT) were prepared by solid-state synthesis; they have been shown to exhibit excellent properties suited for high-temperature dielectric applications. The X-ray diffraction data showed a single-phase perovskite structure for all the compositions prepared ( x ≤ 0.1 BZT). The compositions with less than 0.075 BZT exhibited tetragonal symmetry at room temperature and pseudo-cubic symmetry above it. Most notably, a significant improvement in insulation properties was measured with the addition of BZT. Both low-field AC impedance and high-field direct DC measurements indicated an increase in resistivity of at least two orders of magnitude at 400°C with the addition of just 0.03 BZT (~107 Ω-cm) into the solid solution as compared to pure BT (~105 Ω-cm). This effect was also evident in dielectric loss data, which remained low at higher temperatures as the BZT content increased. In conjunction with band gap measurements, it was also concluded that the conduction mechanism transitioned from extrinsic for pure BT to intrinsic for 0.075 BZT suggesting a change in the fundamental defect equilibrium conditions. It was also shown that this improvement in insulation properties was not limited to BT- BZT, but could also be observed in the paraelectric SrTiO3-BZT system. [ABSTRACT FROM AUTHOR]

Polarized states of polymer/inorganic inclusion P(VDF-TrFE)-(Pb,Ba)(Zr,Ti)O 3 composites are studied at the nanoscale using both piezoresponse force microscopy (PFM) and Kelvin probe force microscopy (KPFM). It has been shown that inorganic inclusions can be visualized using KPFM due to a discontinuity of the surface potential and polarization at the interface between the inclusions and the polymer matrix. The temperature evolution of the PFM and KPFM signal profiles is investigated. Softening of the polymer matrix on approaching the Curie temperature limits application of the contact PFM method. However non-contact KPFM can be used to probe evolution of the polarization at the phase transition. Mechanisms of the KPFM contrast formation are discussed.