H.R. Zeng

Abnormal piezoresponse behavior of Pb(Mg1/3Nb2/3)O3–30%PbTiO3 single crystal studied by high-vacuum scanning force microscope

The piezoresponse behavior dependence of the Pb(Mg1/3Nb2/3)O3-30%PbTiO3 single crystal on the vacuum degree has been investigated by scanning force microscopy in the piezoresponse mode under high vacuum. Unusual piezo-response behavior related to the screening charges compensation mechanism is observed on the (111) crystal face. The significant piezoresponse degradation behavior with low piezoresponse signal under high vacuum is attributed to the instability of the polarization state due to the insufficient compensation of the intrinsic screening charges for the polarization charges in PMN-30%PT single crystal. In contrast, the remarkable domain contrast of the sample at ambient pressure is owing to the dominant surface screening charges deriving from surface adsorption, which plays an important role in determining the stability of the domain behavior and in achieving the optimal properties.

Ferroelectric and anisotropic electrical properties of BaMgF4 single crystal for vacuum UV devices

Ferroelectric and anisotropic electrical behaviors of barium magnesium fluoride (BaMgF4) single crystal grown under CF4 atmosphere by the Czochralski method are comprehensively studied by polarization hysteresis and impedance spectroscopy measurements, respectively. The coercive field (Ec) varies not only with applied frequency but also with ramp rates, while spontaneous polarization Ps∼6.9 C/cm2 remains the same. Dielectric polarization and ionic conductivity measurements at various temperatures and frequencies reveal quasi-one-dimensional ionic conduction phenomena along the c-axis and non-Debye dielectric relaxation along the axes.

Effect of La content on characterization of PLZT ceramics

Abstract This work has been undertaken with a view to study the effect of lanthanum content on properties of PLZT ceramics. The polycrystalline complex compounds of PLZT with Pb1−xLax(Zr0.40Ti0.60)1−x/4O3, +10% PbO formula were prepared from the nano-size individual oxides powders by hot-pressed process. Transparent PLZT (x/40/60) bulk ceramics with pure tetragonal phase was obtained. The studies of the microstructures, dielectric and ferroelectric properties of the ceramics were carried out. The experiment results showed that when La content increased from 7 to 13 mol.%, the grain size increased from 2 to 7 μm. La content also effects the dielectric property obviously, the dielectric constant increased with La content increasing. Moreover, the ferroelectric properties are sensitive to the variation of La content.

The influence of PbZrO3/PbTiO3 ratio on diffuse phase transition of Pb(Zn1/3Nb2/3)O3-PbZrO3-PbTiO3 system near the morphotropic phase boundary

The diffuse phase transition of Pb(Zn1/3Nb2/3)O3–PbZrO3–PbTiO3 (PZN–PZ–PT) ternary solid solution near the rhombohedral/tetragonal morphotropic phase boundary (MPB) is reported in this paper for the first time. All compositions near MPB exhibit a relaxor behavior around dielectric permittivity peak. It is found that the extent of diffuse phase transition of PZN–PZ–PT increases with the increases of PbZrO3/PbTiO3 ratio.

Influence of stress on the magnetic domain structure in Fe81Ga19 alloys

Grains, grain boundaries, magnetic domain distributions, and their correlations in Fe81Ga19 alloys as-cast, annealed, and under compressive and grinding stresses were investigated using scanning electron acoustic microscopy (SEAM) and magnetic force microscopy (MFM). For as-cast and annealed samples, the main domain structure obtained using SEAM is not clear. For samples under stresses, the main domains are obvious and regular. For the sample under compressive stress, its stripe domains array orderly and perpendicularly to the stress direction. The subdomains of as-cast sample observed using MFM show a clear dendritic structure. However, for the sample under compressive stress, the subdomains are irregular. These results may be helpful to understand the magnetostrictive behavior of Fe–Ga alloys under stress.

Local characterization of compositionally graded Pb(Zr,Ti)O3 thin films by scanning force microscope

Abstract Compositionally graded PZT thin film was prepared by a sol–gel technique. Nanoscale domain structure and polarization reversal behavior in an individual grain were investigated by means of scanning force microscopy (SFM) in piezoresponse mode. Domain as small as 30 nm in size was visualized. The observed complex domain contrast was attributed to the crystallographic orientation of the grains and to the built-in potential difference in compositionally graded PZT thin film under an ac field. The built-in potential difference, defect and space charge gave rise to strong domain pinning behavior during the polarization reversal.

Near-field acoustic and piezoresponse microscopy of domain structures in ferroelectric material

Three kinds of near-field microscopy imaging mode including SEAM (Scanning electron acoustic microscopy), PFM (Piezoresponse force microscopy) and SPAM (Scanning probe acoustic microscopy) have been developed to investigate domain structures of ferroelectric ceramics, crystals and thin films in our studies. The domain imaging mechanisms are presented individually in three imaging modes. Sub-surface micro-domain configuration of ferroelectric BaTiO3 ceramics and single crystal and their dynamic behavior under external fields were clearly visualized by SEAM. Ferroelectric domain structures of ferroelectric PZT thin film and PMN-PT single crystal were characterized by PFM. Nanoscale switching behavior and local field-induced nanoscale displacement behavior of domain structures in ferroelectric thin film were studied by PFM. Antiparallel domain patterns in ferroelectric transparent PLZT ceramics were also characterized by SPAM. The combination of SEAM, PFM and SPAM in application to imaging domain structures undoubtedly enrich our understanding of the nature of piezoelectricity and ferroelectricity at submicro-, even nano-meter scale

Piezoelectric Force Microscope Investigation and Ferroelectric Hysteresis Behavior of High Volume Piezoelectric Ceramic in 0–3 Lead Zirconate Titanate-Cement Composites

Piezoelectric lead zirconate titanate (PZT) ceramic-cement composites using a high volume of ceramic content (80%) in 0–3 connectivity were fabricated. Piezoelectric Force Microscope (PFM) characterization was carried out and ferroelectric hysteresis behavior of the composites were investigated. Domain configurations of PZT ceramic can be seen at the interfacial zone of PZT-cement composites. Ceramic particles were seen to bind well with the cement matrix. The ferroelectric hysteresis loop at 50 Hz and 10–25 kV/cm showed a slim loop with low loss behavior for this type of composite due to increase in the PZT ceramic in 0-3 PZT-cement composites.

Near-field acoustic microscopy of ferroelectrics and related materials

Ferroelectric ceramics and crystals, semiconductor on insulator material and MEMS device have been observed in scanning electron acoustic microscope. The images demonstrate the ability of the microscope to image surface texture, subsurface defect, domain structure and to penetrate opaque layers non-destructively. Ferroelectric domains viewed by scanning probe acoustic microscope based on atomic force microscope are also presented in order to compare both near-field acoustic techniques.

Contrast mechanism of magnetic domains in electron acoustic imaging

Contrast origin of magnetic domain structure imaged by scanning electron acoustic microscopy (SEAM) is studied by analyzing qualitatively the interaction between an incident electron beam and a sample. Some parameters related to the acoustic signal detected by a piezoelectric transducer are obtained through solving a vibration equation. Contrasted with magnetic domain structures of Terfenol-D and Fe81Ga19 alloys obtained by SEAM in linear and nonlinear (second harmonic) modes, imaging mechanism of magnetic domains is attributed to piezomagnetic coupling mechanism, magnetostrictive coupling mechanism, and thermal-wave coupling mechanism.