Solid Solution Pb Research Articles

Optical Second Harmonic Generation Microscopy as a Tool of Material Diagnosis

The second harmonic generation microscope (SHGM) constructs images of intensity distributions of SH waves produced by the interaction of fundamental waves with a polar material. We have developed this nonlinear optical microscope in order to make possible nondestructive, three-dimensional (3D) observations of various kinds of inorganic and organic materials. The SHGM can disclose also inverted domain structures of antiparallel spontaneous polarizations using the interference with the reference SH waves. The observation principle and several applications to structural characterizations of LiNbO3 and LiTaO3 quasi-phase matching devices, domain structure analyses of a relaxor/ferroelectric solid solution Pb(Zn1/3Nb2/3)O3-9%PbTiO3 at the morphotropic phase boundary, development of order parameter in a quantum paraelectric relaxor Li-doped KTaO3, and antiphase polar domain structures of muscle fibers and myofibrils are surveyed by stressing the high effectiveness of the SHGM as a tool of material diagnosis.

The temperature effect on the resonant spectra of thin piezoelectric ceramic disk

This study examines the influence of the temperature on the low-frequency resonant spectrum of piezoelectric ceramics based on lead zirconate titanate solid solution Pb(Zr,Ti)O3-based piezoelectric ceramics with heat variations ranging from 25 to 150°C, concluding that temperature increases cause the resonant spectrum to shift to higher frequencies. Furthermore, the variation in fundamental series resonant frequency fs (with temperature variation) is larger than the variation of fundamental parallel resonant frequency fp (with temperature variation). Another result of increased temperature is the decrease in effective electromechanical coupling factor keff. Finally, the effect of temperature on the overtone mode is more obvious than that of the fundamental mode.

SHG microscopic observation of Pb(Zn1/3Nb2/3)O3–9%PbTiO3 single crystal

Non-destructive and contactless observations of the domain structures in a single crystal of solid solution Pb(Zn1/3Nb2/3)O3–9%PbTiO3 (PZN–9PT) was performed using the scanning second-harmonic generation (SHG) microscopy with the spatial resolution of optical wavelength scale. A novel method of the 2D mapping of SHG polarization dependence (Pol-D) is proposed. The result indicates that the Pol-Ds correspond well to the observed SHG images of domain structures. The directions of ferroelectric spontaneous polarizations are quantitatively analysed by comparing SHG images and the Pol-Ds. It is confirmed that PZN-9PT has the monoclinic symmetry at room temperature.

Electric-field and stress effects on depoling and overpoling phenomena in [001]-poled transverse mode pb(zn1/3nb2/3)o3-(6-7)%pbtio3 single crystal of [110] length cut

Solid-solution Pb(Zn(1/3)Nb(2/3))O(3)-PbTiO(3) (PZN-PT) single crystals, touted as next-generation piezoelectric materials, have been studied extensively in the past decade. This work addresses the advantages and limitations of transducers made of transverse mode PZN-(6-7)%PT single crystals of [110](L) X [001](T)(P) cut. This cut exhibits superior electromechanical properties, with k(31) ≈ 0.85 and d(31) ≈-1450 pC/N, and an extremely high d(31)/S(E)(11) value of >35 C/m(2). It also has relatively high overpoling, i.e., rhombohedralto- tetragonal phase transformation, field of ≈2 kV/mm. This overpoling field further decreases with increase in axial compressive stress. Despite these good attributes, this crystal cut has a low depoling field of ≤ 0.3 kV/mm, a result of low coercive fields of [001]-poled relaxor-based single crystals, which decreases further with increasing axial compressive stress, limiting its bipolar drive capability. The axial compressive stress required to cause overpoling via rhombohedral-to-tetragonal phase transformation of relevant domain variants in the crystal is found to be >90 MPa. In contrast, this crystal cut depolarizes at comparatively low axial tensile stress of ≈15 MPa, the magnitude of which is not significantly affected by the moderate forward field applied.

Structural Ordering and Magnetic Property of Complex Perovskite Solid Solution (1-x)Pb(Fe<SUB>2/3</SUB>W<SUB>1/3</SUB>)O<SUB>3</SUB>-xPb(Mg<SUB>1/2</SUB>W<SUB>1/2</SUB>)O<SUB>3</SUB>

以无机盐为前驱体, 利用溶胶?凝胶法固溶合成了(1- x )Pb(Fe 2/3 W 1/3 )O 3 - x Pb(Mg 1/2 W 1/2 )O 3 多铁性固溶体. XRD分析表明, 在0≤ x ≤1.0的掺杂范围内, 700℃煅烧所得产物都具有钙钛矿结构; x =0时得到的纯Pb(Fe 2/3 W 1/3 )O 3 为长程无序结构, x =1.0时可获得完全有序的纯Pb(Mg 1/2 W 1/2 )O 3 相, 其单胞为Pb(Fe 2/3 W 1/3 )O 3 单胞的2倍; 当0 x x )Pb(Fe 2/3 W 1/3 )O 3 - x Pb(Mg 1/2 W 1/2 )O 3 固溶体也为有序结构, 出现1/2 (111)及1/2 (311) XRD衍射峰, 且强度随掺杂系数x的升高逐渐增大. TEM分析证实, 煅烧产物为具有钙钛矿结构的单相固溶体, 而非两相复合物; 固溶相形貌以立方颗粒为主, 随掺杂量增加其晶胞常数线性增大, 而晶粒尺寸先减小后变大. 性能测试发现, 固溶相的磁学性能随x的增加而逐渐下降, 起因于抗磁性的Pb(Mg 1/2 W 1/2 )O 3 破坏了Pb(Fe 2/3 W 1/3 )O 3 原有的价键结构所致.

Relaxor Ferroelectric Spectroscopy in Zr-doped PMT Binary Systems

The dielectric and the relaxor properties at various frequencies in the solid solution (1 x)Pb(Mg1/3Ta2/3)O3-xPbZrO3 binary system were studied. The mixed oxide was prepared using columbite precursor methods and then sintering at 1200 C for 2 hours. The grain sizes of the sintered specimens were measured and ranged from 1.6 2.2 µm. The composition of 0.55Pb(Mg1/3Ta2/3)O3-0.45PbZrO3 was found to have the maximum dielectric constant and remanent polarization, on the order of 27000 and 175 µC/cm 2 , respectively. The relaxor ferroelectric (1 x)Pb(Mg1/3Ta2/3)O3-xPbZrO3 composition showed a large frequency dependence for the dielectric constant and loss. Also, the remanent polarization decreased gradually with increasing temperature, but did not vanish at the transition temperature.

Freezing of polarization dynamics in relaxor ferroelectric (1− x)Pb(Mg 1/3Nb 2/3)O 3− xBi(Zn 1/2Ti 1/2)O 3 solid solution

Ceramics of a the binary solid solution (1− x)Pb(Mg 1/3Nb 2/3)O 3− xBi(Zn 1/2Ti 1/2)O 3 [(1− x)PMN− xBZT] have been prepared with x = 0.10 and 0.15 and examined by dielectric spectroscopy to reveal the temperature dependences of the relaxor ferroelectric behavior. Both compositions studied show a broad and diffuse peak in the temperature dependence of dielectric permittivity ɛ’( T), the temperature of which increases with increasing measurement frequency, indicating the typical relaxor behavior. Detailed analysis of the dielectric response shows that it involves the same types of polarization contributions as the prototypical relaxor Pb(Mg 1/3Nb 2/3)O 3. One of the contribution to the permittivity arises from the conventional relaxor polarization, χ C R ∗ , which can be described by the Kohlrausch–Williams–Watts (KWW) law, P ∝ exp [ − ( t / τ ) β ] . It is found that the β and τ parameters both follow the Vogel–Fulcher law, with the freezing temperature T f decreasing with increasing BZT content. The change in diffuseness and freezing temperature can be attributed to the increase in chemical disorder because the addition of BZT end member introduces two more heterovalent cations (Zn 2+ and Ti 4+) on the perovskite octahedral B-site and the Bi 3+ cations on the perovskite A-site of PMN.

Synthesis and thermoelectric properties of the PbSe 1− xTe x alloys

The PbSe 1− x Te x alloys with x = 0.2, 0.3, 0.5, 0.85 and 1.0 were prepared by induction melting, ball milling and spark plasma sintering techniques. The thermoelectric properties of the samples were investigated. The XRD analysis indicated that all samples are NaCl-type structure solid solutions Pb(Se,Te) containing nanograins. Increasing Te content resulted in increasing the lattice parameter a. The thermoelectric measurements show that all samples are n-type semiconductors in temperature range from 300 K to 673 K. The electrical resistivity of the doped sample is much smaller than that of pure PbSe, but comparable to that of PbTe. The absolute Seebeck coefficients for the doped sample PbSe 1− x Te x with x = 0.2, 0.3 and 0.5 range from 150 μV/K at 300 K to 250 μV/K at 673 K, which is much larger than that of pure PbSe (66–138 μV/K), but smaller than that of PbTe (230–310 μV/K) in the same experimental conditions. The thermal conductivity for the doped sample PbSe 1− x Te x with x = 0.2, 0.3 and 0.5 range from 0.95 to 0.66 W/m K, which is much smaller than that of pure PbSe (2.1–1.3 W/m K) or PbTe (1.4–1.1 W/m K). As a result, the figure of merit for the doped sample can be enhanced. The maximum dimensionless figure of merit ZT of 1.15 was obtained in the sample PbTe 0.5Se 0.5 at 573 K, more than 50% higher than that of pure PbTe prepared in the same condition.

Synthesis, Characterization, and Crystallographic Study of the PbO−Bi2O3−V2O5 System: Pb3−xBi2x/3V2O8 (0.20 ≤ x ≤ 0.50)

A new solid solution Pb(3-x)Bi(2x/3)V(2)O(8) (0.20 < or = x < or = 0.50), stabilizing the high-temperature gamma form of Pb(3)V(2)O(8), has been isolated in the system Pb(3)V(2)O(8)-BiVO(4). The single-crystal structure of the composition x = 0.50 (Pb(2.5)Bi(1/3)V(2)O(8)) was solved using single-crystal X-ray diffraction (XRD) technique. The compound crystallizes in the trigonal crystal system R3m (No. 166) with a palmierite structural type with a = 5.7463(3) A, c = 20.3047(12) A, V = 580.64(5) A(3), and Z = 3. The final R1 value of 0.0406 was achieved for 217 independent reflections during the structure refinement. The variable-temperature powder XRD shows the absence of any phase transition for all of the members of the solid solution in the limit of 398-80 K. The new solid solution has been characterized by neutron powder diffraction, solid-state UV-vis diffuse-reflectance spectra, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). Alternating-current impedance studies indicate conductivity on the order of 10(-4) Omega(-1) cm(-1) for Pb(2.5)Bi(1/3)V(2)O(8). The change in color of the samples from brown to yellow at high temperature was explained by XPS studies, which indicate the plausible formation of the ppm level of Bi(2)O(3) at such elevated temperature ranges.

Elastic–plastic deformation of Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 single crystals during nanoindentation

The elastic–plastic deformation behavior of (001)- and (011)-oriented single crystal solid solutions of Pb(Zn1/3Nb2/3)O3–(6–7)% PbTiO3 (PZN–PT) have been studied using a nanoindentation technique. A procedure is presented here to isolate the elastic, elastic–plastic and plastic contributions to the deformation using the unloading data, and a parameter, referred to as relaxation, is defined to characterize the elastic–plastic deformation during nanoindentations. This relaxation parameter increases with the maximum indentation load due to the higher indentation stress induced, and it also causes less recovery of the material upon indentation unloading compared to predicted pure elastic recovery. For a (001) surface, the relaxation value remains virtually unchanged within the range of the maximum indentation load of 10–50 mN, possibly due to a complete localized depoling of the non-180° domain switching. It is also found that the unpoled surface is more prone to stress-induced depolarization compared to the poled surfaces. Furthermore, by applying the continuous stiffness measurement (CSM) technique, the effects of multiple loading/unloading are studied for both (001)- and (011)-oriented PZN–PTs using the maximum indentation loads of 20 and 50 mN. With more loading/unloading cycles at higher CSM frequencies, stress-induced depolarization becomes prevalent and the contribution of the domain reorientation towards elastic recovery is significantly reduced. As a consequence, the relaxation value is increased, indicating more elastic–plastic deformation. This CSM effect is especially pronounced for poled (011) surfaces.

Large signal electromechanical properties of low loss (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 single crystals

The use of single crystals based on the solid solution (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMNT) has been demonstrated in many piezoelectric devices, but the low mechanical quality factor has limited its use in high power projector applications. In this work, 33-mode properties of PMNT single crystals with various modifications were evaluated to see if self-heating may be reduced by decreasing the mechanical and electrical losses within the active material. Three modifications were evaluated: incorporating ternary components, adding acceptor dopants, or orienting the crystal along different crystallographic directions. The electromechanical properties of these modified crystals were evaluated under increasing levels of dynamic strain. The results suggest that modified single crystal PMNT may improve the source level from a projector while reducing thermal effects from self-heating, making them appropriate for high power applications.

Verwey-type transition within the Pb 3Rh 7−xMn xO 15 solid solution

A complete solid solution was found between isostructural Pb 3Mn 7O 15 and Pb 3Rh 7O 15. Single-crystals of two members of the solid solution Pb 3Rh 7− x Mn x O 15 ( x=1.07 and 2.26) were grown and their crystal structures were determined. The Verwey-type transition for Pb 3Rh 7O 15 at 185 K remains with a 3% substitution of Mn for Rh but disappears with 4% substitution of Mn for Rh. The magnetic ordering temperature found for Pb 3Mn 7O 15 at about 70 K is maintained at a 43% substitution of Rh for Mn but has disappeared for 57% substitution of Rh for Mn. The unit cell volume of this layered structure contracts with increasing x for Pb 3Rh 7− x Mn x O 15 phases, but the structure actually expands in the direction perpendicular to the layers due to increased separation between the layers.

Study on phase transition of Pb–Bi eutectic alloy by neutron transmission spectroscopy

LBE (Lead Bismuth Eutectic), which is a candidate for spallation targets, has some problems. One of them is expansion after solidification, which may bring about serious damage of an LBE loop. Two solid phases of β-phase (inter-metallic compound) and γ-phase (solid solution of Pb in Bi) appear in LBE, and it was reported that an increase of the γ-phase observed by X-ray corresponds to the volume expansion of LBE. We performed neutron spectroscopic transmission experiments using a pulsed neutron source in order to observe crystal transformation depending on the position and time for slow and rapid cooling LBE samples. It was found that the crystal structure of the slow cooling LBE varied depending on position while it was rather homogeneous for the rapid cooling sample. The re-crystallization of the γ-phase was more clearly observed for the rapid cooling sample than the slow one. We were able to obtain information of re-crystallization over the whole volume of the samples.

Synthesis and properties of solid solutions (1–х–y)Pb(Zn₁/₃Nb₂/₃)O₃—xPbTiO₃—yBaTiO₃

Synthesis and properties of solid solutions (1–х–y)Pb(Zn₁/₃Nb₂/₃)O₃—xPbTiO₃—yBaTiO₃

STRUCTURAL, DIELECTRIC AND TRANSPORT PROPERTIES OF (PbSm)(ZrTi)O3 CERAMICS

The solid solutions of Pb 1-x Sm x( Zr 0.50 Ti 0.50)1-x/4 O 3 (PSZT), x = 0.00, 0.03, 0.06 and 0.09 were prepared by a mixed oxide method at high temperature (sintering temperature 1200°C). Preliminary X-ray structural analysis suggests the formation of single-phase compounds at room temperature in tetragonal crystal system. The microstructural SEM analysis shows that the grains of the materials are almost spherical and also uniformly distributed over the surface. Detailed studies of dielectric properties (ε, tan δ and σ) of the materials in a wide temperature range (30–500°C) at different frequencies (103–106 Hz) reveal that the compounds have transition temperatures well above the room temperature. The analysis of the diffusivity of the dielectric peaks in these compounds provides values between 1 and 2, where the higher values indicate great disorder in the system. The temperature dependence of ac conductivity and the value of activation energy in different regions suggest that the conduction process is of mixed type (i.e. singly ionized in ferroelectric region and doubly ionized in paraelectric phase).

Effect of Sm on structural, dielectric and conductivity properties of PZT ceramics

Solid solutions of Pb 1− x Sm x (Zr 0.55Ti 0.45) 1− x/4 O 3 (PSZT) ( x = 0.00, 0.03, 0.06 and 0.09) were synthesized by mixed oxide method at high temperature. The formations of single-phase compounds were confirmed by X-ray diffraction studies with tetragonal structure at room temperature. Detailed studies of dielectric properties of PSZT materials were made at various temperatures and frequencies which reveal that the compounds have transition temperature well above the room temperature. The diffusivity ( γ) of the dielectric peaks in the compounds exhibited the values between 1 and 2 where the higher value indicated the greater disorder in the system. The temperature dependence of ac conductivity indicated that the conduction process is due to singly ionized (in ferroelectric region) and doubly ionized (in paraelectric region) oxygen vacancies.

Deformation behavior of PZN–6%PT single crystal during nanoindentation

The deformation behavior of [001]T- and [011]T-cut single crystal solid solution of Pb(Zn1/3Nb2/3)O3–6% PbTiO3 (PZN–6%PT) in both unpoled and poled states has been investigated by nanoindentation. Nanoindentation experiments reveal that material pile-up and local damage around the indentation impressions are observed at ultra-low loads. These pile-ups and local damage cause a pop-in event (i.e. a sudden increase in displacement at an approximately constant load) in the nanoindentation load–displacement curve (P–h curve). Detailed studies of the relationships between indentation load (P), displacement (h) and harmonic contact stiffness (S) suggest that there is a surface layer, possibly due to crystal fabrication processes, which possesses different mechanical properties from the interior. The thickness of this surface layer is estimated to be approximately 300 nm. Furthermore, it is found that [011]T-cut crystal is stiffer than [001]T-cut crystal. On the other hand, both [001]T- and [011]T-cut crystals in unpoled state possess lower contact stiffness than poled crystals. This finding suggests that poling improved the mechanical property of the crystal. In summary, poled [001]T-cut crystals have an elastic modulus of (107 ± 6) GPa and a hardness of (5.1 ± 0.4) GPa. In contrast, the modulus for [011]T-cut crystals is not constant but increases with indentation depth.

Effects of Pressure on Piezoelectric and Dielectric Responses of Relaxor Ferroelectric Solid Solution Pb(Mg1/3Nb2/3)O3–PbTiO3 Binary System Ceramics near a Morphotropic Phase Boundary Composition

The piezoelectric and dielectric properties of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMNT) ceramics with compositions near a morphotropic phase boundary (MPB) were investigated under pressures p up to 700 MPa at 25 °C. The resonance and antiresonance frequency characteristics of impedance and phase in the k31 mode for PMNT (67/33) and (69/31) ceramics were observed under various pressures. The effect of pressure on their responses were clearly observed. The electromechanical coupling coefficient k31 in the k31 mode increases and the electromechanical quality factor Q decreases with increasing p at pressures lower than 100 MPa. The decrease in Q with p is due to the scattering of ultrasonic waves from the domain boundary. The relative permittivity εr increases with increasing p. Such increases in both k and εr with p seem to be related to the increase in topographical domain-wall density associated with monoclinic distortions. At pressures higher than 100 MPa, their electromechanical suppression in PMNT ceramics occurs at each pressure, corresponding to the electromechanical coupling coefficient k. εr increases with pressure-induced electromechanical suppression. The change in εr with such suppression corresponds to k. Such a phenomenon seems to be due to the increase in piezoelectric load based on the increase in complex domain wall density coming from the increase in free energy with pressure.

Effects of addition of BT on structural phase formation and electrical properties of relaxor ferroelectric Pb(In 0.5Nb 0.5) (1− x) Ti ( x) O 3 ceramics

In this study, the solid solution of Pb(In 0.5Nb 0.5) (1− x) Ti ( x) O 3 with 20 mol% of BT (where x = 0.0, 0.1, 0.2 and 0.3) ceramics was prepared by the wolframite precursor method via a vibro-milling technique. The concentration of 20 mol% of BT was the lowest amount of BT to help stabilize the perovskite phase formation of PIN ceramics in this study. The variation of x between 0.0 and 0.3 (0.0 ≤ x ≤ 0.3; Δ x = 0.1) was chosen based on the non-MPB composition of this PINT system to focus on the compositions with relaxor behavior. The phase formation of the ceramics was investigated as a function of compositions. The XRD patterns investigation showed that the ceramics gradually changed from the pseudo-cubic to tetragonal phase between the compositions x = 0.2 and 0.3, indicating a shift in the MPB of the PINT system with BT addition. Correspondingly, large dielectric constant maximum ( ɛ m) was observed over the same compositions. The remanent polarization ( P r) was also maximized at this composition, which indicated enhanced electrical properties near the MPB of this PBINT system. These results clearly indicated that the addition of BT had strong influence on phase formation and the electrical properties of the PINT system.

Pressure-modulated free energy change in piezoelectric and dielectric responses for relaxor ferroelectric solid solution Pb(Mg1∕3Nb2∕3)O3–PbTiO3 binary system single crystal and ceramics near a morphotropic phase boundary composition

The electromechanical and dielectric responses in transverse and longitudinal modes for relaxor ferroelectric solid solution Pb(Mg1∕3Nb2∕3)O3–PbTiO3 (PMNT) near a morphotropic phase boundary composition were investigated under hydrostatic pressures up to 700MPa at 25°C. The effect of pressure on their responses remarkably appeared. Their electromechanical suppression in PMNT single crystal and ceramics occurs at each pressure, corresponding to electromechanical coupling coefficient k. The permittivity ε increased with pressure-induced electromechanical suppression. The change in ε with such suppression corresponds to k. Such phenomena were considered to be due to the increase in piezoelectric load based on decrease of domain size coming from increase in free energy with pressures.