Ferroelectric Lead Zirconate Titanate Research Articles

In situ investigation of thermally influenced phase transformations in (pb0.92sr0.08) (zr0.65ti0.35)o3 thin films using micro-raman spectroscopy and x-ray diffraction

Thin films of ferroelectric strontium-doped lead zirconate titanate [PSZT, (Pb(0.92)Sr(0.08))(Zr(0.65)Ti(0.35))O(3)] deposited by RF magnetron sputtering have been analyzed by in situ analysis techniques. The in situ techniques employed for this study include micro-Raman spectroscopy and X-ray diffraction (XRD), and variations in thin film structure and orientations for temperatures up to 350 degrees C and 750 degrees C for the respective techniques have been studied. The samples analyzed were PSZT thin films deposited on platinum-coated silicon substrates at either room temperature or at 750 degrees C. In situ measurements using micro-Raman spectroscopy and XRD techniques have been used to identify the Curie point for poly-crystalline PSZT thin films and to determine the temperature-activating significant grain growth for room-temperature-deposited PSZT thin films. To study the presence of hysteresis, analysis was carried out during both temperature ramp-up and ramp-down cycles. Raman measurements showed expected bands (albeit weak), and the in situ measurements have detected variations in the crystal structure of the thin film samples, with negligible variations between the heating and cooling cycles. A combination of the Raman and XRD results has shown that the temperature-activating significant grain growth for the room-temperature-deposited films is about 275 degrees C and the Curie point lies between 325 and 400 degrees C. This relatively high Curie point makes these films suitable for wide temperature range applications.

Nanodomain faceting in ferroelectrics

We show that after long times (24 h), individual circular domains in 50 nm thick[001] epitaxial films of ferroelectric lead zirconate titanate (PZT) developfacets due to the crystalline anisotropy, e.g. along [100] directions. This appearsto be a creep process (Tybell et al 2002 Phys. Rev. Lett. 89 097601; Paruchet al 2006 J. Appl. Phys. 100 051608) and was first seen in a nanoarray of180° domains (Ganpule et al 2002 Phys. Rev. B 65 014101). The effect is independent of polarityand thus rules out any electronic dependence on different work functions for top andbottom electrodes. The phenomenon is interpreted instead as a mechanical relaxation dueto highly inhomogeneous stress distributions on the nanodisks, assumed to have stress-freeedges.

Crystallographic mapping of ferroelectric thin films using piezoresponse force microscopy and electron backscatter diffraction

Ferroelectric lead zirconate titanate (PZT) thin films have been analysed using electron backscatter diffraction (EBSD). Grain orientation mapping has been demonstrated, showing that features smaller than 100 nm may be successfully indexed. In conjunction with piezoresponse force microscopy (PFM), which was used to map and quantify the piezoelectric response from the same region of the films with a resolution of 10 nm, an analysis of the effects of grain orientation on the measured response at the nanoscale was possible. The microtexture of the film showed the presence of both mono- and multi-domains within grains exhibiting sizes of hundreds of nanometres.

Low-temperature growth of ferroelectric lead zirconate titanate thin films using the magnetic field of low power 2.45GHz microwave irradiation

Pb(ZrxTi1−x)O3 (PZT) thin films were coated on Pt∕Ti∕SiO2∕Si substrates by the sol-gel method and then crystallized by using the magnetic field of 2.45GHz microwave irradiation. The elevated temperature generated by microwave irradiation used to obtain the perovskite phase was only 450°C, which is significantly lower than that of conventional thermal processing. The PZT films crystallized by microwave irradiation showed similar ferroelectric properties to those of the films crystallized by conventional thermal processing at 600°C. It is clear that single-mode 2.45GHz microwave irradiation in the microwave magnetic field is effective for obtaining perovskite PZT thin films at low temperatures.

Optical properties of Pb(Zr,Ti)O3 films prepared by aerosol deposition

The optical properties and related band structure of ferroelectric lead zirconate titanate [PZT, Pb(Zr0(0.6)Ti0(0.4))O(3)] films prepared on glass substrates at room temperature by aerosol deposition were investigated. The reflectance and transmittance of the PZT films were measured in the wavelength range from UV to nearinfrared. The measured optical spectra were analyzed using dielectric function models that describe optical transitions in the band gap region. Optical absorption of the as-deposited PZT films was found to be larger than that of the annealed PZT films in the near-infrared wavelength range. The analyzed results indicated that post-deposition annealing increased the band gap energy of the PZT films, corresponding to a decrease in optical absorption.

Importance Of Solution Chemistry In Preparing Sol–Gel PZT Thin Films Directly On Copper Surfaces

The ferroelectric material lead zirconate titanate (PZT) has traditionally been considered incompatible with base metal technology because PbO volatility makes conventional thermodynamic equilibriu...

Dielectric and Pyroelectric Properties of Compositionally Graded Pb(Zr1-xTix)O3 Thin Films Prepared by Sol-gel Process

Compositionally graded ferroelectric lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) thin films were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process. The final structure consists of six layers, up-graded graded films starting from PbZrO3 on the Pt electrode to the top PZT(50) layer, it consists of no Ti, 10%Ti, 20%Ti, 30%Ti, 40%Ti, and 50%Ti respectively. Whereas films with opposite gradient are called down-graded graded films. Structure and dielectric properties of the graded films was investigated by X-ray diffraction, Auger electron spectroscopy and by impedance analysis. The up-graded and down-graded PZT films annealed at 600C, exhibited the remanent polarization values of 18.0 and 24.2 C/cm2, respectively. The typical small signal dielectric constants and loss tan at a frequency of 100 Hz were 523 and 0.018, 544, and 0.020, respectively, for up-graded and down-graded PZT thin films. The temperature dependence of pyroelectric coefficients of the graded PZT films was measured by a dynamic technique. From 20C to 82C, the pyroelectric coefficients of the up-graded and down-graded PZT films up to 374 and 407 C/m2K, respectively.

Grain size effect on the switching current in soft ferroelectric lead zirconate titanate

Recently, we reported on the appearance of a double peak in the switching current during the reverse poling. In the present paper, the switching current measurements have been carried out on a soft lead zirconate titanate as a function of grain size. While in small grains only a small single switching peak is observed, large grains, however, showed double peak switching, as commonly observed in this material. The pyroelectric coefficient curves show a consistent trend with the switching curves. This behavior is attributed to non-180° domain switching during the reversed poling case as a result of residual stresses developed during forward poling.

In situsynchrotron diffraction investigation of morphotropicPb[Zr1−xTix]O3under an applied electric field

For understanding the reaction of the domain structure and crystallographic structure of ferroelectric lead zirconate titanate, $\mathrm{Pb}[{\mathrm{Zr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}]{\mathrm{O}}_{3}$, to an applied electric field and its high piezoelectric properties for compositions in the vicinity of the morphotropic phase boundary (MPB), investigations of structural changes under in situ conditions are of great importance. As we have shown in recent studies [L. A. Schmitt et al., J. Appl. Phys. 101, 074107 (2007); K. A. Sch\"onau et al., Phys. Rev. B 75, 184117 (2007)] the domain structure miniaturizes at the MPB. This nanodomain structure and its stability field are crucial for the character of the poling behavior of the material. In situ electric field synchrotron powder diffraction studies across the entire compositional range of the MPB show changes in phase fractions, domain structure, and phase transitions under electric field dependent on the nanodomain content. For a certain range of tetragonal $c∕a\ensuremath{-}$ratio the nanodomains are stabilized, straining tetragonal microdomains under electric field, while with further decreasing $c∕a\ensuremath{-}$ratio at higher Zr contents they are transformed into a structure associable with rhombohedral microdomains.

Double-peak switching current in soft ferroelectric lead zirconate titanate

Switching current measurements have been carried out on a soft lead zirconate titanate (PXE52, donor doped, modified proprietary composition with the overall formula PbZr0.415Ti0.585O3). The experiments showed a single switching current peak during the application of electric field to a nonpoled (virgin) sample. However, an unusual double peak for the switching current was observed upon reversing the electric field polarity. The pyrocurrent for a forward and reverse poled sample showed a related behavior. A single pyropeak is observed in the forward poled case and broadened peak was observed in case of a reverse poled sample. This behavior is attributed to non-180° domain switching during the reverse poled case as a result of residual stresses developed during the forward poling.

Optical Characterisation of a Three Layer Waveguide Structure by m-Lines Spectroscopy

A three layer planar waveguide structure, consisting of a light guiding ferroelectric lead zirconate titanate thin film, embedded between two transparent zinc oxide electrodes, was elaborated and studied by m-lines spectroscopy. The three layer modal dispersion equations are established and we demonstrate experimentally the ability to retrieve the refraction index and the thickness of each individual layer of the composite waveguide from one single m-lines spectroscopy measurement.

A Comparative Study of the Structure and Properties of Sn‐Modified Lead Zirconate Titanate Ferroelectric and Antiferroelectric Ceramics

Comparative studies of the structure and property of a ferroelectric Pb0.99Nb0.02[(Zr0.57Sn0.43)0.88Ti0.12]0.98O3 and an antiferroelectric Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3 ceramic were conducted. In addition to their different crystal structures, domain morphologies, Raman modes, and dielectric/ferroelectric properties, distinct fracture behaviors under Vickers indentation are also clearly seen. We propose that the antiferroelectric‐to‐ferroelectric phase transformation may have been triggered during the fracture process. Supporting evidence for localized phase transformation was provided by an in situ Raman spectroscopic experiment.

Hydrogen‐Induced Semiconductor Transformation of Lead Zirconate Titanate Ferroelectric Ceramics

Semiconductor transformation of lead zirconate titanate (PZT)‐5H ferroelectric ceramics induced by hydrogen has been investigated. The results showed that hydrogen caused the PZT‐5H ferroelectric ceramics to transform from a yellow insulator into a black n‐type semiconductor, and the leakage current and carrier concentration increased but the resistivity decreased with increasing hydrogen concentration. During charging in H2 at a temperature higher than the Curie point, hydrogen would restrain the PZT‐5H ferroelectric ceramics to transform from cubic into tetragonal phase, resulting in the disappearance of ferroelectricity at room temperature. Charging at a temperature below the Curie point, however, did not change the crystal structure of the tetragonal ferroelectric ceramics. The properties and color of PZT‐5H ferroelectric ceramics were restored after outgassing at a high temperature.

Development of perovskite and phase transition in lead cobalt niobate modified lead zirconate titanate system

Abstract Ferroelectric lead zirconate titanate–lead cobalt niobate ceramics with the formula (1 − x )Pb(Zr 1/2 Ti 1/2 )O 3 – x Pb(Co 1/3 Nb 2/3 )O 3 where x = 0.0–0.5 were fabricated using a high temperature solid-state reaction method. The formation process, the structure and homogeneity of the obtained powders have been investigated by X-ray diffraction method as well as the simultaneous thermal analysis of both differential thermal analysis (DTA) and thermogravimetry analysis (TGA). It was observed that for the binary system (1 − x )Pb(Zr 1/2 Ti 1/2 )O 3 – x Pb(Co 1/3 Nb 2/3 )O 3 , the change in the calcination temperature is approximately linear with respect to the PCoN content in the range x = 0.0–0.5. In addition, X-ray diffraction indicated a phase transformation from a tetragonal to a pseudo-cubic phase when the fraction of PCoN was increased. The dielectric permittivity is remarkably increased by increasing PCoN concentration. The maximum value of remnant polarization P r (25.3 μC/cm 2 ) was obtained for the 0.5PZT–0.5PCoN ceramic.

High transition temperature lead magnesium niobate–lead zirconate titanate single crystals

Recently developed relaxor lead magnesium niobate–ferroelectric lead zirconate titanate single crystals exhibit large length extensional k33 coupling, improved thermal stability, and a higher coercive field compared to morphotropic lead magnesium niobate–lead titanate single crystals. Experimental results and implications for sound projectors are presented and discussed in terms of the morphotropic phase boundary slope and width. Spontaneous polarizations derived from the calculated atom shifts in both crystals compared favorably with experimental values.

Fabrication of PZT Tubular Structures by a Template-wetting Process

Nanotubes and microtubes of ferroelectric lead zirconate titanate (PZT) were synthesized by means of a simple and convenient process called a template-wetting process. Nanoporous alumina and macroporous Si were used as template materials to fabricate the corresponding tubes. For the improvement of the wetting properties of the wetting solution, the PZT solution was mixed with a polymer. The polymer was removed completely during annealing. The grain growth processes of the PZT nanotubes during baking and furnace annealing were examined by means of field emission electron microscope (FE-SEM) and X-ray diffractometry (XRD).

Dielectric Properties of Sol Infiltrated Lead Zirconate Titanate Ferroelectric Thick Films

Ferroelectric PZT(70/30) thick films were fabricated by the hybrid technique adding the sol coating process to the screen-printing process to obtain a good densification. Structural and electrical properties of the thick films with the sol concentration were investigated. The relative dielectric constant increased and dielectric loss decreased with increasing the sol concentration, the values of the thick film coated with sol concentration of 1.5 M were 698 and 2.5 % at 1 kHz, respectively. And the remanent polarization and dielectric breakdown strength of the thick film coated with sol concentration of 1.5 M were about 38 μC/cm2 and 200 kV/cm, respectively. The leakage current densities were less than 10-8 A/cm2 at the applied electric field range of 0-100 kV/cm in all thick films.

‘Time-resolved and orientation-dependent electric-field-induced strains in lead zirconate titanate ceramics

Electric-field-induced lattice strains in a tetragonal ferroelectric lead zirconate titanate bulk ceramic are characterized under application of subcoercive cyclic electric fields using neutron diffraction and a stroboscopic data collection technique. At a driving electric field equal to half of the coercive field, the field-induced lattice strains are found to be a function of orientation with the greatest electric-field-induced strain coefficient of 680pm∕V in crystal orientations such that the 211 pole is parallel to the electric field. A time dependence of the 111 strain was also observed. Suggestions as to the nature of these dependences are discussed.

Stress dependence of the polarized Raman spectrum of polycrystalline lead zirconate titanate

The stress dependence of the Raman spectrum of a relaxor-based polycrystalline ferroelectric lead zirconate titanate–lead nickel niobate–lead zinc niobate (PZT–PNN–PZN) has been investigated using polarized Raman microprobe spectroscopy. Emphasis has been placed on explicitly working out the second harmonic equations that relate Raman intensities to the angle between the laser polarization direction and selected crystalline axes. Based on these assessments, the effect under polarized light of crystal orientation on the intensity of selected Raman modes has been rationalized and the obtained experimental data interpreted. Raman spectra were collected with both parallel and cross polarization filters and their dependence on stress calibrated with loading the PZT–PNN–PZN samples in a four-point flexural jig. The use of polarized light allowed us to clarify the effect of domain orientation on the Raman spectrum of PZT–PNN–PZN and to perform precise calibrations of the stress dependence of the A1(TO4) Raman mode, independent of domain orientation in both poled and unpoled PZT–PNN–PZN samples. This study demonstrates the feasibility of microscopic stress (in addition to local domain orientation) evaluations in PZT materials using a polarized Raman microprobe.

Direct patterning of complex oxides by pulsed laser deposition through stencils

The possibilities to grow isolated structures of complex oxides by pulsed laser deposition through stencils were investigated. A stencil consisting of a SiN membrane with apertures of several hundred nanometers embedded in a Si chip is placed in front of a heated substrate (up to 750 degrees Celsius). Deposition through these apertures results in resistless, direct patterning by local deposition of complex oxides like ferroelectric Lead Zirconate Titanate. The created isolated structures were analyzed by AFM imaging. Under-deposition, in this work called broadening, is inevitable during stencil deposition and is depending on deposition parameters, especially pressure. Different causes of broadening are mapped and discussed.