Domain and lattice contributions to dielectric and piezoelectric properties of Pb(Zrx, Ti1−x)O3 thin films as a function of composition

In situ reactively sputter deposited, 300-nm-thick Pb(Zrx, Ti1−x)O3 thin films were investigated as a function of composition, texture, and different electrodes (Pt,RuO2).X-ray diffraction analysis, ferroelectric, dielectric, and piezoelectric measurements were carried out. While for dielectric properties bulklike contributions from lattice as well as from domains are observed, domain wall contributions to piezoelectric properties are very much reduced in the morphotropic phase boundary (MPB) region. Permittivity and d33 do not peak at the same composition; the MPB region is broadened up and generally shifted to the tetragonal sid

Excess lead in the perovskite lattice of PZT thin films made by in-situ reactive sputtering

The incorporation of up to 40 % lead excess into the perovskite lattice of Pb(Zr,Ti)O-3 (PZT) has been investigated. Three independent chemical composition analysis methods confirmed the correct determination of the lead excess, present as Pb2O3. High resolution TEM excludes any second phases and restricts the occurrence of lead excess to the perovskite lattice, suggesting a lead oxide perovskite of the form Pb2+Pb4+O3 with a 4-valent ion on the B-site. PZT containing such lead excess is thus a solid solution of PbZrO3, PbTiO3 and PbPbO3. The measured volume increase of the lattice due to a larger average B-ion matches very well with the calculated behavior based on standard ion radii and the B-ion radius dependence of the unit cell dimensions of PZT crystals. Structure factors as determined from Synchrotron X-ray diffraction are much better compatible with the B-site lead model than with the standard PZT ion lattice

Texture control of PbTiO3 and Pb(Zr,Ti)O-3 thin films with TiO2 seeding

The nature and the role of 1 to 5 nm thick TiO2 seed layers for the growth of textured PbTiO3 and Pb(Zr, Ti)O-3 thin films on textured Pt(111) thin film substrates have been studied. Under otherwise identical in situ sputter deposition process conditions, the PbTiO3 texture could be turned from (100) to (111) orientation by adding the seed layer. This is demonstrated by patterning the TiO2 film. Auger electron spectroscopy and x-ray photoemission spectroscopy showed that the seed layer was a continuous TiO2 film. X-ray photoelectron diffraction measurements revealed epitaxial ordering in the seed layer. As there is no azimutal order among the Pt grains, the reduced information of azimutally averaged polar cuts is obtained. These give strong evidence for a strained rutile (110) structure. Various deposition experiments indicated that the TiO2 is effective only when it is ordered before the PbTiO3 nucleation starts. The epitaxial relationship between PbTiO3(111) and Pt(111) is thus mediated by the intermediate, epitaxial TiO2 film, which is dissolved of transformed to PbTiO3 afterwards. The observed growth behavior is discussed in terms of surface and interface energies. (C) 1998 American Institute of Physics. [S0021-8979(98)03607-X]

Mixed titania-lead oxide seed layers for PZT growth on Pt(111): a study on nucleation, texture and properties

Growth and properties of sputter in situ sputter deposited Pb(Z,Ti)O-3 (PZT) thin films have been studied on (111)-textured Pt electrodes as a function of seed layers of the type (TiO2)(x)(PbO)(y). The PZT process was run with a limited lead excess resulting in pyrochlore nucleation on bare Pt electrodes. When the electrode was covered with a dense seed layer, perovskite was obtained everywhere. Ti rich seed layers yielded (111)-textured PZT even for very thin seed layers. Pb rich seed layers nucleated as PbTiO3{100} and gave rise to (100)-textured PZT. In an intermediate zone, the major perovskite orientations (100), (110) and (111) have been found together With pyrochlore for a small seed layer thickness. In this zone, the seed layer nucleates in islands leaving bare Pt spots. The intermediate region is a transition region between (111) seeds and (100) seeds. The latter exhibit diverging critical sizes at a given critical flux ratio, leading to large nuclei and bare Pt. (C) 2003 Elsevier Ltd. All rights reserved

Piezoelectric and dielectric properties of sputter deposited (111), (100) and random-textured Pb(ZrxTi1-x)O-3 (PZT) thin films

Highly textured PZT(111), PZT(001/100) and random PZT films have been grown on Pt and RuO2 bottom electrodes by means of an in-situ, multimagnetron reactive sputtering process with three metal targets (Pb, Zr, Ti). The orientation was varied with the bottom electrode/PZT initial interlayer deposition conditions. Series of 300 nm thick films with varying composition x have been prepared. The Ti and Zr ratio was changed by adjusting the powers of the corresponding targets. The lead content was self stabilized by the process at the deposition temperature of 570 degrees C. Polarization, dielectric and piezoelectric properties were studied. Coercive field, built-in electric field and unswitchable polarization for Ti-rich compositions have been determined by polarisation hysteresis loops

Origin of voltage offset and built-in polarization in in-situ sputter deposited PZT thin films

Voltage offset and built-in polarization were investigated in in-situ reactively sputter deposited PZT thin films on Pt, as a function of composition, doping and cooling conditions. The voltage offset increases with increasing Ti content. Hot-poling treatments show that the voltage offset originates from non-mobile defects. Cooling the samples at various 02 partial pressures leads to a change in lattice parameters and orientation, showing a 'bulk' effect rather than a simple 'surface' effect. While doping with Nb does not change the status of the films, doping with Fe increases coercive fields but removes the asymmetrical behavior of the voltage offset after hot-poling at positive and negative voltages. Annealing/cooling cycles are reversible in the suppression/creation of voltage offset and built-in polarization, respectively, excluding the idea of oxygen and lead vacancy dipolar defects. Experimental data suggest that oxygen is lost and the vacancies diffuse during cooling without being compensated to equilibrate with surface or electrode band bending, resulting in the creation of an internal bias field

Preparation of La1-xSrxCoO3 electrodes for ferroelectric thin films by RF magnetron sputtering

(100)-oriented stoichiometric LSCO films were deposited on Pt/TiO2/SiO2/Si, TiO2/Pt/TiO2/SiO2/Si and Si substrates with rf magnetron sputtering using a single self fabricated oxide target. Best conductive LSCO film was obtained at 600 degrees C, yielding a specific resistivity of 90 mu Ohm cm. The PZT film deposited on the LSCO(100) electrode oriented to (100) or (001). Maximum value of d(33) coefficientwas 73.5 pm/V

Effective transverse piezoelectric coefficient e(31,f) of (100)/(001) textured PZT thin films

Effective transverse piezoelectric coefficient e(31,f) has been measured on (100)/(001) sol-gel Pb(ZrXTi1-X) thin films with compositions between 30% and 45% Zr. A maximum value of 8.07 +/- 0.36 C/m(2) at 40% Zr is found. The influence of the poling field ranging from 50 kV/cm to 250 kV/cm has been evaluated

Which PZT thin films for piezoelectric microactuator applications?

The effective piezoelectric coefficient e(31) has been measured on sol-gel processed Pb(ZrxTi1-x)O-3 thin films with Zr concentrations ranging from 45 to 60%. The largest value was observed at 45% Zr, although dielectric constant and effective d(33) peak at 53% Zr. The findings suggest that the optimal composition for microactuators and sensors is less than 45% Zr, i.e., in the tetragonal part of the phase diagram