Properties Of PbZr0 Research Articles

Comparison between the ferroelectric/electric properties of the PbZr0.52Ti0.48O3 films grown on Si (100) and on STO (100) substrates

Ferroelectric/electric properties of PbZr0.52Ti0.48O3 (PZT) thin films grown by pulsed laser deposition (PLD) on two different substrates, Si (001) and SrTiO3 (STO) (001), were comparatively analyzed. The structural characterization has revealed the epitaxial relationship between the grown layers and the two types of substrates, with larger density of structural defects for the films deposited on Si (001) with buffer STO layer. The ferroelectric/electric properties are also different, with lower remnant polarization (about half of the value obtained on STO substrate), higher dielectric constant (about two times larger), and lower leakage current (about two orders of magnitude lower) for the PZT films deposited on Si (001) compared to those deposited on (001) STO substrates. Nevertheless, the results show that the use of a STO buffer layer on Si can be a solution to obtain good quality PZT capacitor structures without using expensive single-crystal oxide substrates. In this way, applications based on PZT capacitors (e.g. non-volatile memories, pyroelectric detectors, light switches, etc.) would be more easily integrated directly on Si wafers.

Magnetoelectric Response in (1−x)PbZr0.65Ti0.35O3–xBaFe12O19 Multiferroic Ceramic Composites

The magnetoelectric (ME) properties of PbZr0.65Ti0.35O3–BaFe12O19 (PZT–BaM) multiferroic ceramic composites have been investigated in this work. These materials, containing both the ferroelectric PZT and ferrimagnetic BaM phases, were prepared from the conventional solid‐state reaction method, and their main (micro)structural characteristics are provided. The ME measurements were performed over wide frequency and temperature ranges, and the influence of the BaM content was appraised. An enhanced ME coefficient (α) was obtained for the applied magnetic field of 0.8 kOe, at 97 kHz. In addition, the results reveal a high thermal stability of α in the whole analyzed temperature range, showing that the studied PZT‐based ceramic composites have great potential for practical applications.

Ferroelectric Properties of Microwave Processed PZT-NiZn Ferrite Composites

Being materials with a large number of interesting properties, ferroelectric-ferrite based composites have recently been developed. People are showing a great interest in these materials due to some unique properties like magnetoelectric effect in addition to the ferroelectric, dielectric and magnetic properties. After a review of literature it is found that the variation in different properties of PZT ceramics is found to depend on the amount of ferrite content. In this paper, we are reporting the variation in ferroelectric properties of PbZr0.65Ti0.35O3 (PZT) by varying Ni-Zn ferrite (NZF) content. The studied system having compositional formula (1-x) PZT–x NZF (0 ≤ x ≤ 0.025, in steps of 0.005), was prepared by solid state route using microwave sintering. Remanant polarization was found to be monotonically decreasing with increasing ferrite content as observed from the recorded P-E hysteresis loops for all the samples at 20 Hz. Microwave sintering results in significant improvements in properties as compared to conventionally sintered samples.

Improved Ferroelectric Properties of (111)-Oriented PbZr0.52Ti0.48O3 Thin Films on SrRuO3/Pt Hybrid Electrodes

(111) oriented PbZr0.52Ti0.48O3 thin films were epitaxially grown on SrRuO3 and SrRuO3/Pt electrode coated Al2O3(0001) substrates by pulsed-laser deposition, respectively. The X-ray diffraction analysis revealed that PZT films on SrRuO3/Pt electrode had better crystal quality than the films on SrRuO3 electrode. Compared to the SrRuO3 electrode, the SrRuO3/Pt hybrid electrode could significantly improve ferroelectric properties of PbZr0.52Ti0.48O3 films with 1 times larger remnant polarization (2Pr = 40.1 μC/cm2), 0.4 times smaller coercive field (2Ec = 40 kV/cm), better fatigue endurance (8.8% degradation at 1011 switching cycles) and lower leakage current density (10−8 A/cm2 at an applied voltage of 5 V). The reliable ferroelectric properties in PbZr0.52Ti0.48O3 films with SrRuO3/Pt hybrid electrode indicate that the combination of the excellent fatigue behavior using SrRuO3 electrodes with the low leakage currents with Pt electrodes can be suitable for the application of integrated ferroelectric devices.

Evidence for the monoclinic–tetragonal phase coexistence inPb(Zr0.53Ti0.47)O3 thin films

The structure and ferroelectric properties ofPbZr0.53Ti0.47O3 thin films were investigated in detail by using the x-ray diffraction technique. Thesurface morphology of the film was studied by using the atomic force microscopytechnique, showing a film with a dense morphology and a smooth surface. Basedon recent results reported by Pandey et al (2008 Acta Crystallogr. A64 192),Rietveld refinements of the structure were conducted considering different modelsproposed in the literature. Results suggested the monoclinic and tetragonal(M+T) phasecoexistence, with P4mm and Cm space groups, respectively. The monoclinic phase (68 mol%) is dominant over the tetragonalphase (32 mol%) for this PZT film composition.

Effect of poly(vinyl acetate) on structures and properties of PbZr0.52Ti0.48O3 thick films

Pb Zr 0.52 Ti 0.48 O 3 (PZT) thick films are prepared by a polymer-assisted metallo-organic compound decomposition process. The addition of a polymer, poly(vinyl acetate) (PVAc), in PZT precursor solutions promotes the formation of the perovskite phase. Meanwhile, the crack formation is effectively suppressed. The single-layer thickness of PZT films increases from 0.07to0.22μm. It is found that PZT recrystallizes after the PVAc-related organic compounds are decomposed. Nanosized pores are observed in the morphological surfaces of PZT thick films. The crack-free PZT thick films with thickness of 1.3μm by the repeated deposition exhibit good electrical properties with dielectric constant of 996, dielectric loss around of 3%, remanent polarization of 36.3μC∕cm2, and coercive field of 78.5kV∕cm, which are potential candidates for microelectromechanical system (MEMS) applications.

Combined annealing temperature and thickness effects on properties of PbZr 0.53Ti 0.47O 3 films on LaNiO 3/Si substrate by sol–gel process

PbZr 0.53Ti 0.47O 3 (PZT) films with different thickness were deposited on LaNiO 3-coated Si substrate by modified sol–gel process. The thickness effect on structure and properties of PZT films annealed at different temperature have been investigated. Single perovskite-phase PZT films with preferred [1 0 0] orientation and denser columnar structure were obtained, when annealed at a lower temperature of 600 °C, whereas a higher annealing temperature of 700 °C resulted in [1 1 0] preferred orientation and porous structure. The dielectric and ferroelectric properties of PZT films annealed at different temperature were evaluated systemically as a function of thickness, and the dielectric and ferroelectric properties of PZT films were found to greatly depend on both thickness and annealing temperature.

Analyzed by Kelvin Force Microscopy of PbZr<sub>0.3</sub>Ti<sub>0.7</sub>O<sub>3</sub> Thin Films Grown on La<sub>0.5</sub>Sr<sub>0.5</sub>CoO<sub>3</sub> or LaMnO<sub>3</sub> Bottom Electrodes

We have investigated structural and electrical properties of PbZr0.3Ti0.7O3 (PZT) thin films deposited by pulsed laser deposition methods. In order to improve the ferroelectric properties of PZT thin films, we have controlled grain size or surface morphology by changing bottom electrode or deposition time. PZT thin films have been deposited on La0.5Sr0.5CoO3 (LSCO) or LaMnO3 (LMO) bottom electrodes with LaAlO3 substrates during different deposition times. X-ray diffraction data have shown that all the PZT films and bottom electrodes are highly oriented with their c-axes normal to the substrates. The thickness of each film is determined by field-emission scanning electron microscope. We have also observed alternation of grain sizes (80~180 nm) by using atomic force microscopy mode and surface potential distribution and retention behavior of ferroelectric domains by using Kelvin force microscopy mode. A PZT/LMO structure has shown superior ferroelectric and retention properties to a PZT/LSCO structure.

EPITAXIALLY GROWN PbZr0.3Ti0.7O3 THIN FILMS ON LaMnO3 APPLICABLE TO NANO-STORAGE MEDIA

ABSTRACT We have investigated structural and electrical properties of PbZr0.3Ti0.7O3 (PZT) thin films deposited by pulsed laser deposition methods. PZT thin films have been deposited on LaMnO3 (LMO) bottom electrodes with LaAlO3 substrates during different deposition times. High-resolution x-ray diffraction data have shown that all the PZT films and bottom electrodes are highly oriented with their c-axes normal to the substrates. The thickness of each film is determined by field-emission scanning electron microscope. We have also observed root mean square roughness of 1 to 10 Å by using atomic force microscopy mode, and local polarization distribution and retention behavior of a ferroelectric domains by using piezoelectric force microscopy mode. A PZT/LMO structure has shown good ferroelectric and retention properties as a media for the nano-storage devices.

Ferroelectric Properties of PbZr0.40Ti0.60O3/ LaxSr1−xCoO3 Heterostructures Prepared by Chemical Solution Routes

PbZr0.40Ti0.60O3/La x Sr1 − x CoO3 (PZT/LSCO) heterostructures have been grown on Si-based substrates by chemical solution routes. X-ray diffraction analysis showed that PZT on LSCO are polycrystalline with (110) orientation and entirely perovskite phase. The resistance of LSCO is strongly affected by the ratio of La/Sr and the annealing atmosphere for the LSCO thin films. The ferroelectricity of PZT is strongly dependent on LSCO electrode, the P-E hystersis loops of PZT deposited on LSCO which annealed in air is more asymmetry than that annealed in oxygen. At the applied electric field of 300 kV/cm, all PZT films have the resisitivity larger than 1010 Ω · cm. The fatigue resistance is strongly affected by the resistance of the LSCO electrode. The ferroelctric properties are strongly improved by LSCO buffer layer between PZT and Pt bottom electrode.

Heteroepitaxial Growth and Ferroelectric Properties of PbZr0.52Ti0.48O3/SrRuO3 Structure on TiO2-Terminated SrTiO3 (100) by Pulsed Laser Deposition

Epitaxial ferroelectric PbZr0.52Ti0.48O3 (PZT)/SrRuO3 (SRO) heterostructures have been grown on TiO2-terminated SrTiO3 (100) (STO) substrates by pulsed laser deposition. Atomically flat terraces of STO substrate were obtained by chemical (BHF pH–5.8, ultrasonic 10 sec) and physical (O2, 1000°C, 60 min) treatment. The 7 nm thick-SRO thin films indicate transition from three-dimension to two-dimension growth mode. The 14 nm thick-SRO film shows a structure of terraces and steps, which typically have one unit-cell height. The growth relationship of PZT(00l)/SRO(h00)/STO(h00) has been achieved. No diffraction peaks from lead deficient pyrochlore phases were observed in the XRD pattern, indicating that the film is a single crystal. The 2Pr and 2Ec values of Pt/PZT/SRO/STO structure were found to be 64 μ C/cm2 and 191 kV/cm, respectively, at the applied voltage of 5 V.

Characterization of Ferroelectric Properties of PZT Grains Utilizing KFM Measurements

Ferroelectric properties of PbZr0.4Ti0.6O3 (PZT) grains were examined by monitoring the surface potential. Hysteretic and time dependent behaviors of small grain were compared with those of large grain. The smaller grain yields smaller value of the surface potential. However, the normalize voltage versus surface potential behavior indicates the earlier saturation with respect to writing voltages. On the other hand, the surface potential hysteresis loop obtained from the smaller grain shows a similar shape that might be obtained from Zr rich PZT film, whereas hysteresis loop of the larger grain looks like that obtained from Ti-rich film. In addition, the time dependent behaviors of the smaller grains also reveal the better response than those of the larger grains. The overall ferroelectric property of smaller grain seems to be better than that of larger grain. At present, it is not sure about the whether the difference is due to the difference in the stoichiometry or not. In this study, the Ti/Zr ratio of PZT film was 60/40.

Effective Orientation Control of Pb(Zr0.4Ti0.6)O3 Thin Films Using A New Ti/Pb(Zr0.4Ti0.6)O3 Seeding Layer

ABSTRACTThe effect of thin Ti/PbZr0.4Ti0.6O3 seed layers on the properties of PbZr0.4Ti0.6O3 (PZT) capacitors has been investigated. The seed layer is based on a bi-layer of thin Ti and thin PZT with a total thickness ranging from 10 to 25 nm, which was deposited on Ir/Pt or Ir/IrO2/Pt by sputtering. After crystallization of the seed layers the main 130-nm-thick PZT film was deposited and crystallized. As a result, a highly preferred (111)-orientation of the PZT was obtained on a 10-nm-thick seed layer, where the peak intensity ratios of (111)/{100} and (111)/{110} are about 100 and 20, respectively. The 10-nm-thick seed forms a pyrochlore phase with a very smooth surface, where the formation of the pyrochlore phase is attributed to Pb diffusion, resulting in a Pb deficient stoichiometry. The seed layer transformed to the perovskite phase during the main PZT crystallization. It is shown that an IrO2 layer beneath the Pt can prevent Pt layer degradation related to the volume expansion due to the oxidation of Ir during the main PZT crystallization. Capacitors with the 10-nm-thick seed layer fabricated on the Ir/Pt and Ir/IrO2/Pt substrates showed typical 2 Pr values of 44.0 μC/cm2 and 41.2 μC/cm2, respectively. The voltage found for 90%-polarization saturation is about 3.0 V, and the capacitors are fatigue-free at least up to 1010 switching cycles.

DC Biased Dielectric Property of MPB PZT Ceramics with Monoclinic Distortion at Low Temperatures

Complex dielectric properties of PbZr 1 m x Ti x O 3 ceramics with compositions in the vicinity of the morphotropic phase boundary (x=0.46, 0.48, and 0.51), as a function of dc bias fields, were measured under small ac signal conditions. In monoclinic phase, dielectric permittivity shows hysteresis behavior and decreases with increasing bias field when E bias >E c . For compositions of tetragonal phase and near the on-set of the monoclinic phase transitions, dielectric permittivity increases with increasing bias electric field, indicating a continued polarization switching process. Such anomalous behavior is attributed to the E-field induced monoclinic phase, which allows polarization rotation without domain reversal. Temperature dependence of the dc biased dielectric property between 12K and 300K is also reported. Dielectric dispersion is mostly clamped out for both PZT 54:46 and PZT 52:48 as temperatures approaching 12K; however, remains significant in PZT 49:51.

Effect of hydrolysis on properties of PbZr 0.50Ti 0.50O 3 ferroelectric thin films derived from a modified sol–gel process

Lead zirconate titanate PbZr 0.50Ti 0.50O 3 (PZT) ferroelectric thin films were successfully deposited on Pt(1 1 1)/Ti/SiO 2/Si substrates by a modified sol–gel method using zirconium nitrate as a substitute for the conventional zirconium alkoxide. The precursor solutions were hydrolyzed with different H 2O/Pb ratios. The effect of hydrolysis ratios of the solution on the microstructure for the PZT thin films were investigated via X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. The XRD results show that the PZT films exhibit (1 1 1)-orientation and the degree of the (1 1 1)-orientation decreases with the increase of hydrolysis ratio. These results indicate that the ferroelectric behavior can be improved by an appropriate choice of H 2O/Pb ratio.

Effects of temperature on the ferroelectric properties of PbZr0.53Ti0.53O3-based capacitors prepared by pulsed laser-ablation deposition

Abstract The effects of elevated temperature on the long and short term ferroelectric properties of La0.5Sr0.5Co3(LSCO)/PbZr0.53 Ti0.47O3(PZT)/La0.5Co3(LSCO) heterostructure capacitors are presented in this paper. Capacitors are evaluated in the temperature range of 25°C to 100°C. Polarization values (switched and non-switched), coercive voltages, and PZT resistivity are measured as a function of temperature. Rate of fatigue, tendency to imprint, and retention loss are also investigated in the 25–100°C temperature range. An activation energy for the process responsible for loss of remanent polarization is determined from the fatigue data.