Effects of crystallization conditions on dielectric and ferroelectric properties of PZT thin films

This paper reports studies on dielectric and ferroelectric properties of lead zirconate titanate (PZT) thin films crystallized by conventional thermal annealing (CTA) and rapid thermal annealing (RTA) in air, oxygen and nitrogen atmospheres to better understand, control and optimize these properties. The dielectric constant (epsilon) and dissipation factor (tan delta) values, at a frequency of 100 kHz; for film crystallized in air by CTA process, were 358 and 0.039, respectively. Considering the same frequency for film crystallized in air by RTA, these values were 611 and 0.026, respectively. The different dielectric values were justified by a space-charge or interfacial polarization in films, often characterized as Maxwell-Wagner type. This effect was also responsible to dispersion at frequencies above 1 MHz in film crystallized in air by CTA process and film crystallized by RTA in oxygen atmosphere. The film crystallized by RTA under nitrogen atmosphere presented an evident dispersion at frequencies around 100 Hz, characterized by an increase in both epsilon and tan delta. This dispersion was attributed to conductivity effects. The remanent polarization (P-r) and coercive field (E-c) were also obtained for all films. Films obtained from RTA in air presented higher P-r (17.8 muC cm(-2)) than film crystallized from CTA (7.8 muC cm(-2)). As a function of the crystallization atmospheres, films crystallized by RTA in air and nitrogen presented essentially the same P-r values (around 18 muC cm(-2)) but the P-r (3.9 muC cm(-2)) obtained from film crystallized under oxygen atmosphere was profoundly influenced.

Dielectric and pyroelectric properties of a composite of ferroelectric ceramic and polyurethane

Flexible piezo- and pyroelectric composite was made in the thin film form by spin coating. Lead Zirconate Titanate (PZT) ceramic powder was dispersed in a castor oil-based polyurethane (PU) matrix, providing a composite with 0-3 connectivity. The dielectric data, measured over a wide range of frequency (10(-5) Hz to 105 Hz), shows a loss peak around 100 Hz related with impurities in the polymer matrix. There is also an evidence of a peak in the range 10(-4) Hz, possibly originating from the glass transition temperature T of the polymer. The pyroelectric coefficient at 34 K is 7.0x10(-5) C(.)m(-2.)K(-1) which is higher than that of P-PVDF (1X10(-5) C(.)m(-2.)K(-1)).

Ionized oxygen vacancy-related electrical conductivity in (Pb(1-x)La(x)) (Zr(0.90)Ti(0.10))(1-x/4)O(3) ceramics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phase transition and dielectric properties of La-doped Pb(Zr, Ti)O-3 antiferroelectric ceramics

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of lanthanum modification on dielectric properties of Pb(Zr-0.90,Ti-0.10)O-3 ceramics: enhanced antiferroelectric stability

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

PZT FOR MEASURING ENERGY FLUENCE RATE of X-RAY USED IN SUPERFICIAL CANCER THERAPY

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Piezo and Dielectric Properties of PHB-PZT Composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photopyroelectric response of PTCa/PEEK composite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese e caracterização da cerâmica PZT dopada com íons bário

Pós de titanato zirconato de chumbo (PZT) puros e dopados com bário foram obtidos pelo método de precursores poliméricos, conformados uniaxialmente, na forma de cilindros, utilizando 15 MPa, e prensados isostaticamente à 210MPa. Com o objetivo de estudar o comportamento de sinterização os compactos foram divididos em dois lotes. Sendo um sinterizado em um forno acoplado a um dilatômetro até a temperatura de 1300 °C e o outro sinterizado em forno tipo mufla, em sistema fechado, na temperatura de 1100 °C por 4 horas. Verificou-se que a adição do íon bário influencia na cinética de sinterização, na densificação final, na microestrutura e nas propriedades elétricas da cerâmica. A adição de bário aumenta a concentração da fase tetragonal no PZT, em função da substituição do chumbo por bário na rede perovskita. As amostras dopadas com concentrações maiores que 5,0 mol % em bário apresentaram segregação de PbO no contorno de grão, inibindo seu crescimento.

Photoluminescence properties and synthesis of a PZT mesostructure obtained by the microwave-assisted hydrothermal method

Micro-cube-shaped lead zirconate titanate was synthesized using the microwave-assisted hydrothermal method. Photoluminescence and field emission scanning electron microscopy were used for monitoring the formation of mesocrystals. Based on these results, a growth mechanism was then proposed which involved nanoparticle aggregation, nanoplate self-assembly on specific architecture and the final formation of mesoscopic micro-cube-shaped lead zirconate titanate. (C) 2011 Elsevier B. V. All rights reserved.

Hyperfine interaction measurements on ceramics: PZT revisited

The solid solution of PbZr1-xTixO3, known as lead-zirconate titanate (PZT), was probably one of the most studied ferroelectric materials, especially due to its excellent dielectric, ferroelectric and piezoelectric properties. The highest piezoelectric coefficients of the PZT are found near the morphotropic phase boundary (MPB) (0.46 <= x <= 0.49), between the tetragonal and rhombohedral regions of the composition-temperature phase diagram. Recently, a new monoclinic phase near the MPB was observed, which can be considered as a bridge between PZT's tetragonal and rhombohedral phases. This work is concerned with the study of the structural properties of the ferroelectric PZT (Zr/Ti = 52/48, 53/47) by hypertine interaction (HI) measurements obtained from experiments performed by using the nuclear spectroscopy time differential perturbed angular correlation (TDPAC) in a wide temperature range. (c) 2006 Elsevier B.V. All rights reserved.

Characterization and application of PZT/PU and graphite doped PZT/PU composite

Composites, made of lead zirconate titanate (PZT) ceramic powder and castor oil-based polyurethane (PU), were prepared in the film form. The films were obtained in the thickness range 100-300 mum using up to 50/50 vol.% of ceramic. Another composite (PZT/C/PU) was obtained by adding a small amount (1.0 vol.%) of graphite (C) to the PZT/PU composite. By increasing the conductivity of PU-containing graphite, polarization of PZT could be carried out with better efficiency. A comparison of piezo- and pyroelectric activities and spatial distribution of polarization between graphite doped and undoped composites reveal the advantages of using semiconductor filler. These composites were used as sensors to detect acoustic emission (AE). The detection was made using two simulated sources of AE, i.e., ball bearing drop and pencil lead break. PZT/C/PU composite was able to detect both flexural and extensional components of wave vibration. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Voltage responsivity of pyroelectric sensor

Composites polymer-ceramic using castor oil-based polyurethane (PU) as non-ferroelectric matrix and Lead Zirconate Titanate (PZT) as ceramic powder have been prepared at thin films form by spin coating. The samples are poled by appropriated electric field to show piezo and pyroelectric activity. The pyroelectric coefficient p(T) at 343 K is obtained to be equal 5.8 X 10(-5) C m(-2) K-1 for a composite with 32 vol.% of ceramic. The figure of merit of this composite is six times higher than of PZT ceramic. The voltage responsivity of the pyroelectric is reduced when the thickness of the sample increases. It was used modulated white light as radiation source to excite the sensor film. The electric signal of the sensor decreases with the light modulation frequency by 1/f. (C) 1999 Elsevier B.V. S.A. All rights reserved.

The nature of the photo luminescence in amorphized PZT

The polymeric precursor method was used to synthesize lead zirconate titanate powder (PZT). The crystalline powder was then amorphized by a high-energy ball milling process during 120h. A strong photoluminescence emission was observed at room temperature for the amorphized PZT powder. The powders were characterized by XRD and the percentage of amorphous phase was calculated through Rietveld refinement. The microstructure for both phases was investigated by TEM. The optical gap was calculated through the Wood and Tauc method using the UV-Vis. data. Quantum mechanical calculations were carried out to give an interpretation of the photoluminescence in terms of electronic structure. (C) 2004 Elsevier B.V. All rights reserved.

Preparation of Pb(Zr,Ti)O-3 thin films by soft chemical route

Lead zirconate titanate, Pb(Zr0.3Ti0.7)O-3 (PZT) thin films were prepared with success by the polymeric precursor method. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), Micro-Raman spectroscopy and X-ray diffraction (XRD) were used to investigate the formation of the PZT perovskite phase. X-ray diffraction revealed that the film showed good crystallinity and no presence of secondary phases was identified. This indicates that the PZT thin films were crystallized in a single phase. PZT thin films showed a well-developed dense grain structure with uniform distribution, without the presence of rosette structure. The Raman spectra undoubtedly revealed these thin films in the tetragonal phase. For the thin films annealed at the 500-700 degreesC range, the vibration modes of the oxygen sublattice of the PZT perovskite phase were confirmed by FT-IR. The room temperature dielectric constant and dielectric loss of the PZT films, measured at 1 kHz were 646 and 0.090, respectively, for thin film with 365 nm thickness annealed at 700 degreesC for 2 h. A typical P-E hysteresis loop was observed and the measured values of P-s, P-r and E-c were 68 muC/cm(2), 44 muC/cm(2) and 123 kV/cm, respectively. The leakage current density was about 4.8 x 10(-7) A/cm(2) at 1.5 V. (C) 2003 Elsevier Ltd. All rights reserved.