Structural and electrical studies of CeO 2 modified lead zirconate titanate ceramics (original) (raw)
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Structural and Electrical Properties of Lead Zirconate Titanate [Pb(ZrxTi1-x)O3] Ceramics
Lead Zirconate Titanate [PZT: Pb(ZrxTi1-x)O3; x = 0.40, 0.45, 0.55 and 0.60] ceramics were prepared by mixed oxide method at high temperature. Preliminary structural analysis through X-ray diffraction technique suggests about the formation of compounds at room temperature in tetragonal crystal system. Their tetragonality exhibits a decreasing trend with the increase in Zr4+ concentration. Micro structural analysis using SEM-microphotographs suggests that the grains are uniformly distributed on the surfaces of the samples with small porosity. Study of dielectric properties at different temperatures and frequencies exhibits high dielectric constant and low loss tangent along with the transition temperature well above the room temperature. The ferroelectric to paraelectric transition temperature in PZT samples exhibits a decreasing trend with the increase in Zr4+ concentration. Study of ac-conductivity at different temperatures and the value of activation energy in different regions suggest that the conduction process in the materials is of mixed type; singly ionized in ferroelectric region and doubly ionized in paraelectric region.
Piezoelectric and mechanical properties of ceria-doped lead zirconate titanate ceramics
Journal of Materials Science, 1992
Phases, microstructures and properties of lead-zirconate-titanate (PZT) ceramics with the compositions Pb(Zro.535_~Ce~Tio.465)03 where 6 = 0.0, 0.001, 0.01, 0.02 and 0.05 were studied. Rhombohedral and tetragonal phases were present at 5-0.0. The amount of the rhombohedral phase increased with increasing 5, and only the tetragonal phase was present for 5 > 0.001. The c/a ratio of the tetragonal phase also increases with increasing 5. Particles of Ce02 were found to be present in compositions with 5 > 0.01, indicating that the solubility of CeO2 is less than 1 a/o on the metals basis. The piezoelectric and electromechanical constants achieved maximum values for 5-0.001. The hardness increased monotonically with increasing 6. The modulus of rupture and the fracture toughness, however, went through a minimum and both stayed lower than their values for 5-0.
Journal of the European Ceramic Society, 2007
In the present investigation we studied the effect of lead content on a hard type ceramics starting from lack to excess PbO. Specimens of Pb x (Mn 0.017 Sb 0.033 Zr 0.48 Ti 0.47)O 3 with 0.96 ≤ x ≤ 1.06 were prepared by conventional oxide mixing technique and sintered at temperatures between 1280 and 1350 • C. In samples with lower Pb concentration the pyrochlore phase appeared, while in those with higher Pb an excess of PbO phase was detected. These phases proved detrimental for the properties of sintered ceramics. The highest values of piezoelectric properties were observed only for samples with an excess lead of about 2% sintered at 1340 • C, indicating that it represents the optimum amount of PbO. For such samples, the density ρ was 7.77 g/cm 3 , the remnant polarization P r was 37 C/cm 3 the planar coupling coefficient k p was 0.57 and the charge constant d 33 was 340 pC/N.
Materials Science and Engineering: B, 1999
The effect of net PbO content (obtained by taking into account the amount of excess PbO added and PbO loss during sintering) on the mechanical and piezoelectric properties of lead zirconate titanate (PZT) ceramics has been studied. The samples were prepared by the solid state route using the morphotropic phase boundary composition Pb(Zr 0.535d Ti 0.465)O 3. Excess PbO was also added to the samples in varying amounts from 0-1.0 wt.%. To vary PbO volatility the samples were sintered with and without a PbO rich atmosphere at 1220°C for 2 h. The resulting Pb content as given by x in Pb 1 + x (Zr 0.535 Ti 0.465)O 3 + x varied from x= −1.7 ×10 − 2 to 1.8 ×10 − 2. The sintered density was found to increase with increasing lead content. The precipitation of the second phase believed to be ZrO 2 is observed for x= −1.7× 10 − 2. The fracture mode changed from intergranular to transgranular with increasing x. The fracture toughness (K IC) and strength are minimum near x =0 and increase with increasing as well as decreasing x. The maximum values of K IC and strength are 1.45 MPa m 1/2 and 90 MPa, respectively, for x =1.8× 10 − 2. The dielectric constant and piezoelectric strain coefficient d 33 increased with x.
Powders wet-chemically synthesized by the " oxidant-peroxo method " with PbZr 05 Ti 0.5 O 3 composition were sintered at 1000 and 1100° C for 2 and 4 h, resulting in dense ceramic bodies that were structurally characterized by Raman scattering spectroscopy and by x-ray diffraction at room temperature. Their electrical properties (dielectric constant and dielectric loss) were measured in the temperature range from 25 to 450° C at different current frequencies (1, 10, and 100 kHz). Microstructures were observed using a scanning electronic microscopy equipped with a x-ray energy dispersive spectrometer for chemical analysis. It was observed that the sintered bodies show tetragonal structure, and apparent densities calculated as 90% – 94% of the theoretical density.
Physica B: Condensed Matter, 2013
The perovskite Pb (1 À x) Ba x Zr 0.55 Ti 0.45 O 3 material (x ¼0.00, 0.01, 0.02, 0.03, 0.05, and 0.07) was synthesized by solid state reaction route. Green bodies were sintered at 1250 1C. All samples were subjected to X-ray diffraction analysis and they were found to be in single phase. Dielectric properties were studied as a function of temperature and frequency. Ferroelectric properties were studied as a function of temperature. Remnant polarization, saturation polarization and coercive field were determined for all the samples using ferroelectric loops. Piezoelectric properties such as d 33 and electromechanical coupling factor (k p) were also measured at room temperature for all samples.
Journal of Nanoscience and Nanotechnology, 2011
Perovskite crystal structure is found in many ionic solids like CaTiO 3 , BaTiO 3 and Lead Zirconate Titanates (PZT). In this structure off-center position of cations in oxygen octahedral causes polarization and produces direct and indirect piezoelectric responses in ceramic materials that are suitable for many ultrasonic applications. In the present study 9% Sr doped PZT ceramics were prepared and their dielectric and piezoelectric properties measured. X ray Diffraction (XRD) analysis of calcined powders demonstrated a decrease in the PbO content during the calcination stage at 850 C. This was counterbalanced by adding excess PbO at the time of preparation of mixtures. Sintering was carried out at 1200 C for 2 hours in lead rich atmosphere. The properties achieved were Dielectric Constant (K) = 1440, Tangent Loss (Tan = 0 0062, Charge Coefficient (d 33 = 335 pC/N and density = 7 55 g/cm 3. SEM analysis of sintered samples demonstrated that grain size was 2-3 m with clean grain boundaries and no large size porosity observed. XRD analysis of sintered pellets exhibited that material prepared was free of any precipitated phase usually harmful for the piezo effect.
Role of Impurities in the Sintering Behavior and Properties of Lead Zirconate Titanate Ceramics
Journal of the American Ceramic Society, 2009
Small amounts of impurities are always present in the raw materials for the mass production of lead zirconate titanate (PZT) ceramics. In this work, the effects of these impurities on sintering kinetics were investigated. The sintering behavior of PZT ceramics was monitored in situ by a thermo-optical measuring device. Two sources of raw materials were used, industrially used and highly pure (99.99%) powders. The highly pure powders were doped with different impurities, characteristic of industrially used materials. Sintering was enhanced by Si and-to a smaller extent-by Na, Ca, and Ba. Hf can have a large impact, if the stoichiometry is not adjusted properly according to its concentration. In addition, the crystal phase of the titania component affected its reactivity and lead loss during calcination, which indirectly changed the sintering behavior. The effects of the impurities on the dielectric and piezoelectric properties were also discussed.
IOP Conference Series: Materials Science and Engineering, 2011
Ferroelectric ceramics with formula (Bi 0.487 Na 0.487 La 0.017 )TiO 3 /xPb(Zr 0.52 Ti 0.48 )O 3 (when x = 0, 0.1, 0.5, 1.0 and 3.0 wt%) were prepared by solid-state mixed-oxide method and sintered at 1050 -1200°C for 2 h. The optimum sintering temperature was 1100°C at which all samples had the density at least 98% of theoretical values. X-ray diffraction results suggested that addition of PZT did not significantly affect unit cell of BNLT. An addition of PZT into BNLT effectively increased density and reduced grain size of the ceramics. These changes played an important role on mechanical properties improvement. Room temperature dielectric constant increased with increasing PZT concentration. The addition of PZT into BNLT slightly degraded ferroelectric properties, but improved the piezoelectric properties.
Current Applied Physics, 2008
Ferroelectric lead zirconate titanate-lead cobalt niobate ceramics with the formula (1 À x)Pb(Zr 1/2 Ti 1/2 )O 3 -xPb(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 À x)Pb(Zr 1/2 -Ti 1/2 )O 3 -xPb(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 lC/cm 2 ) was obtained for the 0.5PZT-0.5PCoN ceramic.