Kinetics of formation of the pyrochlore and perovskite phases in sol-gel derived lead zirconate titanate powder

1998 ◽  
Vol 13 (8) ◽  
pp. 2170-2173 ◽  
Author(s):  
V. S. Tiwari ◽  
Arun Kumar ◽  
V. K. Wadhawan ◽  
Dhananjai Pandey
Keyword(s):  
Lead Zirconate Titanate ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Lead Zirconate ◽  
Oxygen Stoichiometry ◽  
X Ray ◽  
Zirconate Titanate ◽  
Kinetics Of Formation ◽  
Kinetics Of

Lead zirconate titanate (PZT) powder is prepared by the sol-gel method. The formation of pyrochlore and perovskite phases is investigated by high temperature x-ray diffraction (XRD) and thermal analysis techniques. The pyrochlore phase first appears in x-ray amorphous form, and then gets converted to crystalline state on annealing in air. We show that vacuum annealing of the pyrolyzed amorphous PZT gel suppresses the formation of the crystalline pyrochlore phase. This, in turn, enhances the kinetics of conversion of pyrochlore to perovskite, such that a pyrochlore-free perovskite phase can be obtained by annealing at about 500 °C. On the other hand, if annealing is carried out in air, a crystalline pyrochlore phase is formed, which requires annealing temperatures higher than 600 °C for transformation to the perovskite phase. These observations are explained tentatively in terms of the oxygen stoichiometry of the two phases.

Phase transformations in rapid thermal processed lead zirconate titanate

1995 ◽  
Vol 10 (12) ◽  
pp. 3149-3159 ◽  
Author(s):  
Ellen M. Griswold ◽  
L. Weaver ◽  
M. Sayer ◽  
I.D. Calder
Keyword(s):  
Thin Films ◽  
Lead Zirconate Titanate ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Pyrochlore Phase ◽  
Lead Zirconate ◽  
Grain Structure ◽  
Avrami Model ◽  
Pzt Thin Films ◽  
Zirconate Titanate

The crystallization kinetics of the pyrochlore to perovskite phase transformation in lead zirconate titanate (PZT) thin films have been analyzed using rapid thermal processing (RTP). Sol-gel PZT thin films, fabricated on platinum electrodes, were annealed at 550 °C to 650 °C with hold times ranging from 1 s to 5 min. Glancing angle x-ray diffraction (XRD) was used for depth profiling to identify the location of phases in the films. Transmission electron microscopy (TEM) provided information on grain structure, nucleation, and growth. The phase information was correlated to the ferroelectric and dielectric properties. The perovskite phase nucleated in the pyrochlore phase throughout the film thickness, and at 650 °C the transformation was complete in 15 s. Fast growing (100) PZT nucleated at the platinum and consumed a small-grained matrix until a columnar structure was obtained. A ramp rate of 100 °C/s was sufficiently fast to prevent transformation during heating and allowed the direct application of an Avrami model for transformation kinetics. An activation energy of 610 kJ/mol was determined.

Time-resolved small angle X-ray scattering study of sol–gel precursor solutions of lead zirconate titanate and zirconia

2012 ◽  
Vol 369 (1) ◽  
pp. 184-192 ◽  
Author(s):  
Tomasz M. Stawski ◽  
Rogier Besselink ◽  
Sjoerd A. Veldhuis ◽  
Hessel L. Castricum ◽  
Dave H.A. Blank ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Small Angle ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Zirconate Titanate ◽  
Scattering Study ◽  
Ray Scattering

Chemical Modification of Alkoxide Precursors for Lead Zirconate Titanate Formation

1996 ◽  
Vol 49 (5) ◽  
pp. 569
Author(s):  
S Tursiloadi ◽  
H Imai ◽  
H Hirashima
Keyword(s):  
Lead Zirconate Titanate ◽  
Perovskite Phase ◽  
Pyrochlore Phase ◽  
Lead Zirconate ◽  
Significant Feature ◽  
Metal Alkoxide ◽  
Titanium Tetraisopropoxide ◽  
Zirconate Titanate ◽  
Diffraction Peaks ◽  
Alkoxide Precursors

Lead zirconate titanate (PZT) gel monolith was prepared by partially hydrolysing metal alkoxide solutions which were modified with acetylacetone ( acacH ). Lead diisopropoxide zirconium tetrabutoxide and titanium tetraisopropoxide were used as starting materials. After aging of the translucent monolithic gel at room temperature for several days or drying at 90°C for 18 h, the most significant feature in the infrared spectrum is the presence of bands at about 1550 cm-1 which can be assigned to the v(C-O) and v(C-C) vibrations of the acetylacetonate group coordinated to the metal cations of titanium and zirconium. Diffraction peaks of PbO were found after heating at 300°C for 2 h. After heating at 450°C for 2 h, diffraction peaks of pyrochlore Pb2Ti2O6 and perovskite PZT phases were observed. The diffraction peaks of PbO and the pyrochlore phase disappeared after heating at 600°C, and the tetragonal perovskite phase was stable up to 1000°C. Diffraction peaks of the perovskite phase were also found after heating at 430°C for 24 h.

scholarly journals Orientation of rapid thermally annealed lead zirconate titanate thin films on (111) Pt substrates

1994 ◽  
Vol 9 (10) ◽  
pp. 2540-2553 ◽  
Author(s):  
Keith G. Brooks ◽  
Ian M. Reaney ◽  
Radosveta Klissurska ◽  
Y. Huang ◽  
L. Bursill ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Lead Zirconate Titanate ◽  
Pyrolysis Temperature ◽  
Pyrochlore Phase ◽  
Lead Zirconate ◽  
Zirconate Titanate ◽  
Excess Lead ◽  
Kinetics Of

The nucleation, growth, and orientation of lead zirconate titanate thin films prepared from organometallic precursor solutions by spin coating on (111) oriented platinum substrates and crystallized by rapid thermal annealing was investigated. The effects of pyrolysis temperature, post-pyrolysis thermal treatments, and excess lead addition are reported. The use of post-pyrolysis oxygen anneals at temperatures in the regime of 350–450 °C was found to strongly affect the kinetics of subsequent amorphous-pyrochlore-perovskite crystallization by rapid thermal annealing. The use of such post-pyrolysis anneals allowed films of reproducible microstructure and textures [both (100) and (111)] to be prepared by rapid thermal annealing. It is proposed that such anneals and pyrolysis temperature affect the oxygen concentration/average Pb valence in the amorphous films prior to annealing. Such changes in the Pb valence state then affect the stability of the transient pyrochlore phase and thus the kinetics of perovskite crystallization.

Microstructural development in sol-gel derived lead zirconate titanate thin films: The role of precursor stoichiometry and processing environment

1996 ◽  
Vol 11 (8) ◽  
pp. 2076-2084 ◽  
Author(s):  
M. J. Lefevre ◽  
J. S. Speck ◽  
R. W. Schwartz ◽  
D. Dimos ◽  
S. J. Lockwood
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Lead Zirconate Titanate ◽  
Single Phase ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Lead Zirconate ◽  
Microstructural Development ◽  
Zirconate Titanate

The role of precursor stoichiometry and local firing environment on the microstructural development of sol-gel derived lead zirconate titanate (PZT) thin films was investigated. Typically, excess Pb is added to films to compensate for PbO volatilization during heat treatment. Here, it is shown that the use of stoichiometric precursors with either a PbO atmosphere powder or a PbO overcoat during the crystallization heat treatment is an attractive and viable alternative method for control of film stoichiometry. Using these approaches, we have fabricated single phase perovskite thin films with microstructures and electrical properties (Pr ∼ 36 μC/cm2 and Ec ∼ 45 kV /cm) comparable to those of films using optimized solution chemistries and excess Pb additions. The potential advantage of increasing PbO partial pressure, or activity, during firing versus excess Pb additions is discussed from the standpoint of a proposed crystallization scenario based on the kinetic competition between Pb loss and the nucleation and growth rates of the perovskite phase.

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