PREPARATION OF LEAD ZIRCONATE (PbZrO3)
BY HOMOGENEOUS PRECIPITATION AND CALCINATION
Researchers: Ersin Emre OREN, Ercan TASPINAR and A. Cüneyt TAS
Department of Metallurgical and Materials Engineering,
* Journal of The American
Ceramic Society, Vol. 80, (1997) pp. 2714-2716.
(------> download pdf: pz.pdf)
* E.E. Oren, E. Taspinar, and
A.C. TAS, "Chemical Synthesis of Antiferroelectric
Lead Zirconate (PbZrO3) by Homogeneous
Precipitation," III. Ceramics Congress, Proceedings
Book, Vol. 2, pp. 59-65,
Abstract
Antiferroelectric PbZrO3 has
been synthesized by homogeneous precipitation from aqueous solutions in the
presence of urea (NH2CONH2) and calcination
for 6 hours at 700°C. SEM studies displayed the presence of sub-micron
powder, with a significant degree of agglomeration.
Introduction
Lead
zirconate, PbZrO3, is
an antiferroelectric ceramic with a Curie temperature
of 230°C. It is reported that the antiferroelectric
(AFE) to ferroelectric transition (under the application of a strong electric
field to the ceramic in the antiferroelectric state)
leads to significant energy storage for DC field. This feature of PbZrO3 makes
it a candidate material for energy storage applications (1). Piezoelectric and
dielectric properties of lead zirconate thin films,
derived from a sol-gel technique, were studied and
compared with the most
significant piezoelectric compositions (2, 3).
PbZrO3 was also searched for
its microwave dielectric properties but it shows a dielectric relaxation
near microwave frequencies (4). A strong correlation between the lattice defect
concentration and dielectric loss at microwave frequencies has also been
reported (5, 6). The volatility of Pb species at the
temperatures needed to prepare lead zirconate
ceramics is believed to be the reason for the relaxation in PbZrO3 phase (4).
Therefore, a decrease in the processing temperature of lead zirconate
phase may result in an improvement in the final electrical properties of the
ceramic part.
Preparation
of lead zirconate by conventional processes; that is,
mixing and firing of the binary oxides (PbO and
ZrO2), requires the use of high temperatures at which PbO
volatility also becomes significant. It is reported that the full development
of pure PbZrO3 phase occurs after sintering at temperatures above 1200°C for at
least 2 hours in controlled PbO atmospheres (4-5,7-8).
Lead
zirconate was previously synthesized by a sol-gel
method (8), which necessitated the use of complex processing practices and a
strict control of many process parameters, such as pH of the solutions,
temperature, and concentrations of the cations. For
the sol-gel method, the calcination temperature to
yield pure PbZrO3 was reported to be as low as 700°C for 6 hours of soaking
time (8). The phase formation temperature for pure PbZrO3, by the citrate
route, was also reported to be in the vicinity of 700°C (9).
In
the present study, the experimental details and results of the synthesis of the
lead zirconate phase from water soluble salts of Pb and Zr (chlorides) by
homogeneous precipitation via urea decomposition are presented. The
decomposition of urea in aqueous solutions is accompanied by the slow and
controlled supply of ammonia and carbon dioxide into the solution [10]. The
smooth pH increase obtained by the decomposition of urea, in unison with the
steady supply of OH- and CO32- ions, typically
lead to the precipitation of metal hydroxycarbonates
of controlled particle morphology [11-13]. Homogeneous precipitation from
aqueous solutions, in the presence of urea, have been used to produce disperse
spherical particles of basic lanthanide carbonates [14], cerium oxide [15],
Y3Al5O12 [16], and LaAlO3 [17]. In this study, homogeneous precipitation
techniques, similar to those described in the literature (11-17), were employed
and shown to be successful for the preparation of phase-pure PbZrO3 after calcination at 700°C.
The
below XRD diagram shows the crystallization behavior of the hydroxycarbonate
precursors of the PZ phase as a function of increasing calcination
temperature.
References
1)
K. Singh, “Antiferroelectric Lead Zirconate, A Material
For Energy Storage,”
Ferroelectrics, 94, 433 (1989).
2) Ji-Fang Li,
3) T. Tani, Jie-Fang
Li, D. Viehland and D. A. Payne, “Antiferroelectric -
Ferroelectric Switching and Induced Strains For Sol-Gel Derived Lead Zirconate Thin Layers,” J. Appl. Phys., 75(1),
3017-3023 (1994).
4) M. T. Lanagan, J. H. Kim, S. Jang and R. E.
Newnham, “Microwave
Dielectric Properties of Lead Zirconate,” J. Am. Ceram. Soc., 71, 311 (1988).
5) K. Wakino, M. Murata and H. Tamura, “Far-Infrared Reflection Spectra of Ba(Zn1/3Ta2/3)O3 - BaZrO3 Dielectric Resonator Material,” J. Am. Ceram. Soc., 69, 34-37 (1986).
6) B. D. Silverman, “Microwave
Absorption in Cubic Strontium Titanate,”
Phys. Rev., 125 (6), 1921 (1962).
7) W. N. Lawless, “Glasslike
Thermal Properties of Lead Zirconate,” Phys. Rev. B, 30, 6555-6559
(1984).
8) D. M. Ibrahim and H. W. Hennicke,
“Preparation of Lead Zirconate by a Sol Gel Method,” Trans. J. Br. Ceram. Soc., 80, 18-22 (1981).
9) Y. S. Rao and C. S. Sunandana, “Low Temperature
Synthesis of Lead Zirconate,” J. Mat. Sci. Letters, 11,
595-597 (1992).
10) H.H. Willard and N.K. Tang, “A Study of the Precipitation of Aluminum Basic Sulphate by Urea,”
J. Am. Chem. Soc., 59, 1190-1192 (1937).
11) B.C. Cornilsen and J.S. Reed, “Homogeneous Precipitation of Basic Aluminum Salts as
Precursors for Alumina,” Am. Ceram. Soc. Bull., 58, 1199-1200 (1979).
12) J.E. Blendell, H.K. Bowen and R.L. Coble, “High-Purity Alumina by Controlled Precipitation from
Aluminum Sulphate Solutions,” Am. Ceram. Soc. Bull., 63,
797-802 (1984).
13) J. Sawyer, P. Caro and L. Eyring, “Hydroxy-Carbonates of the Lanthanide
Elements,” Revue de Chimie Minerale, 10, 93-104
(1973).
14) D.J. Sordelet and M. Akinc,
“Preparation of Spherical, Monosized, Y2O3 Precursor Particles,” J. Colloid and Interface Science,
122, 47-59 (1988).
15) P. Chen and I-Wei Chen, “Reactive Cerium(IV)
Oxide Powders by the Homogeneous Precipitation Method,” J. Am. Ceram. Soc., 76,
1577-1583 (1993).
16) D.J. Sordelet, M. Akinc,
M. L. Panchula, Y. Han and M.H. Han, “Synthesis of Yttrium Aluminum
Garnet Precursor Particles by Homogeneous Precipitation,” J. Eur. Ceram. Soc.,
14, 123-127 (1994).
17) E. Taspinar and A. C. Tas,
“Low Temperature Chemical
Synthesis of Lanthanum Monoaluminate,” J. Am. Ceram.
Soc., 80 ?1?, 133-141 (1997).
18) D.E. Appleman and H.T. Evans, “Least-Squares and Indexing Software for XRD Data,” Document No. PB-216188,
