Abstract :
Starting from a novel water-based Zr(IV)-
peroxo-citrato solution, an entirely aqueous solutiongel
synthesis of Pb(Zr0.53,Ti0.47)O3 (PZT) was carried
out. Because of the tendency of Zr4+-ions to hydrolyze
and condensate extensively in water, the Zr4+-ions had
to be chemically modified by reaction with hydrogen
peroxide and citric acid in a two-step precursor
synthesis. A transparent amorphous PZT gel precursor
was obtained by evaporating the solvent (water). This
resulted in a network of cross-linked ammoniumcarboxylate
bonds that holds Zr(IV)-peroxo-citrato,
Ti(IV)-peroxo-citrato and Pb(II)-citrate complexes. By
combining complementary thermal analysis techniques
such as HT-DRIFT (high-temperature diffuse reflectance
Fourier-transform infrared spectroscopy), TGAMS
(thermogravimetrical analysis online coupled to
mass spectrometry) and DTA (differential thermal
analysis) insight in the decomposition mechanism of
the PZT gel was gained. Three major regions could be
distinguished; consecutively the non-coordinative matrix
surrounding the metal ion complexes, the precursor
complexes and the remaining organic matrix are
being decomposed. The phase formation of crystalline
perovskite PZT was investigated in situ by means of
HT-XRD (high-temperature X-ray diffraction). It
shows that sublimation of PbO leads to the phase
segregation of a Zr-rich PZT phase when a stoichiometric
PZT precursor is used. Single phase perovskite
PZT however can be obtained at low temperature
(~610 C) when a 16 % lead excess is applied.
