PREPARATION OF OXALATE PRECURSOR OF PLZT - CHARACTERIZATION OF THE INDIVIDUAL COMPONENTS

The stability behaviour of each individual component of PLZT, in aqueo us solutions of oxalic acid, has been investigated. The aim of this st udy was, on the one hand, to better understand the chemistry of the di fferent metal ions in complexation with C2O42- and OH-, and in the oth er hand, to define the effect of pH on the structure of the precipitat e and in its formation yield stability calculations for the different soluble metal complexes were firstly done starting from the available constants. Then, for each ion, a convenient pH and concentration range has been established for quantitative precipitation. By application o f the calculations, metallic salts were precipitated from solutions co ntaining aqueous oxalic acid and ammonia. Some unexpected and unknown precipitates have been synthesized. These new crystalline phases have been identified by different techniques (TGA, FTIR, XRD). (C) 1998 Els evier Science Limited All rights reserved.