Effect of dispersant on preparation of barium–strontium titanate powders through oxalate co-precipitation method

The quantitative precipitation of barium–strontium titanyl oxalate: (Ba0.6Sr0.4TiO(C2O4)2·4H2O, BSTO) precursor powders were successfully prepared through oxalate co-precipitation method. The pyrolysis of BSTO at 800 °C/4 h produced the barium–strontium titanate (Ba0.6Sr0.4TiO3, BST) powders. Two kinds of dispersants namely ammonium salt of poly mathacrylic acid (PMAA-NH4) and polyethylene glycol (PEG) were added respectively during the co-precipitation procedure. The powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), etc. Experimental results show that the addition of the dispersants reduced the productive rate of BST powders. The BSTO and BST powders obtained by aforementioned technique without dispersants were homogeneous with quasi-orbicular morphology. The particles grew into spindle shape with the effect of PEG. The morphology homogeneity was broke with small grains as well as large agglomerated particles concurrent when PMAA-NH4 was added. The mechanism of the effect of the two dispersants was investigated in detail.