Perovskite-type ceramics, which had been sintered in pure O at 1400C, were investigated as a function of La contents ranging from 0 to 0.6. Optical and scanning electron microscopy, X-ray analysis, X-ray diffraction and pyconometry were used to determine the mechanism that was responsible for the compensation of the electronic excess charge that resulted from adding La. Pure Sr-vacancy compensation mechanism was observed at La contents of up to 0.3. At La contents above 0.4, Ti vacancies also occurred but their concentration remained negligible when compared to that of the predominating Sr vacancies. No indication of a reported solubility limit of La, at a content of 0.4, was observed. At La contents of 0.5 and 0.6, the lattice structure was slightly distorted: tetragonally and orthorhombically, respectively.

R.Moos, T.Bischoff, W.Menesklou, K.H.Härdtl: Journal of Materials Science, 1997, 32[8], 4247-52