CHARGE COMPENSATION IN GD-DOPED CATIO3

Ca-(1-x)Gd-(x)TiO3 samples prepared by sintering in air at 1550 degree s C exhibit a primary perovskite-structured solid solution for x up to about 0.2. It is concluded from quantitative X-ray microanalysis usin g a scanning electron microscope that charge compensation in these sol id solutions takes place via the formation of one formula unit of Ti3 per formula unit of Gd. High-resolution transmission electron microsc opy showed that the x = 0.15 sample consisted of a pure perovskite str ucture, with no observable stacking faults and only a few dislocations . Microanalysis showed that Gd3+ substituted for Ca2+ can be charge co mpensated by Al3+ substituted for Ti4+, as expected. Microanalysis als o indicated that charge compensation can take place in air-fired Ca-(1 -3x/2)Gd-(x)TiO3 by x/2 formula units of Ca vacancies per formula unit of Gd for compositions in which x < 0.3. (C) 1996 Academic Press, Inc .