Charge Compensation in Gd-Doped CaTiO3

✍ Scribed by E.R. Vance; R.A. Day; Z. Zhang; B.D. Begg; C.J. Ball; M.G. Blackford

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 240 KB
• Volume: 124
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1996.0210

✦ Synopsis

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, rather than unity (which would Ca (1؊x) Gd (x) TiO 3 samples prepared by sintering in air at be the value if charge compensation occurred by reduction 1550؇C exhibit a primary perovskite-structured solid solution of Ti 4ϩ to Ti 3ϩ ), so precise chemical analysis of the Gdfor x up to about 0.2. It is concluded from quantitative X-ray doped perovskite should enable us to distinguish between microanalysis using a scanning electron microscope that charge these models. We have prepared samples of composition compensation in these solid solutions takes place via the forma-Ca (1Ϫx) Gd (x) TiO 3 , which would be expected to be single tion of one formula unit of Ti 3؉ per formula unit of Gd. Highphase if charge compensation occurs by reduction of resolution transmission electron microscopy showed that the Ti 4ϩ to Ti 3ϩ . A further series of samples of composition x ‫؍‬ 0.15 sample consisted of a pure perovskite structure, with Ca (1Ϫ3x/2) Gd (x) TiO 3 , which would be single phase if comno observable stacking faults and only a few dislocations. Micropensation occurs by Ca vacancies, was also prepared. The analysis showed that Gd 3؉ substituted for Ca 2؉ can be charge compositions of individual grains in these samples were compensated by Al 3؉ substituted for Ti 4؉ , as expected. Microdetermined by analytical electron microscopy. Measureanalysis also indicated that charge compensation can take place in air-fired Ca (1؊3x/2) Gd (x) TiO 3 by x/2 formula units of Ca vacan-ments were also made on further samples, of composition cies per formula unit of Gd for compositions in which x Ͻ Ca (1Ϫx) Gd (x) Ti (1Ϫx) Al (x) O 3 , where the ratio (Ca ϩ Gd)/ 0.3.