Defect concentration in Ti-substituted YIG from TG curves

• Published in: Journal of thermal analysis and calorimetry 2006-09, Vol.86 (1), p.195-198
• Main Authors: González Arias, A., Torres, C., de Francisco, C., Muñoz, J. M., Hernández Gómez, P., Alejos, O., Montero, O., Iñiguez, J. I.
• Format: Article
• Language: English
• ISSN: 1388-6150; 1572-8943
• DOI: 10.1007/s10973-005-7155-0

The article discusses theory and experiment about the measurement of defect concentration in Ti-substituted yttrium iron garnet by means of thermogravimetry techniques. The two possible cases arising from oxygen interchange with atmosphere, oxygen vacancies and interstitial cations, may be analyzed quantitatively from the derived expressions. The possibility of another type of defects being present in the samples, not associated to oxygen evolution, is not excluded. Measurements were carried out in air and CO2 for different Ti contents. The substitution tends to increase slightly the defect parameter 9 in YIG, while a CO2 reducing atmosphere is much more effective than the Ti substitution for increasing 9. Calculations for a given single-phased sample sintered in air show two possibilities: a deficit of one oxygen atom for every 2.5 unit cells of 96 atoms, or one excess cation for every 3.5 cells. Other samples show very similar results. The accuracy involved in the measurements is about 2-3%.