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Defect Structure and Electrical Conductivity of ThO 2 ‐Y 2 O 3 Solid Solutions
Author(s) -
SUBBARAO E. C.,
SUTTER P. H.,
HRIZO J.
Publication year - 1965
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1965.tb14794.x
Subject(s) - ion , solid solution , electrical resistivity and conductivity , conductivity , fluorite , oxygen , vacancy defect , analytical chemistry (journal) , materials science , chemistry , inorganic chemistry , crystallography , chromatography , metallurgy , organic chemistry , electrical engineering , engineering
Compositions in the system ThO 2 ‐YO 1.5 were coprecipitated as oxalates and converted to oxides. Disks were pressed and sintered in oxygen at 1400° to 2200°C. Densities of the sintered disks were 96 to 98% of theoretical. Solid solutions with the fluorite‐type structure were formed up to 20 to 25 mole % YO 1.5 at 1400°C and up to 45 to 50 mole % YO 1.5 at 2200°C. Density data showed that these solid solutions correspond to Th 1— x Y x O 2—0.5 x , having a complete cation sub‐lattice filled by Th 4+ and Y 3+ ions, and vacancies in the anion sublattice. The observed increase in electrical conductivity with increase in YO 1.5 content is consistent with charge transport by oxygen ions through a vacancy mechanism. Approximately 7 mole % ThO 2 is soluble in YO 1.5 at 2200°C. Density results indicate an anion interstitial structure for the Y 2 O 3 phase. Transference number measurements indicate that the electrical conductivities are only partly due to ions.