Domain formation and interfaces in praseodymium and terbium oxides obtained by reduction of PrO/sub 2/ and TbO/sub 2/: a comparison with group theory predictions

Journal Article · Thu Jan 01 04:00:00 EST 1987 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(87)90227-1· OSTI ID:6837317

Boulesteix, C; Eyring, L

The reduction of PrO/sub 2/ and TbO/sub 2/ may occur during their study by electron microscopy with the formation of ordered intermediate phases which can be considered as superstructures of a common prototype structure: the fluorite-type with unordered oxygen vacancies. Indeed, the different oxides that may occur are directly or indirectly obtained by reduction of fluorite-type PrO/sub 2/ and TbO/sub 2/ crystals. Reduction frequently ends with Pr/sub 7/O/sub 12/ or Tb/sub 7/O/sub 12/ (iota structure) to which special attention has been devoted here. Eight orientation variants of iota could occur within a unique fluorite prototype. Generally, only two of them are observed together. This has been attributed to a possible thin layer effect. Seven glide domains may also be present in the same iota orientation variant resulting from reduction of the fluorite prototype structure. Such glide domains are usually observed in Pr/sub 7/O/sub 12/ and sometimes in Tb/sub 7/O/sub 12/. Layers occurring between glide domains have been identified as regions of different composition. Twelve different orientation variants can occur within the zeta (Pr/sub 9/O/sub 16/) or delta (Tb/sub 11/O/sub 20/) structures; two of them are frequently observed together. Different kinds of interfaces can be observed between different kinds of domains. For example, interfaces are generally irregular between different iota variants but are perfectly planar between iota and zeta phases. It is shown that the latter case must result from the formation of strain-free (low energy) interfaces.

• Research Organization: Arizona State Univ., Tempe
• OSTI ID: 6837317
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 66:1; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTAL-PHASE TRANSFORMATIONS
DATA
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
GROUP THEORY
INFORMATION
MATHEMATICS
MICROSCOPY
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PRASEODYMIUM COMPOUNDS
PRASEODYMIUM OXIDES
RARE EARTH COMPOUNDS
REDUCTION
TERBIUM COMPOUNDS
TERBIUM OXIDES