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Influence of Nd 2 O 3 Doping on the Reaction Process and Sintering Behavior of BaCeO 3 Ceramics
Author(s) -
Lu ChungHsin,
Jonghe Lutgard C.
Publication year - 1994
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.1151-2916.1994.tb04638.x
Subject(s) - sintering , materials science , orthorhombic crystal system , doping , microstructure , grain boundary , grain growth , analytical chemistry (journal) , grain size , phase (matter) , solid solution , grain boundary diffusion coefficient , ceramic , mineralogy , chemical engineering , crystallography , metallurgy , crystal structure , chemistry , optoelectronics , organic chemistry , engineering , chromatography
The influence of Nd 2 O 3 doping on the reaction process and sintering behavior of BaCeO 3 is investigated. Formation of BaCeO 3 is initiated at 800°C and completed at 1000°C. When Nd 2 O 3 is added to the starting materials, the formation of BaCe 1–x Nd x O 3–δ is delayed and the temperature for complete reaction is increased to 1100°C. Only a BaCe 1‐x Nd x O 3–δ solid solution with an orthorhombic crystal structure is present in the specimens for x ≤ 0.1. A secondary phase rich in Ce and Nd is formed within grains and at grain boundaries, when the Nd 2 O 3 content is greater than the solubility limit (x ≥ 0.2). Pure BaCeO 3 is difficult to sinter, even at 1500°C, and only a porous microstructure could be obtained. However, doping BaCeO 3 with Nd 2 O 3 markedly enhances its sinterability. The enhancement of the sinterability of Nd 2 O 3 ‐doped specimens at x ≤ 0.1 is attributed to the increase in the concentration of oxygen ion vacancies, which increases the diffusion rate. At x ≥ 0.2, the grain size is abnormally coarsened, which is caused by the formation of a liquid phase. While this liquid phase accelerates sintering, its beneficial effect on densification is counteracted by the segregation of the secondary grain‐boundary phase which inhibits sintering.