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Energetics of Cerium–Zirconium Substitution in the x Ce 0.8 Y 0.2 O 1.9 −(1− x )Zr 0.8 Y 0.2 O 1.9 System
Author(s) -
Chen Weiqun,
Navrotsky Alexandra,
Xiong Yue Ping,
Yokokawa Harumi
Publication year - 2007
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.1551-2916.2006.01427.x
Subject(s) - calorimetry , solid solution , enthalpy , cubic zirconia , zirconium , crystallography , cerium , oxygen , materials science , monoclinic crystal system , oxide , analytical chemistry (journal) , chemistry , inorganic chemistry , crystal structure , thermodynamics , metallurgy , ceramic , physics , chromatography , organic chemistry
Energetics of Ce–Zr substitution in x Ce 0.8 Y 0.2 O 1.9 −(1− x )Zr 0.8 Y 0.2 O 1.9 (0≤ x ≤1) solid solutions, potential candidates for electrolytes in solid oxide fuel cells, were investigated by high temperature oxide melt drop solution calorimetry. The enthalpies of formation relative to the solid solution end‐members, Ce 0.8 Y 0.2 O 1.9 and Zr 0.8 Y 0.2 O 1.9 (Δ H f,ss ), are slightly positive. The whole substitution range can be divided into three regimes: a zirconia‐dominated region (0≤ x <0.4), where Δ H f,ss increases from 0 to 3.9 kJ/mol; a ceria‐dominated region (0.6< x ≤1), where Δ H f,ss remains nearly constant at 0 to 0.7 kJ/mol; and a transitional region (0.4≤ x ≤0.6), where Δ H f,ss decreases from 3.9 to 0.7 kJ/mol. Such a trend in Δ H f,ss strongly supports a scavenging effect of Zr 4+ on oxygen vacancies, i.e. oxygen vacancies prefer the nearest neighboring sites of Zr 4+ as in yttria‐stabilized zirconia. The formation enthalpy from binary oxides, fluorite CeO 2 , monoclinic ZrO 2 and C‐type YO 1.5 , (Δ H f,ox ) is also slightly positive, varying analogously to Δ H f,ss .