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Electrochemical Determination of the Gibbs Energy of Formation of MgAl 2 O 4
Author(s) -
Jacob K. Thomas,
Jayadevan Kampurath P.,
Waseda Yoshio
Publication year - 1998
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.1151-2916.1998.tb02316.x
Subject(s) - gibbs free energy , spinel , standard enthalpy of formation , enthalpy , electrolyte , electrochemistry , solid solution , chemistry , atmospheric temperature range , standard enthalpy change of formation , thermodynamics , lattice energy , crystallography , analytical chemistry (journal) , materials science , crystal structure , electrode , metallurgy , physics , organic chemistry , chromatography
The standard Gibbs energy of formation of the spinel MgAl 2 O 4 from component oxides, MgO and α‐Al 2 O 3 , has been determined in the temperature range 900 to 1250 K using a solid‐state cell incorporating single‐crystal CaF 2 as the solid electrolyte. The cell can be represented as—Pt,O 2 ,MgO+MgF 2 |CaF 2 |MgF 2 +MgAl 2 O 4 +α‐Al 2 O 3 ,O 2 ,Pt—The standard Gibbs energy of formation from binary oxides, computed from the reversible emf, can be represented by the expression—capdelta G ° f,ox =−23600 − 5.91 T (±150) J/mol—The ‘second‐law’ enthalpy of formation of MgAl 2 O 4 obtained in this study is in good agreement with high‐temperature solution calorimetric studies reported in the literature.