Premium
Phase Diagram of a Nickel‐Zinc Ferrite of Composition Ni 0.685 Zn 0.177 Fe 2.138 O 4+γ
Author(s) -
BRACCONI PIERRE,
GALLAGHER P. K.
Publication year - 1979
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.1151-2916.1979.tb19047.x
Subject(s) - nickel , phase diagram , zinc , analytical chemistry (journal) , metastability , phase boundary , ferrite (magnet) , enthalpy , materials science , chemical composition , mineralogy , phase (matter) , chemistry , metallurgy , thermodynamics , physics , organic chemistry , chromatography , composite material
The oxygen content of Ni 0.685 Zn 0.177 Fe 2.138 O 4+γ was determined gravimetrically at atmospheric pressure in varying Po 2 , 3.5 × 10 −4 to 1.0 atm at 600° to 1450°C. The phase boundary associated with the precipitation of α‐Fe 2 O 3 was determined from the change in slope of γ vs T plots observed on heating. Metastability is particularly evident for curves observed on cooling. Isacompositional lines (0.002 < γ < 0.045) are shown on a plot of log PO 2 vs 1/T. An enthalpy of ‐21.6 kcal/mol is calculated for the oxidation of Fe 2+ .