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Mechanochemical Processing of Mn and Co Oxides: An Alternative Way to Synthesize Mixed Spinels for Protective Coating
Author(s) -
Masi Andrea,
Bellusci Mariangela,
Carlini Maurizio,
McPhail Stephen J.,
Padella Franco,
Reale Priscilla
Publication year - 2016
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/jace.13863
Subject(s) - materials science , ball mill , manganese , chemical engineering , cobalt , coating , calcination , van der pauw method , solid solution , thermal treatment , mineralogy , metallurgy , electrical resistivity and conductivity , nanotechnology , chemistry , composite material , catalysis , engineering , biochemistry , electrical engineering , hall effect
High‐Energy Ball Milling ( HEBM ) is proposed as a cost effective and environmental friendly technique to produce Co‐ and Mn‐ based oxides suitable for application as protective coating. Mixtures of manganese and cobalt oxides in different molar ratio (Co:Mn = 1:1 and Co:Mn = 2:1) were subjected to mechanochemical treatment up to 100 h and morpho‐structural evolution was evaluated. XRD analysis results show that the HEBM treatment promotes the solid‐state reaction of the starting compounds, with the formation of different crystalline phases when compared to high‐temperature solid‐state synthesis. SEM obs erv ations and N 2 adsorption measurements suggest that all processed powders are composed by aggregates of nanometric particles. While long milling time is required to complete the reaction, 10 hours are enough to activate the powders to obtain the desired phases after a mild thermal treatment, as evidenced by in situ thermal XRD analysis. Electrical conductivity measures performed with the Van der Pauw method on sintered pellets evidence a significant difference between the two compositions, related to the dual‐phase nature of Co:Mn = 1:1 material at intermediate temperatures (i.e., T < 700°C), Co:Mn = 2:1 sample showing higher conductivity values in the whole tested range (500°C–800°C).