title: Controlling role of pH and temperature on CoFe2O4 nanostructures produced by hydrothermal synthesis.
abstract: The hydrothermal synthesis (HS) of CoFe2O4 nanoparticles (NPs) has been investigated as a function of reaction temperature and pH, using complementary characterisation techniques of transmission electron microscopy and X-ray diffractometry. The HS of CoFe2O4 NPs (< 25 nm) at pH - 8 proceeded through the formation and dissolution of intermediate Fe(OH)3 and [FeCo3(OH)8]+ x [Cl- x H2O]- phases with increasing reaction temperature. In contrast, HS of CoFe2O4 NPs (< 50 nm) at pH - 12 resulted in the formation of additional intermediate Co(OH)2, CoOOH and alpha-FeOOH phases, with residual alpha-Fe2O3 present in the final reaction product. This research demonstrates the size and phase purity of the CoFe2O4 NPs may be controlled through the formation and dissolution of the intermediate phases at various pH values in the alkaline pH regime.
authors: Division of Materials, Mechanics and Structures, Department of Mechanical, Materials and Manufacturing Engineering, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors: Trevor P
authors: TP
authors: Almeida
authors: Mike
authors: M
authors: Fay
authors: Yanqiu
authors: Y
authors: Zhu
authors: Paul D
authors: PD
authors: Brown
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D006358:Hot Temperature; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D046911:Macromolecular Substances; D014867:Water; C000499:ferric oxide; D003035:Cobalt