Effect of cationic substituents on particle morphology of goethite and the magnetic properties of maghemite derived from substituted goethite
| Autor: | Chandran Sudakar, T.R.N. Kutty, G. N. Subbanna |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Ionic radius
Materials science Goethite Mechanical Engineering Inorganic chemistry Nucleation Maghemite Coercivity engineering.material Magnetocrystalline anisotropy Crystallography Mechanics of Materials visual_art Mössbauer spectroscopy engineering visual_art.visual_art_medium General Materials Science Particle size |
| Zdroj: | Journal of Materials Science. 39:4271-4286 |
| ISSN: | 0022-2461 |
| Popis: | Preparation of nanoparticles with the desired shape and size by the wet-chemical precipitation process is a challenging task. Thus, the effects of different substitutional impurities such as Al, Cr, Co or Ni on the particle morphology and phase stability of goethite have been investigated. Goethite is prepared by air oxidation of $Fe(OH)_2 · xH_2O$ gel under near neutral conditions. Below certain concentration levels of dopants $(Al^{3+} \leq 10; Cr^{3+} \leq 5; Co^{2+} \leq 10$ and $Ni^{2+} \leq 5 at.%)$ the samples remained monophasic as revealed by XRD, TEM, and IR studies. Above these levels, the substituents produce traces of secondary phases such as lepidocrocite, spinel ferrite and $M^n(OH)_n$. The goethite structure is stable in spite of the iso- or aliovalent substitutions. The individual additives have divergent influence on the particle morphology; $Al^{3+}$ and $Cr^{3+}$ decreases the particle size to |
| Databáze: | OpenAIRE |
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