Rietveld refinement 4 goethite 4 Acid dissolution 2 Adsorption 2 Al- 2 Alkalinity 2 Aluminum 2 BET surface area measurement 2 Chemical analysis 2 Co ferrites 2 Co- 2 Co-ferrite 2 Cobalt 2 Crystallite size 2 Ferrite 2 Hyperfine characterization 2 Hyperfine magnetic fields 2 Hyperfine properties 2 Hyperfines 2 Inhomogeneous distribution 2 Manganese 2 Mn-goethite 2 Mn-goethites 2 Mn-hematite 2 Multi-substitution 2 Particle size 2 Particle size analysis 2 Rietveld analysis 2 Scanning electron microscopy 2 Specific surface area 2