Magnetic particles FeOOH

A1203 matrix [38], nanoscale FeOOH particles [39], dispersed ultrafine Mn-Zn ferrite particles [40], polydispersed ferrite particles in a magnetic fluid [41], Fe-based nanoparticles in a polyethylene matrix [42], a granular Cu-Co alloy [43] and maghemite (/-Fe203) nanoparticles in ferrofluids [32], No... 

The inconsistencies were explained by Dezsi and Fodor [43], who found that three out of five deposits of natural a-FeOOH and a synthetic sample all gave a unique hyperfine pattern, while the other two did show clear evidence of two fields. The latter result was found to be true of samples containing excess water deposits of stoichiometric a-FeOOH do not show evidence for more than two magnetic sublattices. The Neel temperature was found to be only 367 K, and relaxation occurred at up to 30° below this. It would appear that the defect structure and particle size are both important in determining the properties of a specific sample. 

The effects of interaction between closely packed microcrystals of a-FeOOH have been reported by M<Mossbauer spectra obtained with increasing temperature show firstly pronounced asymmetric line shapes and then the collapse of the hyperfine field, without any coexistence of magnetic and collapsed components that characterises the spectra of isolated particles. 

There are other types of pores in a single solid particle. a-FeOOH is a precursor material for magnetic tapes, a main component of surface deposits and atmospheric corrosion products of iron-based alloys, and a mineral. The a-FeOOH microcrystal is of thin elongated plate [83],... 

Paramagnetic fractions produce quadrupole doublets (QS) in the spectrum. Their parameters are close to those of hydroxides (e.g., lepidocrocite, y-FeOOH) or to small superparamagnetic particles of iron oxides or hydroxides with a mean diameter of about 10 nm. It should be noted that it is not difficult to distinguish among different magnetically ordered phases when they are present in a well-ordered crys-... 

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