Influence of la substitutions on the magnetic after-effect in hexaferrites and garnets

Abstract

Magnetic relaxation has been measured in La-Co substituted M-type Sr hexaferrites and La substituted YIG polycrystalline samples prepared by means of standard ceramic techniques. In the temperature range between 80 and 420 K, the magnetic disaccommodation has been measured. The isochronal disaccommodation spectra show the presence of different relaxation processes. In hexaferrites, the La doping distort the lattice size and the arrangement of cations within the structure, changing the strenght of relaxation processes regarding unsubstituted samples. In garnets, substitution rate only modify lattice size, whereas with CO2 atmosphere the formation of secondary perovskite phase is detectable with this technique.