Cation distribution and high field magnetization studies on SrFe12-xCrxO19

With the aim of a better understanding of both cationic distribution and magnetic properties of the uniaxial SrFe12-xCrxO19hexagonal ferrites, M��ssbauer spectroscopy, neutron diffraction and high field magnetization measurements have been carried out. The Cr3+ions occupy the octahedral sites of the M structure with a preference hierarchy within them. The magnetic measurements, together with the deduced cationic distribution, indicate that some sublattices have a random spin canting around the c-axis.

Spin-glass behaviour in mixed metal oxides with a rutile-type structure

We report here on the magnetic properties of compounds of composition Fe1���xCrxSbO4 and Fe1���xGaxSbO4. The introduction of paramagnetic Cr3+ and diamagnetic Ga3+ into the rutile���related iron antimonate lattice does not destroy the antisite atomic ordering which exists in iron antimonate of composition FeSbO4. The initial slope of the Curie temperature dependence on x is similar in both series, indicating that Fe3+���Cr3+ interactions are very small. The magnetic susceptibility measurements recorded from the compounds of composition Fe1���xCrxSbO4, x<0.4, and Fe0.9Ga0.1SbO4 show them to behave as spin glasses at low temperatures. The inhibition of compounds of the type Fe1���xCrxSbO4, x>0.4, and Fe1���xGaxSbO4, x>0.1 to undergo a spin���glass transition above 4.2 K is associated with a dilution effect.